Long noncoding RNAs (lncRNAs) have emerged as new regulatory molecules implicated in diverse biological processes, including therapeutic resistance. However, the mechanisms underlying lncRNA-mediated temozolomide (TMZ) resistance in glioblastoma (GBM) remain largely unknown. To illustrate the role of lncRNA in TMZ resistance, we induce TMZ-resistant GBM cells, perform a lncRNA microarray of the parental and TMZ-resistant cells, and find an unreported lncRNA in GBM, lnc-TALC (temozolomide-associated lncRNA in glioblastoma recurrence), correlated with TMZ resistance via competitively binding miR-20b-3p to facilitate c-Met expression. A phosphorylated AKT/FOXO3 axis regulated lnc-TALC expression in TMZ-resistant GBM cells. Furthermore, lnc-TALC increased MGMT expression by mediating the acetylation of H3K9, H3K27 and H3K36 in MGMT promoter regions through the c-Met/Stat3/p300 axis. In clinical patients, lnc-TALC is required for TMZ resistance and GBM recurrence. Our results reveal that lnc-TALC in GBM could serve as a therapeutic target to overcome TMZ resistance, enhancing the clinical benefits of TMZ chemotherapy.

Ovarian cancer is the leading cause of death from gynecological cancers. MicroRNAs (miRNAs) are small, non-coding RNAs that interact with the 3' untranslated region (3' UTR) of target genes to repress their expression. We have previously reported that miR-590-3p promoted ovarian cancer growth and metastasis, in part by targeting Forkhead box A (FOXA2). In this study, we further investigated the mechanisms by which miR-590-3p promotes ovarian cancer development. Using luciferase reporter assays, real-time PCR, and Western blot analyses, we demonstrated that miR-590-3p targets cyclin G2 (CCNG2) and Forkhead box class O3 (FOXO3) at their 3' UTRs. Silencing of CCNG2 or FOXO3 mimicked, while the overexpression of CCNG2 or FOXO3 reversed, the stimulatory effect of miR-590-3p on cell proliferation and invasion. In hanging drop cultures, the overexpression of mir-590 or the transient transfection of miR-590-3p mimics induced the formation of compact spheroids. Transfection of the CCNG2 or FOXO3 plasmid into the mir-590 cells resulted in the partial disruption of the compact spheroid formation. Since we have shown that CCNG2 suppressed β-catenin signaling, we investigated if miR-590-3p regulated β-catenin activity. In the TOPFlash luciferase reporter assays, mir-590 increased β-catenin/TCF transcriptional activity and the nuclear accumulation of β-catenin. Silencing of β-catenin attenuated the effect of mir-590 on the compact spheroid formation. Taken together, these results suggest that miR-590-3p promotes ovarian cancer development, in part by directly targeting CCNG2 and FOXO3.

BACKGROUND: The aberrant expression of long noncoding RNAs (lncRNAs) has recently emerged as key molecules in human cancers; however, whether lncRNAs are implicated in the progression of clear cell renal cell carcinoma (ccRCC) remains unclear.
METHODS: Candidate lncRNAs were selected using microarray analysis and quantitative real-time PCR (qRT-PCR) was performed to detect lncRNAs expression in human ccRCC tissues. Overexpression and knocking down experiments in vivo and in vitro were performed to uncover the biological roles of lncRNA-URRCC on ccRCC cell proliferation and invasion. Microarray, chromatin immunoprecipitation, Luciferase reporter assay and western blot were constructed to investigate the molecular mechanisms underlying the functions of lncRNA-URRCC.
RESULTS: The microarray analysis and qRT-PCR identified a new lncRNA, URRCC, whose expression is upregulated in RCC samples and associated with poor prognosis, leading to promote ccRCC cell proliferation and invasion. Mechanistically, URRCC enhances the expression of EGFL7 via mediating histone H3 acetylation of EGFL7 promoter, activation of P-AKT signaling, and suppressing P-AKT downstream gene, FOXO3. In return, FOXO3 could inhibit the transcription of URRCC via binding to the special region on the promoter of URRCC.
CONCLUSIONS: Our data suggests that targeting this newly identified feed-back loop between LncRNA-URRCC and EGFL7/P-AKT/FOXO3 signaling may enhance the efficacy of existing therapy and potentially imparts a new avenue to develop more potent therapeutic approaches to suppress RCC progression.

