Multicausal Nature of Cancer
With several dividing cells in the organism and the various proto-oncogenes and tumor suppressor genes that can be changed to cause cancer. one might expect cancer to be a more common event than it is. Several biologists believe that probably our/body has many initiated cells acquired throughout our life time but the several defense mechanisms of the body destroy them before they can cause cancer. Increasing proof now suggests that any single mutation in a cell is never by itself enough to cause cancer. Just only when a single cell suffers several sequential mutations does it lastly lose its regulation over its cell cycle and a fully fledged cancer results. One of the diseases which explains this concept is colorectal cancer. Primarily, in normal epithelium a suppressor gene on chromosome 5 is inactivated or lost. Next comes hypomethylation of DNA that is followed by mutation of ras proto-oncogene.
The losses of chromosomes 18 and 17 whole the transformation into a cancer cell. Further chromosome losses give the tumor the ability to form metastases. More and more research is being done on what in fact activates or turns on the genes in tumor cells and the role that individual oncogenes play in making the cells cancerous. By comparing DNA sequences of known oncogenes along with genes for cell growth and growth receptors, investigators have begun to identify key genes. For instance, an oncogenes has been found to correspond to the gene that functions as a growth factor in the healing of wounds. The invention of newer oncogenes is leading towards a better understanding of normal cell growth pathways and as well the-role of proto-oncogenes in development processes. The current efforts in prevention and treatment of cancers are characterized via a multidisciplinary approach. Early detection and characterization of the tumor is an important prerequisite for effective treatment. Understanding the cellular and molecular aspects of growth, differentiation and neoplastic change will provide clues to development of effective drugs for treatment. The combined efforts of developmental biologists and medical scientists can eventually lead to alleviation of human suffering from the disease.