抑癌基因LKB1与乳腺癌他莫昔芬耐药性之间的关系

The relationship between tumor suppressor LKB1 and tamoxifen resistance of breast cancer

目的:研究抑癌基因LKB1对乳腺癌他莫昔芬耐药的影响及机制。方法:运用免疫组化技术对68例乳腺癌组织中LKB1、雌激素受体(ER)和孕激素受体(PR)的表达进行检测,并且利用GEPIA数据库验证实验结果;利用Kaplan-Meier Plotter数据库分析LKB1基因与ER/PR阳性的Luminal A/B亚型乳腺癌预后之间相关性;运用实时定量PCR、免疫印迹和免疫荧光技术分析LKB1在他莫昔芬耐药细胞系中的表达及定位;运用免疫印迹和免疫荧光技术分析他莫昔芬对LKB1表达及定位的影响。结果:在乳腺癌中LKB1与ER/PR的表达呈现显著的正相关性,ER/PR(+++)和ER/PR(+)两组间LKB1的表达差异具有显著的统计学意义(P<0.001);LKB1的表达量与乳腺癌预后呈现正相关性,在Luminal A/B亚型的乳腺癌中LKB1表达越低其预后越差;在他莫昔芬耐药细胞系及对照细胞中LKB1的mRNA和蛋白表达量差异无统计学意义,但是在耐药细胞中LKB1的定位发生了从细胞质向细胞核的移行;在体外他莫昔芬能够诱导LKB1表达并且促进LKB1从细胞质向细胞核的移行。结论:在Luminal A/B亚型的乳腺癌中,LKB1的低表达是一种不良预后的指标,并且该蛋白从细胞质向细胞核的移行与乳腺癌他莫昔芬耐药密切相关,而耐药与蛋白的表达量无关。

Objective ：To investigate the effect of LKB1 on tamoxifen resistance, and the underlying mechanism. Methods ：The expression level of LKB1 and ER/PR in 68 cases of breast cancer tissue sample were analyzed by im-munohistochenfistry,and the relationship between LKB1 and ER/PR was validated with GEPIA database. Then, we used Kaplan-Meier Plotter database to analyze the relationship between LKB1 expression and relapse free survival of LuminalA/B breast cancer. Real-time quantitative PCR, Western blot and immunofluorescence was conducted to de-termine the expression and location of LKB1 in tamoxifen resistance cell lines. Western blot and inmmnofluorescence was used to examine the impacts of tamoxifen on LKB1 expression and localization. Results ： LKB1 expression was sig-nificant positive correlation with EPCPR status in breast cancer. LKB1 expression was highly expressed in EPCPR（ ＋ ＋ ＋ ） than that ER/PR（ ＋ ） breast cancer tissues（P 〈 0.001 ）. The Kaplan- Meier survival analysis demonstrated LKB1 expression associated with relapse free survival of Luminal A/B subtype of breast cancer. Next, RT-PCR and Western blot assays showed that the mRNA and protein expression of LKB1 was no significant difference in tamoxifen-resistant cell lines and control cells,but the localization of LKB1 was change from the cytoplasm to the nucleus in tamoxifen-resistant cells. Finally, tamoxifen increased the level of LKB1 expression in vitro, meanwhile the location of LKB1 was change from the cytoplasm to the nucleus. Conclusion：The results indicated that the low expression of LKB1 is an indicator of poor prognosis in Luminal A/B subtype of breast cancer,and the migration of LKB1 from the cytoplasm to the nucleus was closely related to tamoxifen resistance in breast cancer.