α‑Fetoprotein (AFP)‑producing gastric cancer (AFPGC) is recognized as one of the most aggressive tumors with subsequent poor prognosis compared with common gastric cancer (GC) subtypes. However, the molecular mechanism remains to be elucidated. We previously identified that miR‑122‑5p could be a useful biomarker in AFPGC patients. We examined herein the biological function of miR‑122‑5p and the molecular mechanism underlying tumor progression in AFPGC. We used the AFPGC cell line (FU97) and miR‑122‑5p inhibitor to examine the function of miR‑122‑5p. Moreover, we investigated the possible targets of miR‑122‑5p. The expression level of miR‑122‑5p was significantly increased in the FU97 cell line than in common GC cell lines. Also, suppression of miR‑122‑5p significantly reduced AFP levels and proliferation in AFPGC through an induction of apoptosis. Western blotting revealed that the expression of anti‑apoptotic protein (Bcl‑2) was decreased and that of pro‑apoptotic protein (caspase‑3) was increased in miR‑122‑5p suppression of FU97. Moreover, we revealed that FOXO3 was an important target of miR‑122‑5p in AFPGC, which inhibited apoptosis and subsequently manifested aggressiveness. In conclusion, miR‑122‑5p inhibited apoptosis and facilitated tumor progression by targeting FOXO3 in AFPGC, which indicates the possibility of miR‑122‑5p as a potential therapeutic target in AFPGC.

BACKGROUND: The resistance to EGF receptor (EGFR) tyrosine kinase inhibitors (TKI) is a major challenge in the treatment of non-small cell lung cancer (NSCLC). Understanding the molecular mechanisms behind resistance is therefore an important issue. Here we assessed the role of EGFR pathway substrate 8 (EPS8) and Forkhead box O 3a (FoxO3a) as potentially valuable targets in the resistance of NSCLC .
METHODS: The expression levels of EPS8 and FoxO3a in patients with NSCLC (n = 75) were examined by immunohistochemistry staining, while in cells were detected by qPCR and western blot. The effects of EPS8 and FoxO3a on resistance, migration and invasion, cell cycle arrest were detected by MTT, transwell and flow cytometry, respectively. Chromatin immunoprecipitation and luciferase reporter assays were performed to determine the mechanisms of EPS8 expression and FoxO3a regulation.
FINDINGS: We observed that the expression of EPS8 inversely correlated with FoxO3a in NSCLC cell lines and NSCLC patients. FoxO3a levels were significantly decreased in tumor tissues compared with para-carcinoma tissues, while EPS8 is opposite. Besides, they play reverse roles in the resistance to gefitinib, the migration and invasion abilities, the cell cycle arrest in vitro and the tumor growth in vivo. Mechanistically, FoxO3a inhibits EPS8 levels by directly binding its gene promoter and they form a negative loop in EGFR pathway.
INTERPRETATION: Targeting FoxO3a and EPS8 in EGFR signaling pathway prevents the progression of NSCLC, which implied that the negative loop they formed could served as a therapeutic target for overcoming resistance in NSCLC.
FUNDS: National Natural Science Foundation of China, Science and Technology Project of Henan, Outstanding Young Talent Research Fund of Zhengzhou University and the National Scholarship Fund.

BACKGROUND & AIMS: Diminished forkhead box O3 (FOXO3) function drives inflammation and cancer growth; however, mechanisms fostering these pathobiologies are unclear. Here, we aimed to identify in colon loss of FOXO3-dependent cellular and molecular changes that facilitate inflammation-mediated tumor growth.
METHODS: FOXO3 knockout (KO) and wild-type (WT) mice were used in the AOM/DSS model of inflammation-mediated colon cancer. Bioinformatics were used for profiling of mRNA sequencing data from human and mouse colon and tumors; specific targets were validated in human colon cancer cells (shFOXO3).
RESULTS: In mice, FOXO3 deficiency led to significantly elevated colonic tumor burden (incidence and size) compared with WT (P < .05). In FOXO3 KO colon, activated molecular pathways overlapped with those associated with mouse and human colonic inflammation and cancer, especially human colonic tumors with inflammatory microsatellite instability (false discovery rate < 0.05). FOXO3 KO colon, similar to tumors, had increased neutrophils, macrophages, B cells, T cells, and decreased natural killer cells (false discovery rate < 0.05). Moreover, in KO colon differentially expressed transcripts were linked to activation of inflammatory nuclear factor kappa B, tumorigenic cMyc, and bacterial Toll-like receptor signaling. Among differentially expressed transcripts, we validated altered expression of integrin subunit alpha 2 (ITGA2), ADAM metallopeptidase with thrombospondin type 1 motif 12, and ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 5 in mouse WT and FOXO3 KO colon and tumors (P < .05). Similarly, their altered expression was found in human inflammatory bowel disease and colon cancer tissues and linked to poor patient survival. Ultimately, in human colon cancer cells, FOXO3 knockdown (shFOXO3) led to significantly increased ITGA2, and silencing ITGA2 (siRNA) alone diminished cell growth.
CONCLUSIONS: We identified the loss of FOXO3-mediated immune landscape, pathways, and transcripts that could serve as biomarkers and new targets for inflammatory colon cancer treatment.

