Hypothermia Is a Potential New Therapy for a Subset of Tumors with Mutant p53.

The tumor suppressor p53 gene is mutated in approximately 50% of all human tumors. Many tumor-associated mutant p53 proteins misfold into a common, denatured conformation and accumulate to high levels in human tumors. In such tumors, these mutant forms of p53 provide a "gain of function" to promote tumor progression. Therefore, targeting mutant p53 has become an attractive approach for cancer therapy. In this issue, the study by Lu and colleagues supports the premise that certain forms of mutant p53 are temperature sensitive in conformation; these forms of p53 are mutant in conformation at physiologic temperature, but can refold into a normal, or "wild-type" conformation at lower temperature (32°C to 34°C). Notably, these temperature-sensitive mutants account for up to 7.5% of all human tumors that carry mutant p53, so this fraction of patients is estimated to be quite significant. Results from this study show that employing therapeutic hypothermia to reduce the core temperature of mice bearing tumors with these temperature-sensitive mutant forms of p53 (ts mutant p53) causes ts mutant p53 to switch to a wild-type conformation in tumors, inhibiting tumor growth. Moreover, combining hypothermia with chemotherapy leads to durable remission of such tumors, with no obvious toxicity to normal tissues.