Decreased expression of SAM68 in human testes with spermatogenic defects

Objective To assess the expression patterns of SAM68 in the testes of azoospermic patients with normal and abnormal spermatogenesis. Design Retrospective study and in vitro study. Setting University hospital. Patient(s) Testicular biopsies of azoospermic men with normal spermatogenesis (OAZ; n = 20), with maturation arrest at the spermatocyte stage (MA; n = 20), and with Sertoli cell–only syndrome (SCOS; n = 10). Intervention(s) No interventions with patients. Knockdown of Sam68 was performed in the GC-2spd(ts) cell line. Main Outcome Measure(s) SAM68 expression was analyzed using quantitative real-time reverse transcriptase–polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry analysis in tissues. Moreover, Sam68 was knocked down in GC-2spd(ts) cells. Cell viability was measured using the MTT assay, and the apoptosis rate was detected using flow cytometry with the Annexin V–FITC kit. Result(s) Using qRT-PCR, the expression level of testicular SAM68 mRNA in MA and SCOS patients was statistically reduced compared with in OAZ patients. In addition, using qRT-PCR, Western blot, and immunohistochemistry analyses, mRNA and protein expressions of SAM68 were absent or barely detectable in testicular tissues in 45% (9 of 20) of patients with MA and in all patients with SCOS. Furthermore, decreased expression of Sam68 suppressed germ cell proliferation and induced apoptosis in transfected GC-2spd(ts) cells. Conclusion(s) Deficient SAM68 expression was observed in the human testis with MA at the spermatocyte stage and SCOS. These results may offer new perspectives on the molecular basis of abnormal spermatogenesis.