Gene Summary

Gene:AKT3; v-akt murine thymoma viral oncogene homolog 3
Aliases: MPPH, PKBG, MPPH2, PRKBG, STK-2, PKB-GAMMA, RAC-gamma, RAC-PK-gamma
Summary:The protein encoded by this gene is a member of the AKT, also called PKB, serine/threonine protein kinase family. AKT kinases are known to be regulators of cell signaling in response to insulin and growth factors. They are involved in a wide variety of biological processes including cell proliferation, differentiation, apoptosis, tumorigenesis, as well as glycogen synthesis and glucose uptake. This kinase has been shown to be stimulated by platelet-derived growth factor (PDGF), insulin, and insulin-like growth factor 1 (IGF1). Alternatively splice transcript variants encoding distinct isoforms have been described. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:RAC-gamma serine/threonine-protein kinase
Source:NCBIAccessed: 25 June, 2015


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 (1990-2015)
Graph generated 25 June 2015 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.

Tag cloud generated 25 June, 2015 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: AKT3 (cancer-related)

Turner KM, Sun Y, Ji P, et al.
Genomically amplified Akt3 activates DNA repair pathway and promotes glioma progression.
Proc Natl Acad Sci U S A. 2015; 112(11):3421-6 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
Akt is a robust oncogene that plays key roles in the development and progression of many cancers, including glioma. We evaluated the differential propensities of the Akt isoforms toward progression in the well-characterized RCAS/Ntv-a mouse model of PDGFB-driven low grade glioma. A constitutively active myristoylated form of Akt1 did not induce high-grade glioma (HGG). In stark contrast, Akt2 and Akt3 showed strong progression potential with 78% and 97% of tumors diagnosed as HGG, respectively. We further revealed that significant variations in polarity and hydropathy values among the Akt isoforms in both the pleckstrin homology domain (P domain) and regulatory domain (R domain) were critical in mediating glioma progression. Gene expression profiles from representative Akt-derived tumors indicated dominant and distinct roles for Akt3, consisting primarily of DNA repair pathways. TCGA data from human GBM closely reflected the DNA repair function, as Akt3 was significantly correlated with a 76-gene signature DNA repair panel. Consistently, compared with Akt1 and Akt2 overexpression models, Akt3-expressing human GBM cells had enhanced activation of DNA repair proteins, leading to increased DNA repair and subsequent resistance to radiation and temozolomide. Given the wide range of Akt3-amplified cancers, Akt3 may represent a key resistance factor.

Samaan S, Lichner Z, Ding Q, et al.
Kallikreins are involved in an miRNA network that contributes to prostate cancer progression.
Biol Chem. 2014; 395(9):991-1001 [PubMed] Related Publications
MicroRNAs (miRNAs) are short RNA nucleotides that negatively regulate their target genes. They are differentially expressed in prostate cancer. Kallikreins are genes that encode serine proteases and are dysregulated in cancer. We elucidated a miRNA-kallikrein network that can be involved in prostate cancer progression. Target prediction identified 23 miRNAs that are dysregulated between high and low risk biochemical failure and are predicted to target five kallikreins linked to prostate cancer; KLK2, KLK3, KLK4, KLK14 and KLK15. We also identified 14 miRNAs that are differentially expressed between Gleason grades and are predicted to target these kallikreins. This demonstrates that kallikreins are downstream effectors through which miRNAs influence tumor progression. We show, through in-silico and experimental analysis, that miR-378/422a and its gene targets PIK3CG, GRB2, AKT3, KLK4 and KLK14 form an integrated circuit in prostate cancer. Our analysis shows that a minisatellite sequence in the kallikrein locus consists of a number of microsatellite repeats that represent predicted miRNA response elements. A number of kallikrein and non-kallikrein prostate cancer-related genes share these microsatellite repeats. We validated some of these interactions in prostate cancer cell lines. Finally, we provide preliminary evidence on the presence of a miRNA-mediated cross-talk between kallikreins, including a kallikrein pseudogene.

Fabi F, Asselin E
Expression, activation, and role of AKT isoforms in the uterus.
Reproduction. 2014; 148(5):R85-95 [PubMed] Related Publications
The three isoforms of AKT: AKT1, AKT2, and AKT3, are crucial regulators of both normal and pathological cellular processes. Each of these isoforms exhibits a high level of homology and functional redundancy with each other. However, while being highly similar and structurally homologous, a rising amount of evidence is showing that each isoform possesses specific targets as well as preferential subcellular localization. The role of AKT has been studied extensively in reproductive processes, but isoform-specific roles are yet to be fully understood. This review will focus on the role of AKT in the uterus and its function in processes related to cell death and proliferation such as embryo implantation, decidualization, endometriosis, and endometrial cancer in an isoform-centric manner. In this review, we will cover the activation of AKT in various settings, localization of isoforms in subcellular compartments, and the effect of isoform expression on cellular processes. To fully understand the dynamic molecular processes taking place in the uterus, it is crucial that we better understand the physiological role of AKT isoforms as well as their function in the emergence of diseases.

