FREQUENT DELETIONS WITHIN FRA7G AT 7Q31.2 IN INVASIVE EPITHELIAL OVARIAN-CANCER

We previously showed that FRA7G, an aphidicolin-inducible common fragi le sire at 7q31.2, colocalized with the common region of loss of heter ozygosity (LOH) in a number of different tumors. Based on the sequence analysis of 150 Kb in the FRA7G region, we identified four new polymo rphic microsatellite markers. In this article, we have used these four microsatellite markers and eight additional markers from 7q22-32 to a nalyze the breakage and loss of the region surrounding FRA7G in 49 inv asive epithelial ovarian cancers and three borderline ovarian tumors. No allelic loss was detected in the ovarian tumors of borderline malig nancy, bur 71% (35/49) of the invasive tumors showed LOH at one or mor e loci in the region analyzed. Of the 12 markers analyzed, most of the markers exhibiting a high frequency of LOH were within FRA7G, and the highest frequency of LOH was seen with the new marker 7G14 (37%, 15/4 1). Breakpoint analysis in tumors with LOH demonstrated that the frequ ent loss of DNA sequences seen within the FRA7G region was due to freq uent small interstitial deletions and not a result of loss of the whol e fragile site region. These findings indicate that FRA7G does play a role in the breakage and loss of 7q sequences in invasive ovarian canc er. In addition, the newly identified markers enable us to further del ineate a smallest common region of loss in invasive ovarian rumors to a 150-Kb region flanked by markers D7S486 and 7G14. Genes Chromosomes Cancer 24:48-55, 1999. (C) 1999 Wiley-Liss, Inc.