A correlation analysis revealed a negative relation between DNA methylation and gene expression levels that showed a trend towards statistical significance ( P- value = 0.1336, S7B Fig ), thus demonstrating that DNA methylation in rhesus CRC affected gene expression levels.
There were no significant methylation differences between other tumor sub-groups (MSS/MSI-L) and normal tissue samples ( S8 Fig ) ; however, there was a clear trend of higher levels of MLH1 promoter methylation among rhesus sporadic MSI-H compared to MSS tumors as well as a notorious absence of MLH1 methylation in the only LS tumor tested, which is consistent with human CRC biology.