Therapeutic benefits of maintaining mitochondrial integrity and calcium homeostasis by forced expression of Hsp27 in chemotherapy-induced peripheral neuropathy

Background: Vincristine, a widely used antineoplastic agent, is known to be neurotoxic and to lead to chemotherapy -induced peripheral neuropathy (CIPN), which is characterized by nerve damage. Growing evidence suggests that disruption of intracellular calcium homeostasis in peripheral neurons contributes largely to the pathological conditions of CIPN. Our previous study showed that forced expression of a peripheral nerve injury induced small heat shock protein (Hsp), Hsp27, accelerates axon regeneration and functional recovery. In the current study, we examined whether neuronal expression of human Hsp27 (hHsp27) can prevent the inhibitory effects of vincristine in two mouse models of peripheral nerve injury, namely, sciatic nerve crush and CIPN. Methods: The protective effects of hHsp27 against vincristine were examined in mouse models of both sciatic nerve crush and CIPN using multiple approaches, including animal behavioral tests, histology, electrophysiology, transmission electron microscopy and calcium imaging. Results: Vincristine delayed functional recovery in littermate mice; however, hHsp27 Tg mice were unaffected after vincristine treatment and sciatic nerve crush. In CIPN mice, hHsp27 protected against vincristine-induced mechanical and cold allodynia by preventing axonal degeneration, demyelination, mitochondrial dysfunction, and apoptosis. Strikingly, vincristine-induced calcium influx was markedly attenuated in sensory neurons of hHsp27 Tg mice. Conclusions: Our findings suggest that preserving myelin and mitochondrial integrity as well as maintaining intracellular calcium homeostasis is beneficial for preventing CIPN, and these findings shed new light on the development of anti-CIPN drugs.