Tissue-specific and androgen-regulated expression of human prostate-specific transglutaminase

Transglutaminases (TGases) are calcium-dependent enzymes catalysing the post-translational cross-linking of proteins. In the prostate at least two TGases are present, the ubiquitously expressed tissue-type TGase (TG(C)), and a prostate-restricted TGase (TG(P)). This paper deals with the molecular cloning and characterization of the cDNA encoding the human prostate TGase (hTG(P)). For this purpose we have screened a human prostate cDNA library with a probe from the active-site region of TG(C). The largest isolated cDNA contained an open reading frame encoding a protein of 684 amino acids with a predicted molecular mass of 77 kDa as confirmed by in vitro transcription-translation and subsequent SDS/PAGE. The hTG(P) gene was tissue-specifically expressed in the prostate, yielding an mRNA of approx. 3.5 kb. Furthermore, a 3-fold androgen-induced upregulation of hTG(P) mRNA expression has been demonstrated in the recently developed human prostate cancer cell line, PC346C. Other well established human prostate cancer cell lines, LNCaP and PC-3, showed no detectable hTG(P) mRNA expression on a Northern blot. The gene coding for prostate TGase was assigned to chromosome 3.