Her-2/Neu and Breast Cancer
Final rept. 8 Jul 1994-7 Jul 1999
OREGON HEALTH SCIENCES UNIV PORTLAND
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HER-2neu is a potent oncogene that predicts poor outcome when overexpressed in ovarian cancer. The SKOV-3 ovarian carcinoma cell line, one of the only models for HER2-driven ovarian cancer, expresses a major uncharacterized 8 kb alternative HER-2 transcript. The aim of this study was to characterize the structure, determine the origin of the alternative sequence, and examine the possible role of the 8 kb alternative transcript in overexpression of the HER-2 gene. The structure of the 8 kb transcript was investigated using the polymerase chain reaction PCR and nucleotide sequencing of cDNA clones. PCR analysis of genomic DNA was used to assess the origin of the 8 kb transcript. The stability of the 8 kb mRNA was assessed by Northern blot analysis of RNA extracted from cells treated with transcriptional inhibitors. Similar 5UTR and coding sequence but an extended 3UTR was contained in the 8 kb compared to the well-characterized 4.5 kb HER-2 transcript. Genomic DNA had continuity between the novel 3UTR sequence from the 8 kb transcript and adjacent HER-2 terminal exon sequence. The 8 kb transcript had a half-life of 13 h compared to 5.5 h for the 4.5 kb transcript p 0.01. The 8 kb transcript is generated from alternative polyadenylation site usage rather than gene rearrangement. Since the 8 kb transcript contains alternative sequence found at the 3end of the normal HER-2 gene, it could be expressed in other cells. Increased stability of the 8 kb transcript may confer a selective advantage for SKOV-3 cells by providing enhanced HER-2 expression.
- Genetic Engineering and Molecular Biology
- Medicine and Medical Research