BACKGROUND: Early invasion and metastasis are responsible for the dismal prognosis of pancreatic ductal adenocarcinoma (PDAC), and epithelial-to-mesenchymal transition (EMT) is recognized as a crucial biological progress in driving tumor invasion and metastasis. The transcription factor FOXO3a is inactivated in various types of solid cancers and the loss of FOXO3a is associated with EMT and tumor metastasis. In this study, we sought to explore whether SPRY2, a regulator of receptor tyrosine kinase (RTK) signaling, is involved in FOXO3a-mediated EMT and metastasis in PDAC.
METHODS: Immunohistochemistry was performed in 130 paired PDAC tissues and paracarcinomatous pancreatic tissues. Cell proliferation and apoptosis were assessed by cell counting kit and flow cytometry, while cell migration and invasion were evaluated with wound healing and transwell assays. The changes in mRNA and protein levels were estimated by qRT-PCR and western blot. BALB/c nude mice xenograft model was established to evaluate tumorigenesis and metastasis in vivo.
RESULTS: FOXO3a expression was remarkably reduced in PDAC tissues, and correlated with metastasis-associated clinicopathologic characteristics and poor prognosis in patients with PDAC. In addition to the promotion of proliferation and suppression of apoptosis, knockdown of FOXO3a or SPRY2 induced EMT and promoted the migration and invasion of PDAC cells via activation of the β-catenin/TCF4 pathway. Moreover, silencing of SPRY2 reversed the suppressor effects induced by FOXO3a overexpression on EMT-associated migration and invasion of PDAC cells, while blockade of β-catenin reversed the effects of SPRY2 loss. FOXO3a knockdown decreased SPRY2 protein stability, whereas SPRY2 knockdown enhanced β-catenin protein stability. In vivo, FOXO3a knockdown promoted the tumorigenic ability and metastasis of PDAC cells.
CONCLUSIONS: Our study suggests that knockdown of FOXO3a induces EMT and promotes metastasis of PDAC by activation of the β-catenin/TCF4 pathway through SPRY2. Thus, FOXO3a may represent a candidate therapeutic target in PDAC.

The development of chemotherapeutic drugs resistance such as doxorubicin (DOX) and cisplatin (DDP) is the major barrier in gastric cancer therapy. Emerging evidences reveal that microRNAs (miRNAs) contribute to chemosensitivity. In this study, we investigated the role of miR-633, an oncogenic miRNA, in gastric cancer chemoresistance. In gastric cancer tissue and cell lines, miR-633 expression was highly increased and correlated with down regulation of Fas-associated protein with death domain (FADD). Inhibition of miR-633 significantly increased FADD protein level and enhanced DOX/DDP induced apoptosis in vitro. MiR-633 antagomir administration remarkably decreased tumor growth in combination with DOX in vivo, suggesting that miR-633 targets FADD to block gastric cancer cell death. We found that the promoter region of miR-633 contained putative binding sites for forkhead box O 3 (Foxo3a), which can directly repress miR-633 transcription. In addition, we observed that DOX-induced nuclear accumulation of Foxo3a leaded to the suppression of miR-633 transcription. Together, our study revealed that miR-633/FADD axis played a significant role in the chemoresistance and Foxo3a regulated this pathway in gastric cancer. Thus, miR-633 antagomir resensitized gastric cancer cells to chemotherapy drug and had potentially therapeutic implication.

BACKGROUND: Globally, colon cancer (CC) is the third reason of tumor-related deaths. Previous reports indicate that Forkhead box O3 (FOXO3) is involved in the development of various tumors and may have different effects depending upon the types of tumors. Hence, this study was to examine the effects of FOXO3 on CC cells and uncover the possible mechanisms.
METHODS: MTT and cell count assay were applied to analyze the viability of transfected CC cells. rVista, dual luciferase reporter assay, and chromatin immunoprecipitation assay were used to identify the downstream target of FOXO3 in HCT116 cells. The mRNA and protein abundance of FOXO3 and MDR1 were determined by quantitative PCR and Western blot, respectively.
RESULTS: Forkhead box O3 stimulated the proliferation of both HCT116 and DLD1 cells. Moreover, FOXO3 overexpression inhibited doxorubicin sensitivity of HCT116 cells, while the knockout of FOXO3 by FOXO3 shRNA restored the doxorubicin sensitivity in doxorubicin-resistant HCT116 DR cells. Next, we found that FOXO3 directly bound to the promoter of MDR1 and enhanced MDR1 expression in HCT116 cells. MDR1 overexpression enhanced the viability and doxorubicin resistance of CC cells. Besides, MDR1 overexpression plasmid significantly abrogated the decrease in cell proliferation and resistance of HCT116 cells to doxorubicin caused by FOXO3 knockout.
CONCLUSION: Forkhead box O3 exhibited promotive effects on the proliferation and doxorubicin resistance in CC cells via targeting MDR1.

