TNF-α/miR-5001-5p/Mnk2a通路在三阴性乳腺癌侵袭转移中的作用及机制研究

Triple negative breast cancer (TNBC) is prone to invasion and metastasis with poor prognosis. Tumor necrosis factor alpha (TNF-α) is closely related to distant metastasis of TNBC, but the mechanism is unknown. We found in the early stage that: ① TNF-α significantly promote the invasion and migration of TNBC compared with non-TNBC; ② unlike non-TNBC，TNF-α significantly up-regulated miR-5001-5p in TNBC cells；its target gene mitogen-activated protein kinase action kinase 2a (Mnk2a) was significantly down-regulated. It is known that down-regulation of Mnk2a expression in breast cancer can activate the p38 MAPK pathway to exert a tumor suppressor effect, which can inhibit the invasion and metastasis of breast cancer. Therefore, we believe that TNF-α can down-regulate Mnk2a expression in TNBC cells by up-regulating miR-5001-5p, thereby inhibit the activation of p38 MAPK signaling pathway and promote the invasion and metastasis of TNBC. This project will use TNBC as the research object, and explore the mechanism of miR-5001-5p targeting Mnk2a to promote the invasion and metastasis of TNBC and its effect on p38 MAPK pathway under the intervention of TNF-α, provide a theoretical basis and new targets for TNBC targeted therapy.

三阴性乳腺癌（TNBC）易侵袭转移，预后差。肿瘤坏死因子α（TNF-α）与TNBC远处转移密切相关，但机制不明。我们前期研究提示：①与非TNBC相比，TNF-α更易促进TNBC侵袭迁移；②不同于非TNBC，TNF-α作用于TNBC细胞后，miR-5001-5p显著上调；而miR-5001-5p可抑制其靶基因有丝分裂原活化蛋白激酶作用激酶2a（Mnk2a）并促进TNBC细胞侵袭迁移。已知Mnk2a可激活p38 MAPK通路，而该通路可抑制乳腺癌侵袭转移。因此我们认为，TNF-α可通过调控miR-5001-5p/Mnk2a通路抑制p38 MAPK活化而促进TNBC侵袭转移。本项目将以TNBC为研究对象，从分子、细胞、动物及临床层面探讨TNF-α通过miR-5001-5p靶向抑制Mnk2a，进而抑制p38 MAPK通路促进TNBC侵袭转移的机制，以期为TNBC靶向治疗提供理论基础和潜在的新靶点。

现有研究结果表明TNF-α可能在三阴性乳腺癌（triple negative breast cancer，TNBC）的进展和远处转移中起着独特的作用但具体机制尚不明确。在本研究中我们分析了TNF-α影响三阴乳腺癌侵袭迁移能力的机制。我们研究结果发现与非TNBC细胞相比，TNF-α在15ng/ml时促进TNBC细胞侵袭迁移的能力更强。进一步miRNA表达谱差异分析发现，在经TNF-α处理后，与非TNBC细胞相比，TNBC细胞中miR-5001-5p表达水平显著性增高，并且在添加/不添加TNF-α情况下，均为上调miR-5001-5p可以促进TNBC细胞侵袭迁移，而下调miR-5001-5p则可抑制TNBC细胞侵袭迁移，提示TNF-α可通过miR-5001-5p影响TNBC细胞侵袭迁移。同时，用miR-5001-5p mimic转染MDA-MB-231细胞后，结合转录组结果提示Mnk2a可能是miR-5001-5p的靶基因。我们同时借助双荧光素酶报告基因系统发现，miR-5001-5p可以通过与Mnk2a mRNA 3’UTR区域相结合抑制Mnk2a的表达。而作为一种丝氨酸/苏氨酸蛋白激酶，Mnk2a可以使p38MAPK蛋白磷酸化进而激活p38MAPK通路抑制细胞侵袭迁移。综上所述，我们发现了TNF-α影响三阴乳腺癌侵袭迁移能力的可能的机制。我们研究结果表明TNF-α可以通过上调miR-5001-5p水平抑制Mnk2a的表达进而促进三阴性乳腺癌细胞侵袭迁移。TNF-α/miR-5001-5p/Mnk2a通路有望成为针对三阴性乳腺癌治疗的有效靶点。