L1 - Cancer history and overview Flashcards
What percentage of tumours are non-cancer cells?
35-65%
Cancer definition
Cancer cells typically follow the following trends:
- Escaped the normal limitations of external cue-driven cell division
- Have modified their local environment to exceed the naturally defined tissue borders
- Forms a multicellular mass driven by a “transformed” cancer cell
- Have mechanisms to survive immune surveillance and cell death
Examples of cell growth stimulators
- Epidermal Growth Factor (EGF)
- Fibroblast Growth Factor (FGF)
- Estrogen
- Testosterone
What examples are there of things that regulate cell growth and division?
- ECM proteins: collagen and laminin - can regulate cell growth and division by providing a mechanical and chemical signal
- pH
- Temperature
- Nutrient availability (sugars, lipids, amino acids etc)
- Cytokines - small proteins that are released primarily by immune cells and stimulate angiogenesis and cell cycle
What types of ECM modifications do cancer cells cause to occur?
- ECM degradation - using matrix metalloproteinases (MMPs)
- ECM remodelling - using the production and secretion of ECM proteins
- ECM crosslinking - modifying the ECM proteins by crosslinking, which makes the ECM stiffer and stronger
- ECM receptors - express receptors on their surface that bind to specific ECM proteins such as integrins
- Angiogenesis - promote the formation of new blood vessels
How are cancer cells transformed?
Repeated mutations through natural selection to bypass all cancer prevention and thrive
How do cancer cells ignore the immune system?
As Cd4, Cd8, Nk, Nkt (etc) cells eliminate cancer cells, further mutations are required to avoid Elimination
Once cancer has reached a point that it is in balance with the killer cells, it is in Equilibrium
Once the cancer cells have outnumbered the killer cells (may be due to growth or could be due to other illnesses weakening the immune system), the cancer cells can Escape and reign terror!
What methods of cell death are there?
Programmed cell death:
* Programmed necrosis
* Autophagy
*Apoptosis
Non-programmed cell death:
* Necrosis - mitochondrial and cell swelling, membrane rupture
Programmed cell death
- Programmed necrosis - Pyroptosis, ferroptosis, necroptosis, and parthonatos
- Autophagy - membrane, blebbing, autophagy vacuoles, and increased lysosomal activities
- Apoptosis - chromatin condensation, nuclear fragmentation, apoptotic body, membrane blebbing, cell shrinking (animal cells)
Programmed necrosis
- Pyroptosis - Maintained mitochondrial activity, cell swelling, membrane rupture
- Ferroptosis - Mitochondrial swelling, cell swelling, membrane rupture
- Necroptosis - chromatin condensation and nuclear fragmentation
- Parthonatos - increased membrane density, small mitochondria
What mechanisms are there to avoid cell death/immune surveillance and what examples of them are there?
Mutations in genes that regulate apoptosis - p53
Upregulation of anti-apoptotic proteins - BCL-2, MCL-1 ( inhibit the initiation of apoptosis)
Downregulation of pro-apoptotic proteins: BAX/BAK
Activation of survival signalling pathways - PI3K/AKT/mTOR, RAS/RAF/MEK/ERK
Altering the balance of death receptors and ligands - FAS, TNFR1
What cells does cancer come from?
- Epithelial cells
- Mesenchymal cells
- Hematopoietic cells
- Lymphoid cells
- Germ cells
- Gliomas
- Meningiomas
- Pituitary tumors
- Neuroblastomas
- Schwannomas
Epithelial cells: what are they and what cancers do they give rise to?
These cells line the surface of internal organs and glands, forming barriers
Epithelial cells can give rise to a wide variety of carcinomas, including lung carcinoma, colon carcinoma, and breast carcinoma
Mesenchymal cells: what are they and what cancers do they give rise to?
These cells form the connective tissue multiple cell types, including bone cells, muscle cells, and fat cells
They can give rise to sarcomas, such as osteosarcoma (bone cancer) and leiomyosarcoma (a cancer of smooth muscle tissue)
Hematopoietic cells: what are they and what cancers do they give rise to?
Cells found in the bone marrow that give rise to blood cells
Can give rise to leukemias, such as acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML)