Oxaliplatin is a key drug commonly used in colorectal cancer treatment. Despite high clinical efficacy, its therapeutic application is limited by common, dose-limiting occurrence of neuropathy. As usual symptomatic neuropathy treatments fail to improve the patients' condition, there is an urgent need to advance our understanding of the pathogenesis of neuropathy to propose effective therapy and ensure adequate pain management. Oxaliplatin-induced neuropathy was recently reported to be associated with protein kinase C (PKC) activation. It is unclear, however, whether PKC inhibition can prevent neuropathy. In our current studies, we found that a PKC inhibitor, tamoxifen, inhibited oxaliplatin-induced neuropathy via the PKC/ extracellular signal-regulated kinase (ERK)/c-Fos pathway in lumbar spinal cords (lumbar segments 4-6). Additionally, tamoxifen was shown to act in synergy with oxaliplatin to inhibit growth in tumor cells-implanted mice. Moreover, mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, PD0325901, suppressed oxaliplatin-induced neuropathy and enhanced oxaliplatin efficacy. Our results indicate that oxaliplatin-induced neuropathy is associated with PKC/ERK/c-Fos pathway in lumbar spinal cord. Additionally, we demonstrate that disruption of this pathway by PKC and MEK inhibitors suppresses oxaliplatin-induced neuropathy, thereby suggesting that PKC and MEK inhibitors may be therapeutically useful in preventing oxaliplatin-induced neuropathy and could aid in combination antitumor pharmacotherapy.Oxaliplatin, a third-generation organoplatinum compound, has become the principal chemotherapy agent used in combination with 5-fluorouracil and leucovorin against colorectal cancer in both adjuvant and palliative therapy.1 However, neuropathy associated with oxaliplatin use is the predominant reason for dose modification, treatment schedule extension and termination of therapy.2 Oxaliplatin induces two different forms of neuropathy.3 A dose-limiting sensory neuropathy occurs at a cumulative dose above 540-850 mg/m 2 and may develop gradually following oxaliplatin treatment.
4A transient, acute syndrome consisting of cold-induced paraesthesia, dysesthesia or pain in the hands, feet, face and perioral regions appears in 80% of patients during the first or second cycle. 4 Current therapeutic options for alleviating neuropathy are mainly limited to drugs approved for other pain conditions, and none of the current agents proven to provide relief. 5 As chemotherapy becomes more effective, the number of cancer survivors is likely to increase, and neuropathy will become an important factor affecting their quality of life. Thus, it is of critical importance to elucidate the mechanism of oxaliplatin-induced neuropathy and consequently develop effective treatment strategies for this debilitating syndrome.Temperature-activated transient receptor potential (TRP) ion channels play important roles in pain sensation. Two particular TRP channels, TRPM8 and TRPA1, have been linked to the sensation of cold. Recently, i...