Hyperthermia induces apoptosis by targeting Survivin in esophageal cancer

Hyperthermia is considered the fifth pillar of cancer treatment. It induces cancer cell apoptosis, however, its molecular mechanisms remain unclear. In the present study, the role of Survivin in hyperthermia-induced apoptosis in esophageal cancer was investigated. Different temperatures were used to treat EC109 esophageal cancer cells, and their viability was found to be significantly inhibited with a concomitant increase in apoptosis and necrosis. Necrosis increased in a temperature‑dependent manner, whereas peak apoptosis was reached at 43˚C. The hyperthermia-induced apoptosis was due to the inhibition of Survivin and the activation of caspase-3. Subsequently, overexpression of Survivin inhibited the activation of caspase-3 and hyperthermia-induced apoptosis, however, this inhibition was reversed in the absence of XIAP. Immunoprecipitations showed that Survivin did not directly bind to caspase-3, whereas XIAP interacted with Survivin and caspase-3. Immunohistochemistry was performed to detect the expression of Survivin in esophageal cancer patient samples. A higher expression of Survivin in esophageal cancer tissues compared to normal tissues was observed, and a high expression correlated with poor prognosis. The results indicated that hyperthermia decreases the expression of Survivin, prevents its binding to XIAP, activates caspase-3 and induces apoptosis. Due to its correlation with poor prognosis, Survivin may be a target for hyperthermia in the treatment of esophageal cancer.