Liver cancer is the leading cause of cancer‑related mortality worldwide and its incidence is increasing. Considerable effort has been made in recent decades to improve the diagnosis and treatment of liver cancer. Advanced liver cancer often exhibits a poor response to chemotherapy and poor prognosis due to acquired chemoresistance and tumor recurrence. Understanding the precise molecular mechanisms that are responsible for chemotherapeutic drug‑induced cell death could potentially identify novel therapeutic targets and improve liver cancer treatment. In the present study, it was demonstrated that in response to doxorubicin, the most frequently used chemical compound for liver cancer treatment, histone deacetylase sirtuin 6 (SIRT6) is specifically downregulated. This enables forkhead box O3 (FOXO3) upregulation, translocation into the nucleus and increased expression of its target genes p27 and Bim, which further induce apoptosis. Overexpression of SIRT6, but not enzyme‑inactivated mutants, prevents FOXO3 translocation into the nucleus and doxorubicin‑induced cell death. SIRT6 interacts with FOXO3 and this interaction increases FOXO3 ubiquitination and decreases its stability. Finally, it was identified that the effect of SIRT6 in preventing doxorubicin‑induced cell death requires FOXO3. Overexpression of SIRT6 could not prevent doxorubicin‑induced cell death in FOXO3‑knockdown cells. Therefore, it was concluded that SIRT6 plays a central role in determining doxorubicin‑induced cell death via modulation of FOXO3 activity. Therapeutic targeting of SIRT6 and/or FOXO3 may offer novel strategies for treatment of liver cancer.

ALK mutations occur in 10% of primary neuroblastomas and represent a major target for precision treatment. In combination with MYCN amplification, ALK mutations infer an ultra-high-risk phenotype resulting in very poor patient prognosis. To open up opportunities for future precision drugging, a deeper understanding of the molecular consequences of constitutive ALK signaling and its relationship to MYCN activity in this aggressive pediatric tumor entity will be essential. We show that mutant ALK downregulates the 'HMG-box transcription factor 1' (HBP1) through the PI

BRD4 assembles transcriptional machinery at gene super-enhancer regions and governs the expression of genes that are critical for cancer progression. However, it remains unclear whether BRD4-mediated gene transcription is required for tumor cells to develop drug resistance. Our data show that prolonged treatment of luminal breast cancer cells with AKT inhibitors induces FOXO3a dephosphorylation, nuclear translocation, and disrupts its association with SirT6, eventually leading to FOXO3a acetylation as well as BRD4 recognition. Acetylated FOXO3a recognizes the BD2 domain of BRD4, recruits the BRD4/RNAPII complex to the CDK6 gene promoter, and induces its transcription. Pharmacological inhibition of either BRD4/FOXO3a association or CDK6 significantly overcomes the resistance of luminal breast cancer cells to AKT inhibitors in vitro and in vivo. Our study reports the involvement of BRD4/FOXO3a/CDK6 axis in AKTi resistance and provides potential therapeutic strategies for treating resistant breast cancer.

BACKGROUND: Esophageal cancer is a high incident cancer worldwide with poor survival and limited therapeutic options. Alterations of microRNAs are common in cancers, and many of these micro RNAs are potential therapeutic and diagnostic targets to treat these cancers. miR-10b-3p located in chromosome region 2q31.1, and its expression is frequently increased in esophageal squamous cell carcinoma (ESCC). However, the biological functions, clinical significance and therapeutic implications of miR-10b-3p in ESCC remain unclear.
METHODS: The expression levels of miR-10b-3p in ESCC specimens were analyzed by in situ hybridization (ISH) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays. Ectopic overexpression of miR-10b-3p in ESCC cells, mouse xenograft model, and metastasis model were used to evaluate the effects of miR-10b-3p on proliferation, and migration of cancer cells. Luciferase reporter assay and Western blot were performed to validate the potential targets of miR-10b-3p after the preliminary screening by computer-aided microarray analysis.
RESULTS: We found that miR-10b-3p expression levels were significantly upregulated in the tumor tissues and serum samples of patients with ESCC. The expression levels of miR-10b-3p in both tumor tissues and serum samples were inversely associated with lymph node metastasis and clinical stages. We identified the expression level of miR-10b-3p in ESCC cancer samples as an independent prognostic marker of the overall survival rates of ESCC patients. We found more frequent hypomethylation of the CpG sites located upstream of the miR-10b-3p gene in the ESCC tissues compared with in the adjacent normal tissues, and the DNA methylation status of miR-10b-3p promoter region inversely correlated with the expression levels of miR-10b-3p. Ectopic overexpression of miR-10b-3p promoted cell proliferation, colony formation, migration and invasion in ESCC. While knockdown of miR-10b-3p had the opposite effects, particularly in promoting apoptosis. Mouse xenograft model confirmed that miR-10b-3p functions as a potent oncogenic miRNA in ESCC, which also promoting ESCC metastasis. Mechanistically, we found miR-10b-3p regulated FOXO3 expression by directly binding to the 3'-untranslated region. And systemic delivery of miR-10b-3p antagomir reduced tumor growth and inhibit FOXO3 protein expression in nude mice.
CONCLUSIONS: Collectively, our findings suggested upregulated expression of miR-10b-3p caused by promoter hypomethylation contributed to the progression of ESCC; Thus, miR-10b-3p is a potentially effective biomarker for ESCC that could have further therapeutic implications.

