Oncogenes and tumor progression.

Although tumors are often characterized as being the result of uncontrolled proliferation, clinically the morbidity from cancer results from its ability to invade and metastasize and to become resistance to our current therapeutic modalities such as chemotherapy and radiation. The study of oncogenes has largely stressed their ability to alter cell growth, but in fact they also influence these crucial features of tumor progression. In this review, we will summarize the data from our laboratory that indicated that the ras oncogene can induce metastasis as well as tumorigenicity and that the ras oncogene can also influence the development of radiation resistance. We have found that these changes in cells are sometimes accompanied by characteristic non-random chromosomal alterations in the transformed cells and will speculate that these accompanying chromosomal changes also may contribute to the features of tumor progression.