Organization of type III collagen in benign and malignant ovarian tumors. An immunohistochemical study

BACKGROUND: Abnormal interaction with the extracellular matrix is a basic property of malignant cells. Type III collagen is a major constituent of the extracellular matrix of soft tissues. METHODS: Deposition of the aminoterminal propeptide of type III procollagen (PIIINP) was studied in benign (n = 41), borderline (n = 4), and malignant (n = 32) human ovarian tumors using the avidin-biotin-immunoperoxidase technique and affinity-purified antibodies to human PIIINP: It was then compared with the serum PIIINP concentrations of the patients at the time of operation. RESULTS: In malignant tumors, the distribution of PIIINP was irregular both close to the epithelial cancer cells and further away, in the stroma. Another feature typical of malignant tumors was the varying staining intensity of the PIIINP-positive fibers. The benign tumors were characterized by a regular organization and an intensive staining of PIIINP: Borderline tumors showed a slightly decreased staining intensity and altered PIIINP distribution. A significant positive correlation was found between the PIIINP concentration in serum and the degree of irregularity in the distribution of PIIINP: CONCLUSIONS: These preliminary results indicate that malignant transformation in ovarian tumors is associated with disintegration of adjacent collagenous structures and with alterations in type III procollagen metabolism, which also leads to increased serum PIIINP levels. They suggest that biochemical or immunohistochemical detection of the PIIINP antigen could be clinically useful in ovarian tumors.