Module 3: Cancer Flashcards
(80 cards)
What is cancer?
A complex group of >100 diseases affecting a wide range of tissues
Caused by mutations in genes controlling cell growth after exposure to carcinogens
What percentage of mutations in cancer are inherited?
1%
Extra somatic mutations are also required for cancer development
What characterizes cancer?
Loss of growth control leading to an unregulated increase in cell number, metastasis, and invasion of other tissues
How does cancer incidence affect the population?
Affects 1 in 3 people worldwide, leading cause of death in NZ and second worldwide
What was the incidence of cancer in NZ in 2015?
23,215 cases/year
Mortality was 9,615 deaths/year
What is a benign tumor?
Tumor where neoplastic cells are clustered in a single mass, well differentiated, and do not metastasize
What is a malignant tumor?
Tumor with less differentiated cells that invade surrounding tissues and metastasize
How are benign tumors classified?
Tissue name + ‘-oma’
What are carcinomas?
Malignant tumors derived from epithelial cells
What are examples of carcinomas?
Adenocarcinoma, squamous cell carcinoma
Includes cancers of lung, colon, breast, and prostate
What is the difference between normal cells and tumor cells regarding growth factors?
Normal cells depend on growth factors; tumor cells can divide without them
What is the G1/S checkpoint?
Regulates progression into DNA synthesis phase, ensuring growth factors, nutrients, and DNA integrity are present
What is the ‘multi-hit hypothesis’ in cancer?
Each cancer arises from an accumulation of several mutations over a lifetime
What role do proto-oncogenes play in cancer?
They positively regulate cell division; mutations can turn them into oncogenes
What is the function of tumor suppressor genes?
Negatively regulate cell division, preventing abnormal proliferation
What is the main function of p53?
Acts as a sensor for DNA damage and can cause cell-cycle arrest or apoptosis
What is the Ras-MAPK pathway?
A growth factor signaling pathway that, when activated, allows progression through the G1/S checkpoint
What is the significance of telomerase activity in cancer?
Increased telomerase activity allows cells to proliferate indefinitely, leading to cancer
What is the role of DNA repair genes in cancer?
Mutations in these genes can cause genome instability, making further mutations more likely
What types of mutations are involved in cancer development?
Point mutations, insertions, deletions, translocations
These mutations can lead to a gain of function in oncogenes
What is Knudson’s two-hit hypothesis?
Both alleles of a tumor suppressor gene must be inactivated for tumorigenesis to occur
What does ‘contact inhibition of growth’ mean?
Normal cells stop dividing when they come into contact with other cells; tumor cells do not exhibit this
What is the role of growth factors in the G1/S checkpoint?
They activate Cdk4/6, allowing progression through the checkpoint
What is the typical progression of cancer development?
Initiation, promotion, progression
Involves exposure to carcinogens and genetic changes