Sirolimus induces apoptosis and reverses multidrug resistance in human osteosarcoma cells in vitro via increasing microRNA-34b expression

Abstract

Aim: Multi-drug resistance poses a critical bottleneck in chemotherapy. given the up-regulation of mToR pathway in many chemoresistant cancers, we examined whether sirolimus (rapamycin), a first generation mTOR inhibitor, might induce human osteosarcoma (os) cell apoptosis and increase the sensitivity of os cells to anticancer drugs in vitro. Methods: human os cell line Mg63/aDM was treated with sirolimus alone or in combination with doxorubicin (aDM), gemcitabine (GEM) or methotrexate (MTX). Cell proliferation and apoptosis were detected using CCK-8 assay and flow cytometry, respectively. MiRnas in the cells were analyzed with miRna microarray. The targets of miR-34b were determined based on Targetscan analysis and luciferase reporter assays. The expression of relevant mRna and proteins was measured using qRT-PCR and Western blotting. MiR-34, PaK1 and aBCB1 levels in 40 tissue samples of os patients were analyzed using qRT-PCR and in situ hybridization assays. Results: Sirolimus (1−100 nmol/L) dose-dependently suppressed the cell proliferation (IC 50 =23.97 nmol/L) and induced apoptosis. Sirolimus (10 nmol/L) significantly sensitized the cells to anticancer drugs, leading to decreased IC 50 values of aDM, geM and MTX (from 25.48, 621.41 and 21.72 μmol/L to 4.93, 73.92 and 6.77 μmol/L, respectively). Treatment of with sirolimus increased miR-34b levels by a factor of 7.5 in the cells. upregulation of miR-34b also induced apoptosis and increased the sensitivity of the cells to the anticancer drugs, whereas transfection with miR-34b-aMo, an inhibitor of miR-34b, reversed the anti-proliferation effect of sirolimus. Two key regulators of cell cycle, apoptosis and multiple drug resistance, PaK1 and aBCB1, were demonstrated to be the direct targets of miR-34b. In 40 tissue samples of OS patients, significantly higher miR-34 ISH score and lower PAK5 and ABCB1 scores were detected in the chemo-sensitive group. Conclusion: sirolimus increases the sensitivity of human os cells to anticancer drugs in vitro by up-regulating miR-34b interacting with PaK1 and aBCB1. a low miR-34 level is an indicator of poor prognosis in os patients.

The roles of microRNA-34b-5p in angiogenesis of thyroid carcinoma

“…Regulation of Notch1 signalling pathways, as well as downstream effects on Bcl-2 and VEGF-A further, attributes to the mechanism behind miR-34b-5p induced cell cycle, apoptotic and angiogenic changes in thyroid carcinoma cells. As miR-34b-5p increases cell death in different carcinomas, miR-34b-5p induced apoptotic changes might be a common event in the pathogenesis of cancer [50][51][52]. Thus, our results further confirm the tumour suppressor role for miR-34b-5p in thyroid carcinomas.…”

Sulforaphane suppresses EMT and metastasis in human lung cancer through miR-616-5p-mediated GSK3β/β-catenin signaling pathways

“…Mechanically, microRNAs have been shown to be involved in the anti-cancer effect of natural plant extracts. miRNAs have various functions, such as induction of apoptosis [18] , anti-metastasis [19] , antiangiogenesis [20] , proliferation inhibition [21] and suppression of cancer stem-like cells [22] . Combining the microarray data with TCGA data, we identified miR-616-5p as a prominent regulator of NSCLC progression.…”

Targeting the Mammalian Target of Rapamycin in Lung Cancer

“…Interestingly, decreased expression of miR-34b was detected in samples of chemoresistant osteosarcoma patients when compared to chemosensitive samples. 44 miR-147 is upstream of mTOR and suppresses mTOR-mediated proliferation, invasion and migration of breast cancer cells. 45 Selective knockdown of miR-208, which targets mTOR, inhibited growth and sensitivity to radio-resistance in lung cancer cells.…”