Tissue kallikrein, the oldest member and kinin-releasing enzyme, and KLK3/PSA, a tumor biomarker for prostate cancer are the most prominent components of the family.
The potential regulatory elements and high-frequency mutant genes (<i>RPS4Y2, KLK1, PKD1</i> and <i>FOLH1B</i>) may have key functions in prostate cancer.
Several SNPs in very strong linkage disequilibrium in the KLK 6 region and located within the same haplotype (rs113640578, rs79324425, rs11666929, rs28384475, rs3810287), identified individuals at increased risk of aggressive PCa in both discovery (odds ratio [OR] = 3.51-3.64, 95% confidence interval [CI] = 2.01 to 6.36, P = 1.0x10 -5 -8.4x10 -6 ) and validation (OR = 1.89-1.96, 95% CI = 0.99 to 3.71, P = .04-.05) cohorts.
On the other hand, the expression of human kallikrein 1-related peptidase (KLK) 4, which activates plasma HGF activator zymogen, in prostate cancer patients with bone metastasis or advanced stage has also been reported.