HER2 Affects the Biological Behaviours of Bladder Cancer Cells and is Closely Associated with the Progression and Prognosis of Bladder Cancer

Objective: Given the growing recognition of molecular targets in oncology, this study aimed to examine the expression pattern and prognostic significance of human epidermal growth factor receptor-2 (HER2) in bladder cancer (BC) and the effects of HER2 knockdown on the biological behaviours of BC cells. Methods: A total of 126 BC tissue samples and 20 samples of normal bladder mucosa were collected for immunohistochemical staining. The clinicopathological data were obtained from patients with BC. HER2 was knocked down in two BC cell lines (T24 and 5637) using lentiviral delivery of short hairpin RNA (shRNA), referred to as shHER2, with a blank control group (shCtrl) for comparison. A range of assays, including cell counting kit-8, colony formation, transwell, wound healing, and flow cytometry, were performed to assess the effects of HER2 knockdown on the proliferation, migration, cell cycle entry, and apoptosis of BC cells. Results: The study revealed a notable overexpression rate of HER2 in BC tissues (57.1%) than in normal bladder mucosa (0%) (p < 0.001). HER2 overexpression was associated with tumour number (p < 0.0001), pathological grade (p < 0.0001), lymph node metastasis (p = 0.040), distant metastasis (p = 0.037), overall survival (p = 0.0006), and recurrence-free survival (RFS) (p < 0.0001). In contrast, no significant association was identified between HER2 overexpression and demographic factors such as sex (p = 0.687), age (p = 0.430), tumour size (p = 0.053), or T stage (p = 0.134). Furthermore, the experimental knockdown of HER2 in BC cells inhibited the proliferation and migration and promoted their apoptosis and cell cycle arrest in the G1 phase. Conclusions: The findings suggest HER2 as a potential therapeutic target for BC and underscore the promise of developing anti-HER2-targeting strategies for BC management.