Distribution of DNA polymerase Cm in normal and malignant human tissues

The distribution in human tissues has been determined of the new DNA polymerase activity designated DNA polymerase Cm, first isolated from the human melanoma cell line A-375. Tissue samples were fractionated by ion exchange chromatography on diethylaminoethyl cellulose and phosphocellulose and by affinity chromatography on poly(2'-O-methylcytidylate)-Sepharose. DNA polymerase activity was monitored with poly(2'-O-methylcytidylate) . oligodeoxyguanylate and poly(adenylate) . oligodeoxyribothymidylate, the most specific and most sensitive template primers, respectively, for DNA polymerase Cm. Tissues were scored as to presence or absence of detectable DNA polymerase Cm activity as well as to their validity for scoring dependent on content of total DNA polymerase activity. On this basis, seven of 14 malignant and none of 11 normal or embryonic tissues were found to contain detectable levels of DNA polymerase Cm.