Human tissue kallikreins and testicular cancer

Human tissue kallikreins are fifteen homologous genes encoding for secreted serine proteases and residing tandemly on chromosome 19q13.4. These enzymes are highly expressed in a variety of tissues and participate in diverse physiological processes. Human tissue kallikreins were found to be associated with several malignancies, especially endocrine-related cancers, including prostate, ovarian, breast and testicular cancer. In testicular germ cell tumors, some tissue kallikrein genes, including KLK5, KLK10, KLK13 and KLK14, were found to be significantly down-regulated. Tissue-specific splice variant forms of some kallikreins have been identified in the testis. In this paper, the expression of KLK5, KLK10, KLK13 and KLK14 in testicular cancer and their possible roles during testicular cancer development, as well as their clinical applications are briefly reviewed.