Gene Summary

Gene:PDPK1; 3-phosphoinositide dependent protein kinase 1
Aliases: PDK1, PDPK2, PDPK2P, PRO0461
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:3-phosphoinositide-dependent protein kinase 1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Cancer Gene Expression Regulation
  • Neoplastic Cell Transformation
  • Sirtuin 1
  • Phosphatidylinositol 3-Kinases
  • fms-Like Tyrosine Kinase 3
  • Pancreatic Cancer
  • Proto-Oncogene Proteins
  • Prostate Cancer
  • Protein Kinase Inhibitors
  • Signal Transduction
  • Class I Phosphatidylinositol 3-Kinases
  • ras Proteins
  • Non-Small Cell Lung Cancer
  • 3-Phosphoinositide-Dependent Protein Kinases
  • Messenger RNA
  • MAP Kinase Signaling System
  • AKT1
  • Down-Regulation
  • Stomach Cancer
  • RNA Interference
  • Immunohistochemistry
  • Breast Cancer
  • Tumor Burden
  • Apoptosis
  • TOR Serine-Threonine Kinases
  • Western Blotting
  • HEK293 Cells
  • Cell Proliferation
  • Protein-Serine-Threonine Kinases
  • Cell Survival
  • MicroRNAs
  • PTEN
  • Up-Regulation
  • Enzyme Activation
  • Lung Cancer
  • Neoplasm Invasiveness
  • Chromosome 16
  • Enzymologic Gene Expression Regulation
  • Mutation
  • Phosphorylation
  • Cell Movement
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: PDPK1 (cancer-related)

Coppé JP, Mori M, Pan B, et al.
Mapping phospho-catalytic dependencies of therapy-resistant tumours reveals actionable vulnerabilities.
Nat Cell Biol. 2019; 21(6):778-790 [PubMed] Related Publications
Phosphorylation networks intimately regulate mechanisms of response to therapies. Mapping the phospho-catalytic profile of kinases in cells or tissues remains a challenge. Here, we introduce a practical high-throughput system to measure the enzymatic activity of kinases using biological peptide targets as phospho-sensors to reveal kinase dependencies in tumour biopsies and cell lines. A 228-peptide screen was developed to detect the activity of >60 kinases, including ABLs, AKTs, CDKs and MAPKs. Focusing on BRAF

Chen HF, Wu LX, Li XF, et al.
Ginsenoside compound K inhibits growth of lung cancer cells via HIF-1α-mediated glucose metabolism.
Cell Mol Biol (Noisy-le-grand). 2019; 65(4):48-52 [PubMed] Related Publications
Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths. Compound K, an active metabolite of ginsenosides, is reported to exhibit anti-cancer property in various types of human malignancies. The present study investigated the role of compound K on glucose metabolism in NSCLC cells and its underlying mechanism. Our study found that compound K dose-dependently inhibited the cell viability of NSCLC cells. Moreover, administration with compound K decreased glucose uptake and lactate secretion under normoxic and hypoxic conditions. Consistently, the expression of key enzymes (HK II, PDK1 and LDHA) involved in glucose metabolism were inhibited in compound K-treated tumor cells. In addition, compound K inhibited the expression of HIF-1α and its downstream gene GLUT1. On the contrary, overexpression of HIF-1α elevated metabolic reactions and partly attenuated the inhibitory role of compound K on NSCLC cell growth. These results demonstrate that compound K suppresses NSCLC cell growth via HIF-1α mediated metabolic alteration, contributing to novel anticancer therapy by targeting glucose metabolism.

Katase N, Nishimatsu SI, Yamauchi A, et al.
DKK3 knockdown confers negative effects on the malignant potency of head and neck squamous cell carcinoma cells via the PI3K/Akt and MAPK signaling pathways.
Int J Oncol. 2019; 54(3):1021-1032 [PubMed] Related Publications
Dickkopf‑related protein 3 (DKK3), which is a member of the Dickkopf WNT signaling pathway inhibitor family, is considered to be a tumor suppressor, due to its reduced expression in cancer cells and its ability to induce apoptosis when overexpressed by adenovirus. However, our previous study demonstrated alternative functions for DKK3 in head and neck squamous cell carcinoma (HNSCC). Our study reported that DKK3 expression was predominantly upregulated in HNSCC cell lines and tissue samples, and its expression was significantly correlated with poor prognosis. Furthermore, DKK3 overexpression in HNSCC cells significantly increased cancer cell proliferation, migration, invasion and in vivo tumor growth. These data have led to the hypothesis that DKK3 may exert oncogenic functions and may increase the malignant properties of HNSCC. The present study established a stable DKK3 knockdown cell line (HSC‑3 shDKK3) using lentivirus‑mediated short hairpin RNA, and assessed its effects on cancer cell behavior using MTT, migration and invasion assays. In addition, its effects on in vivo tumor growth were assessed using a xenograft model. Furthermore, the molecular mechanisms underlying the effects of DKK3 knockdown were investigated by microarray analysis, pathway analysis and western blotting. Compared with control cells, HSC‑3 shDKK3 cells exhibited significantly reduced proliferation, migration and invasion, and formed significantly smaller tumor masses when subcutaneously transplanted into nude mice. In addition, in HSC‑3 shDKK3 cells, the expression levels of phosphorylated (p)‑protein kinase B (Akt) (Ser473), p‑phosphoinositide 3‑kinase (PI3K) p85 (Tyr467), p‑PI3K p55 (Try199), p‑3‑phosphoinositide‑dependent protein kinase‑1 (PDK1) (Ser241) and total p38 mitogen‑activated protein kinase (MAPK) were reduced. Furthermore, phosphorylation of mechanistic target of rapamycin (mTOR) (Ser2448) was slightly decreased in HSC‑3 shDKK3 cells, which may be due to the increased expression of DEP domain‑containing mTOR‑interacting protein. Conversely, DKK3 overexpression in HSC‑3 shDKK3 cells rescued cellular proliferation, migration and invasion. With regards to expression levels, p‑PI3K and p‑PDK1 expression was not altered, whereas mTOR and p‑p38 MAPK expression was elevated. These data supported the hypothesis and indicated that DKK3 may contribute to the malignant phenotype of HNSCC cells via the PI3K/Akt/mTOR and MAPK signaling pathways.

