组蛋白乙酰化修饰对瘦素诱导的乳腺癌MDA-MB-231细胞生长的影响

Histone Acetylation Involved in Leptin-induced Proliferation of Breast Cancer MDA-MB-231 Cells

目的:研究组蛋白乙酰化修饰对瘦素诱导的乳腺癌MDA-MB-231细胞生长的影响。方法:采用实时定量PCR、Western blot法测定瘦素和组蛋白去乙酰化酶(histone deacetylase,HDAC)抑制剂SAHA对乳腺癌MDA-MB-231细胞生长的影响。应用染色质免疫沉淀(chromatin immunoprecipitation,Ch IP)技术了解瘦素和SAHA影响组蛋白乙酰化水平的程度。结果:瘦素与乳腺癌MDA-MB-231细胞作用后HDAC1的mRNA和蛋白表达明显增强,并伴有组蛋白H3、H4乙酰化水平降低(P<0.05)。ChIP结果显示瘦素处理的乳腺癌细胞p21^(WAF/CIP1)启动子区域与乙酰化组蛋白H3、H4结合的染色质物质明显少于未处理细胞组的相同区域(P<0.05)。结论:瘦素诱导乳腺癌细胞增殖过程中伴随组蛋白乙酰化水平的变化,通过激活HDAC的活性使核心组蛋白去乙酰化,从而抑制p21^(WAF/CIP1)的表达,最终促进细胞周期从G1→S期的进程。

Objective： To study the role of histone aeetylation on Leptin-indueed proliferation of breast cancer MDA-MB-231 cells. Methods： Quantitative real-time PCR and Western blot were used to measure the effects of Leptin and SAHA （a histone deaeetylase inhibitor） on proliferation of breast cancer MDA-MB-231 cells. Chromatin immunopreeipitation （CHIP） was used to detect the levels of histone aeetylation after Leptin and SAHA treatment. Results： Leptin significantly enhanced the HDAC1 activity in MDA-MB-231 cells, accompanied with lower levels of histone H3 and H4 acetylation （P 〈 0.05） . ChIP analysis showed that activated HDAC1 reduced the load of aeetylated histones （H3 and H4） to the p21^WAF/CIP1 promoter, which significantly decreased the expression levels of p21^WAF/CIP1 mRNA and protein （P 〈 0.05）, and accelerated the cell cycle progression. Conclusion： Leptin＇s effects on MDA-MB-231 cells are associated with HDAC1 activation, which decrease H3/H4 aeetylation status and restrains the effects of p21^WAF/CIP1 on cell cycle, thereby contributing to triple-negative breast carcinogenesis.