Abstract
Breast cancer is the most common malignant tumor and the leading cause of cancer-related death in women. The ubiquitin-proteasome system regulates the stability of most proteins controlling various biological processes in human cells. PSMD7, as a core component of the 26S proteasome, is critical for the degradation of ubiquitinated proteins in the proteasome. Currently, PSMD7 expression and its roles in the progression of breast cancer remain largely unknown. In this study, we assessed the level of PSMD7 in breast cancer tissues and investigated the underlying molecular events by which PSMD7 could play a role in tumor progression. The results showed that the PSMD7 level was significantly upregulated in breast cancer tissues. PSMD7 expression was closely associated with tumor subtype, tumor size, lymph node invasion, and TNM stage. A high PSMD7 level predicted poor overall survival (OS) and disease-free survival (DFS) in breast cancer patients. Furthermore, univariate Cox regression analysis indicated that lymph node invasion, distant metastasis, and PSMD7 expression were associated with OS and DFS. Multivariate regression analysis indicated that PSMD7 was an independent predictor of OS (HR=1.310, 95% CI=1.038-1.652). Importantly, PSMD7 knockdown induced cell cycle arrest in the G0/G1 phase, leading to cell senescence and apoptosis. PSMD7 knockdown inhibited the expression of key cell cycle-related proteins and promoted the stability of p21 and p27 in breast cancer cells. PSMD7 may be a valuable prognostic indicator and potential therapeutic target for breast cancer.