Imbalanced expression of mitogen-activated protein kinase phosphatase-1 and phosphorylated extracellular signal-regulated kinases in lung squamous cell carcinoma

Objective： Mitogen-activated protein kinases （MAPKs） are correlated with a more malignant phenotype in many cancers. This study was designed to evaluate the predictive value of the expression of MAPK phosphatase-1 （MKP-1） and phosphorylated extracellular signal-regulated kinase 1/2 （p-ERKl/2）, as the key regulatory mechanism of the MAPKs, in lung squamous cell carcinoma （SCC）. Methods： We assessed the expressions of MKP-1 and p-ERK1/2 in twenty subjects at different differentiation degree of SCC and five normal lungs by immunohistochemistry and real-time reverse transcriptase polymerase chain reaction （RT-PCR） analysis. Results： Immunohistochemistry and real-time RT-PCR assay showed that the expression of MKP-1 was gradually decreased as tissue type went from normal lung tissues to increasingly undifferentiated carcinoma, and it was negatively correlated with tumor differentiation （P〈0.01）. However, the expression of p-ERK1/2 or ERKl/2 was gradually increased as tissue type went from normal lung tissues to increasingly undifferentiated carcinoma, and it was positively correlated with tumor differentiation （P〈0.01）. Conclusions： Our data indicates the relevance of MKP-1 and p-ERK1/2 in SCC as a potential positive and negative prognostic factor. The imbalanced expression of MKP-1 and p-ERKl/2 may play a role in the development of SCC and these two molecules may be new targets for the therapy and prognosis of SCC.

Down-regulation of HIV-1 Infection by Inhibition of the MAPK Signaling Pathway

The human immunodeficiency virus type 1 （HIV-1） can interact with and exploit the host cellular machinery to replicate and propagate itself. Numerous studies have shown that the Mitogen-activated protein kinase （MAPK） signal pathway can positively regulate the replication of HIV-1, but exactly how each MAPK pathway affects HIV-1 infection and replication is not understood. In this study, we used the Extracellular signal-regulated kinase （ERK） pathway inhibitor, PD98059, the Jun N-terminal kinase （JNK） pathway inhibitor, SP600125, and the p38 pathway inhibitor, SB203580, to investigate the roles of these pathways in HIV-1 replication. We found that application of PD98059 results in a strong VSV-G pseudotyped HIV-1NL4-3 luciferase reporter virus and HIV-1NL4-3 virus inhibition activity. In addition, SB203580 and SP600125 also elicited marked VSV-G pseudotyped HIV-INL4-3 luciferase reporter virus inhibition activity but no HIV-1NL4-3 virus inhibition activity. We also found that SB203580 and SP600125 can enhance the HIV-1 inhibition activity of PD98059 when cells were treated with all three MAPK pathway inhibitors in combination. Finally, we show that HIV-1 virus inhibition activity of the MAPK pathway inhibitors was the result of the negative regulation of HIV-1 LTR promoter activity.

Bim和细胞外调节蛋白在肝癌多药耐药细胞中的表达

目的检测人肝癌耐药细胞Hep G-2/ADM和亲本细胞Hep G-2中ERK1,ERK2、ERK5和Bim的表达,探讨其对肝癌细胞多药耐药的影响。方法小剂量缓慢诱导法诱导建立人肝癌耐药细胞株Hep G-2/ADM;CCK-8法测定Hep G-2/ADM对多种化疗药物的交叉耐药性;Western-blotting检测MRP-1,P-gp,ERK1,ERK2,ERK5和Bim蛋白水平的表达;荧光定量PCR检测Bim mRNA的表达。结果化疗药物能够体外诱导肿瘤细胞产生耐药性,Hep G-2/ADM对ADM、5-FU和CDDP的耐药指数分别为6.8,4.1和4.5,且高表达MRP-1和P-gp蛋白;与亲本细胞Hep G-2相比,Hep G-2/ADM中ERK1,ERK2和ERK5的表达均升高,ERK1蛋白磷酸化水平无显著变化,ERK2磷酸化水平下降,且p-ERK1/2与ERK1/2的比值下降;Bim的mRNA和蛋白表达均下降。结论细胞外调节蛋白激酶ERKs和Bcl-2家族的促凋亡蛋白Bim的表达与人肝癌多药耐药的发生密切相关。