Outline of Disease Process- pt.1 what is cancer?

Question 1

What is cancer?

Answer 1

cancer is a disease of the genome occurring as a result of unregulated cell growth

Question 2

What are the three types of cancer cells?

Answer 2

epithelial cells
mesoderm cells
glandular cells

Question 3

Describe epithelial cells?

Answer 3

for e.g. squamous
-cuboidal
-columnar
-85% of cancers - line body surfaces

make up CARCINOMAS

Question 4

Describe mesoderm cells?

Answer 4

inbetween ectoderm and endoderm - form blood cells and connective tissue

-bone
-muscle

make up SARCOMAS

Question 5

Describe glandular cells?

Answer 5

group of organized secretory epithelial cells

breasts- exocrine glands
oesophagus
lung

ADENOCARCINOMAS

Question 6

What are the hallmarks of cancer?

Answer 6

evading growth suppressors

avoiding immune destruction

enabling replicative immortality

tumour promoting inflammation

activating invasion and metastasis

inducing angiogenesis

genome instability and mutation

resisting cell death

deregulating cellular energetics

sustaining proliferative signalling

Question 7

Describe how cancer sustains proliferative signalling?

Answer 7

normal cells require an external growth signal to divide

cancer cells bypass normal growth factor pathways
leading to unregulated growth
occurs as result of acquired mutations-
allowing self production of growth factors and increase levels of receptor proteins on cancer cells

Question 8

Describe how cancer evades inhibitory growth signals?

Answer 8

inhibitory growth signals maintain homeostasis within the tissue

cells are not continually dividing as a result

cancer cells ignore these signals - enabled by acquired mutations and gene silencing ( interruption or suppression of gene expression at transcriptional or translational level)

Question 9

How do cancer cells avoid immune destruction?

Answer 9

some cancer cells are able to avoid detection by not initiating an immune response

cancer cells hijack immune checkpoints and modulate immune response via STING (stimulator and interferon genes)

STING -crucial in controlling transcription of body’s defence genes

Question 10

Describe how cancer cells have unlimited replicative potential?

Answer 10

normal cells have a counting device (telomeres) that monitor and adjust the number of cell doublings

once cell numbers have reached this finite number they enter senescence

cancer cells maintain telomere length- replication overdrive begins

Question 11

Describe tumour promoting inflammation?

Answer 11

all tumours have inflammatory immune cells

inflammatory cells provide growth factors that promote angiogenesis and invasion

cell death by necrosis gives rise to inflammation

necrotic cells release bioactive regulatory factors 1L-1

inflammatory cells can release radical oxygen species that give rise to mutations

Question 12

Describe invasion and metastasis in cancer cells?

Answer 12

cancer cells develop the ability to migrate to other areas
formation of metastasis is a major cause of death in cancer
mutations within the genome may affect the enzymes involved in cell - cell adhesion e.g. E-cadherin

Question 13

Describe angiogenesis in cancer cells?

Answer 13

creation of new blood vessels by the tumour
provides supply of oxygen and nutrients
new blood cells are friable leading to tumour cell escape
-many drugs have been developed to target angiogenesis

Question 14

Describe genome instability in cancer cells?

Answer 14

alterations in DNA lead to instability
faulty DNA repair pathways or hereditary predisposition contribute to the development of DNA alterations (mutations)
single point and large chromosomal abnormalities can be found in tumour DNA
accumulation of mutations over a period time explains why cancer is more frequent in the ageing population

Question 15

Describe evasion of cell death in cancer cells?

Answer 15

regulated= apoptosis
unregulated= necrosis

cancer cells evade death as a result of mutations within the apoptosis pathway

caspases play central role in apoptosis therefore mutations in the family will allow cancer cells to pass through unchecked

Question 16

Where does cell death occur?

Answer 16

in physiological conditions e.g. menstruation/ embryogenesis and in pathological conditions e.g. DNA damage

Question 17

Describe how cancer deregulates cell energetics?

Answer 17

this is reprogramming energy metabolism

aerobic glycolysis- used by cancer cells to redirect energy

allows cancer cell to fuel cell growth and division

Question 18

Describe somatic mutations?

Answer 18

most common and is acquired

Question 19

Describe germline mutations?

Answer 19

hereditary

Question 20

Describe gene?

Answer 20

composed of DNA, everyone has two copies of each gene. One from each parent

Question 21

Describe oncogene?

Answer 21

mutated gene giving rise to tumour formation in a dominant fashion. Only recquire one alelle to possess a mutation

Question 22

Describe tumour suppressor gene?

Answer 22

inhibits tumour formation

Question 23

What are PD1 AND PD2?

Answer 23

PDL1 AND PDL2 are transmembrane proteins that suppress adaptive arm of immune system during particular events.

PD1 on t cell is activated by cell surface ligands on tumour cell

Question 24

What is PET scanning?

Answer 24

position emission tomography- to visualise the abnormal glucose activity of the cancer cell using radio labelled glucose analogue FDG

Question 25

Can mutations occur in tumour suppressor genes?

Answer 25

yes but are recessive, require two alleles to have a mutation