Doldo E, Costanza G, Ferlosio A, et al.
CRBP-1 expression in ovarian cancer: a potential therapeutic target.
Anticancer Res. 2014; 34(7):3303-12 [PubMed] Related Publications
BACKGROUND/AIM: Cellular retinol binding protein-1 regulates retinol bioavailability and contributes to cell differentiation maintenance, but its role in ovarian carcinogenesis remains uncertain. We investigated CRBP-1 expression in ovarian tumors and CRBP-1 signaling-regulated pathways.
MATERIALS AND METHODS: We performed immunohistochemistry, methylation-specific PCR, gene copy number analysis in ovarian tumors and proliferation/apoptosis evaluation, gene array, blot and real-time PCR in CRBP-1-transfected A2780 ovarian cancer cells.
RESULTS: CRBP-1 expression was reduced or absent in G2 and G3 ovarian carcinomas. CRBP-1 silencing in 60% of G2 and 66.7% of G3 carcinomas was due to CRBP-1 promoter methylation. A2780 CRBP-1-transfected cells showed increased retinol-induced apoptosis, retinoid-induced reduced clonogenicity and down-regulation of proliferation and transcription genes, including AKT1, AKT3, EGFR, FOS, JUN, STAT1 and STAT5A.
CONCLUSION: CRBP-1 loss in G2/G3 ovarian carcinomas and increased apoptotic susceptibility to retinoids in CRBP-1-transfected-A2780 cells suggest CRBP-1 screening as a target to ensure efficacy of an adjuvant retinoid therapy.

Dumble M, Crouthamel MC, Zhang SY, et al.
Discovery of novel AKT inhibitors with enhanced anti-tumor effects in combination with the MEK inhibitor.
PLoS One. 2014; 9(6):e100880 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
Tumor cells upregulate many cell signaling pathways, with AKT being one of the key kinases to be activated in a variety of malignancies. GSK2110183 and GSK2141795 are orally bioavailable, potent inhibitors of the AKT kinases that have progressed to human clinical studies. Both compounds are selective, ATP-competitive inhibitors of AKT 1, 2 and 3. Cells treated with either compound show decreased phosphorylation of several substrates downstream of AKT. Both compounds have desirable pharmaceutical properties and daily oral dosing results in a sustained inhibition of AKT activity as well as inhibition of tumor growth in several mouse tumor models of various histologic origins. Improved kinase selectivity was associated with reduced effects on glucose homeostasis as compared to previously reported ATP-competitive AKT kinase inhibitors. In a diverse cell line proliferation screen, AKT inhibitors showed increased potency in cell lines with an activated AKT pathway (via PI3K/PTEN mutation or loss) while cell lines with activating mutations in the MAPK pathway (KRAS/BRAF) were less sensitive to AKT inhibition. Further investigation in mouse models of KRAS driven pancreatic cancer confirmed that combining the AKT inhibitor, GSK2141795 with a MEK inhibitor (GSK2110212; trametinib) resulted in an enhanced anti-tumor effect accompanied with greater reduction in phospho-S6 levels. Taken together these results support clinical evaluation of the AKT inhibitors in cancer, especially in combination with MEK inhibitor.

Paul-Samojedny M, Suchanek R, Borkowska P, et al.
Knockdown of AKT3 (PKBγ) and PI3KCA suppresses cell viability and proliferation and induces the apoptosis of glioblastoma multiforme T98G cells.
Biomed Res Int. 2014; 2014:768181 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
Glioblastoma multiforme (GBM) is the most malignant and invasive human brain tumor that is difficult to treat and has a very poor prognosis. Thus, new therapeutic strategies that target GBM are urgently needed. The PI3K/AKT/PTEN signaling pathway is frequently deregulated in a wide range of cancers. The present study was designed to examine the inhibitory effect of AKT3 or PI3KCA siRNAs on GBM cell growth, viability, and proliferation.T98G cells were transfected with AKT3 and/or PI3KCA siRNAs. AKT3 and PI3KCA protein-positive cells were identified using FC and Western blotting. The influence of specific siRNAs on T98G cell viability, proliferation, cell cycle, and apoptosis was evaluated as well using FC. Alterations in the mRNA expression of AKT3, PI3KCA, and apoptosis-related genes were analyzed using QRT-PCR. Knockdown of AKT3 and/or PI3KCA genes in T98G cells led to a significant reduction in cell viability, the accumulation of subG1-phase cells and, a reduced fraction of cells in the S and G2/M phases. Additionally, statistically significant differences in the BAX/BCL-2 ratio and an increased percentage of apoptotic cells were found. The siRNA-induced AKT3 and PI3KCA mRNA knockdown may offer a novel therapeutic strategy to control the growth of human GBM cells.

Wu H, Xiao Z, Zhang H, et al.
MiR-489 modulates cisplatin resistance in human ovarian cancer cells by targeting Akt3.
Anticancer Drugs. 2014; 25(7):799-809 [PubMed] Related Publications
MicroRNAs are a conserved class of small noncoding RNA molecules that harbour the capacity to regulate protein-coding gene expression at the post-transcriptional level. In the current study, we show that miR-489 is downregulated in cisplatin (CDDP)-resistant ovarian cancer cells, SKOV3/CDDP and OVCAR3/CDDP cells. MiR-489 overexpression results in an inhibition of SKOV3 and OVCAR3 cell survival and cell growth after CDDP treatment and an induction of cell apoptosis. Inhibition of miR-489 yields the opposite results. In addition, miR-489 overexpression increases the sensitivity of SKOV3/CDDP and OVCAR3/CDDP cells to CDDP and inhibits their colony number. Akt3 is validated as a direct target of miR-489 in SKOV3, OVCAR3, SKOV3/CDDP and OVCAR3/CDDP cells. In addition, miR-489 suppresses Akt3 protein expression by binding sites on its 3'UTR. Knockdown of Akt3 results in a similar effect as that because of miR-489 overexpression; importantly, Akt3 silencing rescues the functions induced by miR-489. Furthermore, we also use the Akt3 inhibitor, MK-2206 2HCl, to determine the role of Akt3 in CDDP resistance. Our study showed that MK-2206 2HCl increased the sensitivity of SKOV3/CDDP and OVCAR3/CDDP cells to CDDP. Taken together, our results indicate that miR-489 inhibited CDDP resistance and cell growth, and promotes apoptosis by suppressing Akt3 expression. Furthermore, the identification of a novel miR-489-based pathway in CDDP-resistant ovarian cancer will facilitate the development of therapeutic strategies.

