Oncogenes

Definition

Oncogenes are mutated forms of normal genes, known as proto-oncogenes, that have the potential to cause cancer by promoting uncontrolled cell growth and division. These genetic alterations can occur due to various factors, including mutations, gene amplifications, or chromosomal rearrangements, leading to the activation of pathways that drive tumorigenesis. Understanding oncogenes is crucial in molecular biology as they illuminate the mechanisms behind cancer development and progression.

5 Must Know Facts For Your Next Test

1. Oncogenes can lead to cancer by producing proteins that drive excessive cell division and inhibit normal apoptosis.
2. Common oncogenes include RAS, MYC, and HER2, which are often involved in specific types of cancers such as lung, breast, and leukemia.
3. The activation of oncogenes can occur through point mutations, gene amplification, or chromosomal translocations.
4. Targeting oncogenes with specific therapies has become a key strategy in cancer treatment, leading to personalized medicine approaches.
5. The study of oncogenes has revealed critical insights into the molecular basis of cancer and has paved the way for developing new diagnostic and therapeutic strategies.

Review Questions

• How do oncogenes differ from proto-oncogenes and what is their role in cancer development?
  • Oncogenes are mutated versions of proto-oncogenes, which are normal genes that promote cell growth and division. When proto-oncogenes undergo mutations or alterations, they can become oncogenes that lead to uncontrolled cell proliferation. This shift from normal regulation to abnormal activation is crucial for the initiation and progression of cancer.
• Discuss how specific mutations in oncogenes can lead to distinct types of cancers and give examples.
  • Specific mutations in oncogenes can result in particular cancers by altering cellular functions. For instance, mutations in the RAS gene are frequently associated with pancreatic and colorectal cancers, while overexpression of the HER2 gene is linked to aggressive breast cancer. These mutations change the signaling pathways within cells, leading to increased growth and survival signals that favor tumor development.
• Evaluate the impact of targeting oncogenes in developing new cancer therapies and how this has changed treatment paradigms.
  • Targeting oncogenes has significantly transformed cancer treatment strategies by enabling more precise therapies tailored to individual patients. For example, drugs like trastuzumab target HER2-positive breast cancers directly by inhibiting the activity of the overexpressed protein. This approach has shifted treatment paradigms from generalized chemotherapy to personalized medicine, improving outcomes and reducing side effects for patients with specific genetic profiles linked to their tumors.

Related terms

proto-oncogenes: Normal genes that regulate cell growth and differentiation, which can become oncogenes when mutated.

tumor suppressor genes:

Genes that normally inhibit cell division or promote apoptosis; mutations in these genes can contribute to cancer development.

signal transduction pathways:

Biological pathways that transmit signals from outside the cell to elicit a cellular response, often involving oncogenes in promoting proliferation.