Effect and mechanism of atorvastatin on cytotoxicity of human NK cells to colon cancer cells / 中国免疫学杂志

Objective:To explore the mechanism of the cytotoxicity of human NK cells induced by atorvastatin to colon cancer cell lines. Methods:After colon cancer cells (HCT-116,SW-480,Caco-2) were cultured with different concentrations of atorvastatin, CCK-8 assay was used to assess the effect of atorvastatin on growth of colon cancer cells. The amplification of human NK cells was induced by SCGM medium in vitro. Automatic biochemical analyzer was applied to test the cytotoxicity of NK cells to colon cancer cells which cultured with different concentration of atorvastatin. FCM was used to detect the expression rate of MICA/B on the cells. Results:(1) The cultivation of NK cells:The proportion of NK cells attained to 93. 1% from 4. 5% after cultured for 10 days. (2) The effects of atorvastatin on the growth of the colon cancer cells:After cultured with atorvastatin,the inhibition rate of HCT-116 cells was higher than that in control when the density of atorvastatin increased from 5 μmol/L to 40 μmol/L after 48 h and from 1. 25 μmol/L to 40 μmol/L after 96 h ( P<0. 05 ) . Correlation analysis showed that the concentration of atorvastatin and the growth inhibition rate of HCT-116 cells were positively correlated(r[48 h]=0. 13,r[96 h]=0. 22,P<0. 05). (3) The cytotoxicity of NK cells to colon cancer cells effected after atorvastatin: In different atorvastatin concentrations groups,the cytotoxicity of NK cells to three colon cancer cell lines was all higher than that in control ( P<0. 05 ) . The atorvastatin concentration was from 2. 5 μmol/L to 10 μmol/L for HCT-116 cells,from 5 μmol/L to 20μmol/L for SW-480 cells,and from 2. 5μmol/L to 20μmol/L for Caco-2 cells. Among the three cell lines, the cytotoxicity of NK cells to HCT116 was the highest in the same concentration. (4)NK cells by atorvastatin cutting statins 96 h,the concentration of 20 mmol/L and 40 mmol/L inhibition rate was higher than that of control group,more than other groups on NK cell growth without significant effect. ( 5 ) The impact of atorvastatin on MICA/B expression of colon cancer cells: After cultured with different concentrations of atorvastatin,the expression of MICA/B on colon cancer cells was higher than that in control(P<0. 05). The concentration was 2. 5μmol/L and 5μmol/L for HCT-116 cells,10μmol/L and 20μmol/L for SW-480 cells,and from 2. 5μmol/L to 40 μmol/L for Caco-2 cells. Conclusion:Atorvastatin could inhibit the growth of colon cancer cells (HCT-116,SW-480 and Caco-2) in a dose-dependent manner;and it could enhance the cytotoxicity of NK cells to colon cancer cells;it also could promote the expression of MICA/B of colon cancer cells,and improve the immunogenicity of colon cancer cells.

Bacillus spp. or Bacillus spp.-Derived Membrane Vesicles Induce the Intrinsic Pathways of Apoptosis of Human Colon Cancer Cell Lines

The striking increase in colorectal cancer (CRC) has shown the great fatality in Korea for more than 15 years. The leading edge of this rising incidence rate is mainly due to the people's dietary changes in Korea. Some studies have reported that the dietary fiber does not have significant cytotoxic effects on CRC cells, which contrasts to the effects of probiotics. It gives a positive evaluation that the nonpathogenic spore-forming Bacillus species among the probiotics including fermented bacteria might have optimistic effects on CRC incidence rate. Recently, we isolated Bacillus lentus (BL) from Korean soybean fermented food. BL showed the cytotoxic effect on human colon carcinoma cell lines HCT116 and SW480. Interestingly, BL did not have effect on human dermal fibroblast cells and human hepatoma cell line HepG2. It suggested that BL has the target cell-specific cytotoxicity toward human colon carcinoma cells. To clarify the death signaling pathway underlying the BL-induced apoptosis in cancer cells, we analyzed the expression of caspases, Bax and Bcl-2 by western blotting. The apoptotic effects by cytotoxic elements were executed by direct BL contact or membrane-derived vesicles isolated from BL. Treatment of HCT116 with BL activated caspase-9, -3 and increased cleavage form of poly (ADP-ribose) polymerase (PARP). However, caspase-8 activity was not increased by BL. BL-activated intrinsic pathway increased the pro-apoptotic Bax, decreased the anti-apoptotic Bcl-2 proteins on mitochondria, disrupted the mitochondrial membrane potential, and then released the cytochrome c from mitochondria. The membrane-derived vesicles (MVs) from BL induced apoptosis of the HCT116. Here, we propose that BL as a strong candidate for the development of apoptosis-specific anti-tumor agent will give great contribution to the understandings of the tumor-microbe interdisciplinary areas.

Roles of cFLIPL in Fas-mediated Apoptosis of Colon Cancer

PURPOSE: Substantial numbers of the colon cancer cells have been observed to express Fas/Fas ligands, but are resistant to Fas-mediated apoptosis, suggesting that colon tumors might develop the specific mechanisms to overcome Fas-mediated apoptosis. Recently, cellular FLICE-like inhibitory protein (cFLIP) has been identified as an endogenous inhibitor of Fas- or other receptor-mediated apoptosis and its altered high expression has been suspected to be associated with tumor development or progression. This study investigated the prevalence of cFLIPL alterations in colon carcinomas and possible implications in the progression of colon cancers. METHODS: In order to investigate the function of cFLIPL for the development and progression of the colon cancer, we analyzed the expression of the cFLIPL in 58 colon cancer and 6 colon cancer cell lines. RESULTS: The study results demonstrated that cFLIPL is one of the major determinants for sensitivity to Fas-mediated apoptosis in colon cancer cell lines. In addition, we analyzed cFLIPL expression in 58 cases of adenocarcinoma of the colon and showed that cFLIPL, expression was increased in adenocarcinoma as compared to matched normal mucosa. CONCLUSION: Taken together, our data strongly suggested that abnormal overexpression of cFLIPL is a frequent event in colon carcinomas and might contribute to in vivo tumor transformation.