The described invention provides methods for modulating gene expression of a gene related to proliferation of a population of tumor cells. The method entails administering a therapeutic amount of a therapeutic compound to a cell, a tissue, or a mammal, wherein the therapeutic amount of the therapeutic compound is effective to suppress methyltransferase activity of a protein arginine methyltransferase. Modulation of the protein arginine methyltransferase activity in turn modulates methylation of a target protein that affects gene expression of the gene, and may suppress the proliferation of the population of tumor cells.
