BRCA1 is an important tumor suppressor gene associated with inherited breast and ovarian cancers. In this investigation, two novel BRCA1 splicing variants were cloned from breast cancer cell line ZR-75-30. These transcripts, named BRCA1-PI21-Δ2-21 and BRCA1-Δ2-14, lacked most exons of full length BRCA1 gene, but maintained the original reading frame. We also demonstrated the presence of BRCA1-PI21-Δ2-21 in several human cell lines. Expression of both variants fused with green fluorescent protein (GFP) showed that they targeted different subcellular compartments in the transfected cells. Viability of the cells expressing both fusion proteins decreased notably compared with the viability of cells expressing only GFP. Fluorescence activated cell sorting assay confirmed that the overexpression of two splicing variants resulted in cell apoptosis. Taken together, the different subcellular localization and cell effects of two BRCA1 splicing variants imply that they can have different biological functions in breast cancer cells. Elucidating the functions of BRCA1 splicing variants would help to understand the exact roles of the BRCA1 gene in tumor suppression.

中文翻译：

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两种新型 BRCA1 剪接变体的克隆和功能鉴定

BRCA1 是与遗传性乳腺癌和卵巢癌相关的重要肿瘤抑制基因。在这项研究中，从乳腺癌细胞系 ZR-75-30 中克隆了两种新的 BRCA1 剪接变体。这些转录本，命名为 BRCA1-PI21-Δ2-21 和 BRCA1-Δ2-14，缺乏全长 BRCA1 基因的大部分外显子，但保持了原始阅读框。我们还证明了 BRCA1-PI21-Δ2-21 在几种人类细胞系中的存在。与绿色荧光蛋白 (GFP) 融合的两种变体的表达表明它们靶向转染细胞中的不同亚细胞区室。与仅表达 GFP 的细胞的活力相比，表达两种融合蛋白的细胞的活力显着降低。荧光激活细胞分选试验证实两种剪接变体的过表达导致细胞凋亡。总之，两种 BRCA1 剪接变体的不同亚细胞定位和细胞效应意味着它们在乳腺癌细胞中可能具有不同的生物学功能。阐明 BRCA1 剪接变体的功能将有助于了解 BRCA1 基因在肿瘤抑制中的确切作用。