Expression of the normal epithelial cell-specific 1 (NES1; KLK10) candidate tumour suppressor gene in normal and malignant testicular tissue

The normal epithelial cell-specific 1 (NES1) gene (official name kallikrein gene 10: KLK10) is a new member of the expanding human kallikrein gene fam ily and encodes for a secreted serine protease. Experimental evidence sugge sts that NES1 controls normal cell growth and may function as a tumour supp ressor. NES1 is down-regulated during breast cancer progression. The NES1 g ene is highly expressed in testicular as well as in other tissues. In this study, we investigated the expression level of the NES1 gene in cancerous a nd normal testicular tissues with reverse transcriptase-polymerase chain re action (RT-PCR) and immunohistochemistry. In all 14 primary testicular germ -cell tumours examined, the NES1 gene expression was markedly reduced compa red to adjacent (paired) normal tissues. We further examined 6 randomly sel ected primary germ-cell tumours and 8 normal tissues (obtained from differe nt individuals). We confirmed the differential expression of the NES1 gene in germ-cell tumours (GCT) and pre-malignant carcinoma in situ (CIS). Our f indings suggest that NES1 may act as a tumour suppressor and may play a rol e in the pathogenesis and progression of this malignancy. (C) 2001 Cancer R esearch Campaign http://www.bjcancer.com.