Zhou Y, Zheng X, Xu B, et al.
Circular RNA hsa_circ_0004015 regulates the proliferation, invasion, and TKI drug resistance of non-small cell lung cancer by miR-1183/PDPK1 signaling pathway.
Biochem Biophys Res Commun. 2019; 508(2):527-535 [PubMed] Related Publications
Circular RNAs (circRNAs) were recently reported to be involved in the pathogenesis of Non-small cell lung cancer (NSCLC), however, the molecular mechanisms of circRNAs in cell proliferation, invasion and TKI drug resistance remain largely undetermined. Here, we identified hsa_circ_0004015 was upregulated in NSCLC tissues, and was associated with the poor overall survival rate of NSCLC patients. Knockdown of hsa_circ_0004015 significantly decreased cell viability, proliferation, and invasion, whereas overexpression exhibited opposed effects in vivo and in vitro. Furthermore, hsa_circ_0004015 could enhance the resistance of HCC827 to gefitinib. In mechanism, hsa_circ_0004015 acted as a sponge for miR-1183, and PDPK1 was revealed to be target gene of miR-1183. Subsequently, functional assays illustrated that the oncogenic effects of hsa_circ_0004015 was attributed to the regulation of miR-1183/PDPK1 axis. In conclusion, circ_0016760/miR-1183/PDPK1 signaling pathway might play vital roles in the tumorigenesis of NSCLC.

Suber TL, Nikolli I, O'Brien ME, et al.
FBXO17 promotes cell proliferation through activation of Akt in lung adenocarcinoma cells.
Respir Res. 2018; 19(1):206 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The ubiquitin-proteasome pathway, mediated in part, by ubiquitin E3 ligases, is critical in regulating cellular processes such as cell proliferation, apoptosis, and migration. FBXO17 was recently identified as an F-box protein that targets glycogen synthase kinase-3β to the E3 ubiquitin ligase protein complex for polyubiquitination and proteasomal degradation. Here, we identified that in several lung adenocarcinoma cell lines, FBXO17 cellular protein was detected at relatively high levels, as was expression in a subset of lung cancers. Hence, we investigated the effects of FBXO17 on cell proliferation.
METHODS: Single cell RNA sequencing analysis was performed on a resection of a non-small cell lung carcinoma tumor to examine FBXO17 expression. Multiple lung cancer cell lines were immunoblotted, and The Cancer Genome Atlas was analyzed to determine if FBXO17 expression was amplified in a subset of lung cancers. A549 cells were transfected with empty vector or FBXO17-V5 plasmid and immunoblotted for Akt pathway mediators including PDK1, ERK1/2, ribosomal protein S6, and CREB. Cell proliferation and viability were analyzed by trypan blue exclusion, BrdU incorporation and an MTS-based fluorometric assay. Studies were also performed after transfecting with sifbxo17. Samples were used in an RNA microarray analysis to evaluate pathways affected by reduced FBXO17 gene expression.
RESULTS: We observed that overexpression of FBXO17 increased A549 cell proliferation coupled with Akt activation. Ectopically expressed FBXO17 also increased ERK1/2 kinase activation and increased phosphorylation of RPS6, a downstream target of mTOR. We also observed an increased number of cells in S-phase and increased metabolic activity of lung epithelial cells expressing FBXO17. FBXO17 knockdown reduced Akt Ser 473 phosphorylation approaching statistical significance with no effect on Thr 308. However, ERK1/2 phosphorylation, cellular metabolic activity, and overall cell numbers were reduced. When we analyzed RNA profiles of A549 cells with reduced FBXO17 expression, we observed downregulation of several genes associated with cell proliferation and metabolism.
CONCLUSIONS: These data support a role for FBXO17 abundance, when left unchecked, in regulating cell proliferation and survival through modulation of Akt and ERK kinase activation. The data raise a potential role for the F-box subunit in modulating tumorigenesis.

Xiao Q, Zheng F, Tang Q, et al.
Repression of PDK1- and LncRNA HOTAIR-Mediated EZH2 Gene Expression Contributes to the Enhancement of Atractylenolide 1 and Erlotinib in the Inhibition of Human Lung Cancer Cells.
Cell Physiol Biochem. 2018; 49(4):1615-1632 [PubMed] Related Publications
BACKGROUND/AIMS: We previously showed that the major bioactive compound of Atractylodes macrocephula Koidz atractylenolide 1 (ATL-1) inhibited human lung cancer cell growth by suppressing the gene expression of 3-Phosphoinositide dependent protein kinase-1 (PDK1 or PDPK1). However, the potentially associated molecules and downstream effectors of PDK1 underlying this inhibition, particularly the mechanism for enhancing the anti-tumor effects of epidermal growth factor receptor-tyrosine-kinase inhibitors (EGFR-TKIs), remain unknown.
METHODS: Cell viability and cell cycle distribution were measured using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. Western blot analyses were performed to examine the protein expressions of PDK1 and of zeste homolog 2 (EZH2). The levels of long non-coding RNA (lncRNA) and HOX transcript antisense RNA (HOTAIR) were examined via qRT-PCR. RNA-binding protein immunoprecipitation assays were used to analyze HOTAIR interaction with EZH2. The promoter activity of the EZH2 gene was determined using Secrete-Pair Dual Luminescence Assay Kit. Exogenous expressions of PDK1, HOTAIR, and EZH2 were conducted via transient transfection assays. A xenografted tumor model was used to further evaluate the effect of ATL-1 in the presence or absence of erlotinib in vivo.
RESULTS: We showed that the combination of ATL-1 and EGFR-TKI erlotinib further inhibited growth and induced cell arrest of the human lung cancer cells, determined by both MTT and flow cytometry assays. ATL-1 inhibited the protein expression and the promoter activity of EZH2, which was reversed in cells with PDK1 overexpression. Interestingly, ATL-1 inhibited the expression levels of HOTAIR. While silencing HOTAIR inhibited the expressions of PDK1 and EZH2, overexpression of HOTAIR reduced the ATL-1-reduced PDK1 and EZH2 protein expressions and EZH2 promoter activity. In addition, ATL-1 reduced the HOTAIR binding to the EZH2 protein. Moreover, we found that exogenously expressed EZH2 antagonized the effect of ATL-1 on cell growth inhibition. Consistent with the in vitro results, ATL-1 inhibited tumor growth and the expression levels of HOTAIR, protein expressions of EZH2 and PDK1 in vivo. Importantly, there was synergy of the combination of ATL-1 and erlotinib in this process.
CONCLUSION: Here, we provide the first evidence that ATL-1 inhibits lung cancer cell growth through inhibiting not only the PDK1 but also the lncRNA HOTAIR, which results in the reduction of one downstream effector EZH2 expression. The novel interplay between the HOTAIR and EZH2, as well as repressions of the PDK1 and HOTAIR coordinate the overall effects of ATL-1. Importantly, the combination of ATL-1 and EGFR-TKI erlotinib exhibits synergy. Thus, targeting the PDK1- and HOTAIR-mediated downstream molecule EZH2 by the combination of ATL-1 and erlotinib potentially facilitates the development of an additional novel strategy to combat lung cancer.

