High levels of protein carboxyl methyltransferase in well-differentiated human endometrial carcinoma.

The levels of protein carboxyl methyltransferase, an enzyme that methylates free carboxyl groups of proteins, were determined in normal human proliferative and secretory endometrium and in poorly and well-differentiated endometrial carcinoma. Protein carboxyl methyltransferase activity was 67% higher in the well-differentiated carcinoma than in the normal tissues, while similar enzyme levels were observed in the two normal tissues and in the poorly differentiated carcinoma. The results suggest that in the well-differentiated tumor there is excessive protein methylation and offer a possible biochemical probe for distinguishing between the two types of tumor.