ABSTRACT
DNA changes that confer growth advantages to tumor cells over normal cells are driver mutations, while those that do not are passenger mutations. Without an adequate supply of blood to provide nutrients and oxygen, and to remove waste products, tumors do not grow beyond the size of a pinhead. The formation and progression of tumors are caused by the rewiring of a core number of signaling pathways brought about by the accumulation of genetic modifications that activate oncogenes and inactivate tumor suppressor genes. Without the contribution of an oncogene, a tumor would cease to grow or progress to the next state, be it benign, malignant, or metastatic. Proto-oncogenes become oncogenes when their activities are increased by one or more genetic mutations, or by overexpression. The targeting of oncogenes and tumor suppressor genes regulated by microRNA represents a novel and potentially powerful therapeutic approach to cancer treatment.
