Implication of heme oxygenase-1 in the sensitivity of nasopharyngeal carcinomas to radiotherapy

High expression of the inducible isoform of heme oxygenase (HO-1) is well known in various solid tumors in human and experimental animal models. To investigate the relationship between HO-1 and nasopharyngeal carcinomas, especially its involvement in the response of nasopharyngeal carcinomas to radiotherapy, thirty-two nasopharyngeal carcinomas were semi-quantitatively analyzed by RT-PCR, and the expression of HO-1 was correlated with the consequence after novel radiotherapy, which was evaluated by the reduction of tumor size. Among 32 nasopharyngeal carcinomas, HO-1 expression was found in 19 samples (59.4%), in which 9 patients (47.4%) showed no response to radiotherapy. Interestingly, in 13 nasopharyngeal carcinoma patients with negative expression of HO-1, radiotherapy exhibited to be effective (9 patients, 69.2%) or responsive (3 patients, 23.1%). In this study, we first demonstrated the expression of HO-1 in nasopharyngeal carcinomas, and more important, these findings strongly suggest the potential of HO-1 as a useful index in identifying patients with well response to radiotherapy, further these data indicate a new therapeutic for nasopharyngeal carcinoma by inhibiting HO-1 activity, which warrants further investigation.