NSG 530 Module 3: Ch. 11 Biology of Cancer

Jun 22, 2024

Biology of Cancer - Chapter 11 Review

Key Concepts

  • Cancer: Abnormal cells that divide uncontrollably and invade other tissues.
    • Difference from normal cells: Cancer cells do not stop growing and invading adjacent tissues.
    • Glycoprotein layer helps them evade the immune system.

Cancer Cells vs. Normal Cells

  • Normal Cells: Stop growing when they contact other cells, do not invade other tissues.
  • Cancer Cells: Do not have contact inhibition, grow uncontrollably, and can invade other tissues.

Tumors

  • Benign Tumors: Slow-growing, encapsulated, can still cause issues but not as aggressively as malignant tumors.
    • Examples: Lipoma (fat cells), Leiomyoma (smooth muscle cells), Fibroma (breast), Meningioma (brain meninges).
  • Malignant Tumors: Lack capsule, invasive, can metastasize through blood or lymphatic systems.
    • Named according to the cell type from which they arise (e.g., Carcinoma, Sarcoma).

Types of Cancer

  • Carcinoma: Epithelial tissues (e.g., skin, GI tract, respiratory tract, urogenital tract).
    • Adenocarcinoma: Glandular or ductal epithelial tissues.
  • Sarcoma: Connective tissues (e.g., ligaments, bones).
  • Lymphoma: Lymphatic tissue.
  • Leukemia: Blood-forming cells.
  • Myeloma: Plasma cells in the bone marrow (not detailed in lecture).
  • In Situ: Still localized, has not invaded other tissues.

Cancer Development Stages

  1. Initiation: Damage to a cell's DNA.
  2. Promotion: Abnormal cell starts changing in structure.
  3. Progression: Abnormal cell becomes fully cancerous through various mutations.
  • Clonal Proliferation/Expansion: Cancerous cells replicate and dominate over their neighbors.

Hallmarks of Cancer

  • Uncontrolled Cellular Proliferation: Due to mutations in proto-oncogenes turning into oncogenes.
  • Evading Growth Suppressors: Mutations in tumor suppressor genes (e.g., TP53) prevent normal regulation of cell growth.
  • Genomic Instability: Increased mutation rates, chromosomal instability.
  • Resistance to Cell Death (Apoptosis): Cancer cells avoid programmed cell death mechanisms.
  • Immortality through Telomerase: Cancer cells maintain the enzyme telomerase, allowing them to replicate indefinitely.
  • Angiogenesis: Formation of new blood vessels to supply the tumor with nutrients and oxygen.

Genetic Mutations and Cancer

  • Proto-oncogenes: Normal genes that regulate cell growth, can mutate into oncogenes leading to uncontrolled growth.
  • Tumor Suppressor Genes: Normal genes that control cell division and repair DNA (mutations here lead to cancer).
  • Caretaker Genes: Repair DNA; mutations in these can contribute to genomic instability.
  • Epigenetic Silencing: Silencing of gene function can prevent proper protein production and functioning.
  • Chromosome Instability: Loss, duplication, or damage of chromosomes contributes to cancer.

Conclusion

Cancer is a complex disease characterized by uncontrolled cell growth and the ability to invade surrounding tissues and metastasize. Understanding the mechanisms and genetic factors underlying cancer can aid in better diagnosis, treatment, and patient care.