Ras Signaling and Its Inhibition with Farnesyltransferase Inhibitors: Effects on Radiation Resistance and the Tumor Microenvironment

RAS activation has many effects on the growth and behavior of tumors. This results from its central role in the propagation of growth and survival signals from cell surface receptors. Ras signals to a number of different pathways so that the effects of RAS activation take various forms. In addition to enhancing radiation resistance, the effects of deregulated RAS signaling include promoting tumor growth both through increased cell proliferation and increased tumor cell survival. RAS activation can also contribute to the tumor micro environment by influencing growth factor production and enzymes involved in tumor metastasis. These factors together make RAS signaling an attractive target for therapeutic intervention.