Stress-activated kinases as therapeutic targets in pancreatic cancer

Pancreatic cancer is a dismal disease with high incidence and poor survival rates.With the aim to improve overall survival of pancreatic cancer patients,new therapeutic approaches are urgently needed.Protein kinases are key regulatory players in basically all stages of development,maintaining physiologic functions but also being involved in pathogenic processes.c-Jun N-terminal kinases(JNK)and p38 kinases,representatives of the mitogen-activated protein kinases,as well as the casein kinase 1(CK1)family of protein kinases are important mediators of adequate response to cellular stress following inflammatory and metabolic stressors,DNA damage,and others.In their physiologic roles,they are responsible for the regulation of cell cycle progression,cell proliferation and differentiation,and apoptosis.Dysregulation of the underlying pathways consequently has been identified in various cancer types,including pancreatic cancer.Pharmacological targeting of those pathways has been the field of interest for several years.While success in earlier studies was limited due to lacking specificity and off-target effects,more recent improvements in small molecule inhibitor design against stress-activated protein kinases and their use in combination therapies have shown promising in vitro results.Consequently,targeting of JNK,p38,and CK1 protein kinase family members may actually be of particular interest in the field of precision medicine in patients with highly deregulated kinase pathways related to these kinases.However,further studies are warranted,especially involving in vivo investigation and clinical trials,in order to advance inhibition of stress-activated kinases to the field of translational medicine.

Efficacy of Cigu Xiaozhi pill(慈菇消脂丸) on non-alcoholic steatohepatitis-associated lipoapoptosis through stress-activated c-Jun N-terminal kinase signalling pathway

OBJECTIVE: To investigate the efficacy of Cigu Xiaozhi pill(慈菇消脂丸, CGXZ) on non-alcoholic steatohepatitis(NASH)-associated lipoapoptosis through the stress-activated c-Jun N-terminal kinase(JNK)/stress-activated protein kinase signalling pathway.METHODS: Sixty male Sprague-Dawley rats were randomly divided into the following groups(10 rats each): blank control, model, low-dose CGXZ,medium-dose CGXZ, high-dose CGXZ, and positive control(treated with SP600125, a JNK inhibitor).The NASH model was established and the histomor-phological characteristics of haematoxylin and eosin-stained liver tissues were examined under a light microscope. Cell apoptosis in liver tissues was assessed via terminal deoxynucleotidyl transferase d UTP nick-end labelling assay. In addition, the m RNA and protein expression levels of p-JNK,p-c-Jun, caspase-8, Fas, and Fas-L were determined via fluorescence-based quantitative real-time PCR,immunohistochemical and Western blot assays.RESULTS: Histopathological examination of the liver showed that the model rats had moderate-to-severe steatosis with infiltration of inflammatory cells as well as significantly higher expression levels of the p-JNK, p-c-Jun, caspase-8, Fas, and Fas-L proteins, compared with those in the blank control group(P < 0.01). Hepatic lobules of the rats in the treatment groups showed significantly reduced vacuolar degeneration and steatosis as well as alleviated inflammatory cell infiltration. The high and medium-dose CGXZ groups exhibited significantly lower m RNA and protein expression levels of p-JNK, p-c-Jun, caspase-8, Fas, and Fas-L, compared with those in the model group(P < 0.05 or P <0.01).CONCLUSION: CGXZ pill inhibited the onset of hepatocyte apoptosis by regulating the expression of p-JNK, p-c-Jun, caspase-8, Fas, and Fas-L, thereby exerting therapeutic effects against NASH.

Electroacupuncture exerts neuroprotective effects on ischemia/reperfusion injury in JNK knockout mice：the underlying mechanism

Simple regulation of c-Jun N-terminal kinase（JNK） or p38 mitogen-activated protein kinase（MAPK） pathways is not enough to trigger cell apoptosis.However,activation of the stress activated pathway（JNK/p38 MAPK） together with inhibition of the growth factor activated extracellular signal-regulated kinase（ERK） pathway can promote cell apoptosis.We hypothesized that inhibition of the JNK or p38 pro-apoptotic pathway and activating the ERK pathway could be the mechanism of anti-apoptosis following cerebral ischemia/reperfusion injury.To investigate the mechanism of the protective effect of electroacupuncture on cerebral ischemia/reperfusion injury in JNK knockout mice,mouse models of cerebral ischemia/reperfusion injury were established by Longa’s method.Electroacupuncture was conducted at acupoints Chize（LU5）,Hegu（LI4）,Sanyinjiao（SP6） and Zusanli（ST36） 1.5 hours after ischemia/reperfusion injury for 20 minutes,once a day.The neurological function was evaluated using neurological deficit scores.The expression of phospho-extracellular signal-regulated kinase（p-ERK） and phospho-p38（p-p38） in JNK knockout mice was detected using double-labeling immunofluorescence and western blot assay.The m RNA expression of ERK and p38 was measured by quantitative real-time polymerase chain reaction.Electroacupuncture improved neurological function,increased the immunoreactivity and relative expression of p-ERK and reduced that of p-p38 in the cerebral cortex and hippocampus on the injured side.Electroacupuncture increased m RNA expression of ERK,but decreased that of p38 in the cerebral cortex and hippocampus on the injured side.In conclusion,electroacupuncture upregulated the protective ERK pathway and inhibited the pro-apoptotic p38 pathway,thereby exerting a neuroprotective effect and improving the neurological function in JNK knockout mice.

Hippocampal activation of c-Jun N-terminal kinase,protein kinase B,and p38 mitogen-activated protein kinase in a chronic stress rat model of depression

Recent studies have shown that varied stress stimuli activate c-Jun N-terminal kinase （JNK）, protein kinase B （Akt）, and p38 mitogen-activated protein kinase （p38） signal transduction pathway, and also regulate various apoptotic cascades. JNK and p38 promote apoptosis, but Akt protects against apoptosis, in hippocampal neurons. However, changes in the transduction pathway in different regions of brain tissues in a chronic stress rat model of depression remain poorly understood. Results from this study showed that JNK phosphorylation levels were significantly greater in the stress group hippocampus compared with the control group （P 〈 0.05）. No significant difference in JNK phosphorylation levels was detected in the rat cerebral cortex between stress and control groups, and no significant difference in Akt and p38 phosphorylation levels was detected in the rat hippocampus and cerebral cortex between stress and control groups （P 〉 0.05）. These results suggested that the JNK signal pathway is activated by JNK phosphorylation and participates in pathophysiological changes in rat models of depression.