Yu Z, Xu Z, Disante G, et al.
miR-17/20 sensitization of breast cancer cells to chemotherapy-induced apoptosis requires Akt1.
Oncotarget. 2014; 5(4):1083-90 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
The serine threonine kinase Akt1 has been implicated in the control of cellular metabolism, survival and growth. Herein, disruption of the ubiquitously expressed member of the Akt family of genes, Akt1, in the mouse, demonstrates a requirement for Akt1 in miRNA-mediated cellular apoptosis. The miR-17/20 cluster is known to inhibit breast cancer cellular proliferation through G1/S cell cycle arrest via binding to the cyclin D1 3'UTR. Here we show that miR-17/20 overexpression sensitizes cells to apoptosis induced by either Doxorubicin or UV irradiation in MCF-7 cells via Akt1. miR-17/20 mediates apoptosis via increased p53 expression which promotes Akt degradation. Akt1⁻/⁻ mammary epithelial cells which express Akt2 and Akt3 demonstrated increased apoptosis to DNA damaging agents. Akt1 deficiency abolished the miR-17/20-mediated apoptosis. These results demonstrated a novel pathway through which miR17/20 regulate p53 and Akt controlling breast cancer cell apoptosis.

Meric-Bernstam F, Frampton GM, Ferrer-Lozano J, et al.
Concordance of genomic alterations between primary and recurrent breast cancer.
Mol Cancer Ther. 2014; 13(5):1382-9 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
There is growing interest in delivering genomically informed cancer therapy. Our aim was to determine the concordance of genomic alterations between primary and recurrent breast cancer. Targeted next-generation sequencing was performed on formalin-fixed paraffin-embedded (FFPE) samples, profiling 3,320 exons of 182 cancer-related genes plus 37 introns from 14 genes often rearranged in cancer. Point mutations, indels, copy-number alterations (CNA), and select rearrangements were assessed in 74 tumors from 43 patients (36 primary and 38 recurrence/metastases). Alterations potentially targetable with established or investigational therapeutics were considered "actionable." Alterations were detected in 55 genes (mean 3.95 alterations/sample, range 1-12), including mutations in PIK3CA, TP53, ARID1A, PTEN, AKT1, NF1, FBXW7, and FGFR3 and amplifications in MCL1, CCND1, FGFR1, MYC, IGF1R, MDM2, MDM4, AKT3, CDK4, and AKT2. In 33 matched primary and recurrent tumors, 97 of 112 (86.6%) somatic mutations were concordant. Of identified CNAs, 136 of 159 (85.5%) were concordant: 37 (23.3%) were concordant, but below the reporting threshold in one of the matched samples, and 23 (14.5%) discordant. There was an increased frequency of CDK4/MDM2 amplifications in recurrences, as well as gains and losses of other actionable alterations. Forty of 43 (93%) patients had actionable alterations that could inform targeted treatment options. In conclusion, deep genomic profiling of cancer-related genes reveals potentially actionable alterations in most patients with breast cancer. Overall there was high concordance between primary and recurrent tumors. Analysis of recurrent tumors before treatment may provide additional insights, as both gains and losses of targets are observed.

AKT isoform-specific signals regulate RNA processing in lung cancer.
Cancer Discov. 2014; 4(3):OF17 [PubMed] Related Publications
IWS1 phosphorylation by AKT1 and AKT3 shifts splicing towards a tumorigenic FGFR2 isoform.

Lee G, Blenis J
Akt-ivation of RNA splicing.
Mol Cell. 2014; 53(4):519-20 [PubMed] Related Publications
Cells must tightly control alternative splicing of RNA to maintain homeostasis; in this issue of Molecular Cell, Sanidas et al. (2014) provide new insights into the regulation of RNA splicing by Akt isoforms through phosphorylation of histone modification machinery.

Gonçalves V, Henriques A, Pereira J, et al.
Phosphorylation of SRSF1 by SRPK1 regulates alternative splicing of tumor-related Rac1b in colorectal cells.
RNA. 2014; 20(4):474-82 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
The premessenger RNA of the majority of human genes can generate various transcripts through alternative splicing, and different tissues or disease states show specific patterns of splicing variants. These patterns depend on the relative concentrations of the splicing factors present in the cell nucleus, either as a consequence of their expression levels or of post-translational modifications, such as protein phosphorylation, which are determined by signal transduction pathways. Here, we analyzed the contribution of protein kinases to the regulation of alternative splicing variant Rac1b that is overexpressed in certain tumor types. In colorectal cells, we found that depletion of AKT2, AKT3, GSK3β, and SRPK1 significantly decreased endogenous Rac1b levels. Although knockdown of AKT2 and AKT3 affected only Rac1b protein levels suggesting a post-splicing effect, the depletion of GSK3β or SRPK1 decreased Rac1b alternative splicing, an effect mediated through changes in splicing factor SRSF1. In particular, the knockdown of SRPK1 or inhibition of its catalytic activity reduced phosphorylation and subsequent translocation of SRSF1 to the nucleus, limiting its availability to promote the inclusion of alternative exon 3b into the Rac1 pre-mRNA. Altogether, the data identify SRSF1 as a prime regulator of Rac1b expression in colorectal cells and provide further mechanistic insight into how the regulation of alternative splicing events by protein kinases can contribute to sustain tumor cell survival.