Wang X, Qi M
miR-718 is involved in malignancy of papillary thyroid cancer through repression of PDPK1.
Pathol Res Pract. 2018; 214(11):1787-1793 [PubMed] Related Publications
BACKGROUND: MicroRNAs bind the 3' untranslated regions (3'-UTRs) of mRNAs and thereby regulate gene expression post-transcriptionally and play an important role in cancer delvelopment. In the present study, we have explored the role of miR-718 in papillary thyroid cancer cell malignancy.
MATERIALS/METHODS: Here we examined the miRNA expression in human papillary thyroid cancer by RT-PCR. Luciferase activity, RT-PCR and western blot assays were used to confirmed the target of miRNA. MTT, colony formation, transwell, glucose consumption and lactate production assays were performed to analyze papillary thyroid cancer cell function. Western blot for signaling proteins was used to reveal the mechanism.
RESULTS: We first determined that miR-718 mRNA expression levels in PTC samples were reduced. The 3'-UTR of 3-Phosphoinositide Dependent Protein Kinase 1 (PDPK1) was then identified as a target of miR-718. Luciferase assays showed that miR-718 does in fact bind the wild-type PDPK1 3'-UTR. We assessed the effects of miR-718 on p-Akt, Akt, p-mTOR and mTOR expression. We determined that miR-718 negatively regulates their levels, respectively, of Akt-mTOR pathway components. We then assessed the effects of miR-718 on PTC cell behavior. The results revealed that miR-718 negatively regulates PTC cell proliferation, migration, and invasion. In addition, miR-718 was found to inhibit cell glucose metabolism, likely through the Akt-mTOR pathway. Finally, PDPK1 could rescue PTC cell inhibition induced by miR-718.
CONCLUSIONS: The present study strongly suggests that miR-718 inhibits PTC cell proliferation, metastasis, and glucose metabolism by negatively regulating the Akt-mTOR signaling pathway.

Manley PW, Caravatti G, Furet P, et al.
Comparison of the Kinase Profile of Midostaurin (Rydapt) with That of Its Predominant Metabolites and the Potential Relevance of Some Newly Identified Targets to Leukemia Therapy.
Biochemistry. 2018; 57(38):5576-5590 [PubMed] Related Publications
The multitargeted protein kinase inhibitor midostaurin is approved for the treatment of both newly diagnosed FLT3-mutated acute myeloid leukemia (AML) and KIT-driven advanced systemic mastocytosis. AML is a heterogeneous malignancy, and investigational drugs targeting FLT3 have shown disparate effects in patients with FLT3-mutated AML, probably as a result of their inhibiting different targets and pathways at the administered doses. However, the efficacy and side effects of drugs do not just reflect the biochemical and pharmacodynamic properties of the parent compound but are often comprised of complex cooperative effects between the properties of the parent and active metabolites. Following chronic dosing, two midostaurin metabolites attain steady-state plasma trough levels greater than that of the parent drug. In this study, we characterized these metabolites and determined their profiles as kinase inhibitors using radiometric transphosphorylation assays. Like midostaurin, the metabolites potently inhibit mutant forms of FLT3 and KIT and several additional kinases that either are directly involved in the deregulated signaling pathways or have been implicated as playing a role in AML via stromal support, such as IGF1R, LYN, PDPK1, RET, SYK, TRKA, and VEGFR2. Consequently, a complex interplay between the kinase activities of midostaurin and its metabolites is likely to contribute to the efficacy of midostaurin in AML and helps to engender the distinctive effects of the drug compared to those of other FLT3 inhibitors in this malignancy.

Nassan MA, Soliman MM, Ismail SA, El-Shazly S
Effect of
Biosci Rep. 2018; 38(6) [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Breast cancer is one of the most prevalent types of cancer and a leading cause of death in women.
MATERIALS AND METHODS: An experimental model of breast cancer was induced in female albino rats using single intragastric dose of 7, 12 dimethylbenz (α) anthracene (DMBA) in sesame oil (50 mg/kg b.wt). Four months after DMBA administration, incidence of breast cancer was confirmed by measuring cancer antigen 15-3 (CA15-3) serum levels.
RESULTS: Level of CA15-3 was normalized in DMBA group administered TOE for 4 weeks. Administration of DMBA increased expression of

Luo D, Xu X, Li J, et al.
The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma.
Int J Oncol. 2018; 53(5):2067-2080 [PubMed] Related Publications
Glioblastoma multiforme (GBM) is the most common primary malignant tumor affecting the human brain. Despite improvements in therapeutic technologies, patients with GBM have a poor clinical result and the molecular mechanisms responsible for the development of GBM have not yet been fully elucidated. 3-phosphoinositide dependent protein kinase 1 (PDK1) is upregulated in various tumors and promotes tumor invasion. In glioma, transforming growth factor-β (TGF‑β) promotes cell invasion; however, whether TGF‑β directly regulates PDK1 protein and promotes proliferation and invasion is not yet clear. In this study, PDK1 levels were measured in glioma tissues using tissue microarray (TMA) by immunohistochemistry (IHC) and RT‑qPCR. Kaplan-Meier analyses were used to calculate the survival rate of patients with glioma. In vitro, U251 and U87 glioma cell lines were used for functional analyses. Cell proliferation and invasion were analyzed using siRNA transfection, MTT assay, RT‑qPCR, western blot analysis, flow cytometry and invasion assay. In vivo, U251 glioma cell xenografts were established. The results revealed that PDK1 protein was significantly upregulated in glioma tissues compared with non-tumorous tissues. Furthermore, the higher PDK1 levels were associated with a large tumor size (>5.0 cm), a higher WHO grade and a shorter survival of patients with GBM. Univariate and multivariate analyses indicated that PDK1 was an independent prognostic factor. In vivo, PDK1 promoted glioma tumor xenograft growth. In vitro, functional analyses confirmed that TGF‑β upregulated PDK1 protein expression and PDK1 promoted cell migration and invasion, and functioned as an oncogene in GBM, by upregulating c‑Jun protein and inducing epithelial-mesenchymal transition (EMT). c‑Jun protein were overexpressed in glioma tissues and positively correlated with PDK1 levels. Moreover, our findings were further validated by the online Oncomine database. On the whole, the findings of this study indicate that in GBM, PDK1 functions as an oncogene, promoting proliferation and invasion.

