Expression of cancer-testis antigens of Mage-a and Mage-b families in mouse embryonic fibroblasts cultured in vitro

Abstract

Cancer-testis antigens are expressed in the spermatogenic and cancer cells as well as in human and mouse pluripotent stem cells. However, the role of cancer-testis antigens of Mage families in the regulation of cellular processes in embryonic cells is largely unknown. In the present study comparative quantitative analysis of the gene expression of Magea and Mageb families was performed in mouse embryonic somatic cells (mouse embryonic fibroblasts, MEFs), long-term cultured in vitro and exposed to factors that inhibit and stimulate proliferation. The analysis revealed low expression of cancer-testis antigens of Mage families and showed that a lower proliferative activity of MEF at late passages was accompanied by slight up-regulation of the Magea gene expression and down-regutation of Mageb gene expression. However, modulation of the activity of MEK/ERK-signaling pathway and DNA demethylation by 5-azacytidine had no significant effects on the expression of Magea and Mageb genes in M EFs. The most essential changes in the expression levels of Mageb and Magea genes were found only when MEFs were exposed to mitomycin C. In all experimental variants, predominantly cytoplasmic localization of Mage antigens was found in MEFs at the phase of DNA synthesis, as well as at other cell cycle phases. Presumably, in actively proliferating mouse embryonic somatic cells the antigens of Magea and Mageb families can act as co-activators in the regulation of cell proliferation and other cellular functions.