EXPRESSION OF MESSENGER-RNAS FOR TYPE-I AND TYPE-III PROCOLLAGENS IN SEROUS OVARIAN CYSTADENOMAS AND CYSTADENOCARCINOMAS

Malignant ovarian tumors induce a strong fibroproliferative reaction c haracterized try the active production of type I and type IlI procolla gen both locally in the ovary as well as more remotely in the peritone al cavity. Our purpose was to determine the origin of the increased co llagen production observed in serous ovarian tumors with different his tological grades of malignancy, ie, whether the malignant cells or the stromal fibroblasts are responsible for the synthesis of collagen fib ers. We visualized the mRNAs corresponding to the pro alpha 1(I) and p ro alpha 2(I) chains of type I procollagen and the pro alpha 1(III) ch ain of type III procollagen by in situ hybridization. Strong signals f or both chains of type I procollagen were seen in stromal fibroblasts next to tumor cell islets, whereas the reaction tons weak or absent ne ar benign ovarian cysts. In poorly, differentiated tumors, the signals were particularly abundant and occasionally also seen in the neoplast ic cells themselves. Type III procollagen mRNA expression was similar, although somewhat less distinct. These findings indicate that the pro duction of interstitial procollagens is related to the degree of malig nancy and neoplastic activity of tumors. The formation of collagen in well differentiated ovarian tumors is a function of stromal fibroblast s, whereas in poorly differentiated tumors, aberrant expression of one or several chains of type I and type III procollagens in the neoplast ic cells is also likely to take place.