MicroRNAs (miRNAs) serve an important role in renal cancer, but renal cancer miRNA expression data remains inconsistent. Therefore, there is a requirement for integrated analysis of these data. An increasing number of studies demonstrate that miR‑122 is dysregulated in numerous cancer types, including liver, lung and breast cancer, yet its role in clear cell renal cell carcinoma (ccRCC) remains unclear. In the present study, an integrated analysis of four ccRCC miRNAs expression datasets was performed and the expression of miR‑122 in the present cohort was validated. The effects of cell proliferation, colony formation, migration and invasion of ccRCC cells in vitro were assayed following transfection with miR‑122 mimics and inhibitor. The target gene of miR‑122 was confirmed using a luciferase reporter assay, and a xenograft mouse model was used to determine the effect of miR‑122 in ccRCC tumorigenicity in vivo. The present results demonstrated that patients with ccRCC with an increased miR‑122 level in tumor tissues had a shortened metastasis‑free survival time as indicated by The Cancer Genome Atlas‑Kidney Renal Clear Cell Carcinoma dataset and the present ccRCC cohort. Overexpression of miR‑122 in 786‑O cells improved cell proliferation, colony formation, migration and invasion, while knockdown of miR‑122 in SN12‑PM6 cells inhibited cell growth, colony formation, migration and invasion. Western blot analysis and luciferase reporter assays were used to identify FOXO3 as a direct target of miR‑122. The present results indicate that miR‑122 serves a tumor‑promoting role by direct targeting FOXO3 in ccRCC.

Arsenic trioxide (As₂O₃), a traditional remedy in Chinese medicine, has been used in acute promyelocytic leukemia (APL) research and clinical treatment. Previous studies have shown that As₂O₃ exerts its potent antitumor effects in solid tumors by regulating cell proliferation and survival. The aim of this study was to investigate whether As₂O₃ inhibited gastric cancer cell migration and angiogenesis by regulating FOXO3a expression. We found that As₂O₃ reduced gastric cancer cell viability in a dose-dependent manner and also inhibited cell migration and angiogenesis in vitro. Western blotting and immunofluorescence showed that As₂O₃ downregulated the levels of p-AKT, upregulated FOXO3a expression in the nucleus, and attenuated downstream Vascular endothelial growth factor (VEGF) and Matrix metallopeptidase 9 (MMP9) expression. Moreover, we demonstrated that knockdown of FOXO3a significantly reversed the inhibition of As₂O₃ and promoted cell migration and angiogenesis in vitro. Further, As₂O₃ significantly inhibited xenograft tumor growth and angiogenesis by upregulating FOXO3a expression in vivo. However, knockdown of FOXO3a attenuated the inhibitory effect of As₂O₃ in xenograft tumors, and increased microvessel density (MVD) and VEGF expression. Our results demonstrated that As₂O₃ inhibited migration and angiogenesis of gastric cancer cells by enhancing FOXO3a expression.

Protein phosphatase 2 A (PP2A) is a tumour suppressor whose strong inhibition underlies the phosphorylation-dependent, anti-apoptotic mechanisms in Chronic Lymphocytic Leukemia (CLL). Inactivation of PP2A is due to the cooperative action of the phosphorylation of Y307 of its catalytic subunit by the aberrant cytosolic pool of the Src Family Kinase Lyn and the interaction with its protein inhibitor SET, which is overexpressed in CLL. In this study, we developed a library of compounds, the most potent being the one named CC11, which restores PP2A activity by disrupting the PP2A/SET complex, thereby triggering the mitochondrial pathway of apoptosis. This process involves the recruitment of the pro-apoptotic BH3-only proteins Bad and Bim to mitochondria, the former upon direct dephosphorylation and the latter being newly expressed upon dephosphorylation and activation of its transcription factor FoxO3a. These findings highlight that PP2A antagonizes the prosurvival pathways controlled by Akt, which phosphorylates and thereby suppresses a variety of pro-apoptotic factors and tumour suppressors including Bad and FoxO3a. Furthermore, the PP2A-mediated pro-apoptotic effect of CC11 is synergistically potentiated by the abrogation of Lyn's activity. Our results show that CC11 represents a promising lead compound for a new therapeutic rationale aimed at abrogating the aberrant oncogenic signals in CLL.

