cPKCγ Inhibits Caspase-9-Initiated Neuronal Apoptosis in an Ischemia Reperfusion Model In Vitro Through p38 MAPK-p90RSK-Bad Pathway.

Strokes are one of the leading causes of death and disability in the world. Previously we have found that conventional protein kinase Cγ (cPKCγ) plays neuroprotective role in ischemic strokes. Further, we found that cPKCγ knockdown increased the level of cleaved (cl)-Caspase-3. However, the precise mechanisms underlying cPKCγ-mediated neuronal death remain unclear. To this end, a model incorporating 1 h oxygen-glucose deprivation/24 h reoxygenation (1 h OGD/24 h R) was established in cortical neurons. We found that cPKCγ knockdown remarkably increased neuronal death after OGD. We also found that cPKCγ knockdown increased the level of cl-Caspase-3 through the upstream initiators Capsases-9 (not Caspase-8/12) in OGD-treated neurons. Overexpression of cPKCγ could decrease neuronal death and cl-Caspase-3 and -9 levels. Moreover, cPKCγ knockdown further reduced the phosphorylation levels of p38 MAPK, p90RSK, and Bad. In addition, the protein levels of Bcl-2 and Bcl-xl were decreased after cPKCγ knockdown, whereas that of Bax was increased. In conclusion, our results suggest that cPKCγ partly alleviates ischemic injury through activating the p38 MAPK-p90RSK-Bad pathway and inhibiting Caspase-9 initiated apoptosis. This may have potential as a therapeutic target for ischemic stroke.

EBV LMP1-C terminal binding affibody molecule downregulates MEK/ERK/p90RSK pathway and inhibits the proliferation of nasopharyngeal carcinoma cells in mouse tumor xenograft models.

Nasopharyngeal carcinoma (NPC), is an Epstein-Barr virus (EBV) associated malignancy most common in Southern China and Southeast Asia. In southern China, it is one of the major causes of cancer-related death. Despite improvement in radiotherapy and chemotherapy techniques, locoregional recurrence and distant metastasis remains the major causes for failure of treatment in NPC patients. Therefore, finding new specific drug targets for treatment interventions are urgently needed. Here, we report three potential ZLMP1-C affibody molecules (ZLMP1-C15, ZLMP1-C114 and ZLMP1-C277) that showed specific binding interactions for recombinant and native EBV LMP1 as determined by epitope mapping, co-localization and co-immunoprecipitation assays. The ZLMP1-C affibody molecules exhibited high antitumor effects on EBV-positive NPC cell lines and displayed minimal cytotoxicity towards EBV-negative NPC cell line. Moreover, ZLMP1-C277 showed higher antitumor efficacy than ZLMP1-C15 and ZLMP1-C114 affibody molecules. The ability of ZLMP1-C277 decrease the phosphorylation levels of up-stream activator phospho-Raf-1(Ser338), phospho-MEK1/2(Ser217/Ser221), phospho-ERK1/2(Thr202/Thr204), thereby leading to downstream suppression of phospho-p90RSK(Ser380) and transcription factor c-Fos. Importantly, tumor growth was reduced in tumor-bearing mice treated with ZLMP1-C277 and caused no apparent toxicity. Taken together, our findings provide evidence that ZLMP1-C277 as a promising therapeutic agent in EBV-associated NPC.

Mitogen- and Stress-Activated Protein Kinase 1 Mediates Alcohol-Upregulated Transcription of Brf1 and tRNA Genes to Cause Phenotypic Alteration.

Upregulation of Brf1 (TFIIB-related factor 1) and Pol III gene (RNA polymerase III-dependent gene, such as tRNAs and 5S rRNA) activities is associated with cell transformation and tumor development. Alcohol intake causes liver injury, such as steatosis, inflammation, fibrosis, and cirrhosis, which enhances the risk of HCC development. However, the mechanism of alcohol-promoted HCC remains to be explored. We have designed the complementary research system, which is composed of cell lines, an animal model, human samples, and experiments in vivo and in vitro, to carry out this project by using molecular biological, biochemical, and cellular biological approaches. It is a unique system to explore the mechanism of alcohol-associated HCC. Our results indicate that alcohol upregulates Brf1 and Pol III gene (tRNAs and 5S rRNA) transcription in primary mouse hepatocytes, immortalized mouse hepatocyte-AML-12 cells, and engineered human HepG2-ADH cells. Alcohol activates MSK1 to upregulate expression of Brf1 and Pol III genes, while inhibiting MSK1 reduces transcription of Brf1 and Pol III genes in alcohol-treated cells. The inhibitor of MSK1, SB-747651A, decreases the rates of cell proliferation and colony formation. Alcohol feeding promotes liver tumor development of the mouse. These results, for the first time, show the identification of the alcohol-response promoter fragment of the Pol III gene key transcription factor, Brf1. Our studies demonstrate that Brf1 expression is elevated in HCC tumor tissues of mice and humans. Alcohol increases cellular levels of Brf1, resulting in enhancement of Pol III gene transcription in hepatocytes through MSK1. Our mechanism analysis has demonstrated that alcohol-caused high-response fragment of the Brf1 promoter is at p-382/+109bp. The MSK1 inhibitor SB-747651A is an effective reagent to repress alcohol-induced cell proliferation and colony formation, which is a potential pharmaceutical agent. Developing this inhibitor as a therapeutic approach will benefit alcohol-associated HCC patients.