ABERRANT SPLICING OF THE TSG101 TUMOR-SUPPRESSOR GENE IN HUMAN BREASTAND OVARIAN CANCERS

OBJECTIVE: To determine whether large deletions or other alterations i n the putative tumor suppressor gene TSG101 play a role in the molecul ar pathogenesis of breast and ovarian cancers. METHODS: Expression of TSG101 transcripts was examined in breast and ovarian cancers using th e reverse transcriptase-polymerase chain reaction (RT-PCR), and select ed transcripts were sequenced. Southern blot analysis was performed to determine whether there were genomic deletions in the TSG101 gene, an d Northern blot analysis was used to examine the relative abundance of various transcripts. RESULTS: All the cancerous and normal breast tis sue examined expressed full length 1145 base pair (bp) TSG101 transcri pts. Additional truncated transcripts were seen using the RT-PCR in 57 (64%) of 89 primary breast cancers, 1 (20%) of 5 breast cancer cell l ines, 3 (50%) of 6 normal breast tissues, 16 (64%) of 25 primary ovari an cancers and 1 (33%) of 3 ovarian cancer cell lines. Only the primar y breast (21%) and ovarian (24%) cancers had three or more truncated t ranscripts. None of the normal tissues or cell lines examined had more than two aberrant transcripts. DNA sequencing revealed that the most commonly expressed truncated transcript arises because of loss of 902 bp between codons 153 and 1055. Only full length TSG101 transcripts we re seen on Northern blot analysis of breast cancer cell lines, however . There was no evidence of genomic deletions in the TSG101 gene on Sou thern blot analysis. CONCLUSION: Truncated TSG101 transcripts that pro bably represent splice variants are present in some breast and ovarian cancers, but there is no evidence to suggest that loss of this putati ve tumor suppressor gene plays a role in the molecular pathogeneis of these cancers. Copyright (C) 1998 by the Society for Gynecologic inves tigation.