ABSTRACT
Objective To investigate the effect of MRE11 on the proliferation and apoptosis of esophageal squamous cancer cells and its molecular mechanism. Methods MRE11 expression was downregulated by MRE11 siRNA transfection in esophageal squamous cancer cells. The AKT agonist SC79 (0, 0.1, 0.5, 1, 1.5, 1.8, 2 μg/ml) were used to treat cells with MRE11 inhibition for 24 h. Overexpression vector pcDNA.3.1-c-myc was constructed and co-transfected cells with MRE11 siRNA. Western blot method was used to detect the protein expressions of MRE11, p-AKT and c-myc in esophageal squamous cancer cells Ec9706 and TE-1. The Annexin-V FITC/PI kit was used to detect the apoptosis of Ec9706 and TE-1 cells; the activity of caspase-3 was detected by the Caspase-3 activity detection kit; the proliferation of Ec9706 and TE-1 cells was tested by the BrdU method. Results The protein expressions of MRE11 in Ec9706 and TE-1 cells were significantly increased, compared with human esophageal epithelial Het-1A cells. After MRE11 siRNA transfection, AKT phosphorylation and the protein expressions of MRE11 and c-myc were significantly decreased in esophageal squamous cancer cells. MRE11 inhibition significantly promoted the apoptosis and caspase-3 activity in Ec9706 and TE-1 cells, while inhibited the proliferation of Ec9706 and TE-1 cells. SC79 (1.5, 1.8 and 2 μg/ml) significantly increased AKT phosphorylation in MRE11-suppressed esophageal squamous cancer cells, and reversed the inhibitory effects of MRE11 inhibition on c-myc protein expression and cell proliferation and the promoting effect on cell apoptosis. Overexpression of c-myc inhibited the inhibitory effect of MRE11 down-regulation on cell proliferation and the promotion on caspase-3 activity. Conclusion MRE11 inhibition could effectively inhibit the proliferation of esophageal squamous cancer cells and promote cell apoptosis by regulating AKT and c-myc.
ABSTRACT
Genome stability can be threatened by both endogenous and exogenous agents. Organisms have evolved numerous mechanisms to repair DNA damage, including homologous recombination (HR) and non-homologous end joining (NHEJ). Among the factors associated with DNA repair, the MRE11-RAD50-NBS1 (MRN) complex (MRE11-RAD50-XRS2 in
ABSTRACT
Objective To evaluate the function of MRE11 in inflammasome activation.Methods Different stimuli,in-cluding Poly(I∶C), Poly(dA∶dT),E.coli gDNA,293T gDNA,CPPD and HSV,were used to identify the effective inflamma-some activator using ELISA.Then, MRE11 siRNA oligos were sythesized and transfected into THP-1 cells while Western blotting was used to analyze the efficacy of MRE 11 knockdown .Finally ELISA and Western blotting were used to analyze the involvement of MRE11 in inflammasome activation induced by Poly (I∶C), Poly(dA∶dT), E.coli gDNA and 293T gDNA. Results The IL-1βsecretion and pro-caspase-1 activation which induced by Poly ( I∶C) , Poly( dA∶dT) , E.coli gDNA and 293T gDNA were reduced with different degrees in MRE 11-knockdown THP-1 cells.Conclusion These results indicate that MRE11 is required for inflammasome activation induced by genetic materials .
ABSTRACT
The gradual loss of telomeric DNA can contribute to replicative senescence and thus, having longer telomeric DNA is generally considered to provide a longer lifespan. Maintenance and stabilization of telomeric DNA is assisted by binding of multiple DNA-binding proteins, including those involved in double strand break (DSB) repair. We reasoned that declining DSB repair capacity and increased telomere shortening in aged individuals may be associated with decreased expression of DSB repair proteins capable of telomere binding. Our data presented here show that among the DSB repair proteins tested, only the expression of Ku70 and Mre11 showed statistically significant age-dependent changes in human lymphocytes. Furthermore, we found that expressions of Ku70 and Mre11 are statistically correlated, which indicate that the function of Ku70 and Mre11 may be related. All the other DSB repair proteins tested, Sir2, TRF1 and Ku80, did not show any significant differences upon aging. In line with these data, people who live in the regional community (longevity group), which was found to have statistically longer average life span than the rest area, shows higher level of Ku70 expression than those living in the neighboring control community. Taken together, our data show, for the first time, that Ku70 and Mre11 may represent new biomarkers for aging and further suggest that maintenance of higher expression of Ku70 and Mre11 may be responsible for keeping longer life span observed in the longevity group.