Li D, Mullinax JE, Aiken T, et al.
Loss of PDPK1 abrogates resistance to gemcitabine in label-retaining pancreatic cancer cells.
BMC Cancer. 2018; 18(1):772 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Label-retaining cancer cells (LRCC) have been proposed as a model of slowly cycling cancer stem cells (CSC) which mediate resistance to chemotherapy, tumor recurrence, and metastasis. The molecular mechanisms of chemoresistance in LRCC remain to-date incompletely understood. This study aims to identify molecular targets in LRCC that can be exploited to overcome resistance to gemcitabine, a standard chemotherapy agent for the treatment of pancreas cancer.
METHODS: LRCC were isolated following Cy5-dUTP staining by flow cytometry from pancreatic cancer cell lines. Gene expression profiles obtained from LRCC, non-LRCC (NLRCC), and bulk tumor cells were used to generate differentially regulated pathway networks. Loss of upregulated targets in LRCC on gemcitabine sensitivity was assessed via RNAi experiments and pharmacological inhibition. Expression patterns of PDPK1, one of the upregulated targets in LRCC, was studied in patients' tumor samples and correlated with pathological variables and clinical outcome.
RESULTS: LRCC are significantly more resistant to gemcitabine than the bulk tumor cell population. Non-canonical EGF (epidermal growth factor)-mediated signal transduction emerged as the top upregulated network in LRCC compared to non-LRCC, and knock down of EGF signaling effectors PDPK1 (3-phosphoinositide dependent protein kinase-1), BMX (BMX non-receptor tyrosine kinase), and NTRK2 (neurotrophic receptor tyrosine kinase 2) or treatment with PDPK1 inhibitors increased growth inhibition and induction of apoptosis in response to gemcitabine. Knockdown of PDPK1 preferentially increased growth inhibition and reduced resistance to induction of apoptosis upon gemcitabine treatment in the LRCC vs non-LRCC population. These findings are accompanied by lower expression levels of PDPK1 in tumors compared to matched uninvolved pancreas in surgical resection specimens and a negative association of membranous localization on IHC with high nuclear grade (p < 0.01).
CONCLUSION: Pancreatic cancer cell-derived LRCC are relatively resistant to gemcitabine and harbor a unique transcriptomic profile compared to bulk tumor cells. PDPK1, one of the members of an upregulated EGF-signaling network in LRCC, mediates resistance to gemcitabine, is found to be dysregulated in pancreas cancer specimens, and might be an attractive molecular target for combination therapy studies.

Lu J, Liu QH, Wang F, et al.
Exosomal miR-9 inhibits angiogenesis by targeting MDK and regulating PDK/AKT pathway in nasopharyngeal carcinoma.
J Exp Clin Cancer Res. 2018; 37(1):147 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Exosomes are small vesicles containing a wide range of functional proteins, mRNA and miRNA. Exosomal miRNAs from cancer cells play crucial roles in mediating cell-cell communication and tumor-microenvironment cross talk, specifically in enabling metastasis and promoting angiogenesis. We focused on miR-9 that was identified as a tumor suppressor previously in nasopharyngeal carcinoma (NPC) tumorigenesis.
METHODS: Differential centrifugation, transmission electron microscopy and nanoparticle tracking analysis were used to isolate and identify exosomes. Quantitative PCR and western blotting analysis were used to detect miR-9, pri-miR-9, CD63, TSG101, MDK, P70S6K P-Ser424 and PDK1 P-Ser241 expression. Laser confocal microscopy was used to trace exosomal miR-9 secreted by NPC cells into HUVECs. The effect of exosomal miR-9 on cell migration and tube formation of HUVECs in vivo and vitro was assessed by using migration assay, tube formation assay and matrigel plug assay, respectively. Bioinformatics analysis and luciferase reporter assay were utilized to confirm the binding of exosomal miR-9 to the 3'untranslated region (3'-UTR) of MDK, while Phosphorylation Array was performed to identify AKT Pathway in HUVECs treated with exosomal miR-9. Furthermore, Immunohistochemistry (IHC) and in situ hybridization (ISH) was used to detected miR-9, CD31 and MDK expression in human NPC tumor samples.
RESULTS: NPC cells transfected with miR-9-overexpressing lentivirus, released miR-9 in exosomes. Exosomal miR-9 directly suppressed its target gene - MDK in endothelial cells. Mechanistic analyses revealed that exosomal miR-9 from NPC cells inhibited endothelial tube formation and migration by targeting MDK and regulating PDK/AKT signaling pathway. Additionally, the level of MDK was upregulated in NPC tumor samples and was positively correlated with microvessel density. Notably, the level of exosomal miR-9 was positively correlated with overall survival, and MDK overexpression was positively associated with poor prognosis in NPC patients, suggesting the clinical relevance and prognostic value of exosomal miR-9 and MDK.
CONCLUSIONS: Taken together, our data identify an extracellular anti-angiogenic role for tumor-derived, exosome-associated miR-9 in NPC tumorigenesis and prompt further investigation into exosome-based therapies for cancer treatment.

Chen J, Cao S, Situ B, et al.
Metabolic reprogramming-based characterization of circulating tumor cells in prostate cancer.
J Exp Clin Cancer Res. 2018; 37(1):127 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Circulating tumor cells (CTCs), an advantageous target of liquid biopsy, is an important biomarker for the prognosis and monitoring of cancer. Currently, detection techniques for CTCs are mainly based on the physical and/or epithelial characteristics of tumor cells. However, biofunctional activity markers that can indicate the high metastatic capacity of CTCs are lacking.
METHODS: Functional microarray, quantitative real-time polymerase chain reaction, and Western blot were used on five prostate cancer cell lines with different metastatic capacities to identify the metastasis-related metabolic genes. The identified genes were detected in the CTCs of 64 clinical samples using the RNA in situ hybridization. A multi-criteria weighted model was used to determine the optimal metabolic markers for the CTCs test. Based on five fluorescent signals targeting DAPI, CD45, metabolic, epithelial (EpCAM/CKs), and mesenchymal (Vimentin/Twist) markers, the filtration-enriched CTCs were classified as GM
RESULTS: Eight metastasis-related metabolic genes were identified, including HK2, PDP2, G6PD, PGK1, PHKA1, PYGL, PDK1, and PKM2. Among them, PGK1 and G6PD were determined as optimal glucose metabolic (GM) markers for CTCs. GM
CONCLUSIONS: The metabolic marker (PGK1/G6PD) is determined as the indicator for the biofunctional activity analysis of CTCs, compared with the existing morphological (EMT) classification on CTCs. The metabolic characterization of CTCs demonstrates that hypermetabolic GM

Davis M, Tripathi S, Hughley R, et al.
AR negative triple negative or "quadruple negative" breast cancers in African American women have an enriched basal and immune signature.
PLoS One. 2018; 13(6):e0196909 [PubMed] Free Access to Full Article Related Publications
There is increasing evidence that Androgen Receptor (AR) expression has prognostic usefulness in Triple negative breast cancer (TNBC), where tumors that lack AR expression are considered "Quadruple negative" Breast Cancers ("QNBC"). However, a comprehensive analysis of AR expression within all breast cancer subtypes or stratified by race has not been reported. We assessed AR mRNA expression in 925 tumors from The Cancer Genome Atlas (TCGA), and 136 tumors in 2 confirmation sets. AR protein expression was determined by immunohistochemistry in 197 tumors from a multi-institutional cohort, for a total of 1258 patients analyzed. Cox hazard ratios were used to determine correlations to PAM50 breast cancer subtypes, and TNBC subtypes. Overall, AR-negative patients are diagnosed at a younger age compared to AR-positive patients, with the average age of AA AR-negative patients being, 49. AA breast tumors express AR at lower rates compared to Whites, independent of ER and PR expression (p<0.0001). AR-negative patients have a (66.60; 95% CI, 32-146) odds ratio of being basal-like compared to other PAM50 subtypes, and this is associated with an increased time to progression and decreased overall survival. AA "QNBC" patients predominately demonstrated BL1, BL2 and IM subtypes, with differential expression of E2F1, NFKBIL2, CCL2, TGFB3, CEBPB, PDK1, IL12RB2, IL2RA, and SOS1 genes compared to white patients. Immune checkpoint inhibitors PD-1, PD-L1, and CTLA-4 were significantly upregulated in both overall "QNBC" and AA "QNBC" patients as well. Thus, AR could be used as a prognostic marker for breast cancer, particularly in AA "QNBC" patients.

