Carcinogenesis Process

All cancers involve the malfunction of genes that control cell growth and division. The process by which cancers develop is called carcinogenesis. This process usually starts when chemicals or radiation damage DNA, the genetic structure inside cells. Viruses induce carcinogenesis by introducing new DNA sequences. Most of the time, when DNA becomes damaged the body is able to repair it. In cancer cells, however, the damaged DNA is not repaired. While normal cells with damaged DNA die, cancer cells with damaged DNA continue to multiply.

There is a long time lag between exposure to a carcinogen and the occurrence of cancer. While cellular mutations cause cancer to develop, it is not exactly clear how this happens. Carcinogenesis is a multistep process, in which as many as ten distinct mutations may have to accumulate in a cell before it becomes cancerous. The fact that so many mutations are needed for a cancer to develop indicates that cell growth is normally controlled through many sets of checks and balances.

The cell cycle is regulated by a large number of cellular genes that are expressed, or exhibited, at different stages of the cycle. The genes code for, or determine, growth factors, growth-factor receptors, and proteins that control gene functions and cell survival. Damaged DNA can lead to cancer because the cell cycle is distorted by the alteration and activation of oncogenes, genes that stimulate cell growth, or by the inactivation of tumor suppressor genes, which ordinarily suppress cell growth. Activated oncogenes drive abnormal, unregulated cell proliferation and lead to tumor formation. Mutations of the tumor suppressor gene p53 are found in about 50 percent of human cancers.

In experimental animals, three stages of chemical carcinogenesis have been identified. These are: (1) initiation, where DNA is irreversibly altered; (2) promotion, which is the multiplication of altered cells; and (3) progression, which involves chromosomal changes, high growth rate, invasiveness, and potential to metastasize.

growth factor: protein that stimulates growth of surrounding cells protein: complex molecule composed of amino acids that performs vital functions in the cell; necessary part of the diet

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

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