Grabinski N, Möllmann K, Milde-Langosch K, et al.
AKT3 regulates ErbB2, ErbB3 and estrogen receptor α expression and contributes to endocrine therapy resistance of ErbB2(+) breast tumor cells from Balb-neuT mice.
Cell Signal. 2014; 26(5):1021-9 [PubMed] Related Publications
ErbB2(+) breast cancer is an aggressive breast cancer subtype generally associated with lower estrogen receptor alpha (ERα) expression and more aggressive tumor behavior compared to ERα(+)/ErbB2(-) breast cancer. The ErbB2(+) phenotype is associated with resistance to endocrine therapy, e.g. the selective estrogen receptor modulator Tamoxifen. However, the mechanisms underlying endocrine resistance are not fully understood. Here, we investigated the impact of AKT signaling and distinct functional roles of AKT isoforms in ErbB2(+) breast cancer from Balb-neuT mice. AKT isoform specific in vitro kinase assays revealed that AKT3 is activated in Balb-neuT breast tumors in comparison to normal murine breast tissue. Knock-down of AKT3, but not of AKT1 or AKT2, led to reduced expression and tyrosine-phosphorylation of ErbB2 and ErbB3 in Balb-neuT-derived mammary tumor cells. In contrast, expression of ERα was strongly up-regulated and phosphorylation of the AKT substrate Foxo3a which regulates ERα transcription was decreased in AKT3 knockdown cells. These data suggest that ERα expression is down regulated via AKT3/Foxo3a signaling in ErbB2(+) breast cancer cells. Furthermore, up-regulation of ERα after depletion of AKT3 resulted in a significant increase in Tamoxifen responsiveness of Balb-neuT-derived mammary tumor cells. In addition, Tamoxifen resistant human breast cancer cell lines showed increased AKT3 expression and activity in comparison to Tamoxifen responsive MCF-7 cells. Finally, by AKT isoform specific in vitro kinase assays of human breast cancer samples, AKT3 activity was detected in ErbB2(+) and triple negative tumors but not in ERα(+) breast cancer. Our data indicate that AKT3 regulates the expression of ErbB2, ErbB3 and ERα and demonstrate that down-regulation of activated AKT3 can sensitize ErbB2(+) breast cancer cells for treatment with Tamoxifen. Therefore, AKT3 targeting might be a new promising strategy for therapy of ErbB2(+)/ERα(-) breast cancer and might further increase the responsiveness to an endocrine therapy approach.

Sanidas I, Polytarchou C, Hatziapostolou M, et al.
Phosphoproteomics screen reveals akt isoform-specific signals linking RNA processing to lung cancer.
Mol Cell. 2014; 53(4):577-90 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
The three Akt isoforms are functionally distinct. Here we show that their phosphoproteomes also differ, suggesting that their functional differences are due to differences in target specificity. One of the top cellular functions differentially regulated by Akt isoforms is RNA processing. IWS1, an RNA processing regulator, is phosphorylated by Akt3 and Akt1 at Ser720/Thr721. The latter is required for the recruitment of SETD2 to the RNA Pol II complex. SETD2 trimethylates histone H3 at K36 during transcription, creating a docking site for MRG15 and PTB. H3K36me3-bound MRG15 and PTB regulate FGFR-2 splicing, which controls tumor growth and invasiveness downstream of IWS1 phosphorylation. Twenty-one of the twenty-four non-small-cell-lung carcinomas we analyzed express IWS1. More importantly, the stoichiometry of IWS1 phosphorylation in these tumors correlates with the FGFR-2 splicing pattern and with Akt phosphorylation and Akt3 expression. These data identify an Akt isoform-dependent regulatory mechanism for RNA processing and demonstrate its role in lung cancer.

Ghersi D, Singh M
Interaction-based discovery of functionally important genes in cancers.
Nucleic Acids Res. 2014; 42(3):e18 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
A major challenge in cancer genomics is uncovering genes with an active role in tumorigenesis from a potentially large pool of mutated genes across patient samples. Here we focus on the interactions that proteins make with nucleic acids, small molecules, ions and peptides, and show that residues within proteins that are involved in these interactions are more frequently affected by mutations observed in large-scale cancer genomic data than are other residues. We leverage this observation to predict genes that play a functionally important role in cancers by introducing a computational pipeline (http://canbind.princeton.edu) for mapping large-scale cancer exome data across patients onto protein structures, and automatically extracting proteins with an enriched number of mutations affecting their nucleic acid, small molecule, ion or peptide binding sites. Using this computational approach, we show that many previously known genes implicated in cancers are enriched in mutations within the binding sites of their encoded proteins. By focusing on functionally relevant portions of proteins--specifically those known to be involved in molecular interactions--our approach is particularly well suited to detect infrequent mutations that may nonetheless be important in cancer, and should aid in expanding our functional understanding of the genomic landscape of cancer.

Chin YR, Yoshida T, Marusyk A, et al.
Targeting Akt3 signaling in triple-negative breast cancer.
Cancer Res. 2014; 74(3):964-73 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
Triple-negative breast cancer (TNBC) is currently the only major breast tumor subtype without effective targeted therapy and, as a consequence, in general has a poor outcome. To identify new therapeutic targets in TNBC, we performed a short hairpin RNA (shRNA) screen for protein kinases commonly amplified and overexpressed in breast cancer. Using this approach, we identified AKT3 as a gene preferentially required for the growth of TNBCs. Downregulation of Akt3 significantly inhibits the growth of TNBC lines in three-dimensional (3D) spheroid cultures and in mouse xenograft models, whereas loss of Akt1 or Akt2 have more modest effects. Akt3 silencing markedly upregulates the p27 cell-cycle inhibitor and this is critical for the ability of Akt3 to inhibit spheroid growth. In contrast with Akt1, Akt3 silencing results in only a minor enhancement of migration and does not promote invasion. Depletion of Akt3 in TNBC sensitizes cells to the pan-Akt inhibitor GSK690693. These results imply that Akt3 has a specific function in TNBCs; thus, its therapeutic targeting may provide a new treatment option for this tumor subtype.

