The miR-491-3p/mTORC2/FOXO1 regulatory loop modulates chemo-sensitivity in human tongue cancer.

Abstract

We found that levels of miR-491-3p were decreased in multidrug-resistant tongue cancer (TC) cells. Induction of miR-491-3p expression sensitized TC cells to chemotherapy. In agreement, functional inhibition of miR-491-3p enhanced resistance of TC cells to chemotherapy. We found that miR-491-3p directly targeted mTORC2 component Rictor and inhibited mTORC2 activity, which was increased in resistant TC cells with high p-Akt(Ser473), p-SGK1(Ser422) and p-FOXO1(Thr24) levels. Inhibition of mTORC2 activity via either Rictor knockdown or mTOR inhibitor in turn sensitized TC cells to chemotherapy. In agreement, overexpression of Rictor increased the mTORC2 activity and induced resistance of TC cells to chemotherapy. As a feedback loop, mTORC2 downregulated miR-491-3p expression by inactivating FOXO1, which otherwise would transcriptionally induce miR-491-3p expression. Levels of miR-491-3 and Rictor or mTORC2 activity negatively correlated in TC tissues. Finally, low levels of miR-491-3p and highly expressed Rictor were associated with poor prognosis in tongue cancer patients. These data provide a rationale for targeted intervention on miR-491-3p/mTORC2 axis to enhance the efficacy of chemotherapy against tongue cancer.

• Authors: Guopei Zheng, Xiaoting Jia, Cong Peng, Yingen Deng, Jiang Yin, Zhijie Zhang, Nan Li, Min Deng, Xiaorong Liu, Hao Liu, Minying Lu, Chengkun Wang, Yixue Gu, Zhimin He
• Journal: Oncotarget (Oncotarget) Vol. 6 Issue 9 Pg. 6931-43 (Mar 30 2015) ISSN: 1949-2553 [Electronic] United States
• PMID: 25749387 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents
• FOXO1 protein, human
• Forkhead Box Protein O1
• Forkhead Transcription Factors
• MIRN491 microRNA, human
• MicroRNAs
• Multiprotein Complexes
• Mechanistic Target of Rapamycin Complex 2
• Proto-Oncogene Proteins c-akt
• TOR Serine-Threonine Kinases

Topics

• Antineoplastic Agents (chemistry)
• Drug Resistance, Neoplasm
• Forkhead Box Protein O1
• Forkhead Transcription Factors (genetics, metabolism)
• Gene Expression Profiling
• Gene Expression Regulation, Neoplastic
• Humans
• Mechanistic Target of Rapamycin Complex 2
• MicroRNAs (genetics, metabolism)
• Multiprotein Complexes (genetics, metabolism)
• Prognosis
• Proto-Oncogene Proteins c-akt (metabolism)
• Signal Transduction
• TOR Serine-Threonine Kinases (genetics, metabolism)
• Tongue Neoplasms (metabolism)