BACKGROUND: Lapatinib has clinical efficacy in the treatment of trastuzumab-refractory HER2-positive breast cancer. However, a significant proportion of patients develop progressive disease due to acquired resistance to the drug. Induction of apoptotic cell death is a key mechanism of action of lapatinib in HER2-positive breast cancer cells.
METHODS: We examined alterations in regulation of the intrinsic and extrinsic apoptosis pathways in cell line models of acquired lapatinib resistance both in vitro and in patient samples from the NCT01485926 clinical trial, and investigated potential strategies to exploit alterations in apoptosis signalling to overcome lapatinib resistance in HER2-positive breast cancer.
RESULTS: In this study, we examined two cell lines models of acquired lapatinib resistance (SKBR3-L and HCC1954-L) and showed that lapatinib does not induce apoptosis in these cells. We identified alterations in members of the BCL-2 family of proteins, in particular MCL-1 and BAX, which may play a role in resistance to lapatinib. We tested the therapeutic inhibitor obatoclax, which targets MCL-1. Both SKBR3-L and HCC1954-L cells showed greater sensitivity to obatoclax-induced apoptosis than parental cells. Interestingly, we also found that the development of acquired resistance to lapatinib resulted in acquired sensitivity to TRAIL in SKBR3-L cells. Sensitivity to TRAIL in the SKBR3-L cells was associated with reduced phosphorylation of AKT, increased expression of FOXO3a and decreased expression of c-FLIP. In SKBR3-L cells, TRAIL treatment caused activation of caspase 8, caspase 9 and caspase 3/7. In a second resistant model, HCC1954-L cells, p-AKT levels were not decreased and these cells did not show enhanced sensitivity to TRAIL. Furthermore, combining obatoclax with TRAIL improved response in SKBR3-L cells but not in HCC1954-L cells.
CONCLUSIONS: Our findings highlight the possibility of targeting altered apoptotic signalling to overcome acquired lapatinib resistance, and identify potential novel treatment strategies, with potential biomarkers, for HER2-positive breast cancer that is resistant to HER2 targeted therapies.

Multiple physiopathological and clinical conditions trigger skeletal muscle atrophy through the induction of a group of proteins (atrogenes) that includes components of the ubiquitin-proteasome and autophagy-lysosomal systems. Atrogenes are induced by FOXO transcription factors, but their regulation is still not fully understood. Here, we showed that the transcription factor ZEB1, best known for promoting tumor progression, inhibits muscle atrophy and atrogene expression by antagonizing FOXO3-mediated induction of atrogenes. Compared to wild-type counterparts, hindlimb immobilization in Zeb1-deficient mice resulted in enhanced muscle atrophy and higher expression of a number of atrogenes, including Atrogin-1/Fbxo32, MuRF1/Trim63, Ctsl, 4ebp1, Gabarapl1, Psma1 and Nrf2. Likewise, in the C2C12 myogenic cell model, ZEB1 knockdown augmented both myotube diameter reduction and atrogene upregulation in response to nutrient deprivation. Mechanistically, ZEB1 directly represses in vitro and in vivo Fbxo32 and Trim63 promoter transcription in a stage-dependent manner and in a reverse pattern with MYOD1. ZEB1 bound to the Fbxo32 promoter in undifferentiated myoblasts and atrophic myotubes, but not in non-atrophic myotubes, where it is displaced by MYOD1. ZEB1 repressed both promoters through CtBP-mediated inhibition of FOXO3 transcriptional activity. These results set ZEB1 as a new target in therapeutic approaches to clinical conditions causing muscle mass loss.

β-Elemene, an active component of natural plants, has been shown to exhibit anticancer properties. However, the detailed mechanism underlying these effects has yet to be determined. In this study, we show that β-elemene inhibits the growth of lung cancer cells. Mechanistically, we found that β-elemene decreased the phosphorylation of signal transducer and activator of transcription 3 (Stat3) and miRNA155-5p mRNA but induced the protein expression of human forkhead box class O (FOXO)3a; the latter two were abrogated in cells with overexpressed Stat3. Notably, miRNA155-5p mimics reduced FOXO3a luciferase reporter activity in the 3-UTR region and protein expression, whereas overexpressed FOXO3a countered the reduction of the miRNA155-5p levels by β-elemene. Moreover, β-elemene increased the mRNA and protein expression levels as well as promoter activity of insulin-like growth factor-binding protein 1 (IGFBP1); this finding was not observed in cells with a silenced FOXO3a gene and miRNA155-5p mimics. Finally, silencing of IGFBP1 blocked β-elemene-inhibited cell growth. Similar findings were observed in vivo. In summary, our results indicate that β-elemene increases IGFBP1 gene expression via inactivation of Stat3 followed by a reciprocal interaction between miRNA155-5p and FOXO3a. This effect leads to inhibition of human lung cancer cell growth. These findings reveal a novel molecular mechanism underlying the inhibitory effects of β-elemene on lung cancer cells.

The constitutive androstane receptor (CAR; NR1I3) is a nuclear receptor orchestrating complex roles in cell and systems biology. Species differences in CAR's effector pathways remain poorly understood, including its role in regulating liver tumor promotion. We developed transgenic mouse models to assess genome-wide binding of mouse and human CAR, following receptor activation in liver with direct ligands and with phenobarbital, an indirect CAR activator. Genomic interaction profiles were integrated with transcriptional and biological pathway analyses. Newly identified CAR target genes included Gdf15 and Foxo3, important regulators of the carcinogenic process. Approximately 1000 genes exhibited differential binding interactions between mouse and human CAR, including the proto-oncogenes, Myc and Ikbke, which demonstrated preferential binding by mouse CAR as well as mouse CAR-selective transcriptional enhancement. The ChIP-exo analyses also identified distinct binding motifs for the respective mouse and human receptors. Together, the results provide new insights into the important roles that CAR contributes as a key modulator of numerous signaling pathways in mammalian organisms, presenting a genomic context that specifies species variation in biological processes under CAR's control, including liver cell proliferation and tumor promotion.

