GDEP, a new gene differentially expressed in normal prostate and prostate cancer

BACKGROUND. The database of human expressed sequence tags (dbEST) is a pote ntial source for the identification of tissue specific genes. The database contains sequences that originate from cDNA libraries from different tissue s cell types and tumors. METHODS. Computer based analysis identified a cluster of sequence homologou s ESTs, containing ESTs derived only from human prostate cDNA libraries. Th e tissue specificity was examined by multiple tissue RNA dot blots and RT-F CR. The new RNA transcript was characterized using northern blot analysis, RACE-PCR, and a ribonuclease protection assay. RESULTS. We have identified a gene differentially expressed in prostate usi ng EST database analysis and experimental studies. We name the gene GDEP fo r gene differentially expressed in prostate. The major GDEP transcript is a bout 520 bp long. GDEP RNA was detected in nine prostate tissue samples, fo ur normal and five cancer. Expression in prostate epithelial cells was esta blished by in situ hybridization. Weak expression was detected in the prost ate cancer cell line LNCaP. In vitro transcription/ translation indicate th at the RNA encodes a small 34 amino acid protein. The major transcript cons ists of two exons with one large intron (> 15 kb). The GDEP gene was mapped to chromosome 4q21.1 by radiation hybrid mapping. CONCLUSIONS. Our data proves that tissue specific genes can be identified b y EST database mining. The prostate specificity of GDEP expression indicate s that GDEP may be useful in the diagnosis or treatment of prostate cancer.