MOLECULAR-GENETIC ANALYSIS OF TGF-BETA-1 IN OVARIAN NEOPLASIA

Malignant ovarian tumours have been associated with a loss of autocrin e growth inhibition by transforming growth factor-beta. This study aim ed to detect abnormalities in the gene structure, expression and local ization of TGF-beta 1, in paraffin-embedded samples from 31 ovarian ne oplasias (21 malignant, 5 borderline and 5 benign). Gene mutations in the region coding for the active protein were detected by PCR-SSCP ana lysis of exons 5, 6 and 7. mRNA expression and localization was studie d by nonisotopic in situ hybridization (NISH) using cDNA probes genera ted by the reverse transcriptase polymerase chain reaction (RT-PCR), a nd immunohistochemistry, using antibodies against both intracellular a nd extracellular (matrix-associated) forms of TGF-beta 1. Four mutatio ns were found: one in exon 6 (serous adenocarcinoma), one in exon 7 (M ullerian tumor), and two in exons 5 and 6 from a serous cystoadenoma. TGF-beta 1 mRNA was expressed in 87% and proteins in 90% of ovarian tu mours. Most tumours expressing large amounts of TGF-beta 1 mRNA, also contained a large number of protein binding sites. In malignant tumors , TGF beta 1 was more strongly expressed in high-grade ovarian carcino mas with a cystic-papillary pattern than in tumours with a solid growt h pattern. Normal ovarian tissue (follicles, granulosa cells) adjacent to tumor showed weak epithelial labeling and staining. Gene mutation did not correlate with histological type of tumor, mRNA or protein exp ression. TGF-beta 1 mutation and abnormalities in its expression seem to occur in benign and malignant ovarian tumors, and could be involved in their pathogenesis. TGF beta 1 gene mutations may act in multistag e ovarian neoplasia, by reducing epithelial cell responsiveness to TGF -beta 1 negative growth control.