Long non‑coding RNAs (lncRNAs) are mainly involved in diverse biological processes in human malignancies. The expression profile and underlying mechanism of the lncRNA growth arrest specific transcript 5 (GAS5) in colorectal cancer (CRC) are poorly understood. Here, we investigated the role of GAS5 in human CRC tissues. lncRNA GAS5 was specifically downregulated in CRC tissues and cell lines. Reduced GAS5 levels were significantly associated with advanced clinical stage and lymph node metastasis in CRC. GAS5 overexpression suppressed CRC cell proliferation and promoted cellular apoptosis. A dual‑luciferase reporter assay showed that GAS5 could negatively regulate the expression of microRNA (miR)‑182‑5p. Upregulated miR‑182‑5p abrogated the effect of GAS5 overexpression on CRC cell proliferation and apoptosis. Furthermore, GAS5 positively regulated the expression of FOXO3a in CRC cells. Taken together, these findings suggest that overexpression of the lncRNA GAS5 inhibits cell proliferation and promotes apoptosis by inhibiting miR‑182‑5p expression, and thus could be a therapeutic target in CRC.

FOXO3a is a member of the FOXO subfamily of forkhead transcription factors that mediate a variety of cellular processes including apoptosis, proliferation, cell cycle progression, DNA damage and tumorigenesis. It also responds to several cellular stresses such as UV irradiation and oxidative stress. The function of FOXO3a is regulated by a complex network of processes, including post-transcriptional suppression by microRNAs (miRNAs), post-translational modifications (PTMs) and protein-protein interactions. FOXO3a is widely implicated in a variety of diseases, particularly in malignancy of breast, liver, colon, prostate, bladder, and nasopharyngeal cancers. Emerging evidences indicate that FOXO3a acts as a tumor suppressor in cancer. FOXO3a is frequently inactivated in cancer cell lines by mutation of the FOXO3a gene or cytoplasmic sequestration of FOXO3a protein. And its inactivation is associated with the initiation and progression of cancer. In experimental studies, overexpression of FOXO3a inhibits the proliferation, tumorigenic potential, and invasiveness of cancer cells, while silencing of FOXO3a results in marked attenuation in protection against tumorigenesis. The role of FOXO3a in both normal physiology as well as in cancer development have presented a great challenge to formulating an effective therapeutic strategy for cancer. In this review, we summarize the recent findings and overview of the current understanding of the influence of FOXO3a in cancer development and progression.

Genomic analyses of chronic lymphocytic leukemia (CLL) identified somatic mutations and associations of clonal diversity with adverse outcomes. Clonal evolution likely has therapeutic implications but its dynamic is less well studied. We studied clonal composition and prognostic value of seven recurrently mutated driver genes using targeted next-generation sequencing in 643 CLL patients and found higher frequencies of mutations in TP53 (35 vs. 12%, p < 0.001) and SF3B1 (20 vs. 11%, p < 0.05) and increased number of (sub)clonal (p < 0.0001) mutations in treated patients. We next performed an in-depth evaluation of clonal evolution on untreated CLL patients (50 "progressors" and 17 matched "non-progressors") using a 404 gene-sequencing panel and identified novel mutated genes such as AXIN1, SDHA, SUZ12, and FOXO3. Progressors carried more mutations at initial presentation (2.5 vs. 1, p < 0.0001). Mutations in specific genes were associated with increased (SF3B1, ATM, and FBXW7) or decreased progression risk (AXIN1 and MYD88). Mutations affecting specific signaling pathways, such as Notch and MAP kinase pathway were enriched in progressive relative to non-progressive patients. These data extend earlier findings that specific genomic alterations and diversity of subclones are associated with disease progression and persistence of disease in CLL and identify novel recurrently mutated genes and associated outcomes.

Casticin, a natural polymethoxyflavone isolated from A. annua, V. trifolia, and V. agnus‑castus induces apoptosis in cancer cells by activating FoxO3a. However, whether casticin inhibits in vitro carcinogenesis and cancer stem cell (CSC) characteristics, and whether casticin activates FoxO3a in small cell lung cancer (SCLC) cells remain unclear. We here demonstrated that casticin decreased sphere‑ and colony‑formation capabilities, and downregulated uPAR and CD133 in second‑generation spheres, which were considered as lung cancer stem‑like cells (LCSLCs), from SCLC H446 cells, in a concentration‑dependent manner. In addition, casticin dose‑dependently elevated the phosphorylation levels of AMPK and ACC, and reduced p‑FoxO3a expression. The above effects were attenuated by AMPK knockdown with small interfering RNAs (siRNAs). FoxO3a silencing resulted in decreased protein expression of FoxO3a, increased in vitro carcinogenesis and CSC characteristics, with no appreciable effects on AMPK and ACC phosphorylation, and displayed similar activities to those neutralizing the effects of casticin on in vitro carcinogenesis and CSC characteristics. These findings reveal a novel mechanism for regulating AMPK/FoxO3a signaling in response to casticin, suggesting a new strategy for SCLC therapy by targeting cancer stem‑like cells.

