MicroRNA-302b targets Mcl-1 and inhibits cell proliferation and induces apoptosis in malignant pleural mesothelioma cells.

MicroRNAs belonging to the miR-302 family are emerging as key players in the control of cell growth, and maintaining pluripotency during cell fate determination and differentiation in embryonic stem cells. However, the mechanisms whereby ephA2/ephirnA1 signaling regulates miR-302b expression and attenuates malignant pleural mesothelioma (MPM) cell growth are not known. Our study identified a novel mechanism of ephrin-A1 mediated anti-oncogenic signaling in MPM. Ephrin-A1 treatment up regulates miR-302b expression in MPM cells and attenuates cell proliferation and tumorsphere formation via repression of myeloid cell leukemia-1 (Mcl-1). The expression of miR-302b was analyzed by qPCR, the expression of Mcl-1 was analyzed by RT-PCR, immuno-blotting and Immunofluorescence staining. To confirm that ephrin-A1 regulates the expression of Mcl-1 mRNA through miR-302b up regulation, cells were transfected with and without miR-302b and miR-302b inhibitor prior to ephrinA1 treatment. The cell proliferation and tumorsphere formation was measured by WST-1 and matrigel assays respectively. In addition, to confirm the binding of miR-302b to the 3'UTR of Mcl-1 Luciferase assay was performed. Ephrin-A1 treatment induced several fold increases of miR-302b expression in MM cells. In ephrin-A1 treated MM cells, Mcl-1 expression was significantly down regulated when compared to control. Moreover, ephrin-A1 activation significantly inhibited MM cell proliferation and tumorsphere growth. Furthermore, ephrinA1 and miR-302b induced apoptosis in MM cells. The present data suggests that ephrin-A1 induces the expression of miR-302b in MM cells which targets Mcl-1 thereby inhibits MM tumorsphere growth by inducing apoptosis.