Oncogenes

Definition

Oncogenes are mutated genes that have the potential to cause normal cells to become cancerous. They are involved in the uncontrolled growth and division of cells, a hallmark of cancer development. Oncogenes disrupt the normal cell signaling pathways that regulate cell proliferation and differentiation.

5 Must Know Facts For Your Next Test

1. Oncogenes can be activated through various mechanisms, including point mutations, gene amplification, and chromosomal rearrangements.
2. The activation of oncogenes disrupts the normal regulation of the cell cycle, leading to uncontrolled cell division and the formation of tumors.
3. Oncogenes often encode proteins involved in key signaling pathways that regulate cell growth, such as receptor tyrosine kinases, Ras proteins, and transcription factors.
4. The overexpression or constitutive activation of oncogenes can lead to the transformation of normal cells into cancer cells.
5. Targeting oncogenes and their signaling pathways is a major focus of cancer therapy, as it can help to selectively kill or inhibit the growth of cancer cells.

Review Questions

• Explain how oncogenes contribute to the development of cancer.
  • Oncogenes are mutated versions of normal cellular genes, called proto-oncogenes, that regulate cell growth and division. When these genes become activated or overexpressed, they can disrupt the normal cell signaling pathways that control the cell cycle, leading to uncontrolled cell proliferation and the formation of tumors. The activation of oncogenes is a key step in the transformation of normal cells into cancer cells, as it allows them to bypass the normal mechanisms that regulate cell growth and division.
• Describe the different mechanisms by which oncogenes can be activated.
  • Oncogenes can be activated through various mechanisms, including point mutations, gene amplification, and chromosomal rearrangements. Point mutations can lead to the constitutive activation of oncogene-encoded proteins, while gene amplification can result in the overexpression of oncogenes. Chromosomal rearrangements, such as translocations, can also lead to the activation of oncogenes by placing them under the control of a different promoter or by fusing them with another gene. These different mechanisms of oncogene activation can all contribute to the development and progression of cancer.
• Discuss the role of oncogenes in cancer therapy and the potential for targeted therapies.
  • Targeting oncogenes and their signaling pathways is a major focus of cancer therapy, as it can help to selectively kill or inhibit the growth of cancer cells. Many targeted cancer therapies, such as tyrosine kinase inhibitors and monoclonal antibodies, have been developed to specifically target the proteins encoded by oncogenes. By disrupting the aberrant signaling pathways driven by oncogenes, these therapies can effectively treat certain types of cancer while minimizing the harm to healthy cells. The continued research and development of targeted oncogene-based therapies hold great promise for improving cancer treatment outcomes and reducing the side effects associated with traditional chemotherapy and radiation therapy.

Related terms

Proto-oncogenes: Normal cellular genes that, when mutated, become oncogenes. Proto-oncogenes regulate cell growth and division.

Tumor Suppressor Genes: Genes that normally act to inhibit cell division and proliferation. Mutations in tumor suppressor genes can lead to cancer.

Cell Cycle: The series of events that cells go through as they grow and divide, including the G1, S, G2, and M phases.