Zhang Y, Guo X, Yang M, et al.
Identification of AKT kinases as unfavorable prognostic factors for hepatocellular carcinoma by a combination of expression profile, interaction network analysis and clinical validation.
Mol Biosyst. 2014; 10(2):215-22 [PubMed] Related Publications
BACKGROUND & AIM: identification of key markers that differentiate occurrence and progression of hepatocellular carcinoma (HCC) is of great significance to develop novel prognostic factors and improve therapeutic strategies. The aim of this study was to screen novel markers for HCC by combining expression profile, interaction network analysis and clinical validation.
METHODS & RESULTS: HCC significant molecules which were differentially expressed in HCC tissues were obtained from five existing HCC related databases (OncoDB.HCC, HCC.net, dbHCCvar, EHCO and Liverome). The protein-protein interaction network of HCC significant proteins was constructed and 331 candidate HCC markers were identified by calculating four topological features of the network ('Degree', 'Betweenness', 'Closeness' and 'K-coreness'). According to the enrichment analysis on Gene ontology items and KEGG pathways, these candidate HCC markers were more frequently involved in cellular protein metabolic processes, translational elongation and intracellular signaling cascade, which are associated with cancer development and metastasis. Among 331 candidate HCC markers, the three AKT kinase family members (AKT1-AKT3) were selected for clinical validation by immunohistochemistry analysis using 130 HCC specimens and matched adjacent non-neoplastic liver tissues. Interestingly, the upregulation of AKT1, AKT2 and AKT3 proteins were all significantly associated with tumor aggressiveness and poor prognosis in patients with HCC.
CONCLUSION: this study provided an integrated analysis by combining expression profile and interaction network analysis to identify a list of biologically significant HCC related markers and pathways. Further experimental validation also indicated that AKT1, AKT2 and AKT3 proteins may all be novel unfavorable prognostic factors for patients with HCC.

Nassirpour R, Mehta PP, Yin MJ
miR-122 regulates tumorigenesis in hepatocellular carcinoma by targeting AKT3.
PLoS One. 2013; 8(11):e79655 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
MicroRNAs (miRNAs) have been implicated in the orchestration of diverse cellular processes including differentiation, proliferation, and apoptosis and are believed to play pivotal roles as oncogenes and tumor suppressors. miR-122, a liver specific miRNA, is significantly down-regulated in most hepatocellular carcinomas (HCCs) but its role in tumorigenesis remains poorly understood. Here we identify AKT3 as a novel and direct target of miR-122. Restoration of miR-122 expression in HCC cell lines decreases AKT3 levels, inhibits cell migration and proliferation, and induces apoptosis. These anti-tumor phenotypes can be rescued by reconstitution of AKT3 expression indicating the essential role of AKT3 in miR-122 mediated HCC transformation. In vivo, restoration of miR-122 completely inhibited xenograft growth of HCC tumor in mice. Our data strongly suggest that miR-122 is a tumor suppressor that targets AKT3 to regulate tumorigenesis in HCCs and a potential therapeutic candidate for liver cancer.

Cizkova M, Vacher S, Meseure D, et al.
PIK3R1 underexpression is an independent prognostic marker in breast cancer.
BMC Cancer. 2013; 13:545 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
BACKGROUND: The present study focused on the prognostic roles of PIK3CA and PIK3R1 genes and additional PI3K pathway-associated genes in breast cancer.
METHODS: The mutational and mRNA expression status of PIK3CA, PIK3R1 and AKT1, and expression status of other genes involved in the PI3K pathway (EGFR, PDK1, PTEN, AKT2, AKT3, GOLPH3, WEE1, P70S6K) were assessed in a series of 458 breast cancer samples.
RESULTS: PIK3CA mutations were identified in 151 samples (33.0%) in exons 1, 2, 9 and 20. PIK3R1 mutations were found in 10 samples (2.2%) and underexpression in 283 samples (61.8%). AKT1 mutations were found in 15 samples (3.3%) and overexpression in 116 samples (25.3%). PIK3R1 underexpression tended to mutual exclusivity with PIK3CA mutations (p = 0.00097). PIK3CA mutations were associated with better metastasis-free survival and PIK3R1 underexpression was associated with poorer metastasis-free survival (p = 0.014 and p = 0.00028, respectively). By combining PIK3CA mutation and PIK3R1 expression status, four prognostic groups were identified with significantly different metastasis-free survival (p = 0.00046). On Cox multivariate regression analysis, the prognostic significance of PIK3R1 underexpression was confirmed in the total population (p = 0.0013) and in breast cancer subgroups.
CONCLUSIONS: PIK3CA mutations and PIK3R1 underexpression show opposite effects on patient outcome and could become useful prognostic and predictive factors in breast cancer.

O'Hurley G, Daly E, O'Grady A, et al.
Investigation of molecular alterations of AKT-3 in triple-negative breast cancer.
Histopathology. 2014; 64(5):660-70 [PubMed] Related Publications
AIMS: Triple-negative breast cancer (TNBC) is responsible for a disproportionate number of breast cancer (BC) deaths, owing to its intrinsic aggressiveness and a lack of treatment options, especially targeted therapies. Thus, there is an urgent need for the development of better targeted treatments for TNBC. Molecular alteration of AKT-3 was previously reported in oestrogen receptor (ER)-positive BC. AKT-3 has also been suggested to play a role in hormone-unresponsive BC. The aim of this study was to investigate molecular alterations of AKT-3 in TNBC, to perform associated survival analysis, and to compare these findings with the incidence of AKT-3 molecular alterations in ER-positive BC.
RESULTS: Our study revealed AKT-3 amplification and deletions in 11% (9/82) and 13% (11/82) of TNBCs, respectively. In contrast, 1% (2/209) of ER-positive BCs were found to have AKT-3 amplifications and deletions. A higher prevalence of AKT-3 copy number gains was observed in TNBC [26% (21/82)] than in ER-positive BC [9% (19/209)]. AKT-3 amplification together with Akt-3 protein expression was negatively associated with recurrence-free survival in TNBC. Furthermore, a negative association between high AKT-3 copy number and recurrence-free survival was observed.
CONCLUSION: AKT-3 amplification could represent a potentially relevant oncogenic event in a subset of TNBCs that may, in turn, select cells sensitive to Akt-3 inhibitors.

