细胞分化在抑制恶性肿瘤中的作用

虽然迄今尚无一家杂志专注于肿瘤形成的遗传抑制作用,而且也没有一个新的生物技术公司决心投资于此项目的商业开发,但肿瘤形成的遗传抑制已成为当前癌症研究的热点。自发现正常细胞中含有抑制恶性表型的基因至今已有20余年了。该实验包括两部分。首先,证明明确的恶性细胞可进行性地生长并置宿主于死地。

ERK signaling pathway may induce gemcitabine chemoresistance in pancreatic cancer cell line SW1990 by regulating the expression of mdr-1 and RRM1 gene

Objective： To investigate the relationship between extracellular signal-regulated kinase （ERK） pathway, multidrug resistance gene （mdr-1）, ribonucleotide recluctase M1 （RRM1） gene and their roles in gemcitabine （GEM） chemoresistance in pancreatic cancer cell line SW1990. Methods： The GEM-resistance cell model was constructed by a stepwise method. Immunohistochemistry was used to measure the expression of ERK protein （ERK1/2） in the established cell strains in a semiquantitative way. The mRNA expression of mdr-1 and RRM1 were detected by RT-PCR. MTT assay was performed to determine the IC50 value. Results： The established GEM-resistant cell strains were able to gain stable growth and passage ability in the medium contained different concentration levels of GEM （0, 30, 60, 100, 150 and 200 nmol/L）. The expression of ERK protein, mdr-1 and RRM1 gene were elevated accompanied by the increase of GEM concentration. There was a highly positive correlation between mdr-1, RRM1 expression and GEM-resistanca level （r = 0.960, P = 0.002 and r = 0.966, P = 0.002）. The expression of ERK protein also correlated with the mdr-1 and RRM1 level （r = -0.943, P = 0.005 and r = -0.883, P = 0.02）. At the GEM-resistance level of 200 nmol/L, the grey scale value of ERK1/2 was 164.22 ±13.17, mdr-1/β-actin and RRM1/β-actin were 1.41 ±0.04 and 1.45 ± 0.18, respectively; after treated with ERK pathway inhibitor U0126, these values synchronously decreased to 186.85 ± 13.14, 0.2 3± 0.02 and 0.21 ± 0.03, respectively; inversely, the ERK1/2 grey scale value was 106.55 ± 16.45, mdr-l/β-actin and RRMl/β-actin were 1.50± 0.07 and 1.52 ± 0.12, respectively, which presented a tendency of synchronously increase after treated with ERK pathway activator EGF. The IC50 values in GEM-resistant cells of 0 nmol/L and 200 nmol/L levels were 4.104 and 10.20, respectively. After treated with U0126, these values decreased to 3.26 and 4.50, respectively; while treated with EGF, the IC50 values increased to 8.89 and 17.17, respectively. Conclusion： The ERK pathway may induce the GEM-chemoresistance in pancreatic cell line SW1990 through the participation in the regulation of the mdr-1 and RRM1 gene expression.

Cilostazol inhibits plasmacytoid dendritic cell activation and antigen presentation

Background Cilostazol, an anti-platelet drug for treating coronary heart disease, has been reported to modulate immune cell functions Plasmacytoid dendritic cells （pDCs） have been found to participate in the progression of atherosclerosis mainly through interferon ct （IFN-ct） production. Whether cilostazol influences pDCs activation is still not clear. In this study, we aimed to investigate the effects of cilostazol on cell activation and antigen presentation ofpDCs in vitro in this study. Methods Peripheral blood mononuclear cells isolated by Ficoll cen- trifugation and pDCs sorted by flow cytometry were used in this study. After pretreated with cilostazol for 2 h, cells were stimulated with CpG-A, R848 or virus for 6 h or 20 h, or stimulated with CpG-B for 48 h and then co-cultured with naive T cell for five days. Cytokines in supernatant and intracellular cytokines were analyzed by ELISA or flow cytometry respectively. Results Our data indicated that cilostazol could inhibit IFN-α and tumor necrosis factor α （TNF-α） production from pDCs in a dose-dependent manner. In addition, the ability of priming na ve T cells of pDCs was also impaired by cilostazol. The inhibitory effect was not due to cell killing since the viability of pDCs did not change upon cilostazol treatment. Conclusion Cilostazol inhibits pDCs cell activation and antigen presentation in vitro, which may explain how cilostazol protects against atherosclerosis.

In vitro study of lovastatin interactions with amiodarone and with carbon tetrachloride in isolated rat hepatocytes

AIM： To investigate the interactions at a metabolic level between Iovastatin, amiodarone and carbon tetrachloride in isolated rat hepatocytes.METHODS： For cell isolation two-step collagenase liver perfusion was performed. Lovastatin was administered alone in increasing concentrations （1μmol/L, 3μmol/L, 5μmol/L and 10μmol/L） and in combination with CCh （86μmol/L）. The cells were also pretreated with 14μmol/L amiodarone and then the other two compounds were added. RESULTS： Lovastatin promoted concentration-dependent significant toxicity estimated by decrease in cell viability and GSH level by 45% and 840, respectively, LDH- activity increased by 114% and TBARS content by 90%, CCl4 induced the expected severe damage on the examined parameters, CCh induced toxicity was attenuated after Iovastatin pretreatment, which was expressed in less increased values of LDH activity and TBARS levels, as well as in less decreased cell viability and GSH concentrations, However, the pretreatment of hepatocytes with amiodarone abolished the protective effect of Iovastatin. CONCLUSION： We suggest that the observed cytoprotective effect was due to interactions between Iovastatin, CCh and amiodarone at a metabolic level.