Detection of Human Kallikrein 4 in Healthy and Cancerous Prostatic Tissues by

hK4), a recently discovered member of the kallikrein gene family, shares many characteristics with prostate-specific antigen, the best available marker for prostate cancer. Because the protein has not been detected in any human tissue, we attempted to develop immunologic methods for hK4 analysis and use them to detect hK4 in healthy and cancerous tissue extracts and biological fluids. Methods: We extracted total RNA from 20 pairs of matched (healthy–cancer) prostate tissue samples. KLK4 cDNA was amplified by reverse transcription-PCR (RT-PCR) and cloned in a pPICZA expression vector. We then transformed the construct product into Pichia pas-toris yeast strains and induced secreted recombinant protein production by addition of methanol. We puri