Cohen MM
The AKT genes and their roles in various disorders.
Am J Med Genet A. 2013; 161A(12):2931-7 [PubMed] Related Publications
AKT (AK mouse plus Transforming or Thymoma) is a common oncogene expressed in most tissues. Both AKT2 and AKT3, although important, have more limited distributions. The regulation of all three genes depends on two receptors-a receptor tyrosine kinase with a growth factor ligand, and a G protein coupled receptor, also with a ligand together with an explanation of how their downsteam components function. AKT2 is amplified or overexpressed in cancer with a higher frequency than those found with AKT1. AKT1 is cardioprotective to the heart by supporting its physiological growth and function. AKT2 is closely linked to Type II diabetes and the implications of various types of mutations are discussed. Various AKT3 mutations are important in neurological disorders, such as microcephaly, hemimegalencephaly, and megalencephaly syndromes. Finally, a reduced level of AKT1 in the frontal cortex has been found during post-mortem brain studies of schizophrenic patients in the populations of many countries.

McQuitty E, Zhang W, Hendrickson H, et al.
Lung adenocarcinoma biomarker incidence in Hispanic versus non-Hispanic white patients.
Arch Pathol Lab Med. 2014; 138(3):390-4 [PubMed] Related Publications
CONTEXT: Lung cancer is the leading cause of cancer deaths in the United States and worldwide. Biomarker testing is critical to personalized therapy in lung adenocarcinoma and has been extensively investigated in non-Hispanic whites, Asians, and African Americans. However, little information addresses the underlying genetic changes in lung adenocarcinoma among Hispanic patients in the United States.
OBJECTIVE: To identify targetable biomarkers other than EGFR and EML4-ALK in Hispanic patients with lung adenocarcinoma.
DESIGN: We tested DNA extracted from 85 lung adenocarcinoma specimens collected from 40 Hispanic and 43 non-Hispanic white patients for previously reported mutations in KRAS, MET, BRAF, mTOR, STAT3, JAK2, PIK3CA, AKT1 through AKT3, and PTEN with a custom Sequenom massARRAY assay (Sequenom, San Diego, California).
RESULTS: Mutations in KRAS were identified in 11 cases (13%; 6 Hispanic [7%], 5 non-Hispanic white [6%]) and had no correlation with sex, age, or smoking history. Mutations in PIK3CA were identified in 2 of the 40 Hispanic patients (5%), including one patient (2.5%) with a concurrent KRAS mutation. The tumors were wild type for all other genes tested.
CONCLUSIONS: Targetable biomarkers other than EGFR and EML4-ALK were identified in 7 of the 40 Hispanic patients (18%) and 5 of the 43 non-Hispanic white patients (12%), suggesting a similar mutational frequency. Our highly multiplexed genotyping assay detected actionable mutations in 14% (12 of 83) more patients than would have been identified by EGFR and EML4-ALK testing alone.

Szczurek E, Misra N, Vingron M
Synthetic sickness or lethality points at candidate combination therapy targets in glioblastoma.
Int J Cancer. 2013; 133(9):2123-32 [PubMed] Related Publications
Synthetic lethal interactions in cancer hold the potential for successful combined therapies, which would avoid the difficulties of single molecule-targeted treatment. Identification of interactions that are specific for human tumors is an open problem in cancer research. This work aims at deciphering synthetic sick or lethal interactions directly from somatic alteration, expression and survival data of cancer patients. To this end, we look for pairs of genes and their alterations or expression levels that are "avoided" by tumors and "beneficial" for patients. Thus, candidates for synthetic sickness or lethality (SSL) interaction are identified as such gene pairs whose combination of states is under-represented in the data. Our main methodological contribution is a quantitative score that allows ranking of the candidate SSL interactions according to evidence found in patient survival. Applying this analysis to glioblastoma data, we collect 1,956 synthetic sick or lethal partners for 85 abundantly altered genes, most of which show extensive copy number variation across the patient cohort. We rediscover and interpret known interaction between TP53 and PLK1, as well as provide insight into the mechanism behind EGFR interacting with AKT2, but not AKT1 nor AKT3. Cox model analysis determines 274 of identified interactions as having significant impact on overall survival in glioblastoma, which is more informative than a standard survival predictor based on patient's age.

Dionysopoulos D, Pavlakis K, Kotoula V, et al.
Cyclin D1, EGFR, and Akt/mTOR pathway. Potential prognostic markers in localized laryngeal squamous cell carcinoma.
Strahlenther Onkol. 2013; 189(3):202-14 [PubMed] Related Publications
INTRODUCTION: EGFR (epidermal growth factor receptor), cyclin D1 and Akt/mTOR pathways are active in head and neck cancer. The aim of this study was to explore biomarker expression, their correlations with clinicopathological parameters and their prognostic utility in a cohort of patients with localized squamous laryngeal carcinoma.
PATIENTS AND METHODS: We assessed relative messenger RNA expression of EGFR, Akt1, 2, and 3, mTOR and CCND1, copy number variants of the EGFR and CCND1 genes and immunohistochemical protein expression of EGFR, p-Akt308, p-Akt473, pmTOR, PTEN, p53 and cyclin D1 in paraffin-embedded tissue samples of localized laryngeal carcinomas.
RESULTS: In 289 patients with T3-4 (77.8%), node-negative (84.1%) tumors of the larynx, high EGFR and CCND1 mRNA correlated with no or ex-smoking, (p = 0.003 and p = 0.029, respectively), while low Akt3 mRNA correlated with alcohol abuse, N0 stage, total laryngectomy, and absence of neck dissection. At a median follow-up of 74.5 months, high mTOR mRNA expression was marginally associated with shorter disease-free survival (hazard ratio [HR] = 1.54; p = 0.093) and high Akt3 mRNA with shorter overall survival (HR = 1.49; p = 0.0786), in univariate analysis. In multivariate analysis, node-positive status, subglottic-transglottic location, surgery other than total laryngectomy and mTOR/CCND1 mRNA interaction with a hazard ratio of 2.16 (p value for interaction:  0.0010) were independent predictors of relapse, while node-positive status and subglottic-transglottic location were associated with higher risk for death.
CONCLUSION: In localized laryngeal cancer, clinicopathological parameters and an interaction of high mTOR and CCND1 mRNA expression were found to be associated with poor patient outcome.

