A proof-of-concept trial of protein kinase C iota inhibition with auranofin for the paclitaxel-induced acute pain syndrome

Roles of Phosphorylation of N-Methyl-D-Aspartate Receptor in Chronic Pain

Phosphorylation of N-methyl-D-aspartate receptor (NMDAR) is widely regarded as a vital modification of synaptic function. Various protein kinases are responsible for direct phosphorylation of NMDAR, such as cyclic adenosine monophosphate-dependent protein kinase A, protein kinase C, Ca²⁺/calmodulin-dependent protein kinase II, Src family protein tyrosine kinases, cyclin-dependent kinase 5, and casein kinase II. The detailed function of these kinases on distinct subunits of NMDAR has been reported previously and contributes to phosphorylation at sites predominately within the C-terminal of NMDAR. Phosphorylation underlies both structural and functional changes observed in chronic pain, and studies have demonstrated that inhibitors of kinases are significantly effective in alleviating pain behavior in different chronic pain models. In addition, the exploration of drugs that aim to disrupt the interaction between kinases and NMDAR is promising in clinical research. Based on research regarding the modulation of NMDAR in chronic pain models, this review provides an overview of the phosphorylation of NMDAR-related mechanisms underlying chronic pain to elucidate molecular and pharmacologic references for chronic pain management.

Speciation Analysis Highlights the Interactions of Auranofin with the Cytoskeleton Proteins of Lung Cancer Cells

Two types of lung cells (epithelial cancer lung cells, A-549 and lung fibroblasts MRC-5) were exposed to the clinically established gold drug auranofin at concentrations close to the half-maximal inhibitory drug concentrations (IC₅₀). Collected cells were subjected to speciation analysis using inductively coupled plasma mass spectrometry (ICP-MS). Auranofin showed better affinity toward proteins than DNA, RNA, and hydrophilic small molecular weight compounds. It can bind to proteins that vary in size (~20 kDa, ~75 kDa, and ≥200 kDa) and pI. However, the possibility of dimerization and protein–protein complex formation should also be taken into account. µRPLC/CZE-ESI-MS/MS studies on trypsinized proteins allowed the indication of 76 peptides for which signal intensity was influenced by auranofin presence in cells. Based on it, identity was proposed for 20 proteins. Except for thioredoxin reductase (TrxR), which is directly targeted by gold complex, the proteins were found to be transformed. Five indicated proteins: myosin, plectin, talin, two annexins, and kinase M3K5, are responsible for cell–cell, cell–protein interactions, and cell motility. A wound healing test confirmed their regulation by auranofin as cell migration decreased by 40% while the cell cycle was not interrupted.

Selective activation of metabotropic glutamate receptor 7 blocks paclitaxel-induced acute neuropathic pain and suppresses spinal glial reactivity in rats

RATIONALE

Paclitaxel-induced acute pain syndrome (P-APS), characterized by deep muscle aches and arthralgia, occurs in more than 70% of patients who receive paclitaxel. P-APS can be debilitating for patients and lead to reductions and discontinuation of potentially curable therapy. Despite being relatively common in clinical practice, no clear treatment exists for P-APS and the underlying mechanisms remain poorly defined. Regulation of glutamatergic transmission by metabotropic glutamate receptors (mGluRs) has received growing attention with respect to its role in neuropathic pain. To our knowledge, no study has been conducted on alterations and functions of group III mGluR7 signaling in P-APS.

OBJECTIVES

In the present study, we determined whether a single administration of paclitaxel induces glutamatergic alterations and whether mGluR7 activation blocks paclitaxel-induced neuropathic pain by suppressing glial reactivity in the spinal cord.

RESULTS

A single paclitaxel injection dose-dependently induced acute mechanical and thermal hypersensitivity, and was associated with increased glutamate level accompanied by reduction in mGluR7 expression in the spinal cord. Selective activation of mGluR7 by its positive allosteric modulator, AMN082, blocked the development of paclitaxel-induced acute mechanical and thermal hypersensitivity, without affecting the normal pain behavior of control rats. Moreover, activation of mGluR7 by AMN082 inhibited glial reactivity and decreased pro-inflammatory cytokine release during P-APS. Abortion of spinal glial reaction to paclitaxel alleviated paclitaxel-induced acute mechanical and thermal hypersensitivity.

CONCLUSIONS

There results support the hypothesis that spinal mGluR7 signaling plays an important role in P-APS; Selective activation of mGluR7 by its positive allosteric modulator, AMN082, blocks P-APS in part by reducing spinal glial reactivity and neuroinflammatory process.

