Role of the ABL tyrosine kinases in the epithelial-mesenchymal transition and the metastatic cascade.

The ABL kinases, ABL1 and ABL2, promote tumor progression and metastasis in various solid tumors. Recent reports have shown that ABL kinases have increased expression and/or activity in solid tumors and that ABL inactivation impairs metastasis. The therapeutic effects of ABL inactivation are due in part to ABL-dependent regulation of diverse cellular processes related to the epithelial to mesenchymal transition and subsequent steps in the metastatic cascade. ABL kinases target multiple signaling pathways required for promoting one or more steps in the metastatic cascade. These findings highlight the potential utility of specific ABL kinase inhibitors as a novel treatment paradigm for patients with advanced metastatic disease. Video abstract.

DNA hypomethylation drives changes in MAGE-A gene expression resulting in alteration of proliferative status of cells.

Melanoma Antigen Genes (MAGEs) are a family of genes that have piqued the interest of scientists for their unique expression pattern. A subset of MAGEs (Type I) are expressed in spermatogonial cells and in no other somatic tissue, and then re-expressed in many cancers. Type I MAGEs are often referred to as cancer-testis antigens due to this expression pattern, while Type II MAGEs are more ubiquitous in expression. This study determines the cause and consequence of the aberrant expression of the MAGE-A subfamily of cancer-testis antigens. We have discovered that MAGE-A genes are regulated by DNA methylation, as revealed by treatment with 5-azacytidine, an inhibitor of DNA methyltransferases. Furthermore, bioinformatics analysis of existing methylome sequencing data also corroborates our findings. The consequence of expressing certain MAGE-A genes is an increase in cell proliferation and colony formation and resistance to chemo-therapeutic agent 5-fluorouracil and DNA damaging agent sodium arsenite. Taken together, these data indicate that DNA methylation plays a crucial role in regulating the expression of MAGE-A genes which then act as drivers of cell proliferation, anchorage-independent growth and chemo-resistance that is critical for cancer-cell survival.