The secretary miR-141 facilitates ovarian cancer metastasis through reprogramming stromal fibroblast cells in pre-metastatic niches formation

Abstract

Introduction: Regardless of the modern advances in cancer therapeutics, cancer metastasis is still a major obstacle in the clinical management of ovarian cancer. Emerging evidence discloses that exosomal miRNAs act as critical roles in multiple cancer development process including cancer metastasis. One of the possibiliy is the secretary miRNAs mediating communications between tumor cells and their tumor microenvironment.However, the functions and mechanisms of miRNAs in regulating cancer metastasis are not fully understood. We have previously identified that Hsa-miR-141 (miR-141) is not only aberrantly expressed in aggressive ovarian cancer but also enhances anoikis resistance in metastatic progression of ovarian cancer through targeting KLF12/SP1/Survivin axis. Here, we report that miR-141 is also an tumor secretary miRNA which is capable of remodeling the stromal cells to facilitate the formation of pre-metastatic niches for ovarina cancer metastasis. Materials and methods: Conditioned media collected from both ovarian cancer cell lines such as A2780cp, CAOV3, COV318, COV413, COV362, ES2, SKOV3, OVKATE, OVMANA, OVSAHO and HEY and stromal fibroblast cell lines such as WPMY-1 and T-HESCs with miR-141 overexpressed were used in functional studies to evaluate the oncogenic reprogramming effect of miR-141. The molecular mechanism of miR-141 mediated reprogramming was examined by LC/MS MS proteomic analysis, QPCR and Western blot analysis. Results and discussion: miR-141 was not only frequently overexpressed in ovarian cancer cells but also secreted to the surrounding through the exosomal pathway. The exosomal miR-141 could be uptaken by other cell types found in the tumor microenvironment of ovarian cancer cells. However, functional and biochemical analyses revealed that miR-141 reprogram enables to reprogram the stromal cells solely because miR-141-exressing stromal cells show an significant increased secretion of cytokines GRO-α and EMMPRIN in their culture conditioned media. Of note, ovarian cancer cells co-cultured with such conditioned media, or the recombinant proteins of GRO-α and EMMPRIN exhibited a remarkable increase in cell proliferation, cell migration and cell invasion capacities in a dose-dependent manner. Further analysis using proteomic profiling on the miR-141 reprogrammed stromal cells identified Yes Associated Protein 1 (YAP1), a key downstream effector of the Hippo pathway, is remarkably suppressed in its expression by miR-141. Depletion of YAP1 in stromal cells led to increased expression of GRO-α and EMMPRIN in the conditioned media as detected similarly in miR-141 expressing stromal cells, whereas restoration of YAP1 attenuated such escalated secretion, indicating that the reduction of YAP1 might favor YAP/TAZ/TEAD transcriptional complex in upregulation of the transcriptional ativities of GRO-α and EMMPRIN. However, further investigations for understanding the functional roles of YAP1 and YAP/TAZ/TEAD in cytokine production in stromal cells are warranted. Conclusion: Our preliminary findings suggest that the exosomal miR-141 could reprogram the stromal cells through altering Hippo/YAP1 signaling in production of GRO-α and EMMPRIN from stromal cells in facilitating metastatic colonization of ovarian cancer cells.