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BRAFV600E cooperates with PI3K signaling, independent of AKT, to regulate melanoma cell proliferation.

ABSTRACT: Mutationally activated BRAF(V600E) cooperates with PTEN silencing in the conversion of normal melanocytes to metastatic melanoma cells, but the mechanism underlying this cooperation is poorly understood. Here, the consequences of pharmacologic blockade of BRAF(V600E) or phosphoinositide 3-kinase (PI3K) signaling were explored using pathway-targeted inhibitors and a panel of human BRAF-mutated melanoma-derived cell lines. Blockade of BRAF(V600E) ? MEK1/2 ? ERK1/2 or class I PI3K inhibited melanoma proliferation, whereas inhibition of AKT had only modest effects, even in cells with mutated or amplified AKT. Although single-agent inhibition of either BRAF(V600E) or PI3K signaling elicited antiproliferative effects, combinatorial inhibition was more potent. Analysis of signaling downstream of BRAF(V600E) or PI3K revealed that these pathways cooperated to regulate protein synthesis through AKT-independent, mTOR complex 1 (mTORC1)-dependent effects on p70(S6K), ribosomal protein S6, and 4E-BP1 phosphorylation. Moreover, inhibition of mTORC1/2 inhibited cell proliferation as profoundly as single-agent inhibition of either BRAF(V600E) or PI3K signaling. These data reveal a mechanism by which BRAF(V600E) and PI3K signaling cooperate to regulate melanoma proliferation through AKT-independent effects on protein translation. Furthermore, this study provides a potential foundation for pathway-targeted combination therapy designed to enhance the therapeutic benefit to patients with melanoma that contain combined alterations in BRAF and PI3K signaling.PI3K, but not AKT, represent potential targets for melanoma therapy.

SUBMITTER: Silva JM

PROVIDER: S-EPMC3966216 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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BRAFV600E cooperates with PI3K signaling, independent of AKT, to regulate melanoma cell proliferation.

Silva Jillian M JM Bulman Christina C McMahon Martin M

Molecular cancer research : MCR 20140114 3

<h4>Unlabelled</h4>Mutationally activated BRAF(V600E) cooperates with PTEN silencing in the conversion of normal melanocytes to metastatic melanoma cells, but the mechanism underlying this cooperation is poorly understood. Here, the consequences of pharmacologic blockade of BRAF(V600E) or phosphoinositide 3-kinase (PI3K) signaling were explored using pathway-targeted inhibitors and a panel of human BRAF-mutated melanoma-derived cell lines. Blockade of BRAF(V600E) → MEK1/2 → ERK1/2 or class I PI3 ...[more]

PMID: 24425783

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Project description:Proliferation is one of the significant hallmarks of gallbladder cancer, which is a relatively rare but fatal malignance. Aim of this study was to examine the biological impact and molecular mechanism of the candidate hub-gene on the proliferation and tumorigenesis of gallbladder cancer. We analyzed the differentially expressed genes and the correlation between these genes with MKI67, and showed that KIF11 is one of the major upregulated regulators of proliferation in gallbladder cancer (GBC). The Gene Ontology, Gene Sets Enrichment Analysis and KEGG Pathway analysis indicated that KIF11 may promote GBC cell proliferation through the ERBB2/PI3K/AKT signaling pathway. Gain-of-function and loss-of-function assay demonstrated that KIF11 regulated GBC cell cycle and cancer cell proliferation in vitro. GBC cells exhibited G2M phase cell cycle arrest, cell proliferation and clone formation ability reduction after treatment with Monastrol, a specific inhibitor of KIF11. Xenograft model showed that KIF11 promotes GBC growth in vivo. Rescue experiments showed that KIF11-induced GBC cell proliferation dependented on ERBB2/PI3K/AKT pathway. Moreover, we found that H3K27ac signals are enriched among the promoter region of KIF11 in the UCSC Genome Browser Database. Differentially expressed analysis showed that EP300, a major histone acetyltransferase modifying H3K27ac signal, is highly expressed in gallbladder cancer and correlation analysis illustrated that EP300 is positively related with KIF11 in almost all the cancer types. We further found that KIF11 was significantly downregulated in a dose-dependent and time-dependent manner after histone acetylation inhibitor treatment. The present results highlight that high KIF11 expression promotes GBC cell proliferation through the ERBB2/PI3K/AKT signaling pathway. The findings may help deepen our understanding of mechanism underlying GBC cancer development and development of novel diagnostic and therapeutic target.

Project description:BackgroundEsophageal cancer is still a leading cause of death among all tumors in males, with unsatisfactory responses to novel immunotherapies such as anti-PD-1 agents. Herein, we explored the role of CD155 in esophageal squamous cell cancer (ESCA) and its underlying molecular mechanisms.MethodsPublicly available datasets were used for differential gene expression and immune infiltration analyses, and their correlation with patient survival. A total of 322 ESCA and 161 paracancer samples were collected and evaluated by performing immunohistochemistry and the H score was obtained by performing semiquantitative analysis. In vitro transfection of ESCA cell lines with lentivirus vectors targeting CD155 was performed to knockdown the protein. These cells were analyzed by conducting RNA sequencing, and the effects of CD155 knockdown on cell cycle and apoptosis were verified with flow cytometry and Western blotting. In addition, in vivo experiments using these engineered cell lines were performed to determine the role of CD155 in tumor formation. A small interfering RNA-mediated knockdown of Nectin3 was used to determine whether it phenocopied the profile of CD155 knockdown.ResultsCD155 is highly expressed in ESCA tissues and is positively associated with PD1, PDL1, CD4, IL2RA, and S100A9 expression. Furthermore, CD155 knockdown inhibited ESCA cells' proliferation by impairing the cell cycle and inducing cell apoptosis. Bioinformatics analysis of the gene expression profile of these engineered cells showed that CD155 mainly contributed to the regulation of PI3K/Akt and MAPK signals. The downregulation of Nectin3 expression phenocopied the profile of CD155 knockdown.DiscussionCD155 may cooperate with PD-1/PD-L1 to support ESCA proliferation in ways other than regulating its underlying immune mechanisms. Indeed, CD155 downregulation can impair ESCA cell pro-cancerous behavior via the inhibition of the PI3K/Akt and MAPK signaling pathways. Moreover, Nectin3 may be a ligand of CD155 and participate in the regulation of ESCA cells' proliferation. Hence, the inhibition of CD155 may enhance the therapeutic effect of anti-PD-1 immunotherapies in ESCA.

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Dataset Information

BRAFV600E cooperates with PI3K signaling, independent of AKT, to regulate melanoma cell proliferation.

Publications

BRAFV600E cooperates with PI3K signaling, independent of AKT, to regulate melanoma cell proliferation.

Similar Datasets

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