Abstract: Background and purpose: As a core member of 19S proteasome lid structure, whether 26S proteasome non-ATPase regulatory subunit 7 (PSMD7) is involved in the tumorigenesis and its molecular mechanism are unclear. The expression of PSMD7 in human esophageal squamous cell carcinoma specimens was investigated, and its effects on cell proliferation and apoptosis  were examined. Methods: The mRNA expression and protein level of PSMD7 were detected by real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) and Western blot. PSMD7 was downregulated by lentivirus transfection in TE-1 cells. Cell proliferation and apoptosis were examined after PSMD7 inhibition. The mitochondrial membrane potential, expression of Cyt C and apoptosis- related proteins were investigated. Results: PSMD7 was highly expressed in human esophageal squamous cell carcinoma specimens at both mRNA and protein levels (P<0.05). The overexpression of PSMD7 was positively correlated with lymph node metastasis (P<0.05). The proliferation of TE-1 cells was decreased and the apoptosis was induced upon PSMD7 downregulation (P<0.05). The mitochondrial membrane potential was reduced whereas expression of cytosolic Cyt C was increased, followed by activation of caspase cascade reaction, suggesting PSMD7 downregulation induced apoptosis through the mitochondrial pathway. Conclusion: PSMD7 is highly expressed in human esophageal squamous cell carcinoma. Cell apoptosis induced by PSMD7 downregulation may be processed via mitochondria-dependent pathway.

Key words: PSMD7, Esophageal squamous cell carcinoma, Proliferation, Apoptosis, Mitochondria