Hyperthermia reduces cancer cell invasion and combats chemoresistance and immune evasion in human bladder cancer

Bladder cancer (BC) is a common malignancy and its most prevalent type is urothelial carcinoma, which accounts for ~90% of all cases of BC. The current treatment options for BC are limited, which necessitates the development of alternative treatment strategies. Hyperthermia (HT), as an adjuvant cancer therapy, is known to improve the efficacy of chemotherapy or radiotherapy. The present study aimed to investigate the anti‑tumor effects of HT on cell survival, invasiveness, chemoresistance and immune evasion in human BC cell lines (5637, T24 and UMUC3). Calcein AM staining was performed to analyze the cytotoxicity of natural killer (NK) cells against human BC cells following HT treatment. Cell migration and invasion affected by HT were analyzed using Transwell migration and invasion assays. It was found that HT inhibited the proliferation of BC cells by downregulating the phosphorylation of protein kinase B. Moreover, HT effectively enhanced the sensitivity of BC cells to the chemotherapy drug cisplatin (DDP) and reduced the chemoresistance of DDP‑resistant cells by downregulating the expression of cadherin‑11. It was further demonstrated that HT inhibited the migration and invasion of BC cells and enhanced the cytotoxic effects of NK cells. In summary, the antineoplastic effects of HT were mediated through three main mechanisms: Enhancement of the chemosensitivity of BC cells and mitigation of DDP‑induced chemoresistance, suppression of the invasive potential of BC cells and reinforcement of the anticancer response of NK cells. Thus, HT appears to be a promising adjunctive therapy for human BC.