Curcumin cytotoxicity is enhanced by PTEN disruption in colorectal cancer cells

AIM:To investigate the effects of phosphatase and tensin homolog deleted on chromosome 10(PTEN) deficiency on the cytotoxicity of chemotherapeutic agents toward colorectal cancer cells.METHODS:PTEN-deficient colorectal cancer(CRC) cells were generated by human somatic cell gene targeting using the adeno-associated virus system. The cytotoxic effects of compounds including curcumin,5-fluorouracil(5-FU),dihydroartemisinin(DHA),irinotecan(CPT-11)and oxaliplatin(OXA) on cancer cells were determined using the MTT assay. Enhanced cytotoxicity of curcumin in PTEN-deficient CRC cells was observed,and this was confirmed using clonogenic assays. Apoptosis and cell cycle progression were analyzed by flow cytometry.Levels of apoptosis and cell cycle-related proteins were examined by Western blotting.RESULTS:We developed an isogenic set of CRC cell lines that differed only in their PTEN status. Using this set of cell lines,we found that disruption of the PTEN gene had no effect on the sensitivity of CRC cells to5-FU,CPT-11,DHA,or OXA,whereas PTEN disruption increased the sensitivity of CRC cells to curcumin. Loss of PTEN did not alter the curcumin-induced apoptosis in CRC cells. However,PTEN deficiency led to an altered pattern of curcumin-mediated cell cycle arrest.In HCT116 PTEN+/+cells,curcumin caused a G2/M phase arrest,whereas it caused a G0/G1 phase arrest in HCT116 PTEN-/-cells. Levels of cell cycle-related proteins were consistent with these respective patterns of cell cycle arrest.CONCLUSION:Curcumin shows enhanced cytotoxicity toward PTEN-deficient cancer cells,suggesting that it might be a potential chemotherapeutic agent for cancers harboring PTEN mutations.

Recql5 protects against lipopolysaccharide/D-galactosamine-induced liver injury in mice

AIM: To investigate the effects of Recql5 deficiency on liver injury induced by lipopolysaccharide/D-galactosamine(LPS/D-Gal).METHODS: Liver injury was induced in wild type(WT) or Recql5-deficient mice using LPS/D-Gal,and assessed by histological,serum transaminases,and mortality analyses. Hepatocellular apoptosis was quantified by transferase d UTP nick end labeling assay and Westernblot analysis of cleaved caspase-3. Liver inflammatory chemokine and cytochrome P450 expression was analyzed by quantitative reverse transcription-PCR. Neutrophil infiltration was evaluated by myeloperoxidase activity. Expression and phosphorylation of ERK,JNK,p65,and H2 A.X was determined by Western blot. Oxidative stress was evaluated by measuring malondialdehyde production and nitric oxide synthase,superoxide dismutase,glutathione peroxidase,catalase,and glutathione reductase activity.RESULTS: following LPS/D-Gal exposure,Recql5-deficient mice exhibited enhanced liver injury,as evidenced by more severe hepatic hemorrhage,higher serum aspartate transaminase and alanine transaminase levels,and lower survival rate. As compared to WT mice,Recql5-deficient mice showed an increased number of apoptotic hepatocytes and higher cleaved caspase-3 levels. Recql5-deficient mice exhibited increased DNA damage,as evidenced by increased γ-H2 A.X levels. Inflammatory cytokine levels,neutrophil infiltration,and ERK phosphorylation were also significantly increased in the knockout mice. Additionally,Recql5-deficicent mice exhibited increased malondialdehyde production and elevated inducible nitric oxide synthase,superoxide dismutase,glutathione peroxidase,catalase,and glutathione reductase activity,indicative of enhanced oxidative stress. Moreover,CYP450 expression was significantly downregulated in Recql5-deficient mice after LPS/D-Gal treatment.CONCLUSION: Recql5 protects the liver against LPS/D-Gal-induced injury through suppression of hepatocyte apoptosis and oxidative stress and modulation of CYP450 expression.