In vitro neuroprotective action of erythrpoietin against docetaxel and cisplatin induced neurotoxicity

Chemotherapy induced Peripheral Neuropathy (CIPN) is a a well known complication limiting Cisplatin (CDDP) and Docetaxel (DOCE) chemotherapy in patients with cancer. Erythropoietin (EPO) is an heamatopoietic growth factor that has been reported to display neurothrophic properties, in particular it has proved to be neuroprotective in several rodent models of nervous system damage, including CDDP induced peripheral neuropathy. In this study we evaluated the neuroprotective ability of EPO against CDDP and DOCE induced neurotoxicity in primary cultures of sensitive neurons dissociated from Dorsal Root Ganglia (DRG) obtained from 15-day-old rat embryos, aiming to investigate the mechanism underlying EPO neuroprotective action. Briefly, primary cultures of sensitive neurons have been exposed to CDDP (25M), DOCE (100nM) or to the same doses of the chemotherapics but in the presence of EPO (10nM). In this in vitro model EPO turned out to be protective against both CDDP and DOCE induced neurotoxicity, in fact an increased neuronal survival was evident in cultures exposed to the combination treatment with CDDP plus EPO and DOCE plus EPO. Several evidences suggest that AKT pathway may play an important role in EPO neuroprotective action. Therefore we analyzed by western blot the levels of expression and activation (phosphorylation) of AKT in neurons exposed to the CDDP, DOCE or to the cotreatment with EPO. Results obtained indicated that modulation of the levels of phosphorylated AKT (pAKT) occurs following 14 hours treatment with CDDP, when a sharp decrease in the levels of activated AKT was highlighted, on the contrary DOCE induced only a sligth increase in the level of pAKT. Cotreatment with EPO was able to partially prevent CDDP induced decrease in the level of pAKT. Using a specific inhibitor of AKT activation (Wortmannin) we therefore investigate the role of AKT in EPO neuroprotection. The presence of Wortmannin (100nM) did prevent EPO neuroprotective action against CDDP induced neurotoxicity, but did not have any effect on EPO action against DOCE induced neurotoxicity. In conclusion in this study EPO has proved to be an effective neuroprotectant against neurotoxicity induced by both Cisplatin and Docetaxel, in addition results obtained suggest that AKT is an essential element in EPO neuroprotection. However, considering that AKT activation appears essential for EPO neuroprotection against CDDP induced neurotoxity, but not against DOCE, we assume that EPO neuroprotective action may act on two distinct cellular signalling pathways following CDDP or DOCE induced neurotoxicity.