LACK OF THE LATENT TRANSFORMING GROWTH-FACTOR-BETA BINDING-PROTEIN INMALIGNANT, BUT NOT BENIGN PROSTATIC TISSUE

Transforming growth factor beta (TGF-beta) is a family of proteins whi ch act as a potent growth inhibitor for most cell types including epit helial cells. TGF-beta is synthesized as latent high molecular weight complexes, composed of TGF-beta, the NH2-terminal part of the TGF-beta precursor and the third molecule, the latent TGF-beta binding protein (LTBP). We here ascertain that TGF-beta is expressed in human prostat ic cancer tissue as well as in cystectomized prostatic tissue and in m aterials from transurethral resectionS with benign prostatic hyperplas ia, analyzed by immunohistochemistry. TGF-beta is observed in both epi thelial cells and stromal cells. No significant correlation was obtain ed between TGF-beta expression in tumor cells and their degree of diff erentiation. However, analysis by immunohistochemistry using antibodie s against LTBP revealed that specimens from histopathologically verifi ed human prostatic cancer are mostly negative for this molecule, al th ough it is expressed in cystectomized prostatic and benign prostatic h yperplasia tissues. These results indicate that in cystectomized prost atic and benign prostatic hyperplasia tissues, TGF-beta may be produce d in a complex associated with LTBP; whereas in prostatic carcinoma, T GF-beta is produced without associating with LTBP. The biological sign ificance of the production of TGF-beta in relation to LTBP and the pos sible association with prognosis are discussed.