COMPARATIVE-ANALYSIS OF THE METHYLATION STATUS OF THE 5' FLANKING REGION OF HA-RAS IN B6C3F1, C3H HE AND C57BL/6 MOUSE-LIVER/

We examined the methylation status of the 5' flanking region of Ha-ras in the liver of the liver tumor-prone B6C3F1 male (C57BL/6 female x C 3H/He male) and C3H/He male, plus the relatively resistant C57BL/6 mal e mouse strains. Southern analysis revealed the presence of CCGG sites methylated at the internal cytosine, as well as unmethylated CCGG sit es in all three strain's. Digestion with StyI and XhoI revealed an unm ethylated Xhol site in the C57BL/6 male. This pattern is not obvious i n the B6C3F1 or C3H/He, indicating sequence variation and/or less meth ylation of Ha-ras in those strains of mice that exhibit a high propens ity towards development of liver tumors.