Pind Molly T, Watson Peter H
Department of Pathology, Faculty of Medicine, University of Manitoba, Winnipeg, Man., Canada.
Breast Cancer Res Treat. 2003 May;79(1):75-82. doi: 10.1023/a:1023338718974.
Altered gene expression during breast tumour progression can occur through alternative splicing of mRNAs. The SR proteins have been identified as important factors in RNA splicing and in the incorporation of alternative exons in experimental systems. We have studied SR protein expression by western blot in human breast cell lines and in a cohort of 101 invasive breast tumours to examine the relationship with alternatively spliced isoforms of the CD44 gene. Multiple SR proteins (SR75, 55, 40, 30) were expressed in most cell lines and tumours, and their relative expression was independent of grade, size, or nodal status. Higher relative expression of SR55 protein was associated with an altered pattern of CD44 variants incorporating exon v7 (p = 0.047) as determined by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis. Nevertheless, transient transfection of MCF7 and HBL100 breast cell lines with SR55 had no direct effect on the expression of CD44 v7 variant expression. We conclude that while SR proteins may be important and necessary factors in mRNA splicing, other factors are also necessary to influence the regulation of alternatively spliced isoforms of CD44.
在乳腺肿瘤进展过程中，基因表达的改变可通过mRNA的可变剪接发生。SR蛋白已被确定为RNA剪接以及在实验系统中可变外显子掺入的重要因素。我们通过蛋白质免疫印迹法研究了人乳腺细胞系和101例浸润性乳腺肿瘤队列中的SR蛋白表达，以检查其与CD44基因可变剪接异构体的关系。多种SR蛋白（SR75、55、40、30）在大多数细胞系和肿瘤中表达，其相对表达与分级、大小或淋巴结状态无关。通过逆转录-聚合酶链反应（RT-PCR）和Southern印迹分析确定，SR55蛋白的相对高表达与包含外显子v7的CD44变体模式改变有关（p = 0.047）。然而，用SR55瞬时转染MCF7和HBL100乳腺细胞系对CD44 v7变体表达没有直接影响。我们得出结论，虽然SR蛋白可能是mRNA剪接中的重要且必要的因素，但其他因素对于影响CD44可变剪接异构体的调控也是必需的。
