Tamoxifen suppresses paclitaxel-, vincristine-, and bortezomib-induced neuropathy via inhibition of the protein kinase C/extracellular signal-regulated kinase pathway.

Chemotherapy-induced neuropathy is a highly problematic, dose-limiting effect of potentially curative regimens of cancer chemotherapy. When neuropathic pain is severe, patients often either switch to less-effective chemotherapy agents or choose to discontinue chemotherapy entirely. Conventional chemotherapy drugs used to treat lung and breast cancer, multiple myeloma, and lymphoma include paclitaxel, vincristine, and bortezomib. Approximately 68% of patients receiving these anticancer drugs develop neuropathy within the first month of treatment, and while strategies to prevent chemotherapy-induced neuropathy have been investigated, none have yet been proven as effective. Recent reports suggest that chemotherapy-induced neuropathy is associated with signal transduction molecules, including protein kinase C and mitogen-activated protein kinases. It is currently unclear whether protein kinase C inhibition can prevent chemotherapy-induced neuropathy. In this study, we found that tamoxifen, a protein kinase C inhibitor, suppressed paclitaxel-, vincristine-, and bortezomib-induced cold and mechanical allodynia in mice. In addition, chemotherapy drugs induce neuropathy via the protein kinase C/extracellular signal-regulated kinase pathway in the spinal cord in lumbar segments 4-6 and dorsal root ganglions. In addition, tamoxifen was shown to act synergistically with paclitaxel to inhibit tumor-growth in mice injected with tumor cells. Our results indicated that paclitaxel-, vincristine-, and bortezomib-induced neuropathies were associated with the protein kinase C/extracellular signal-regulated kinase pathway in the lumbar spinal cord and dorsal root ganglions, which suggest that protein kinase C inhibitors may be therapeutically effective for the prevention of chemotherapy-induced neuropathy when administered with standard chemotherapy agents.

Gabapentin and Duloxetine Prevent Oxaliplatin- and Paclitaxel-Induced Peripheral Neuropathy by Inhibiting Extracellular Signal-Regulated Kinase 1/2 (ERK1/2) Phosphorylation in Spinal Cords of Mice.

Chemotherapy-induced peripheral neuropathy is a common factor in limiting therapy which can result in therapy cessation or dose reduction. Gabapentin, a calcium channel inhibitor, and duloxetine, a serotonin noradrenaline reuptake inhibitor, are used to treat a variety of pain conditions such as chronic low back pain, postherpetic neuralgia, and diabetic neuropathy. It has been reported that administration of gabapentin suppressed oxaliplatin- and paclitaxel-induced mechanical hyperalgesia in rats. Moreover, duloxetine has been shown to suppress oxaliplatin-induced cold allodynia in rats. However, the mechanisms by which these drugs prevent oxaliplatin- and paclitaxel-induced neuropathy remain unknown. Behavioral assays were performed using cold plate and the von Frey test. The expression levels of proteins were examined using western blot analysis. In this study, we investigated the mechanisms by which gabapentin and duloxetine prevent oxaliplatin- and paclitaxel-induced neuropathy in mice. We found that gabapentin and duloxetine prevented the development of oxaliplatin- and paclitaxel-induced cold and mechanical allodynia. In addition, our results revealed that gabapentin and duloxetine suppressed extracellular signal-regulated protein kinase 1/2 (ERK1/2) phosphorylation in the spinal cord of mice. Moreover, PD0325901 prevented the development of oxaliplatin- and paclitaxel-induced neuropathic-like pain behavior by inhibiting ERK1/2 activation in the spinal cord of mice. In summary, our findings suggest that gabapentin, duloxetine, and PD0325901 prevent the development of oxaliplatin- and paclitaxel-induced neuropathic-like pain behavior by inhibiting ERK1/2 phosphorylation in mice. Therefore, inhibiting ERK1/2 phosphorylation could be an effective preventive strategy against oxaliplatin- and paclitaxel-induced neuropathy.

Trametinib suppresses chemotherapy-induced cold and mechanical allodynia via inhibition of extracellular-regulated protein kinase 1/2 activation.

Chemotherapy-induced neuropathy is a common, dose-dependent adverse effect of some anti-cancer drugs and leads to discontinuation of chemotherapy and detrimental dose reductions, thereby affecting the quality of life of cancer patients. Currently, no treatment can effectively prevent or treat chemotherapy-induced neuropathy. Therefore, understanding its underlying molecular mechanisms may help to identify novel therapies for treating it. Some disease-induced neuropathy involve the activation of mitogen-activated protein kinases (MAPKs), such as extracellular-regulated protein kinase 1/2 (ERK1/2). In the present study, we investigated whether ERK1/2 inhibition can prevent chemotherapy-induced neuropathy. We found that trametinib, an MEK inhibitor, suppressed oxaliplatin-, paclitaxel-, vincristine-, and bortezomib-induced cold and mechanical allodynia in mice. In addition, treatment with oxaliplatin, paclitaxel, vincristine, or bortezomib enhanced ERK1/2 and c-Jun N-terminal kinase (JNK) phosphorylation in the spinal cord lumbar segments 4-6, and when combined with trametinib, can prevent chemotherapy-induced neuropathy via the suppression of ERK1/2 activation, but does not affect JNK activation. In conclusion, we demonstrated that the disruption of this pathway by MEK inhibitors suppresses oxaliplatin-, paclitaxel-, vincristine-, and bortezomib-induced neuropathy. This suggests that inhibition of the MEK/ERK pathway could prevent chemotherapy-induced neuropathy and MEK inhibitors could be used in combination with anti-tumor drugs during pharmacotherapy.