Shu X, Lin J, Wood CG, et al.
Energy balance, polymorphisms in the mTOR pathway, and renal cell carcinoma risk.
J Natl Cancer Inst. 2013; 105(6):424-32 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
BACKGROUND: The interplay between obesity, physical activity, weight gain, and genetic variants in the mTOR pathway has not been studied in renal cell carcinoma (RCC). We examined the associations between obesity, weight gain, physical activity, and RCC risk. We also analyzed whether genetic variants in the mTOR pathway could modify the association.
METHODS: Incident RCC case subjects and healthy control subjects were recruited from the University of Texas MD Anderson Cancer Center in Houston, Texas. Case subjects and control subjects were frequency matched. Epidemiologic data were collected by in-person interview. One hundred ninety single nucleotide polymorphisms (SNPs) from 22 genes in the mTOR pathway were extracted from previous genome-wide association studies. Logistic regression and regression spline were performed to obtain odds ratios (ORs). All statistical tests were two-sided.
RESULTS: A total of 577 non-Hispanic white case subjects and 593 healthy control subjects were included. Obesity at age 20 years (OR = 1.92, 95% confidence interval [CI] = 1.05 to 3.50; P = .03) and age 40 years (OR = 2.03, 95% CI = 1.38 to 2.98; P < .001) and moderate (OR = 1.46, 95% CI = 1.02 to 2.09; P = .04) and massive weight gain (OR = 1.62, 95% CI = 1.10 to 2.39; P = .01) from age 20 to 40 years were each statistically significantly associated with increased RCC risk. Low physical activity was associated with a 4.08-fold increased risk. Among 190 SNPs in the mTOR pathway, six SNPs located in the AKT3 gene were statistically significantly associated with increased risk, and those with three or more unfavorable genotypes had a 1.72-fold increased risk of RCC.
CONCLUSION: Obesity, weight gain, physical activity, and genetic variants in the mTOR pathway may individually and jointly influence susceptibility to RCC.

Sarnat H, Flores-Sarnat L, Crino P, et al.
Hemimegalencephaly: foetal tauopathy with mTOR hyperactivation and neuronal lipidosis.
Folia Neuropathol. 2012; 50(4):330-45 [PubMed] Related Publications
BACKGROUND: Hemimegalencephaly (HME) is a hamartomatous malformation of one cerebral hemisphere. As this is a disorder of cellular growth and lineage, we sought evidence of an early ontogenetic disturbance of microtubular assembly or function.
MATERIAL AND METHODS: Three male infants with HME had brain resections for refractory epilepsy. One died postoperatively at 2.5 months and an autopsy was performed. Two were isolated cases and one has Proteus syndrome. The phosphorylated form of the microtubule-associated protein tau was studied, transmission electron microscopy (EM) was performed, and activation of the mTOR pathway was defined.
RESULTS: The hippocampus and neocortex of HME exhibited cytoarchitectural abnormalities and intense tau immunoreactivity. The post-mortem non-HME hemisphere exhibited sparse dysmorphic tau-reactive cortical neurones, intense only in the cingulate gyrus, a few isolated dysmorphic white matter neurons and none in subcortical structures. Numerous enlarged and dysmorphic cells exhibited P-4E-BP1 and phosphoribosomal P-S6 immunoreactivity, indicating mTOR activation. Control brains were negative for tau expression and mTOR activation. EM in each case showed abundant lipid in neurones and astrocytic end-feet on capillaries, and well-preserved mitochondria; oil red O in frozen sections and semi-thin sections also showed lipid storage by light microscopy.
CONCLUSIONS: Because HME tissue exhibited enhanced levels of phosphorylated tau protein and evidence of mTOR hyperactivation, we propose that the pathogenesis of HME may involve an early defect in microtubules, likely related to the AKT3 gene. Lipidosis of neurones and glia suggests metabolic impairment of yet undetermined type and relation to tauopathy in HME. Perinatal treatment of HME with everolimus theoretically is plausible.

Cheung M, Testa JR
Diverse mechanisms of AKT pathway activation in human malignancy.
Curr Cancer Drug Targets. 2013; 13(3):234-44 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
AKT/PKB (Protein Kinase B) are central proteins mediating signals from receptor tyrosine kinases and phosphatidylinositol 3-kinase. AKT kinases are involved in a number of important cellular processes including cell proliferation and survival, cell size in response to nutrient availability, tumor invasion/metastasis, and angiogenesis.Various components of the AKT signaling pathway are encoded by tumor suppressor genes and oncogenes whose loss or activation, respectively, plays an important role in tumorigenesis. The growing body of evidence connecting deregulated AKT signaling with sporadic human cancers and inherited cancer predisposition syndromes is discussed. We also highlight new findings regarding the involvement of activating mutations of AKT1, AKT2, and AKT3 in somatic overgrowth disorders: Proteus syndrome, hypoglycemia with hypertrophy, and hemimegalencephaly, respectively. In addition, we review recent literature documenting the various ways the AKT signaling pathway is activated in human cancers and consequences for molecularly targeted therapies.

