Testis cancer gene D40 expression and its relationship with clinicopathological features in infertile men.

We previously identified a novel human cancer/testis gene, D40, which is dominantly expressed in testicular germ cells, various cancer cell lines and primary human tumors. The expression of D40 mRNA and proteins in various testicular tissues was quantified using the conventional reverse transcription polymerase chain reaction (RT-PCR), real-time quantitative RT-PCR and western blot analysis. The relationship between levels of D40 expression, serum follicle stimulating hormone (FSH) level and Johnsen's score was examined. D40 mRNA expression was observed in the testes of infertile men, except those with Sertoli-cell-only syndrome or Klinefelter's syndrome. The quantity of D40 mRNA and protein was correlated with Johnsen's score and inversely correlated with serum FSH level. The present results show that the expression levels of D40 mRNA and proteins decrease according to the degree of spermatogenesis impairment in male infertile patients.