Cancer Biology and Immune System Quiz

Study Notes

Cancer is a disease characterized by uncontrolled cell growth.
Most adult cells have a limited lifespan, but cancer cells escape these typical limits.
Benign tumors are non-invasive and do not spread to other tissues
Malignant tumors are invasive and spread to other tissues through metastasis.

Mutations in genes controlling cell division lead to uncontrolled cell growth.
Environmental factors such as chemicals, physical agents, and viruses can cause DNA mutations and contribute to cancer development.
Carcinogens are agents that induce DNA mutations and lead to uncontrolled cell proliferation.

Oncogenes promote cell growth and proliferation and contribute to cancer when overactive.
Tumor-suppressor genes suppress cell growth and repair DNA damage.
Apoptosis genes regulate programmed cell death, playing a role in cancer development.

Six original hallmarks describe essential cellular processes distinguishing cancer cells from normal cells:
- Sustained proliferative signaling
- Evading growth suppressors
- Enabling replicative immortality
- Inducing angiogenesis
- Activating invasion and metastasis
- Resisting cell death
Four enabling characteristics that influence the tumor microenvironment were later added:
- Genome instability and mutation
- Tumor-promoting inflammation
- Avoiding immune destruction
- Deregulating cellular energetics

The immune system can suppress and facilitate tumor development, showcasing its dual role.
Immunosurveillance is the immune system's ability to recognize and eliminate pre-cancerous or transformed cells.

Immunoediting reflects the dynamic interaction between the immune system and cancer cells.
It consists of three phases:
- Elimination: Immune cells target and destroy easily recognizable tumor cells.
- Equilibrium: A balance exists between tumor cell destruction and survival of "best" tumor cells.
- Escape: Highly aggressive and least immunogenic tumor cells survive and spread.

Cytokines play a critical role in the immune response to cancer.
IFN-γ enhances tumor-cell removal by immune cells.
IL-12 activates strong TH1 and CTL responses against cancer cells.
TNF-α has complex roles in cancer immunity, potentially promoting or inhibiting anti-cancer effects.

Some tumor cells evade immune recognition and activation.
Reduced MHC expression in tumor cells can impair immune cell recognition.
Tumor cells can also express immunosuppressive molecules, hindering the immune response.