Carcinogenesis

Question 1

What are the three common characteristics of all cancers

Answer 1

It is a genetic disorder caused by DNA mutations

Genetic alterations in cancer cells are transmitted to daughter cells

Mutations and epigenetic alterations give cancer cells hallmarks

Question 2

Name some of the hallmak=rks of cancer

Answer 2

Self sufficent in growth signals, insensitive to inhibitory ones

Evasion of apoptosis and limitless reproductive potential

Systained angiogenesis and altered cell metabolism,

Evasion of immune surveillance, and evasion and metastasis

Question 3

What ccancers can ionising radiation lead to

Answer 3

Acute and chronic myeloid leukaemia, papillary carcinoma of thyroid

Question 4

What cancers can non-ionising radiation cause (UVB, sunlight)

Answer 4

Squamous cell carcinoma, basal cell carcinoma, malignant carcinoma of skin

Question 5

What are oncogenes

Answer 5

Cells which control growth and differentiation

Question 6

What different types of oncogenes are there

Answer 6

Proto-oncogenes: FOr cell growth and differentiation

Growth factor/growth factor receptors (these induce cell growth)

Signal transducers: relay receptor activation to nucleus

Cell cycle regulators mediate progression though the cell cycle

Question 7

What do tumour supressor genes do

Answer 7

Regulate cell growth, decrease risk of tumour formation

notable examples are p53 and retinoblastoma

Question 8

What does p53 do

Answer 8

Tumour supressor gene,

regulates cell cycle and DNA repair, papoptosis. Can be damaged by mutation or loss of alleles.

Question 9

What is the knudson two-hit hypothesis

Answer 9

Both copies of the gene must be knocked out for tumour formation (such as with p53)

Question 10

At what point is p53 active in the cell cycle

Answer 10

During G1 checkpoint, if DNA is found to be damaged, p53 gene is activated, preventing access to S phase, arresting the cell cycle

Question 11

Describe the cell cycle in order

Answer 11

G1 -> S -> G2 - > M -> G1

Question 12

What other Tumour supressor gene acts like p53

Answer 12

Rb

Question 13

What do apoptosis regulators do

Answer 13

prevent apoptosis in normal cells but promote ti in mutated cells with un-repairable DNA

Question 14

How does BCL2 and cytochrome C regulate apoptosis

Answer 14

BCL2 stablises mitochondrial membrane, blocking cytochrome C release. Disruption og BCL2 allows cytocchrome C to leavemitochondria and activate apoptosis.

Follicular lymphoma gets around this

Question 15

What is telomerase and what happens woth cancers

Answer 15

They shorten with serial cell divisions, eventually causing senescence.

Cancer cells show upregulation of telomerase

Question 16

What is angiogenesis and how is it linked to cancers

Answer 16

The new blood vessel formation is needed for tumour survival and growth. Cancers usually produce fibroblast growth factor and vascular endothelial growth factor, both angiogenic, responsible for blood vessel creation

Question 17

What is dysplasia?

Answer 17

disordered cell growth, often precancerous cells.

Theoretically reversible with removal of stressor. Otherwise can progress to irreversible carcinoma

Question 18

What is neoplasia

Answer 18

Unregulated, clonal, irreversible growth. Neoplastic tumours can be benign or malignant

Question 19

What are the characteristics of a benign tumour

Answer 19

Remains localised, slow growing, closely resembles tissue from which they grow, often circumscribed or encapsulated

Question 20

What are the characteristics of malignant tumours

Answer 20

Invades surrounding tissues, many can metastasize. Often rapidly growing, varies in resemblance to tissue of origin, irregular margin

Question 21

What is the difference between in situ and invasive carcinoma

Answer 21

In situ means an epithelial neoplasm exhibiting all cellular features of malignancy, but hasnt invaded through the epithelial basement membrane, separating form potential routes of metastasis

Question 22

What are some characteristic signs of malignanct cells

Answer 22

Increased nuclear/cytoplasmic ratio

Nuclear pleomorphism and hyperchromasia
Irregular chromatin distribution, prominent nucleoli
Irregular nuclear membranes

Question 23

Name characteristics of benign cells

Answer 23

Low nuclear to cytoplasmic ratio

All nuclei of similar size, not hyperchromatic, vesiclular, evenly distributed chromatin, smooth nuclear membranes