MicroRNAs are aberrantly expressed in cancer; microRNA‐143 (miR‐143) is down‐regulated in colon cancer. HCT116 human colorectal cancer cells were used to investigate the biological role of miR‐143. Transient miR‐143 overexpression resulted in an approximate 60% reduction in cell viability. In addition, stable miR‐143 overexpressing cells were selected with G418 and exposed to 5‐fluorouracil. Increased stable expression of miR‐143 was associated with decreased viability and increased cell death after exposure to 5‐fluorouracil. These changes were associated with increased nuclear fragmentation and caspase ‐3, ‐8 and ‐9 activities. In addition, extracellular‐regulated protein kinase 5, nuclear factor‐κB and Bcl‐2 protein expression was down‐regulated by miR‐143, and further reduced by exposure to 5‐fluorouracil. In conclusion, miR‐143 modulates the expression of key proteins involved in the regulation of cell proliferation, death and chemotherapy response. In addition, miR‐143 increases the sensitivity of colon cancer cells to 5‐fluorouracil, probably acting through extracellular‐regulated protein kinase 5/nuclear factor‐κB regulated pathways. Collectively, the data obtained in the present study suggest anti‐proliferative, chemosensitizer and putative pro‐apoptotic roles for miR‐143 in colon cancer.
This study shows a distinct pattern of bile acids in the liver of patients with steatohepatitis. Further, the association between bile acids and histological liver injury suggests an association of specific bile acids and disease progression, possibly through bile acid-induced liver injury.
Although genotype-phenotype correlations may be difficult to establish, they will be of increasing importance for choosing the most appropriate therapy for an individual patient, as new therapeutic strategies may be targeted according to phenotype.
Drug resistance to 5-fluorouracil (5-FU) is still a major limitation to its clinical use. In addition, the clinical value of p53 as a predictive marker for 5-FU-based chemotherapy remains a matter of debate. Here, we used HCT116 human colorectal cancer cells expressing wild-type p53 and investigated whether inhibition of Fas expression by interference RNA modulates 5-FU-induced apoptosis. Cells were treated with 5-FU (1, 4 or 8 microM) for 8-48 h. Cell viability was evaluated by trypan blue dye exclusion. Apoptosis was assessed by changes in nuclear morphology and caspase activity. The interference RNA technology was used to silence Fas expression. Caspase activation, p53, Fas, cytochrome c, and Bcl-2 family protein expression was evaluated by immunoblotting. 5-FU was cytotoxic in HCT116 cells (p<0.001). Nuclear fragmentation and caspase-3, -8 and -9 activities were also markedly increased in HCT116 cells after 5-FU (p<0.001). In addition, wild-type p53 and Fas expression were 25- and 4-fold increased (p<0.05). Notably, when interference RNA was used to inhibit Fas, 5-FU-mediated nuclear fragmentation and caspase activity were markedly reduced in HCT116 cells. Finally, western blot analysis of mitochondrial extracts from HCT116 cells exposed to 5-FU showed a 6-fold increase in Bax, together with a 3-fold decrease in cytochrome c (p<0.001). In conclusion, 5-FU exerts its cytotoxic effects, in part, through a p53/Fas-dependent apoptotic pathway that involves Bax translocation and mitochondrial permeabilization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.