UHRF1与耐药乳腺癌细胞侵袭转移相关性的研究

Clinical and experimental data indicate that the multidrug resistant phenotype is often accompanied by tumor metastasis are the main causes of treatment failure and increased mortality in cancer patients. However, the mechanisms underlying these observations are still unclear. Our pre-experiments found that during the development of drug resistance to adriamycin in MCF-7 cells, the down-regulation of UHRF1 coincides with the promotion of drug resistance as well as increase of cells migrative and invasive abilities in vitro. Therefore, it is assumed that UHRF1 may play a critical role in this process. Here we establish breast carcinoma cell lines up- or down-regulation of UHRF1 expression, and xenograft in nude mouse to investigate the impact of UHRF1 on the multidrug resistant and metastatic potentials of human breast carcinoma cells, and its possible mechanisms also be considered. Moreover, immunohistochemistry was performed in breast carcinoma samples to investigate UHRF1 expression and its correlation with the expression of P-gp, CD147 and MMPs, and the clinicopathological indicators. Our findings will not only provide further insight into the mechanism underlying the functional linkage between drug resistance and tumor metastasis, but also in an effort to provide new strategies for reversal of drug resistance and prevention and treatment of tumor metastasis.

实验研究和临床数据表明，肿瘤细胞对化疗药物产生耐药性的同时，其侵袭转移能力也有所增强，导致临床肿瘤治疗障碍重重，但其机制尚未完全阐明。申请者预实验发现体外阿霉素诱导人乳腺癌细胞（MCF-7）产生耐药性的过程中，UHRF1的表达下调与乳腺癌细胞耐药性的增强和侵袭、迁移能力的提高密切相关，因此推测UHRF1可能在上述过程中起着重要的调控作用。本课题拟通过体外UHRF1基因转染、UHRF1 RNA干扰人乳腺癌细胞以及构建裸鼠移植瘤模型，明确其对人乳腺癌细胞耐药性和侵袭转移能力的影响及其分子机制；并通过人乳腺癌标本的免疫组化检测来观察UHRF1的表达与P-gp、CD147和MMPs表达的相关性，及其与临床病理参数的关系。这些结果不仅为加深理解肿瘤耐药与侵袭转移相关机理奠定基础，而且可为逆转耐药和防治肿瘤转移提供新的策略。

研究发现作为表观遗传调控因子的UHRF1在肿瘤的发生发展过程中起重要的调节作用，但其在乳腺癌进展和转移中的作用及机制尚未十分明确。我们的研究结果显示UHRF1在正常乳腺上皮呈微弱表达或基本无表达，但其表达水平随着侵袭性乳腺癌恶性程度的增加而升高，Kaplan-Meier生存分析揭示，UHRF1的高表达与乳腺癌患者较短的无病生存期和总生存期之间有显著相关性。在高侵袭性的乳腺癌细胞中下调UHRF1的表达，能够抑制乳腺癌细胞的增殖，诱导细胞由间质样形态向上皮样形态转化（MET），抑制细胞的侵袭和迁移，使用下调UHRF1表达的乳腺癌细胞构建裸鼠移植瘤模型，发现UHRF1抑制组移植瘤生长较对照组明显减慢，肿瘤的体积和重量明显下降，局部侵袭和远处转移明显减少，且细胞增殖指标和间质相关指标的表达下调，上皮相关指标表达上调，说明UHRF1在乳腺癌细胞中具有调节细胞侵袭转移和增殖的作用。进一步的机制研究显示UHRF1能够与MET调控因子ZEB1的启动子区相结合，调控ZEB1的表达，影响人乳腺癌细胞的MET和侵袭转移；western blot检测细胞信号通路关键蛋白的表达，发现Wnt/β-catenin、MAPK/Erk和MAPK/p38信号通路，可能是UHRF1调节乳腺癌细胞生长和侵袭转移的主要信号通路。综上所述，UHRF1是抑制乳腺癌细胞增殖和侵袭转移的潜在靶点。