Understanding Cancer: Genes, Carcinogens & Viruses

• 52% of people will develop cancer in their lifetime.
• Cancer arises from genetic mutations that occur during cell division or cell death processes.

Gene Classes and Cancer

• Proto-oncogenes normally promote cell division, essential for processes like healing injuries.
• Tumor-suppressor genes prevent cell division, eliminating damaged cells to restrain growth.
• Caretaker genes protect the genome but become inactive upon mutation affecting their "housekeeping" role.

Carcinogens and Viruses

• Carcinogens are agents capable of mutating DNA, leading to cancer.
• Viruses can cause cancer by integrating their DNA into the host's cells.
• HPV (human papillomavirus) causes warts and is transmitted through contact with infected areas; affects 75% of sexually active individuals.
• Cervical cancer is the third most common cancer in women, with early detection being key to successful treatment.
• HPV contains its DNA and can produce proteins like E5 (44 amino acids long).
• The E5 protein binds to receptors on cervical cells and prompts cell division.
• E5 mimics platelet-derived growth factor (PDGF) to cause dimerization, leading to continuous cell division, inactivating tumor-suppressor genes like P53 and Rb.
• Hepatitis B and C viruses cause liver infections and spread through unprotected sexual conduct and blood.
• Mutations in somatic cells (body cells) are not passed on to offspring.

Oncogenesis and Tumors

• Oncogenesis is the cancer-forming process resulting from gene mutations caused by carcinogens or errors in DNA copying and repair
• A tumor is formed when a cell exceeds normal growth limitations and divides uncontrollably.
• Metastasis occurs when cells from a primary tumor migrate to new sites, forming secondary tumors.
• Tissues are resistant to tumors if they produce proteins that halt division.
• Tissues are resistant to tumors if they contain inhibitors of proteolytic enzymes (to prevent tissue invasion).
• Tissues are resistant to tumors if they have anti-angiogenesis factors (to prevent new blood vessel formation).
• Tumor cells require a blood supply to grow due to oxygen starvation.

Transformed Cancer Cells Properties

• Cancer cells override contact inhibition, growing on top of each other due to a lack of gap junctions.
• Cancer cells grow independently without attachment.
• Cancer cells have a reduced need for ligands (mitogens).
• Basal lamina breaks down.
• There are cytoskeletal changes, including loss of actin microfilaments.
• Cancer cells have enlarged nucleoli, indicating increased ribosome production.

Explore the development of cancer, focusing on genetic mutations, proto-oncogenes, and tumor-suppressor genes. Learn about carcinogens, viruses like HPV, and their roles in causing cancer. Understand the importance of early detection, especially for cervical cancer.