Steiner P, Hora M, Stehlik J, et al.
Tubulocystic renal cell carcinoma: is there a rational reason for targeted therapy using angiogenic inhibition? Analysis of seven cases.
Virchows Arch. 2013; 462(2):183-92 [PubMed] Related Publications
Generally, patients with renal cell carcinoma (RCC) are viewed as potential candidates for antiangiogenic targeted therapy. Tubulocystic RCC (TCRC) is a recently described entity which may behave aggressively, and the rationale for antiangiogenic therapy in this group of renal tumors has yet to be determined. Seven TCRCs and five non-tumor tissue samples from seven patients were subjected to relative expression analysis of mRNA levels of 16 genes involved in three angiogenic signal pathways: (1) VHL/HIF, (2) RTK/mitogen-activated protein kinase (MAPK), and (3) PI3K/Akt/mTOR. Two of them, pathways (2) and (3), are often targeted by antiangiogenic agents. We also determined the mutation and methylation status of the VHL gene. Finally, the levels of vascular endothelial growth factor A (VEGFA), HIF-1α, HIF-2α proteins, and phosphorylated mTOR protein were also determined. The comparison of tumor and control samples revealed no changes of mRNA levels of the following genes: VHL, HIF-1α, HIF-2α, PTEN, Akt2, Akt3, mTOR, VEGFA, KDR, HRas, C-Jun, EGFR, and FGF2. Significantly elevated mRNA level of TP53 was found, while the mRNA levels of FLT1 and C-FOS were reduced in tumor samples. No mutations or methylation in the VHL gene were found. Changes in levels of studied proteins VEGFA, HIF-1α, HIF-2α, and increased phosphorylation of mTOR protein were not found. Three studied angiogenic pathways (VHL/HIF, RTK/MAPK, and PI3K/Akt/mTOR) seem not to be upregulated in TCRC samples, so there appears to be no rationale for a general recommendation of antiangiogenic targeted therapeutic protocols for patients with these tumors.

Williams SV, Hurst CD, Knowles MA
Oncogenic FGFR3 gene fusions in bladder cancer.
Hum Mol Genet. 2013; 22(4):795-803 [PubMed] Article available free on PMC after 17/09/2015 Related Publications
FGF receptor 3 (FGFR3) is activated by mutation or over-expression in many bladder cancers. Here, we identify an additional mechanism of activation via chromosomal re-arrangement to generate constitutively activated fusion genes. FGFR3-transforming acid coiled coil 3 (TACC3) fusions resulting from 4p16.3 re-arrangements and a t(4;7) that generates a FGFR3-BAI1-associated protein 2-like 1 (BAIAP2L1) fusion were identified in 4 of 43 bladder tumour cell lines and 2 of 32 selected tissue samples including the tumour from which one of the cell lines was derived. These are highly activated and transform NIH-3T3 cells. The FGFR3 component is identical in all cases and lacks the final exon that includes the phospholipase C gamma 1 (PLCγ1) binding site. Expression of the fusions in immortalized normal human urothelial cells (NHUC) induced activation of the mitogen-activated protein kinase pathway but not PLCγ1. A protein with loss of the terminal region alone was not as highly activated as the fusion proteins, indicating that the fusion partners are essential. The TACC3 fusions retain the TACC domain that mediates microtubule binding and the BAIAP2L1 fusion retains the IRSp53/MIM domain (IMD) that mediates actin binding and Rac interaction. As urothelial cell lines with FGFR3 fusions are extremely sensitive to FGFR-selective agents, the presence of a fusion gene may aid in selection of patients for FGFR-targeted therapy.

Girouard J, Lafleur MJ, Parent S, et al.
Involvement of Akt isoforms in chemoresistance of endometrial carcinoma cells.
Gynecol Oncol. 2013; 128(2):335-43 [PubMed] Related Publications
OBJECTIVE: In tumors, upstream regulation of Akt is affected by oncogenic events which lead to its constitutive activation and promote cell survival. Since studies have demonstrated that the three Akt isoforms exhibit different physiological functions, Akt isoforms may contribute differently in chemoresistance. The objective of the study was to determine the role of each Akt isoforms in chemoresistance.
METHODS: We stably transfected the chemoresistant KLE endometrial carcinoma cells with specific shRNAs for Akt1, Akt2 or Akt3. Alternatively, we stably transfected the chemosensitive Hec-1-A endometrial carcinoma cells, in which no Akt activity is detected, with constitutively active Akt expression vectors for each isoform.
RESULTS: We demonstrated that Akt1 and Akt2 downregulation by RNAi highly sensitizes KLE cells to cisplatin by inducing the activation of pro-apoptotic factors such as the cleavage of caspases-3, -6, -9 and PARP; downregulation of all Akt isoforms leads to increased sensitivity to doxorubicin while only Akt1-2 downregulation increases taxol sensitivity. Proliferation of Akt1, and mostly Akt2 deficient cells was affected by cisplatin treatment. Constitutive Akt1 or Akt2 expression led to an increased resistance to apoptosis. Akt isoforms have been shown to influence migration in other cancer cells. We showed that Akt2 blocks cell motility, while Akt1-3 had less effect on our endometrial cancer cell models.
CONCLUSION: Our findings highlight the contribution of Akt1 and Akt2 in the molecular mechanisms that govern chemoresistance of endometrial carcinomas. Furthermore, Akt isoform-specific transfectants will provide a strong model to determine the involvement of each Akt isoform in tumor progression and metastasis.

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