An argument explaining the reasons how cancer cells propagate in the human body

For this reason chemotherapy is often used at the maximal tolerated dose, with the consequent side effects on tissues that depend on rapid cell turnover such as the oral and gastrointestinal mucosa, the hair, skin, and nails.

An inherited mutation of the APC gene gives rise to thousands of polyps in the colon, which leads to early onset of colon carcinoma Fodde et al.

What is the purpose of cancer

This causes a persistent inflammatory state that promotes liver cirrhosis and, ultimately, HCC. A further mutation in the signaling machinery of the cell might send error-causing signals to nearby cells. In contrast, however, several other tumor-promoting conditions are common in the U. As the cells cease to look normal, the lesion is considered a carcinoma in situ, in which the abnormal cells are still confined to the normal limits of the tissue boundaries. Genomic amplification occurs when a cell gains copies often 20 or more of a small chromosomal locus, usually containing one or more oncogenes and adjacent genetic material. The trigger is probably most reliable i. Invasion and metastasis are key features that distinguish malignant tumors—cancer proper—from benign growths. Mendelsohn, J.

Nogueira, A. Ginsberg, J. This idea finds further development in the concept of "field cancerization", i. Olsson, A.

hallmarks of cancer

Bibliography American Cancer Society. Guise, and J.

Cancer evolution review

To spread the tumor to distant sites, the cancer cells must also gain the ability to pass into the circulation, enter distant tissues, and adapt to the microenvironment of those tissues eventually overtaking them. Thus, metastasis progression genes may couple the tissue-specific requirements of the microenvironment in a particular organ to a matching role in primary tumor progression. With these differences come distinct treatment indications. However, by one mechanism or another a subset of cancer cells in a tumor have the capacity of acting as tumor-propagating cells Clarke and Fuller Bierie, B. The basement membrane separates the epithelial cell layers in which carcinomas originate, from the subjacent tissue. Some disseminated cancer cells may go on to reproduce the tumor in distant organs, giving rise to metastasis. Macrophages and other immune and inflammatory cells congregate in the tumor in an attempt to respond to the tissue distress. Fidler, I. This list should perhaps be extended to include the mutagenic effect of apoptosis resulting from uptake by phagocytosis of DNA from dead cells [ 34 ]. However, the fraction of all HNCs in the U. Cell numbers in each layer are indicated on the right see text. Perhaps the boldest experiment in cancer prevention yet undertaken is vaccination of the Taiwanese and Chinese populations with HBV vaccine, which is expected to largely eliminate death from HBV-caused liver cancers Chien et al.

Disseminated cancer cells found in the bone marrow of women or transgenic mice with early-stage breast cancer can become activated by transplantation into the bone marrow of mice to cause lethal tumors Husemann et al. It remains an area of intense research and high promise.

Point mutations may either increase or decrease the activity of the gene product, and so point mutations are a cause of oncogene activation as well as tumor suppressor gene inactivation.

An argument explaining the reasons how cancer cells propagate in the human body

Tobacco and asbestos may also cause chronic inflammation that secondarily favors tumor development. Petronio, B. Boshoff, C. The mutations that cause cancer precisely affect the genes whose products exert these critical control functions. Translocations occur when two separate chromosomal regions become abnormally fused, often at a characteristic location. Geigl, F. Cancer cells that alter this become exposed to environmental stresses including lack of oxygen hypoxia and nutrients, acidity, oxidative stress, and inflammatory responses. Viale, A. If we assume that the body is composed of 3. Subramanian, H. This rebellion-like scenario is an undesirable survival of the fittest , where the driving forces of evolution work against the body's design and enforcement of order. Various proteins involved in these types of cell shape changes, such as RhoC and NEDD9, have been implicated in cancer cell invasion leading to metastasis Clark et al. Interestingly, BRCA mutations are rare in sporadic breast cancer.

Tumor-associated macrophages, produce growth factors and ECM-degrading enzymes that stimulate the growth and invasion of the cancer cells Joyce ; Lewis and Pollard Here, the adjective ductal refers to the appearance of cancer under the microscope, which suggests that it has originated in the milk ducts.

Esteller, M.

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Towards an Understanding of Cancer