The human tissue kallikreins (KLKs 1-3) and a novel KLK1 mRNA transcript are expressed in a renal cell carcinoma cDNA library

Renal cell carcinoma (RCC) is the most common form of kidney cancer, for wh ich there is no biochemical marker. We and others have previously shown tha t a prostate specific antigen (PSA)-like protein is elevated in the serum o f women with RCC. PSA is a member of the tissue kallikrein (KLK) gene famil y of enzymes. We have constructed a RCC cDNA expression library and screene d it for PSA and KLK expression to determine whether they may be responsibl e for this PSA-like activity. Since immunoscreening of the RCC library for expressed PSA-like proteins was unsuccessful, polymerase chain reaction (PC R) analysis of the RCC cDNA library was performed using universal KLK prime rs, directed to the common regions in exon 3 and exon 5 of KLK1, KLK2 and K LK3. Sequences identical to all three KLKs were present in the RCC cDNA lib rary. In addition, a novel KLK1 transcript with a 104 base pair deletion in exon 4 that predicted a C terminal sequence minus the crucial Ser(190), wa s detected. The role of these tissue kallikreins in RCC and the significanc e of the variant KLK1 transcript is yet to be established. It is still uncl ear which of these gene products, if any, was detected in the sera of the w omen with RCC. (C) 1999 Elsevier Science B.V. All rights reserved.