Gene expression of proinflammatory cytokines in human coronary artery smooth muscle cells exposed to alkylating mutagen

Abstract

Background. It is known that DNA damage in smooth muscle cells can trigger their clonal expansion and transformation into foam cells. Thus, the study of the molecular genetic mechanisms of the vascular smooth muscle cells response to genotoxic exposure is important and relevant in the context of an in-depth understanding of atherogenesis.Aim. To study mRNA level and concentration of proinflammatory cytokines IL6 and IL8 in the human coronary artery smooth muscle cells exposed to alkylating mutagen.Methods. Gene expression signature of studied cytokines in the human coronary artery smooth muscle cells was accessed by quantitative polymerase chain reaction in the two timepoints – immediately after six-hour exposure to mitomycin C (point 1) and after six-hour exposure to mitomycin C followed by 24 hours of cells being cultivated on mitomycin C-free cell growth medium (point 2). Smooth muscle cells cultured according to the above scheme without genotoxin were used as controls. HPRT1, GAPDH and B2M were used as the reference genes. Gene expression level was calculated by ΔCt method. IL6 and IL8 concentration was evaluated in the culture media in points 1 and 2 by enzyme-linked immunosorbent assay. Statistical analysis was performed in GraphPad Prism 9 software.Results. Immediately after mutagenic exposure (point 1) we discovered no significant changes in the expression level of IL6 and IL8 in the mitomycin C exposed smooth muscle cells compared to controls. Removal of mutagen increased expression of IL6 and IL8 in the experimental group (0,36- and 0,67-fold, respectively). At the same time, we discovered no significant differences in the studied cytokines concentration in the culture medium of mutagen-exposed cells compared to the nonexposed controls.Conclusion. Genotoxic stress in human coronary artery smooth muscle cells exposed to alkylating mutagen (mitomycin C) leads to differential expression but not secretion of proinflammatory cytokines IL6 and IL8. Thus, exposure of smooth muscle cells to mitomycin C do not trigger their proinflammatory phenotype.