蛋白4.1家族在不同乳腺癌细胞株中的表达与定位

Expression and subcellular location of protein 4.1 in breast cancer cells with different metastatic capability

背景与目的:目前,已在多种人类肿瘤中发现蛋白4.1家族成员表达异常。本研究旨在通过检测蛋白4.1家族成员(4.1R/B/G/N)在3株转移能力不同的人乳腺癌细胞株MCF-7、T-47D和MDA-MB-231中的表达和定位,探讨蛋白4.1家族成员与乳腺癌细胞转移能力之间的关系。方法:采用Westernblot检测蛋白4.1家族成员在MCF-7、T-47D和MDA-MB-231细胞中的表达;免疫荧光标记对蛋白4.1家族成员在3株细胞中的表达进行定位。结果:4.1R/B/G在3种细胞系中均有表达,在T-47D细胞中的表达量均明显高于在MCF-7细胞中的表达量(P<0.05);但在高转移性的MDA-MB-231细胞中它们的表达水平转而下降。4.1N在T-47D细胞中的表达量明显低于在MCF-7细胞中的表达量(P<0.01),而在MDA-MB-231细胞中的表达则几乎检测不到,提示4.1N表达下调或缺失与乳腺癌细胞转移能力密切相关。4.1R/B/G/N在MCF-7和T-47D细胞中均主要定位于细胞膜及胞间连接处,同时4.1B在细胞核中也有表达;而在高转移的MDA-MB-231细胞中蛋白4.1家族成员均定位于细胞质中,提示蛋白4.1家族成员亚细胞定位的改变可能是乳腺癌细胞转移过程中的重要事件。结论:4.1N表达缺失和蛋白4.1家族成员亚细胞定位的改变与乳腺癌细胞MDA-MB-231的高转移性密切相关。

Background and purpose：Currently,the abnormal expression of protein 4.1 family has been noticed in several human cancers.This study aimed to investigate the correlation between the protein 4.1 family and the different metastatic capabilities of breast cancer cell lines by detecting the expression and subcellular localization of protein 4.1 family members（4.1R/B/G/N）.Methods：Western blot and immunofluorescence were used to detect the expression and subcellular location of protein 4.1 family members（4.1R/B/G/N）in breast cancer cell lines MCF-7,T-47D and MDA-MB-231.Results：Protein 4.1 family members 4.1R/B/G were detectable in 3 kinds of breast cancer cells.Their level of expression increased significantly in T-47D（P0.05）but declined in MDA-MB-231 with high metastasis.It is important to note that there was a very significant decline in the 4.1N expression levels in T-47D （P0.01）,so significant that it was undetected in MDA-MB-231.This finding suggests a correlation between the level of expression of 4.1N and the metastatic capability of breast cancer cells.In addition,proteins 4.1R/B/G/N were mainly targeted in the membrane and cell to cell junction in MCF-7 and T-47D cells,while at the same time,4.1B is located at the nucleus.However,all of them were only visible in the cytoplasm in MDA-MB-231.Hence,the change of protein 4.1’s subcellular location may be an important event in breast cancer cell metastasis.Conclusion：The absence of 4.1N and the change of protein 4.1’s subcellular location are both closely related to the high metastatic capability of breast cancer cell line MDA-MB-231.