L01 - What is Cancer? Flashcards
Define cancer.
The uncontrolled growth of abnormal cells in a tissue, which are invasive and metastasising
From where do the majority of tumours originate?
Epithelial tissues
List 4 types of cancer and where they arise from.
1 - Carcinoma (epithelium)
2 - Sarcomas (mesenchymal cells)
3 - Leukaemias & lymphoid/myeloid tumours (haematopoietic tissue and immune cells)
4 - Neuroectodermal tumours (CNS and PNS)
List 3 mechanisms that cause mutations in DNA.
1 - Copying errors during DNA replication
2 - Spontaneous depurination
3 - Exposure to carcinogenic agents
What is the function of tumour suppressor genes?
Negative regulation of cell growth
How many alleles of a tumour suppressor gene must be disrupted for tumour suppressor function to be lost?
Why?
Both alleles must be disrupted to lose the suppressor effect because protein produced from one of the two alleles is enough to prevent cell growth
What is the function of oncogenes?
Positive regulation of cell growth
How many alleles of an oncogene must be disrupted to lose oncogenetic function?
Why?
Both alleles must be disrupted to lose the oncogenetic effect because protein produced from one of the two alleles is enough to promote cell growth
List the stages of development of a carcinoma.
Give an example of a protein involved in each stage.
1 - Normal cells become early adenomas (APC protein)
2 - Early adenomas become late adenomas (K-ras protein)
3 - Late adenomas become carcinomas (p53)
What are gate-keeper mutations and driver mutations?
Gate-keeper mutations start tumour development -> irregular growth regulation + differentiation
Driver mutations allow tumour to continue growth -> gives a selective advantage to a clone in its microenvironment, through either increasing its survival or reproduction;
tend to cause clonal expansions
List 6 hallmarks of cancer.
1 - Self-sufficiency in growth signals
2 - Insensitivity to anti-growth signals
3 - Evasion of apoptosis
4 - Limitless replicative potential
5 - Sustained angiogenesis
6 - Tissue invasion & metastasis
What processes are involved in sustaining proliferative signalling?
1 - Alterations of extracellular growth signals
2 - Alterations of transmembrane transducers of growth signals
3 - Alterations of intracellular circuits that translate growth signals
4 - Ability of cancer cells to produce own growth factor to activate own receptors (autocrine signalling)
Describe a mechanism that enables evasion of growth suppressors.
Disruption of pRb (TSG) pathway, leading to a loss of control over progression from G1 into S phase (restriction point)
What is the function of pRb?
Prevents progression of the cell division cycle from the G1 (first gap phase) to S (synthesis phase) phase - the restriction point
Describe a mechanism that enables evasion of apoptosis.
Loss or mutation of p53 (TSG), which is a proapoptotic regulator, therefore there is a reduction in apoptosis of a cancer cell
