The Roles of Differentially Expressed Genes in Human Cryptorchid Testes on testicular differentiation and development

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Purpose : In order to restore fertility, current consensus recommends early orchiopexy for cryptorchidism. Despite early rchiopexy, however, it is reported that transformation of gonocytes into adult dark spermatogonia is already impaired at the time of operation and consequently affects future fertility. To elucidate the biological processes occurring during germ cell maturation in the cryptorchid testes, we identified the genes affected by testicular maldescent using PCR-based suppression subtractive hybridization, and investigated differentially expressed genes in order to determine they are related to cell differentiation and spermatogenesis. Materials and Methods : Testicular tissues were excised from 24 boys who underwent orchiopexy or hydrocelectomy in our hospital (12-59 months old). Between their tissues from age-matched boys with ipsilateral cryptorchidism and descended testis, two-way subtraction was performed. Differential expression was validated by real-time RT-PCR.Furthermore, to clarify the distribution of candidate genes, immunohistochemistry and western blot analysis were performed. Results: We obtained 84 clones corresponding to transcripts representing differential expression. BLAST searches revealed 32 different known genes with 98-100% similarity. Among these, we further investigate three genes, TPT1, EEF1A1 and NuMA1, that were significantly more highly expressed in cryptorchidism than in descended testes, and were detected in the spermatogonia from immature to adult testes. Conclusions : TPT1, EEF1A1 and NuMA1 have cell growth-related functions, suggesting that they play certain roles in germ cell differentiation and maintenance of stem cell potential. Changes in the expression levels of these genes expressions in the testes might enable novel evaluation of spermatogenic failure caused by cryptorchidism.