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Cancer Biology: Oncogenes and Tumor Suppressor Genes


Cancer is one of the main causes of death in most parts of the world, especially in the Western World. It is the second killer in the USA and in a number of European counties after cardiovascular diseases. Cancer is an abnormal growth of cells that results from changes in gene expression. This causes uncontrollable cell multiplication and proliferation in the body of human beings. It is a condition that can easily cause death when the growth of these cells is not taken care of or not detected and treated early enough. Cancer is basically a group of diseases of higher multi-cellular organisms (Melmed & Conn 39).

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Cancer is a family of diseases that is complex and involves carcinogenesis which causes the normal cells in the body of humans to turn into cancer cells. It is a complex process which involves a large group of diseases going up to a hundred or more. These diseases have varying ages of onset, rate of growth, state of cellular differentiation and response to treatment among others. From a molecular and cell biological point of view, cancer is taken a small number of diseases that result from alterations to cell genes.

It is basically a disease of abnormal gene expression. The process of the cancer formation is a complex mechanism characterized by a direct insult to DNA such as a gene mutation, translocation, deletion and amplification among others. All these mechanisms prevent cell death and escalated cell multiplication to an unmanageable level causing the tissues to expand. under normal circumstances, cell proliferation and death are in a state of equilibrium enabling an organism to function normally. Cancer formation is, therefore, a complex process. This paper seeks to interpret the role oncogenes and tumor suppressors play in transformation during cancer formation.

The role oncogenes and tumor suppressors play in transformation

Tumor formation is a process that involves multiple steps. The process involves the uncoupling of interdependent mechanisms of cell proliferation and differentiation. Mostly, the growth of mutant cells is catalyzed by the mutations of either protooncogenes or tumor suppressor genes.

This enables the mutant cells to proliferate at a higher speed than normal cells. This alters the interactions of these cells with their surroundings leading to local invasion and distant metastases. The recent studies in cellular photoocogenes and tumor suppressor genes have improved our understanding of molecular basis of tumorigenesis.

Role of oncogenes

According to Melmed & Conn (23), an oncogene is a gene in the body of an organism with the potential to cause cancer. These genes are usually mutated in tumor cells. In normal cases, the normal cells die after some time and their death is programmed which is called apoptosis. The oncogenes have the ability to make cells that ought to die survive and continue proliferating. However, for oncogenes to cause cancer, they must be accompanied by other processes, such as mutations in another gene.

The oncogenes result from normal gene called proto-oncogene after they are mutated or become highly expressed. Cancer therefore results from the alterations that take place in oncogenes. The alterations of tumor suppressor genes and micro RNA genes may also cause cancer. According to Croce, “These alterations are usually somatic events, although germ-line mutations can predispose a person to heritable or familial cancer” (1).

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A malignant tumor is not caused by a single genetic change but a multistep process of sequential alterations of oncogenes and other genes. It is worth mentioning that, “Oncogenes are found in normal cells and encode proteins involved in the control of replication, apoptosis (cell death) or both and they are involved in the normal function of the cell, but if activated can turn that cell into a cancer cell” (Fischer 1). The activation of these genes takes place in a number of ways like gene amplification, chromosomes rearrangements and mutations as well. The process may occur due to a number of reasons.

The simple case is where there are single point mutations involved. This affects a single base in DNA which has harmful effects for the ells. There are also complex cases involving larger mutations whereby part of the gene is deleted or a new genetic material is inserted in a cell. This may take place during normal cell replication or results from alteration of the structure of a nucleotide in a cell. This is normally caused by external factors like carcinogens.

There are also viruses that can cause mutations. They do so by inserting genome into the cell thus changing the structure of the gene. Other expression which also causes cancer may happen when there is introduction of promoter.

Tumor Suppressor Genes

According to American Cancer Society, “Tumor suppressor genes are normal genes that slow down cell division, repair DNA mistakes, or tell cells when to die (a process known as apoptosis or programmed cell death” (2). When these genes are not properly working they tend to grow in an uncontrollable rate. The uncontrollable growth of cells leads to cancer.

The Tumor Suppressor genes may include TP 53 and BRCA1 among others. Their role is to prevent the cells from dividing too quickly. When the genes are interfered with, especially die to mutations, the cell division may occur uncontrollably. Centrally to oncogenes, tumor suppressors cause cancer when they are activated (Ruddon 15).

The RB gene was the first tumor suppressor gene to be discovered and their changes are likely to cause cancer. Mostly, the kind of cancer caused by these changes is referred to as retinoblastoma which is very common in children. The problem is mostly found in children and normally affects the eyes. The mutations of RB genes may be spontaneous or even passed to the children from the mother. The genes therefore play a key role in the growth of cancer.


Cancer is a leading killer disease in the world. There are many people who have succumbed cancer in the world. The alterations in the normal process of the cellular replication are the sole reason for emergence of cancer. The process of cancer formation is a complex one and involves a number of mechanisms that take place in the cell. There are usually multiple genes that are involved in the progression of cancer when they suffer defects due to mutations.

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The effects of these defects are that the cell loses control over its replication and proliferation. This also results to overgrowth of the tissues which causes cancerous tumor. The oncogenes, and tumor suppressor genes are the main group of genes that cause cancer when they are damaged. Cancer is therefore a very serious disease and there is a need to know the best measures to curb it.

Works Cited

American Cancer Society 2008, Oncogenes, Tumor Suppressor Genes, and Cancer. 2012. Web.

Croce, Carlo. “Oncogenes and Cancer”. N Engl J Med, 358 (2008): 502-511. Print.

Fischer, Alexis. The role of oncogenes in cancer, USA: Helium, Inc. 2010. Print.

Melmed, Shlomo and P. Michael Conn. Endocrinology: Basic and Clinical Principles. New Jersey: Humana Press, 2005. Print.

Ruddon, Raymond. Cancer Biology. Oxford: Oxford University Press, 2007. Print.

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