| Folate deficiency (FD) is associated with cancers of the lung, cervix, pancreas, breast, colon, and liver. It is suggested that carcinogenic effect of FD are related to epigenetic alterations i.e methylation, histone acetylation, and/or chromatin remodeling of the DNA. FD induces decreased SAM levels which in turn could lead to global hypomethylation along with region specific hypermethylation among tumor cells. Working with FD and BER, the endogenous DNA repair pathway, we have shown that FD inhibits the DNA damage inducibility of beta-pol in liver and spleen and an upregulation of beta-pol expression in liver in response to oxidative stress. The region upstream of transcription site for B-pol contains CpG Island, but does not contain any TATA or CART boxes. Hence to elucidate the mechanism by which beta-pol expression is altered, we analyzed the methylation status of beta-pol promoter in response to FD using Bisulfite Sequence Analysis. We have shown that methylation status of exon 1, the first 300 bases of the beta-pol promoter, both in spleen and in liver are not altered by FD. Interestingly none of the CpG islands present in the promoter of beta-pol was methylated in 71 the presence of Folate Adequate (FA)/FD diet. We confirmed the efficiency of the Bisulfite treatment, by looking at the methylation status of p-53 gene for exon 7-8. Hence DNA methylation does not appear to be the underlying mechanism by which FD alters expression of beta-pol and BER capacity. With the insight of this data, we further want to investigate the effect of FD on alternative mechanisms: histone acetylation, chromatin remodeling and regulation of transcription factors with beta-pol promoter. |
