miR-7调控TGFB2/PDGFC的表达促进耐药黑素瘤CAFs活化的机制研究

Since the FDA approval of vemurafenib for the treatment of disseminated melanoma in 2011, melanoma has become the poster child for targeted kinase therapy. Despite encouraging initial clinical responses, most patients ultimately develop drug resistance and relapse. Besides genetic or epigenetic changes in tumor itself, more and more focus has shifted from studying cell-autonomous modes of resistance to determining the impact of the tumor microenvironment on drug sensitivity. Infiltrated and surrounding fibroblasts in the tumor microenvironment, termed CAFs, have the ability to synthesize, deposit and remodel the ECM and produce cytokines and growth factors, which all together promote the transformation process by encouraging tumor growth, angiogenesis and inflammation and contribute to drug resistance. The goal of this study was to identify the mechanisms that underpin the differential infiltration and activation of CAFs in vemurafenib-resistant melanoma and to determine the relevance of these observations to human disease. In the previous study, we found that infiltrating αSMA-positive CAFs decrease in the miR-7 transfested RA375 tumor than the control group, which suggests miR-7 could inhibit the activation of CAFs surrounding vemurafenib-resistant melanoma. Mechanistically, we discovered that TGFB2 and PDGFC are potential targets of miR-7. More importantly, our preliminary results suggest that TGFB2 and PDGFC are highly expressed in the conditioned medium in the miR-7 transfested group and these two cytokines are required for activation of CAFs. Therefore, we propose current study to further determine the role of miR-7/ TGFB2 and PDGFC/ activation of CAFs in the miRNA regulatory axis of resistant melanoma. These studies will deepen our understanding of miRNAs in the pathogenesis of CAFs of resistant melanoma, and establish miR-7/ TGFB2 and PDGFC/ activation of CAFs pathway as a candidate target for resistant melanoma therapy.

自vemurafenib用于治疗黑素瘤以来，黑素瘤的治疗现状极大改善了。但绝大多数患者最终出现耐药。除肿瘤本身基因或表观遗传学的改变导致耐药，肿瘤微环境也参与了耐药。肿瘤微环境中的成纤维细胞CAFs，通过合成、沉积和重塑细胞外间质，产生促癌的细胞因子、生长因子，促进血管生成等方式促使肿瘤耐药。本研究试图阐明耐药黑素瘤中CAFs是如何活化以及CAFs活化与肿瘤进展相关性。前期实验中，我们发现转染miR-7的耐药黑素瘤RA375的裸鼠成瘤组织中，提示CAFs活化的蛋白αSMA降低。miR-7表达下降引起TGFB2和PDGFC的表达增加，后者通过旁分泌的方式促进CAFs活化，而CAFs活化进一步促进耐药黑素瘤的增殖和转移。这些研究将增加我们对黑素瘤耐药过程中CAFs活化及微环境-肿瘤相互作用的认识，从而建立miR-7/TGFB2和PDGFC/活化CAFs这一信号通路为靶点的理论基础。

自vemurafenib用于治疗黑素瘤以来，黑素瘤的治疗现状极大改善了。但绝大多数患者最终出现耐药。除肿瘤本身基因或表观遗传学的改变导致耐药，肿瘤微环境也参与了耐药。肿瘤微环境中的成纤维细胞CAFs，通过合成、沉积和重塑细胞外间质，产生促癌的细胞因子、生长因子，促进血管生成等方式促使肿瘤耐药。本研究试图阐明耐药黑素瘤中CAFs是如何活化以及CAFs活化与肿瘤进展相关性。实验结果表明，我们发现转染miR-7的耐药黑素瘤RA375的裸鼠成瘤组织中，提示CAFs活化的蛋白αSMA降低。转染了miR-7的耐药细胞RA375中TGFB2和PDGFC的表达降低。我们用ELISA方法分析耐药细胞RA375转染miR-7后的培养基中TGFB2和PDGFC的表达情况，发现转染了miR-7的耐药细胞RA375的培养基中TGFB2和PDGFC的表达降低。TGFB2和PDGFC通过旁分泌的方式促进CAFs活化，而CAFs活化进一步促进耐药黑素瘤的增殖和转移。这些研究将增加我们对黑素瘤耐药过程中CAFs活化及微环境-肿瘤相互作用的认识，从而建立miR-7/TGFB2和PDGFC/活化CAFs这一信号通路为靶点的理论基础。