Wang M, Wang W, Wang J, Zhang J
MiR-182 promotes glucose metabolism by upregulating hypoxia-inducible factor 1α in NSCLC cells.
Biochem Biophys Res Commun. 2018; 504(2):400-405 [PubMed] Related Publications
OBJECTIVE: This study aims to demonstrate the role of miR-182 in the glucose metabolism of NSCLC cells and the potential mechanism.
METHODS: MTT Cytotoxicity Assay was used to measure the function of differentially expressed miR-182 on two NSCLC cell lines proliferation. Metabolite analysis was introduced to monitor the glucose consumption, lactate release and glycolytic intermediate metabolites. The mRNA level of critical genes involved in glycolysis was detected by qRT-PCR. The 3'UTRs of predicted gene with a miR-182 binding site and their seed-sequence-mutated version were cloned downstream to the ORF of a Renilla luciferase reporter gene and the ability of miR-182 to downregulate luciferase expression was assessed.
RESULTS: MiR-182 had significantly improved proliferation of NSCLC cell lines. Metabolite analysis of the cells with strengthened miR-182 revealed significantly increased glucose consumption and lactate release, as well as glycolytic intermediate metabolites, or conversely. Among a panel of genes controlling glucose metabolism, miR-182 exhibited significantly influence on ENO1, GLUT1, HIF-1α, HK1, HK2, LDHA and PDK1, especially HIF-1α. For the predicted target gene HIF1AN, the wild-type but not mutated 3'UTR, responded to miR-182  b y directing ∼45% reduction of reporter gene expression.
CONCLUSION: MiR-182 promotes glucose metabolism by upregulating HIF-1α in NSCLC cells.

Cai CF, Ye GD, Shen DY, et al.
Chibby suppresses aerobic glycolysis and proliferation of nasopharyngeal carcinoma via the Wnt/β-catenin-Lin28/let7-PDK1 cascade.
J Exp Clin Cancer Res. 2018; 37(1):104 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Great progress has been achieved in the study of the aerobic glycolysis or the so-called Warburg effect in a variety of cancers; however, the regulation of the Warburg effect in Nasopharyngeal carcinoma (NPC) has not been completely defined.
METHODS: Gene expression pattern of NPC cells were used to test associations between Chibby and β-catenin expression. Chibby siRNAs and over-expression vector were transfected into NPC cells to down-regulate or up-regulate Chibby expression. Loss- and gain-of function assays were performed to investigate the role of Chibby in NPC cells. Western blot, cell proliferation, Glucose uptake, Lactate release, ATP level, and O2 consumption assays were used to determine the mechanism of Chibby regulation of underlying targets. Finally, immunohistochemistry assay of fresh NPC and nasopharyngeal normal tissue sample were used to detect the expression of Chibby, β-Catenin, and PDK1 by immunostaining.
RESULTS: We observed that Chibby, a β-catenin-associated antagonist, is down-regulated in nasopharyngeal carcinoma cell lines and inhibits Wnt/β-Catenin signaling induced Warburg effect. Mechanism study revealed that Chibby regulates aerobic glycolysis in NPC cells through pyruvate dehydrogenase kinase 1(PDK1), an important enzyme involved in glucose metabolism. Moreover, Chibby suppresses aerobic glycolysis of NPC via Wnt/β-Catenin-Lin28/let7-PDK1 cascade. Chibby and PDK1 are critical for Wnt/β-Catenin signaling induced NPC cell proliferation both in vitro and in vivo. Finally, immunostaining assay of tissue samples provides an important clinical relevance among Chibby, Wnt/β-Catenin signaling and PDK1.
CONCLUSIONS: Our study reveals an association between Chibby expression and cancer aerobic glycolysis, which highlights the importance of Wnt/β-catenin pathway in regulation of energy metabolism of NPC. These results indicate that Chibby and PDK1 are the potential target for NPC treatment.

Zhou L, Wang Y, Zhou M, et al.
HOXA9 inhibits HIF-1α-mediated glycolysis through interacting with CRIP2 to repress cutaneous squamous cell carcinoma development.
Nat Commun. 2018; 9(1):1480 [PubMed] Free Access to Full Article Related Publications
Glycolytic reprogramming is a typical feature of many cancers; however, key regulators of glucose metabolism reengineering are poorly understood, especially in cutaneous squamous cell carcinoma (cSCC). Here, Homeobox A9 (HOXA9), a direct target of onco-miR-365, is identified to be significantly downregulated in cSCC tumors and cell lines. HOXA9 acts as a tumor suppressor and inhibits glycolysis in cSCC in vitro and in vivo by negatively regulating HIF-1α and its downstream glycolytic regulators, HK2, GLUT1 and PDK1. Mechanistic studies show that HOXA9-CRIP2 interaction at glycolytic gene promoters impeds HIF-1α binding, repressing gene expression in trans. Our results reveal a miR-365-HOXA9-HIF-1α regulatory axis that contributes to the enhanced glycolysis in cSCC development and may represent an intervention target for cSCC therapy.

Zhang J, Yang C, Zhou F, Chen X
PDK1 inhibitor GSK2334470 synergizes with proteasome inhibitor MG‑132 in multiple myeloma cells by inhibiting full AKT activity and increasing nuclear accumulation of the PTEN protein.
Oncol Rep. 2018; 39(6):2951-2959 [PubMed] Related Publications
Phosphoinositide‑dependent kinase 1 (PDK1) is generally active in multiple myeloma (MM) and higher expression than other hematopoietic cells, which is associated with the drug resistance and the disease progression. Previous studies have demonstrated that PDK1 can be targeted therapeutically in MM. In the present study, we examined the combination effect of GSK2334470 (GSK‑470), a novel and highly specific inhibitor of PDK1, with proteasome inhibitor MG‑132 in MM cell lines. GSK‑470 monotherapy significantly inhibited growth of MM cell lines and induced apoptosis that was associated with the activation of both the intrinsic mitochondrial pathway and the extrinsic death receptor pathway. Moreover, GSK‑470 demonstrated synergistic growth inhibitory effects with MG‑132. Notably, treatment with these inhibitors resulted in an almost complete inhibition of phosphorylation of mammalian target of rapamycin on Ser2448 and Ser2481 and full activation of AKT. The combination therapy also caused an upregulation of PTEN and an increased nuclear accumulation of PTEN protein. Collectively, our results provide the rationale for novel combination treatment with PDK1 inhibitor and proteasome inhibitors to improve outcomes in patients with MM.