Efficacy of the World Health Organization analgesic ladder in the paclitaxel-induced pain syndrome in rats

Paclitaxel use in cancer treatment is limited by a painful syndrome that has no effective treatment. Despite new therapies, drugs of the World Health Organization (WHO) analgesic ladder remain a useful therapeutic tool for cancer pain relief. Since cancer pain is caused by both tumor and chemotherapy, we assessed the efficacy of drugs from the WHO analgesic ladder for cancer pain relief in a paclitaxel-induced pain syndrome (P-IPS) model. P-IPS was induced in rats by one or four injections of paclitaxel on alternate days. The acute and chronic phases were assessed 24 h and 15 days after the first paclitaxel injection, respectively. The mechanical allodynia was evaluated after (step 1 of the ladder) paracetamol, (step 2) codeine alone or plus paracetamol and (step 3) morphine treatment in the acute or chronic phase of P-IPS. Paracetamol, codeine and morphine were equally efficacious in reducing the acute phase of the P-IPS. Codeine plus paracetamol had similar efficacy and potency when administered together in the acute phase of the P-IPS, but produced a longer-lasting effect than when separately managed. Moreover, paracetamol, codeine and morphine partially reduced the chronic phase of P-IPS, losing their efficacy and, in the case of codeine, potency when compared to the acute phase. However, paracetamol plus codeine increased the potency and efficacy of the codeine when compared to codeine administered alone in the chronic phase of P-IPS, producing a long-lasting anti-allodynic effect. Together, analgesics of WHO analgesic ladder reduce both acute and chronic phases of P-IPS, with codeine plus paracetamol presenting more potent, efficacious and long-lasting effect. Thus, in addition to tumor pain, drugs of WHO analgesics ladder could also be useful to treat P-IPS.

Loratadine for Paclitaxel-Induced Myalgias and Arthralgias

Background:

Seventy percentage of patients who receive paclitaxel have diffuse, refractory myalgias, and arthralgias. Based on anecdotal reports, this study explored whether loratadine, an antihistamine, palliates these symptoms.

Methods:

The medical records of postoperative ovarian and patients with endometrial cancer were studied, as these patients are routinely prescribed paclitaxel. Records were screened for patients who received paclitaxel and loratadine concurrently.

Results:

Forty patients are the focus of this report. Eight had paclitaxel-induced myalgias and arthralgias and then took loratadine; of these, 6 (75%; 95% confidence interval: 35%, 97%) manifested evidence of symptom improvement: “She did experience some migrating generalized body aches and pains…but this has resolved.” Of those already receiving loratadine but with no myalgias and arthralgias, only 11 of 32, or 34% (95% confidence interval: 19%, 53%), developed myalgias and arthralgias (in contrast to the previously reported symptom rate of 70%). No adverse events were clearly attributed to loratadine.

Conclusion:

These preliminary data support further study of loratadine for paclitaxel-induced myalgias and arthralgias.

A Novel Atypical PKC-Iota Inhibitor, Echinochrome A, Enhances Cardiomyocyte Differentiation from Mouse Embryonic Stem Cells

Echinochrome A (EchA) is a marine bioproduct extracted from sea urchins having antioxidant, antimicrobial, anti-inflammatory, and chelating effects, and is the active component of the clinical drug histochrome. We investigated the potential use of Ech A for inducing cardiomyocyte differentiation from mouse embryonic stem cells (mESCs). We also assessed the effects of Ech A on mitochondrial mass, inner membrane potential (Δψm), reactive oxygen species generation, and levels of Ca²⁺. To identify the direct target of Ech A, we performed in vitro kinase activity and surface plasmon resonance binding assays. Ech A dose-dependently enhanced cardiomyocyte differentiation with higher beating rates. Ech A (50 μM) increased the mitochondrial mass and membrane potential but did not alter the mitochondrial superoxide and Ca²⁺ levels. The in vitro kinase activity of the atypical protein kinase C-iota (PKCι) was significantly decreased by 50 μM of Ech A with an IC₅₀ for PKCι activity of 107 μM. Computational protein-ligand docking simulation results suggested the direct binding of Ech A to PKCι, and surface plasmon resonance confirmed the direct binding with a low K_D of 6.3 nM. Therefore, Ech A is a potential drug for enhancing cardiomyocyte differentiation from mESCs through direct binding to PKCι and inhibition of its activity.

Developing a genetic signature to predict drug response in ovarian cancer

There is a lack of personalized treatment options for women with recurrent platinum-resistant ovarian cancer. Outside of bevacizumab and a group of poly ADP-ribose polymerase inhibitors, few options are available to women that relapse. We propose that efficacious drug combinations can be determined via molecular characterization of ovarian tumors along with pre-established pharmacogenomic profiles of repurposed compounds. To that end, we selectively performed multiple two-drug combination treatments in ovarian cancer cell lines that included reactive oxygen species inducers and HSP90 inhibitors. This allowed us to select cell lines that exhibit disparate phenotypes of proliferative inhibition to a specific drug combination of auranofin and AUY922. We profiled altered mechanistic responses from these agents in both reactive oxygen species and HSP90 pathways, as well as investigated PRKCI and lncRNA expression in ovarian cancer cell line models. Generation of dual multi-gene panels implicated in resistance or sensitivity to this drug combination was produced using RNA sequencing data and the validity of the resistant signature was examined using high-density RT-qPCR. Finally, data mining for the prevalence of these signatures in a large-scale clinical study alluded to the prevalence of resistant genes in ovarian tumor biology. Our results demonstrate that high-throughput viability screens paired with reliable in silico data can promote the discovery of effective, personalized therapeutic options for a currently untreatable disease.