Chronic inflammation drives colitis-associated colorectal cancer (CAC) in inflammatory bowel disease (IBD). FoxP3

PURPOSE: Osteosarcoma is a common primary malignant bone tumour, and its cure rate has stagnated over the past 25-30 years. Brazilin, a purified natural product from sappan wood (Caesalpinia sappan L.), has been proved to possess potent anti-cancer effects. In this study, we investigated the anti-cancer effect of brazilin on human osteosarcoma and elucidated the underlying mechanisms.
METHODS: We exposed MG-63 cells to different concentrations of brazilin (5, 10 and 20 µM) for 24 h. Western blotting, immunocytofluorescence, luciferase reporter assays, and RT-PCR were used to evaluate whether brazilin activates FOXO family-dependent autophagy.
RESULTS: Brazilin increased autophagic flux in the human osteosarcoma cell line MG-63, as evidenced by the upregulation of LC3-II and the downregulation of P62/SQSTM1. Moreover, the pharmacological or genetic blockade of autophagy decreased brazilin-induced cell death, indicating that brazilin triggered autophagic cell death in MG-63 cells. Specifically, brazilin induced FOXO3A(Ser7) phosphorylation, activated FOXO3A nuclear translocation and increased FOXO3A reporter activity, which contributed to the expression of autophagy-related genes and subsequently initiated autophagic cell death in MG-63 cells. Importantly, the increased expression and nuclear translocation of FOXO3A were tightly related to the disturbance of calcium homeostasis, which could be prevented by chelating intracellular calcium.
CONCLUSIONS: Taken together, these data demonstrate that brazilin induces osteosarcoma cell death by inducing excessive autophagy, which is mediated through the Ca

Calcineurin B homologous protein isoform 2 (CHP2), an essential cofactor for Na

Chronic myelogenous leukemia (CML) accounts for 15-20% of all leukemias affecting adults. Despite recent advances in the development of specific Bcr-Abl tyrosine kinase inhibitors (TKIs), some CML patients suffer from relapse due to TKI resistance. Here, we assessed the efficacy of a novel combinatorial arsenic trioxide (ATO) and cisplatin (CDDP) treatment (Ato-C) in human Bcr-Abl-positive leukemic cells. Combination index analyses revealed that a synergistic interaction of ATO and CDDP elicits a wide range of effects in K562, KU-812, MEG-A2, and KCL-22 cells. Notably, Ato-C synergistically enhanced apoptosis and decreased the survival of both acquired TKI-resistant CML cells and the cells expressing mutant Bcr-Abl

The leading cause of death in cancer patients is metastasis, for which an effective treatment is still necessary. During metastasis, cancer cells aberrantly express several glycans that are correlated with poor patient outcome. This study was aimed toward exploring the effects of O-GlcNAcylation on membranous N-glycans that are associated with the progression of cholangiocarcinoma (CCA). Global O-GlcNAcylation in CCA cells was depleted using specific siRNA against O-GlcNAc transferase (OGT), which transfers GlcNAc to the acceptor proteins. Using an HPLC-Chip/Time-of-Flight (Chip/TOF) MS system, the N-glycans associated with O-GlcNAcylation were identified by comparing the membranous N-glycans of siOGT-treated cells with those of scramble siRNA-treated cells. In parallel, the membranous N-glycans of the parental cells (KKU-213 and KKU-214) were compared with those of the highly metastatic cells (KKU-213L5 and KKU-214L5). Together, these data revealed that high mannose (Hex

Triple-negative breast cancer (TNBC) has a poor prognosis due to its aggressive characteristics and lack of targeted therapies. Cytotoxic chemotherapy may reduce tumor bulk, but leaves residual disease due to the persistence of chemotherapy-resistant breast cancer stem cells (BCSC), which are critical for tumor recurrence and metastasis. Here, we demonstrate that hypoxia-inducible factor (HIF)-1-dependent regulation of mitogen-activated protein kinase (MAPK) signaling pathways contributes to chemotherapy-induced BCSC enrichment. Chemotherapy increased DUSP9 expression and decreased DUSP16 expression in a HIF1-dependent manner, leading to inhibition of ERK and activation of p38 signaling pathways, respectively. Inhibition of ERK caused transcriptional induction of the pluripotency factor Nanog through decreased inactivating phosphorylation of FoxO3, while activation of p38 stabilized Nanog and Klf4 mRNA through increased inactivating phosphorylation of RNA-binding protein ZFP36L1, both of which promoted specification of the BCSC phenotype. Inhibition of HIF1 or p38 signaling blocked chemotherapy-induced pluripotency factor expression and BCSC enrichment. These surprising results delineate a mechanism by which a transcription factor switches cells from ERK to p38 signaling in response to chemotherapy and suggest that therapeutic targeting of HIF1 or the p38 pathway in combination with chemotherapy will block BCSC enrichment and improve outcome in TNBC.