This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dodson, M. K. Articles by Benedict, W. F. Search for Related Content PubMed PubMed Citation Articles by Dodson, M. K. Articles by Benedict, W. F.

Evidence of Functional RB Protein in Epithelial Ovarian Carcinomas despite Loss of Heterozygosity at the RB Locus

Departments of Obstetrics and Gynecology, Division of Gynecologic Oncology [M. K. D., W. A. C., K. C. P.], Laboratory Medicine and Pathology [K. A. D., G. L. K., R. B. J.], and Medical Genetics [R. B. J.], Mayo Clinic and Foundation, Rochester, Minnesota 55905, and Center for Biotechnology, Baylor College of Medicine, The Woodlands, Texas 77381 [H-J. X., S-X. H., J. L., W. F. B.]

The presence of retinoblastoma (RB) protein was evaluated by immunohistochemical staining and correlated with loss of heterozygosity (LOH) at the RB locus in 52 primary epithelial ovarian carcinomas. Forty-eight tumors were informative at the RB locus by molecular genetic analysis. Twenty-five tumors (52%) showed loss of heterzygosity at the RB locus. RB protein expression was found in 23 of these tumors. The remaining two tumors were negative for RB protein product by immunohistochemical staining. All 23 tumors showing no LOH at the RB locus had a normal RB protein pattern.

All but three tumors revealed either no LOH with any marker or, if LOH was found for one chromosome 13 marker, all other informative markers also showed LOH. The three recombinant tumors included two which retained alleles at one or more loci distal and one which retained alleles proximal to the RB locus. LOH at the RB locus was significantly more common in invasive high-grade (grades 3 and 4) tumors as compared to invasive low-grade (grades 1 and 2) tumors (P < 0.001).

Our data suggest that while molecular genetic studies reveal frequent LOH at the RB locus, particularly in high-grade tumors, normal RB protein expression is present in the majority (96%) of these tumors. This implies that another, unidentified, gene or genes located on chromosome 13 may be important in the progression of most epithelial ovarian carcinomas. Additionally, it is likely that the specific chromosome 13 alteration(s) associated with sporadic ovarian neoplasms will be extremely difficult to identify using allelic loss and deletion mapping studies.

¹ To whom requests for reprints should be addressed, at Hilton 970, Mayo Clinic, Rochester, MN 55905.

Received 10/12/93. Accepted 12/17/93.

This article has been cited by other articles:

				G. D'Andrilli, V. Masciullo, L. Bagella, T. Tonini, C. Minimo, G. F. Zannoni, R. L. Giuntoli II, J. A. Carlson Jr., D. R. Soprano, K. J. Soprano, et al. Frequent Loss of pRb2/p130 in Human Ovarian Carcinoma Clin. Cancer Res., May 1, 2004; 10(9): 3098 - 3103. [Abstract] [Full Text] [PDF]

				D. J. Simpson, J. Magnay, J. E. Bicknell, A. L. Barkan, A. M. McNicol, R. N. Clayton, and W. E. Farrell Chromosome 13q Deletion Mapping in Pituitary Tumors: Infrequent Loss of the Retinoblastoma Susceptibility Gene (RB1) Locus Despite Loss of RB1 Protein Product in Somatotrophinomas Cancer Res., April 1, 1999; 59(7): 1562 - 1566. [Abstract] [Full Text] [PDF]