Cancer Traits II (FS Week 9)

Question 1

what is scenescene

Answer 1

Senescence (aging) is an irreversible entrance into a non-proliferative but viable state.

Question 2

Describe the 2 barriers to cell proliferation

Answer 2

• *Senescence** (aging) is an irreversible entrance into a non-proliferative but viable state.
• *Crisis** involves cell death and karyotypic disarray. Some cells emerge from crisis and acquire unlimited replicative potential (immortalization).

Question 3

what are telomeres

Answer 3

they are distinct structures at the end of chromosomes that consist of the same DNA sequence over and over again

Question 4

What is telomerase

Answer 4

a DNA polymerase that adds telomere repeats to end of telomeric DNA - it is overexpressed in immortalised cells

Question 5

What is meant by the Warburg Effect

Answer 5

cancer cells choose glycolysis (anaerobic) by upregulating GLUT1 to be able to promote cell proliferation

Question 6

what is the purpose of the warburg effect

Answer 6

it allows cancer cells to create new cells quicker - used for processes to support cell proliferation

Question 7

How do cancer cells increase mutation rates

Answer 7

• increased sensitivity to mutagenic agents through a breakdown in one or several components of genomic maintenance machinery
• comprising surveillance systems that normally monitor genomic integrity and force genetically damaged cells into scenescence or apoptosis

Question 8

Name some of the caretakers (DNA maintenance machinery) of the genome?

Answer 8

a. p53 tumour suppressor protein: in response to DNA damage causes cell cycle arrest to allow DNA repair or apoptosis if the damage is excessive.
b. Telomerase: loss of telomeric DNA in tumours generates karyotypic instability.

Question 9

Defects in DNA maintenance machinery can effects genes involved in…

Answer 9

• genes involved in detecting DNA damage and activating the repair machinery
• genes involved in directly repairing damaged DNA
• genes involved in inactivating or intercepting mutagenic molecules before they damage the DNA
• genes involved in ensuring correct chromosomal segregation during mitosis

Question 10

Why is genomic instability favourable to cancer cells

Answer 10

it is instrumental for tumour progression as they accelerate the rate at which evolving premalignant cells can accumulate favourable genotypes

Question 11

What is the paradoxical nature inflammation in tumours?

Answer 11

It can enhance tumour growth and progression by supplying bioactive molecules (VEGF, cytokines, MMPs) to the tumour microenvironment.

Question 12

What is immune surveillance

Answer 12

Immune surveillance is a system, from adaptive and innate immune cells, that monitors cells and tissues and recognized and eradicates tumour cells.

Question 13

what immunological processes do tumour cells use to avoid surveillance

Answer 13

1. By recruiting immunological cells (i.e Tregs) that are immunosuppressive
2. paralyse cytotoxic t cells and natural killer cells
3. By damaging the antigen presentation machinery (tumour antigens cannot be recognized)
4. By increasing production of immunosuppressive mediators that affect immune cell functionality.
5. By tolerance or anergy in T cells and by immune deviation (changing T cell subtypes).