Allelotyping defines minimal imbalance at chromosomal region 17q25 in non-serous epithelial ovarian cancers

Allelic deletions of multiple chromosome 17q loci in sporadic ovarian cance r of epithelial origin suggest that inactivation of tumor suppressor gene(s ) in these regions may be important for ovarian tumorigenesis, To further d efine the pattern of allelic imbalance in epithelial ovarian tumors of diff erent histologies, a PCR-based assay was used to assess loss of heterozygos ity (LOH) of polymorphic markers representative of TP53, BRCA1, NME1 and GH 1, and region 17q23-25, LOH was observed for at Least one marker in 68% of malignant tumors (n=60) and in 18% tumors of borderline malignancy (n=11), but not in benign tumors (n=5). The highest frequency of LOH in malignant t umors (64%) was observed with D17S801 on 17q25, Ten of 39 malignant ovarian tumors displaying LOH of at least one 17q marker, displayed a LOH pattern enabling the determination of a minimal region of overlapping deletion defi ned by D17S795 and D17S801, One borderline tumor also displayed an intersti tial LOH pattern that overlapped this 17q25 minimal region of deletion. The histologies of malignant tumors displaying a pattern indicative of interst itial 17q deletions were of the endometrioid, clear cell and mucinous epith elial types. As the minimal region of overlap defined by these tumors overl ap regions deleted in malignant tumors of all histologic types, and in a tu mor of borderline malignancy, the 17q25-tumor suppressor may be implicated in the development of all types of epithelial ovarian tumors.