Inflammatory mediator-induced dysregulation of colorectal carcinogenic pathways.

摘要

Colorectal cancer (CRC) is a leading cause of cancer-related mortality in the U.S. Although CRC is associated with a lifetime risk of 5-6% in the general population, this risk is increased in those with inflammatory bowel disease (IBD) and is influenced by severity, extent and duration of disease. The inflammation seen in IBD is partly the consequence of the collective actions of various cytokines, of which tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) are arguably the most important. Although chronic inflammation has been linked to carcinogenesis, little is known regarding the effect of its mediators on tumor suppressors and proto-oncogenes in IBD-related CRC. The first objective of the research presented herein was to investigate the effects of TNFalpha and IFNgamma on the apoptotic intermediaries p53 and p53 upregulated modulator of apoptosis (PUMA), as dysregulation of the p53 pathway is typical in CRC.;The in vitro study of principal CRC-related signaling pathways relies heavily on the use of cultured cells. The most well-known and repeatedly used established cell lines in public repositories have been maintained for decades. Since long-term cell culture predisposes to spontaneous mutagenesis and altered morphological and behavioral features, a need for novel, characterized cell lines to enrich the current experimental model is necessary. Therefore, the second objective of the discussed research was to develop and characterize novel CRC lines, as well as to compare their microRNA (miRNA) and protein expression profiles to those of the tissue from which they were derived to assess the degree of reliability of these cell lines in their representation of their progenitor tissue.;We have shown that TNFalpha and IFNgamma upregulated PUMA in a p53-independent manner and that this upregulation was synergistic and corresponded to apoptotic activity. These cytokine-induced effects suggest that TNFalpha and IFNgamma may serve protective roles, rather than those promoting tumorigenesis, in CRC. We have also established and characterized four cell lines from fresh CRC tissue. A weak to moderate degree of correlation was demonstrated for miRNA and protein expression profiles between the cell lines and their respective progenitor tissue, while expression levels between the four cell lines, themselves, exhibited a strong level of agreement. Though our cell lines possess distinct features from their tissues of origin, overall, they retain similar miRNA and protein expression, rendering them acceptable for use in studies of cancer biology.