Wang F, Shan S, Huo Y, et al.
MiR-155-5p inhibits PDK1 and promotes autophagy via the mTOR pathway in cervical cancer.
Int J Biochem Cell Biol. 2018; 99:91-99 [PubMed] Related Publications
Cervical cancer is one of the most common malignant tumors and the leading cause of cancer-related mortality in women. Persistent cervical infection by high-risk human papillomavirus (hrHPV) is related to cervical cancer. MicroRNAs could regulate autophagy caused by viral infection. The aim of the present study was to investigate the regulation of autophagy by miR-155-5p in cervical cancer. In HPV+ human cervical lesion tissues, miR-155-5p expression was found to be markedly decreased. Compared to C33A cancer cells (HPV-), the miR-155-5p expression was significantly lower in Siha and HeLa cells (HPV+), which are both hrHPV positive. The level of autophagy was higher in C33A cells than in Siha and HeLa cells. In addition, in C33A, Siha and HeLa cervical cancer cells, miR-155-5p overexpression promoted autophagy, whereas miR-155-5p downregulation had the opposite effects. Furthermore, miR-155-5p downregulation suppressed LC3 and promoted P62 protein expression in C33A cells through promoting the PDK1/mTOR pathway, whereas miR-155-5p overexpression recovered LC3 and suppressed P62 protein expression by suppressing PDK1/mTOR signaling. Taken together, our results indicate the importance of miR-155-5p in cervical cancer cells and suggest a novel mechanism of hrHPV in promoting cervical lesions.

Kim S, Lee E, Jung J, et al.
microRNA-155 positively regulates glucose metabolism via PIK3R1-FOXO3a-cMYC axis in breast cancer.
Oncogene. 2018; 37(22):2982-2991 [PubMed] Free Access to Full Article Related Publications
MicroRNA is an endogenous, small RNA controlling multiple target genes and playing roles in various biological processes including tumorigenesis. Here, we addressed the function of miR-155 using LC-MS/MS-based metabolic profiling of miR-155 deficient breast cancer cells. Our results revealed the loss of miR-155 hampers glucose uptake and glycolysis, via the down-regulation of glucose transporters and metabolic enzymes including HK2, PKM2, and LDHA. We showed this is due to the down-regulation of cMYC, controlled through phosphoinositide-3-kinase regulatory subunit alpha (PIK3R1)-PDK1/AKT-FOXO3a pathway. UTR analysis of the PIK3R1 and FOXO3a indicated miR-155 directly represses these genes. A stable expression of miR-155 in patient-derived cells (PDCs) showed activated glucose metabolism whereas a stable inhibition of miR-155 reduced in vivo tumor growth with retarded glucose metabolism. Furthermore, analysis of 50 triple-negative breast cancer (TNBC) specimens and specific uptake value (SUV) of PET images revealed a positive correlation between miR-155 level and glucose usage in human breast tumors via PIK3R1-PDK/AKT-FOXO3a-cMYC axis. Collectively, these data demonstrate the miR-155 is a key regulator of glucose metabolism in breast cancer.

Yu T, Li L, Liu W, et al.
Silencing of NADPH Oxidase 4 Attenuates Hypoxia Resistance in Neuroblastoma Cells SH-SY5Y by Inhibiting PI3K/Akt-Dependent Glycolysis.
Oncol Res. 2019; 27(5):525-532 [PubMed] Related Publications
Hypoxia-induced chemoresistance is a major obstacle in the development of effective cancer therapy. In our study, the reversal abilities of NADPH oxidase 4 (NOX4) silence on hypoxia resistance and the potential mechanism were investigated. Our data showed that the expression of NOX4 was upregulated in human neuroblastoma cells SH-SY5Y under hypoxia condition time dependently. Knockdown of NOX4 expression by siRNA inhibited glycolysis induced by hypoxia through decreasing the expression of glycolysis-related proteins (HIF-1α, LDHA, and PDK1), decreasing glucose uptake, lactate production, and ROS production, while increasing mitochondria membrane potential. Moreover, NOX4 silence inhibited cell growth under hypoxia condition through suppressing cell proliferation and proliferation-related proteins (Ki-67 and PCNA) compared with the hypoxia 24 h + siRNA NC group. Further, Western blot experiments exhibited that NOX4 siRNA could downregulate the rate of p-Akt/Akt. Treatment with PI3K/Akt signaling activator IGF-1 blocked, while treatment with Akt inhibitor perifosine enhanced the inhibitory effect of si-NOX4 on glycolysis and cell growth. In summary, knockdown of NOX4 had the ability of reversing hypoxia resistance, and the major mechanism is considered to be the inhibition of glycolysis and cell growth via the PI3K/Akt signaling pathway. Therefore, NOX4 could be a novel target against hypoxia resistance in neuroblastoma.

Wang Z, Yao YJ, Zheng F, et al.
Mir-138-5p acts as a tumor suppressor by targeting pyruvate dehydrogenase kinase 1 in human retinoblastoma.
Eur Rev Med Pharmacol Sci. 2017; 21(24):5624-5629 [PubMed] Related Publications
OBJECTIVE: MicroRNAs have caught more attention for their role in tumor progression. Retinoblastoma (RB) is one of these ordinary malignant tumors. This study aims to identify whether mir-138-5p can regulate the development of RB, and find out its potential mechanism.
MATERIALS AND METHODS: Mir-138-5p expression in RB cells was monitored by RT-qPCR. Besides, the role of mir-138-5p in RB development was explored through function experiments in vitro. The potential mechanism was further explored by RT-qPCR, luciferase assay, and Western blot assay.
RESULTS: In our investigation, mir-138-5p was lower-expressed in RB cells than that in retinal pigment epithelial cells. Moreover, overexpression of mir-138-5p repressed cell viability, migration and invasion, and induced apoptosis of RB cells, while downregulated mir-138-5p increased cell viability, migration and invasion, and reduced apoptosis of RB cells. Furthermore, pyruvate dehydrogenase kinase 1 (PDK1) could be downregulated via overexpression of mir-138-5p, while PDK1 was upregulated via knockdown of mir-138-5p.
CONCLUSIONS: Our results suggested that mir-138-5p could repress the development of RB via suppressing PDK1, which may offer a new vision for interpreting the mechanism of RB tumorigenesis.

