Oncogenes and Cancer Cells

Oncogenes and Cancer Cells

Oncogenes are genes that have the potential to cause cancer. They are mutated forms of proto-oncogenes, which are genes that normally promote cell growth and division.

Proto-oncogenes

• Proto-oncogenes are genes that regulate cell growth, division, and survival.
• They code for proteins involved in signal transduction pathways that stimulate cell proliferation.
• Examples of proto-oncogenes include:
  • HER2 (human epidermal growth factor receptor 2)
  • MYC (v-myc avian myelocytomatosis viral oncogene homolog)
  • RAS (rat sarcoma viral oncogene homolog)

Oncogene Activation

• Oncogenes are activated through genetic mutations, such as:
  • Point mutations
  • Gene amplification
  • Chromosomal translocations
• Oncogene activation leads to:
  • Uncontrolled cell growth and division
  • Loss of cell cycle regulation
  • Increased angiogenesis (blood vessel formation)
  • Inhibition of apoptosis (programmed cell death)

Oncogene Functions

• Oncogenes can promote cancer cell growth and survival by:
  • Stimulating cell proliferation
  • Inhibiting apoptosis
  • Enhancing angiogenesis
  • Activating anti-apoptotic pathways
• Oncogenes can also contribute to cancer development by:
  • Disrupting normal cell cycle regulation
  • Inducing genetic instability
  • Promoting epithelial-to-mesenchymal transition (EMT)

Examples of Oncogenes in Cancer

• HER2 in breast cancer
• MYC in Burkitt lymphoma
• RAS in lung, colon, and pancreatic cancer
• BRAF in melanoma and colorectal cancer

Oncogenes and Cancer Cells

Proto-oncogenes

• Regulate cell growth, division, and survival
• Code for proteins involved in signal transduction pathways that stimulate cell proliferation
• Examples include:
  • HER2 (human epidermal growth factor receptor 2)
  • MYC (v-myc avian myelocytomatosis viral oncogene homolog)
  • RAS (rat sarcoma viral oncogene homolog)

Oncogene Activation

• Activated through genetic mutations, including:
  • Point mutations
  • Gene amplification
  • Chromosomal translocations
• Consequences of oncogene activation:
  • Uncontrolled cell growth and division
  • Loss of cell cycle regulation
  • Increased angiogenesis (blood vessel formation)
  • Inhibition of apoptosis (programmed cell death)

Oncogene Functions

• Promote cancer cell growth and survival by:
  • Stimulating cell proliferation
  • Inhibiting apoptosis
  • Enhancing angiogenesis
  • Activating anti-apoptotic pathways
• Contribute to cancer development by:
  • Disrupting normal cell cycle regulation
  • Inducing genetic instability
  • Promoting epithelial-to-mesenchymal transition (EMT)

Oncogenes in Cancer

• HER2 in breast cancer
• MYC in Burkitt lymphoma
• RAS in lung, colon, and pancreatic cancer
• BRAF in melanoma and colorectal cancer

Tumor-Suppressor Genes

• Tumor-suppressor genes regulate the cell cycle, inhibit proliferation from growth signals, stop cell division when cells are damaged, and prevent mutations.
• They are also referred to as anti-oncogenes.
• Inactivation of tumor-suppressor genes contributes to uncontrolled cancer cell proliferation.

Activation of Oncogenes vs. Inactivation of Tumor-Suppressor Genes

• Oncogenes are activated in cancers.
• Tumor suppressors must be inactivated for cancer to occur.

Genetic Mutations

• A single genetic event can activate an oncogene due to its dominant nature.
• Two copies of each tumor-suppressor gene exist, one from each parent.
• Both copies of the tumor-suppressor gene must be inactivated for cancer to occur, requiring two mutations.