Identification and Characterization of New Chemical Entities Targeting Apurinic/Apyrimidinic Endonuclease 1 for the Prevention of Chemotherapy-Induced Peripheral Neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a potentially debilitating side effect of a number of chemotherapeutic agents. There are currently no U.S. Food and Drug Administration-approved interventions or prevention strategies for CIPN. Although the cellular mechanisms mediating CIPN remain to be determined, several lines of evidence support the notion that DNA damage caused by anticancer therapies could contribute to the neuropathy. DNA damage in sensory neurons after chemotherapy correlates with symptoms of CIPN. Augmenting apurinic/apyrimidinic endonuclease (APE)-1 function in the base excision repair pathway reverses this damage and the neurotoxicity caused by anticancer therapies. This neuronal protection is accomplished by either overexpressing APE1 or by using a first-generation targeted APE1 small molecule, E3330 [(2E)-2-[(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4-cyclohexadien-1-yl)methylene]-undecanoic acid; also called APX3330]. Although E3330 has been approved for phase 1 clinical trials (Investigational New Drug application number IND125360), we synthesized novel, second-generation APE1-targeted molecules and determined whether they would be protective against neurotoxicity induced by cisplatin or oxaliplatin while not diminishing the platins' antitumor effect. We measured various endpoints of neurotoxicity using our ex vivo model of sensory neurons in culture, and we determined that APX2009 [(2E)-2-[(3-methoxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)methylidene]-N,N-diethylpentanamide] is an effective small molecule that is neuroprotective against cisplatin and oxaliplatin-induced toxicity. APX2009 also demonstrated a strong tumor cell killing effect in tumor cells and the enhanced tumor cell killing was further substantiated in a more robust three-dimensional pancreatic tumor model. Together, these data suggest that the second-generation compound APX2009 is effective in preventing or reversing platinum-induced CIPN while not affecting the anticancer activity of platins.

[Effect of Electroacupuncture Intervention on CaMK II-CREB Pathway in Spinal Cord in Rats with Spared Nerve Injury].

OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation of "Weizhong" (BL 40)-"Huantiao" (GB 30) on expression of phosphorylated calcium/calmodulin dependent protein kinase II (p-CaMK II) and cAMP response element binding protein (p-CREB) in the spinal cord in rats with spared nerve injury (SNI), so as to explore its mechanism underlying easing neuropathic pain. METHODS: Sixty SD rats were randomly divided into five groups: control (sham-operation) , model, EA, AP-5 (a NMDA receptor antagonist) and L-NAME (a non-selective nitric oxide synthase, NOS inhibitor) (n = 12 in each group). The neuropathic pain model was established by sectioning the right tibal nerve and common peroneal nerve. EA intervention (2 Hz, 1 mA, increasing 1 mA/10 min) was applied to "Weizhong" (BL 40) and "Huantiao" (GB 30) on the injured side for 30 min, once a day for 7 days. Rats of the AP-5 and L-NAME groups were treated by intragastric administration of AP-5 (0.7 mg · kg(-1) · d(-1)) and L-NAME (60 mg · kg(-1) · d(-1)) respectively from the 11 th day after operation, once daily for 7 days. The mechanical pain thresholds were measured before the SNI procedure (baseline) and at the 10th and 16th day after the procedure. The expression of p-CaMK II protein and p-CREB protein and gene of the spinal cord (L4-L6 segments) was determined by Western blot and fluorescence quantitative-polymerase chain reaction (PCR), separately. RESULTS: In comparison to the control group, the mechanical pain threshold was significantly decreased in the model group (P < 0.01). After EA intervention, the mechanical pain thresholds of the EA, AP-5 and L-NAME groups were obviously increased (P < 0.01, P < 0.05) on day 16 post SNI procedure. The expression levels of p-CaMK II and p-CREB proteins and CREB mRNA in the spinal cord were significantly higher in the model group than in the control group (P < 0.05). Compared with the model group, the expression levels of spinal p-CaMK II and p-CREB proteins and CREB mRNA were obviously down-regulated in the EA group (P < 0.05), but not in the AP-5 group and the L-NAME group (P > 0.055. CONCLUSION: EA intervention of BL 40-GB 30 may alleviate pain in neuropathic pain rats, which may be related to its effects in down-regulating spinal CaMK II-CREB pathway function.

Ataxia with loss of Purkinje cells in a mouse model for Refsum disease.

Refsum disease is caused by a deficiency of phytanoyl-CoA hydroxylase (PHYH), the first enzyme of the peroxisomal alpha-oxidation system, resulting in the accumulation of the branched-chain fatty acid phytanic acid. The main clinical symptoms are polyneuropathy, cerebellar ataxia, and retinitis pigmentosa. To study the pathogenesis of Refsum disease, we generated and characterized a Phyh knockout mouse. We studied the pathological effects of phytanic acid accumulation in Phyh(-/-) mice fed a diet supplemented with phytol, the precursor of phytanic acid. Phytanic acid accumulation caused a reduction in body weight, hepatic steatosis, and testicular atrophy with loss of spermatogonia. Phenotype assessment using the SHIRPA protocol and subsequent automated gait analysis using the CatWalk system revealed unsteady gait with strongly reduced paw print area for both fore- and hindpaws and reduced base of support for the hindpaws. Histochemical analyses in the CNS showed astrocytosis and up-regulation of calcium-binding proteins. In addition, a loss of Purkinje cells in the cerebellum was observed. No demyelination was present in the CNS. Motor nerve conduction velocity measurements revealed a peripheral neuropathy. Our results show that, in the mouse, high phytanic acid levels cause a peripheral neuropathy and ataxia with loss of Purkinje cells. These findings provide important insights in the pathophysiology of Refsum disease.

In vitro degradation of amyloid material by four proteases in tissue of a patient with familial amyloidotic polyneuropathy.

The effects of 4 proteolytic enzymes, alpha-chymotrypsin, bromeline, collagenase, and lysozyme on amyloid tissue sections from a patient with familial amyloidotic polyneuropathy (FAP) were evaluated. Degradation of amyloid fibrils was significant with alpha-chymotrypsin, moderate with bromeline and collagenase, and slight with lysozyme. All of these proteases except collagenase are used as oral mucolytics in humans. The possibility of their clinical usefulness in the treatment or prevention of the development of FAP is discussed.