Lu M, Fei Z, Zhang G
Synergistic anticancer activity of 20(S)-Ginsenoside Rg3 and Sorafenib in hepatocellular carcinoma by modulating PTEN/Akt signaling pathway.
Biomed Pharmacother. 2018; 97:1282-1288 [PubMed] Related Publications
Sorafenib, a multikinase inhibitor for hepatocellular carcinoma treatment, inhibits the Raf/MAPK/ERK signaling pathway. However, PI3K/Akt signaling pathway is activated by Sorafenib and cross-talks with the Raf/MAPK/ERK signaling pathway, leading to drug resistance. 20(S)-Ginsenoside Rg3 has been reported with significant anticancer effect to numerous carcinomas by inhibition of PI3K-Akt signaling pathway. Hence, we aim to examine the synergistic anticancer activity of 20(S)-Ginsenoside Rg3 and Sorafenib via modulation of PTEN/Akt signaling pathway. Human hepatocellular carcinoma cell lines HepG2 and Huh7 were used. Cell viability, clonogenic assay, apoptosis assay, western blot analysis, xenograft treatment and immunohistochemistry were carried out. The viability of hepatocellular carcinoma cells significantly decreased by the treatment of Sorafenib combined with 20(S)-Ginsenoside Rg3, as well as the enhanced apoptotic rates. The levels of PTEN, Bax and cleaved caspase-3 expression increased, while the levels of phospho-PDK1 and phospho-Akt expression decreased by the treatment of Sorafenib combined with 20(S)-Ginsenoside Rg3. In vivo, the tumor volumes and weight decreased in the Sorafenib combined with 20(S)-Ginsenoside Rg3 group. The results demonstrated the synergistic anticancer activity of 20(S)-Ginsenoside Rg3 and Sorafenib in HCC by modulating PTEN/Akt signaling pathway. These findings suggest a promising strategy for HCC treatment, which could be performed in a sufficiently frequent manner.

Fischer-Huchzermeyer S, Dombrowski A, Wilke G, et al.
MEK inhibitors enhance therapeutic response towards ATRA in NF1 associated malignant peripheral nerve sheath tumors (MPNST) in-vitro.
PLoS One. 2017; 12(11):e0187700 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: Neurofibromatosis type 1 (NF1) is a hereditary tumor syndrome characterized by an increased risk of malignant peripheral nerve sheath tumors (MPNST). Chemotherapy of MPNST is still insufficient. In this study, we investigated whether human tumor Schwann cells derived from NF1 associated MPNST respond to all-trans retinoic acid (ATRA). We analyzed effects of ATRA and MEK inhibitor (MEKi) combination therapy.
METHODS: MPNST cell lines S462, T265, NSF1 were treated with ATRA and MEKi U0126 and PD0325901. We assessed cell viability, proliferation, migration, apoptosis and differentiation as well as mRNA expression of RAR and RXR subtypes and ATRA target genes such as CRABP2, CYP26A1, RARB and PDK1. We also analyzed CRABP2 methylation in cell lines and performed immunohistochemistry of human MPNST specimens.
RESULTS: ATRA therapy reduced viability and proliferation in S462 and T265 cells, accompanied by differentiation, apoptosis and reduced migration. NSF1 cells which lacked RXRG expression did not respond to ATRA. We furthermore demonstrated that ATRA signaling was functional for common targets, and that mRNA expression of CRABP2 and its targets was raised by ATRA therapy, whereas alternative pathways via FABP5 were not induced. Finally, combination of ATRA and MEKi demonstrated additively reduced viability of T265 and S462 cells.
CONCLUSIONS: We observed therapeutic effects in two of three MPNST cell lines pronounced by combination therapy. These data point to a potentially successful treatment of MPNST by combined application of ATRA and MEK inhibitors such as U0126 or PD0325901.

Ognibene M, Cangelosi D, Morini M, et al.
Immunohistochemical analysis of PDK1, PHD3 and HIF-1α expression defines the hypoxic status of neuroblastoma tumors.
PLoS One. 2017; 12(11):e0187206 [PubMed] Free Access to Full Article Related Publications
Neuroblastoma (NB) is the most common solid tumor during infancy and the first cause of death among the preschool age diseases. The availability of several NB genomic profiles improves the prognostic ability, but the outcome prediction for this pathology remains imperfect. We previously produced a novel prognostic gene signature based on the response of NB cells to hypoxia, a condition of tumor microenvironment strictly connected with cancer aggressiveness. Here we attempted to further define the expression of hypoxia-modulated specific genes, looking at their protein level in NB specimens, considering in particular the hypoxia inducible factor-1α (HIF-1α), the mitochondrial pyruvate dehydrogenase kinase 1 (PDK1), and the HIF-prolyl hydroxylase domain 3 (PHD3). The evaluation of expression was performed by Western blot and immunocytochemistry on NB cell lines and by immunohistochemistry on tumor specimens. Stimulation of both HIF-1α and PDK1 and inhibition of PHD3 expression were observed in NB cell lines cultured under prolonged hypoxic conditions as well as in most of the tumors with poor outcome. Our results indicate that the immunohistochemistry analysis of the protein expression of PDK1, PHD3, and HIF-1α defines the hypoxic status of NB tumors and can be used as a simple and relevant tool to stratify high-risk patients.

Zhang T, Ma Y, Fang J, et al.
A Deregulated PI3K-AKT Signaling Pathway in Patients with Colorectal Cancer.
J Gastrointest Cancer. 2019; 50(1):35-41 [PubMed] Related Publications
BACKGROUND: Molecular switches in phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway may serve as potential targets for the treatment of colorectal cancer (CRC). This study aims to profile the gene alterations involved in PI3K-AKT signaling pathway in patients with CRC.
METHODS: Tumoral and matched peritumoral tissues were collected from 15 CRC patients who went routine surgery. A human PI3K-AKT signaling pathway polymerase chain reaction (PCR) array, which profiled the transcriptional changes of a total number of 84 genes involved in the PI3K-AKT pathway, was then applied to determine the gene alterations in CRC tumoral tissue with matched peritumoral tissue as a healthy control. Subsequent real-time reverse transcription PCR and western blot (WB) with different subgroups of CRC patients were then performed to further validate the array findings.
RESULTS: The PCR array identified 14 aberrantly expressed genes involved in the PI3K-AKT signaling pathway in CRC tumoral tissue, among which 12 genes, CCND1, CSNK2A1, EIF4E, EIF4EBP1, EIF4G1, FOS, GRB10, GSK3B, ILK, PTK2, PTPN11, and PHEB were significantly up-modulated (> two fold) while the remaining two, PDK1 and PIK3CG, were down-regulated (> two fold). These genes involve in the regulation of gene transcription and translation, cell cycle, and cell growth, proliferation, and differentiation. The real-time reverse transcription PCR validation agreed with the array data towards the tested genes, CCND1, EIF4E, FOS, and PIK3CG, while it failed to obtain similar result for PDK1. Interestingly, the WB analyses were further consistent with the PCR results that the protein levels of CCND1, EIF4E, and FOS were apparently up-regulated and that protein PIK3CG was down-modulated.
CONCLUSION: Taken together, the present study identified a deregulated PI3K-AKT signaling pathway in CRC patients, which might serve as therapeutic target(s).

