[Show abstract][Hide abstract] ABSTRACT: Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a major protein kinase that is capable of regulating the activities of many ion channels and receptors. In the present study, the role of CaMKII in the complete Freund's adjuvant (CFA)-induced inflammatory pain was investigated. Intraplantarly injected CFA was found to induce spinal activity of CaMKII (phosphorylated CaMKII), which was blocked by KN93 [[2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine)], a CaMKII inhibitor. Pretreatment with KN93 (i.t.) dose-dependently prevented the development of CFA-induced thermal hyperalgesia and mechanical allodynia. Acute treatment with KN93 (i.t.) also dose-dependently reversed CFA-induced thermal hyperalgesia and mechanical allodynia. The action of KN93 started in 30 min and lasted for at least 2 to 4 h. KN92 (45 nmol i.t.) [2-[N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine], an inactive analog of KN93, showed no effect on CFA-induced CaMKII activation, allodynia, or hyperalgesia. Furthermore, our previous studies identified trifluoperazine, a clinically used antipsychotic drug, to be a potent CaMKII inhibitor. Inhibition of CaMKII activity by trifluoperazine was confirmed in the study. In addition, trifluoperazine (i.p.) dose-dependently reversed CFA-induced mechanical allodynia and thermal hyperalgesia. The drug was also effectively when given orally. In conclusion, our findings support a critical role of CaMKII in inflammatory pain. Blocking CaMKII or CaMKII-mediated signaling may offer a novel therapeutic target for the treatment of chronic pain.
Journal of Pharmacology and Experimental Therapeutics 05/2008; 325(1):267-75. DOI:10.1124/jpet.107.132167 · 3.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Head and neck cancer (HNC) is the fifth most common cancer in the world. In the US alone, HNC accounts for 3-5% of all malignancies annually. Squamous cell carcinoma arising from the mucosa of the upper aerodigestive tract is the most common type of HNC and accounts for 90% of HNC diagnoses. Despite continued advances in the therapeutic options, the disease-free survival, functional outcome, toxicity of therapy and overall survival have remained less than optimal for patients with locally advanced, recurrent or metastatic disease. Therefore, new approaches for the treatment of patients with HNC, particularly patients with advanced stage, are clearly needed. Among the new therapies, molecular-targeted and biological therapies have gained special attention. While clinical trial data support the use of epidermal growth factor receptor (EGFR) inhibition in metastatic and locally advanced HNC, numerous trials are seeking to establish a clear role for new therapies targeting EGFR, the receptor for the type I insulin-like growth factor, as well as anti-angiogenesis agents.
[Show abstract][Hide abstract] ABSTRACT: Protein phosphorylation is a key posttranslational modification mechanism controlling the conformation and activity of many proteins. Increasing evidence has implicated an essential role of phosphorylation by several major protein kinases in promoting and maintaining opioid tolerance. We review some of the most recent studies on protein kinase C (PKC), cyclic AMP dependent protein kinase A (PKA), calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase G (PKG), and G protein receptor kinase (GRK). These kinases act as the molecular switches to modulate opioid tolerance. Pharmacological interventions at one or more of the protein kinases and phosphatases may provide valuable strategies to improve opioid analgesia by attenuating tolerance to these drugs.
Life Sciences 10/2006; 79(18):1681-91. DOI:10.1016/j.lfs.2006.05.023 · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Previous studies have suggested that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) can modulate opioid tolerance and dependence via its action on learning and memory. In this study, we examined whether CaMKII could directly regulate opioid tolerance and dependence. CaMKII activity was increased after the treatment with morphine (100 mg/kg s.c. or 75 mg s.c. of morphine/pellet/mouse); the effect exhibited a temporal correction with the development of opioid tolerance and dependence. In mice treated with morphine (100 mg/kg s.c.), morphine tolerance and dependence developed in 2 to 6 h. An acute supraspinal administration of KN93 [2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine)], a CaMKII inhibitor, was able to dose-dependently reverse the already-established antinociceptive tolerance to morphine (p < 0.001 for 15-30 nmol; not significant for 5 nmol). KN92 [2-[N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine] (30 nmol i.c.v.), a kinase-inactive analog of KN93, did not affect opioid tolerance. Neither KN92 nor KN93 affected basal nociception or acute morphine antinociception (1-10 nmol i.c.v.). Likewise, dependence on morphine was abolished by the acute administration of KN93, but not KN92, in a dose-dependent manner. Pretreatment of mice with KN93 also prevented the development of morphine tolerance and dependence. The effect of acute CaMKII inhibition was not limited to the particular experimental model, because KN93 also acutely reversed the established opioid tolerance and dependence in mice treated with morphine (75 mg/pellet/mouse s.c.) for 6 days. Taken together, these data strongly support the hypothesis that CaMKII can act as a key and direct factor in promoting opioid tolerance and dependence. Identifying such a direct mechanism may be useful for designing pharmacological treatments for these conditions.
Journal of Pharmacology and Experimental Therapeutics 06/2006; 317(2):901-9. DOI:10.1124/jpet.105.097733 · 3.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chronic pain, especially neuropathic pain and cancer pain, is often not adequately treated by currently available analgesics. Animal models provide pivotal systems for preclinical study of pain. This article reviews some of the most widely used or promising new models for chronic pain. Partial spinal ligation, chronic constriction injury, and L5/L6 spinal nerve ligation represent three of the best characterized rodent models of peripheral neuropathy. Recently, several mouse and rat bone cancer pain models have been reported. Primary or permanent cultures of sensory neurons have been established to study the molecular mechanism of pain, especially for neurotransmitter release and signal transduction. The emerging gene microarray, genomics and proteomics methods may be applied to throughly characterize these cells. Each model is uniquely created with distinct mechanisms, it is therefore essential to report and interpret results in the context of a specific model.