Peng F, Wang JH, Fan WJ, et al.
Glycolysis gatekeeper PDK1 reprograms breast cancer stem cells under hypoxia.
Oncogene. 2018; 37(8):1062-1074 [PubMed] Free Access to Full Article Related Publications
Glycolysis is critical for cancer stem cell reprogramming; however, the underlying regulatory mechanisms remain elusive. Here, we show that pyruvate dehydrogenase kinase 1 (PDK1) is enriched in breast cancer stem cells (BCSCs), whereas depletion of PDK1 remarkably diminishes ALDH

Le Rhun E, Bertrand N, Dumont A, et al.
Identification of single nucleotide polymorphisms of the PI3K-AKT-mTOR pathway as a risk factor of central nervous system metastasis in metastatic breast cancer.
Eur J Cancer. 2017; 87:189-198 [PubMed] Related Publications
INTRODUCTION: The PI3K-AKT-mTOR pathway may be involved in the development of central nervous system (CNS) metastasis from breast cancer. Accordingly, herein we explored whether single nucleotide polymorphisms (SNPs) of this pathway are associated with altered risk of CNS metastasis formation in metastatic breast cancer patients.
METHODS: The GENEOM study (NCT00959556) included blood sample collection from breast cancer patients treated in the neoadjuvant, adjuvant or metastatic setting. We identified patients with CNS metastases for comparison with patients without CNS metastasis, defined as either absence of neurological symptoms or normal brain magnetic resonance imaging (MRI) before death or during 5-year follow-up. Eighty-eight SNPs of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian (or mechanistic) target of rapamycin (mTOR) pathway genes were selected for analysis: AKT1 (17 SNPs), AKT2 (4), FGFR1 (2), mTOR (7), PDK1 (4), PI3KR1 (11), PI3KCA (20), PTEN (17), RPS6KB1 (6).
RESULTS: Of 342 patients with metastases, 207 fulfilled the inclusion criteria: One-hundred-and-seven patients remained free of CNS metastases at last follow-up or date of death whereas 100 patients developed CNS metastases. Among clinical parameters, hormonal and human epidermal growth factor receptor-2 (HER2) status as well as vascular tumour emboli was associated with risk of CNS metastasis. Only PI3KR1-rs706716 was associated with CNS metastasis in univariate analysis after Bonferroni correction (p < 0.00085). Multivariate analysis showed associations between AKT1-rs3803304, AKT2-rs3730050, PDK1-rs11686903 and PI3KR1-rs706716 and CNS metastasis .
CONCLUSION: PI3KR1-rs706716 may be associated with CNS metastasis in metastatic breast cancer patients and could be included in a predictive composite score to detect early CNS metastasis irrespective of breast cancer subtype.

Wang J, Yang S, Ge W, et al.
MiR-613 suppressed the laryngeal squamous cell carcinoma progression through regulating PDK1.
J Cell Biochem. 2018; 119(7):5118-5125 [PubMed] Related Publications
MicroRNAs (miRNAs) are aberrantly expressed in several tumors and play important role in tumorigenesis. However, little is known about the role of miR-613 in laryngeal squamous cell carcinoma (LSCC). We determined the expression of miR-613 in a panel of 30 LSCC specimens. Compared with the adjacent normal samples, 20 cases of LSCC tissues exhibited decreased expression of miR-613. The average expression of miR-613 in LSCC tissues was lower than in normal samples. Moreover, we demonstrated that exogenous expression of miR-613 suppressed LSCC cell proliferation, invasion, and blocked G1/S phase transition. We identified that 3-phosphoinositide-dependent protein kinase-1 (PDK1) was a direct target gene of miR-613 in LSCC cell. Overexpression of miR-613 suppressed PDK1 expression in LSCC cell. Furthermore, we demonstrated that PDK1 was upregulated in LSCC tissues. MiR-613 expression was inversely correlated with the expression of PDK1 in LSCC tissues. Moreover, we showed that PDK1 was involved in the miR-613-mediated cancer suppression of LSCC cell. These results suggested that miR-613 played as a tumor suppressor gene in LSCC partly by inhibiting PDK1 expression.

Xiao Q, Zheng F, Wu J, et al.
Activation of ERK and Mutual Regulation of Stat3 and SP1 Contribute to Inhibition of PDK1 Expression by Atractylenolide-1 in Human Lung Cancer Cells.
Cell Physiol Biochem. 2017; 43(6):2353-2366 [PubMed] Related Publications
BACKGROUND/AIMS: Atractylodes macrocephula Koidz is an important ingredient in traditional Chinese herbs. One major bioactive compound, atractylenolide-1 (ATL-1), was reported to have anti-inflammatory and anti-tumor activities. However, the underlying molecular mechanism associated to this has not been well elucidated.
METHODS: Cell viability and cell cycle distribution were measured using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. Western blot analysis was performed to examine the phosphorylation and protein expression of extracellular signaling-regulated kinase 1/2 (ERK1/2), signal transducer and activator of transcription 3 (Stat3), 3-phosphoinositide dependent protein kinase-1 (PDK1) and transcription factor SP1. QRT-PCR was used to examine the mRNA levels of PDK1 gene. Exogenously expressions of Stat3, PDK1 and SP1 were carried out by transient transfection assays. PDK1 promoter activity was measured by Secrete-Pair Dual Luminescence Assay Kit. A nude mice xenograft model was used to confirm the findings in vitro.
RESULTS: We showed that ATL-1 inhibited human lung cancer cell growth and induced cell cycle arrest. Furthermore, we found that ATL-1 stimulated phosphorylation of ERK1/2, inhibited phosphorylation and protein expressions of Stat3 and SP1; the latter were abrogated in the presence of MEK/ERK inhibitor PD98059. Moreover, ATL-1 reduced the protein, mRNA expression and promoter activity of PDK1. Intriguingly, exogenously expressed Stat3 and SP1 overcame ATL-1-inhibited SP1 and Stat3, and PDK1 protein expressions, respectively. Moreover, overexpression of PDK1 resisted the ATL-1-inhibited lung cancer cell growth. In consistent with the results in vitro, ATL-1 inhibited tumor growth, protein expressions of Stat3, SP1 and PDK1, and induced phosphorylation of ERK1/2 in vivo.
CONCLUSION: In summary, our results show that ATL-1 inhibits lung cancer cell growth through activation of ERK1/2, followed by suppressing SP1 protein expression. ATL-1 also reduces phosphorylation and protein levels of Stat3. These are mutual regulation between Stat3 and SP1 proteins affected by ATL-1. This ultimately suppresses PDK1 gene expression. This study reveals a novel mechanism by which ATL-1 inhibits growth of lung cancer cells. Thus, targeting PDK1 pinpoints a potential in the lung cancer treatment.

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