Neoplasia 3

Question 1

What is carcinogensis?

Answer 1

This is the causes of cancer which are both intrinsic and extrinsic.

Question 2

Name some intrinsic causes of cancer

Answer 2

Genders, hormones, age, gender, ethnicity

Question 3

What are extrinsic factors which cause cancer?

Answer 3

Environmental and lifestyle factors.

Question 4

Is cancer prevalence increasing?

Answer 4

Yes, but only because people are living to be older and the older we are the higher risk because the more time we have had to pick up mutations.

Question 5

What are the five major lifestyle and behavioural factors which can cause cancer?

Answer 5

Smoking, lack of exercise, alcohol and high BMI.

Question 6

What are the three extrinsic carcinogens?

Answer 6

Radiation, chemicals and infections.

Question 7

What is 2-napthylamine?

Answer 7

This is a carcinogen of the dye industry which taught us about cancer

Question 8

What can be said about exposure to carcinogens and onset of cancer?

Answer 8

There is frequently a long delay between these two events.

Question 9

What about total carcinogen dosage increases the risk of cancer?

Answer 9

If there is increased exposure then this leads to increased risk of cancer.

Question 10

Why are some cancers only present in certain organs?

Answer 10

Some carcinogens show organ specificity in which they cause cancers.

Question 11

Why are industrial chemicals and tobacco smoke most worried about in relation to cancer?

Answer 11

Due to dose response, this means that household cleaning products do not put us at a significant risk. These two factors do however.

Question 12

What is important about the sequence of carcinogen exposure?

Answer 12

Different carcinogens can be initiators or promoters. This means that initiators need to be given first followed by promoters in order for cancer to form.

Question 13

What is the difference between cellular effect of initiators or promoters?

Answer 13

Initiators are generally mutagens, and then promoters causes prolonged proliferation of the tissue.

Question 14

What is promotion in terms of cancer?

Answer 14

This is monoclonal expansion of mutant cells.

Question 15

What effect does a germ line mutation have on neoplastic cells?

Answer 15

If there is a germ line mutation then it is likely that this person will develop cancer at a younger age because they need to accumulate less mutations.

Question 16

Name some forms of mutagenic chemical carcinogens.

Answer 16

Polycyclic aromatic hydrocarbons, alkylation agents, aromatic amines, N-nitroso compounds, natural products such as asbestos

Question 17

What is a complete carcinogen?

Answer 17

This is both an initiator and a promoter.

Question 18

What damage to cells does radiation cause? How?

Answer 18

It causes damage to DNA. This can be either direct causing strand breaks or altered bases or it can be indirect due to free radical production. Radiation strips electrons off atoms.

Question 19

What is radon?

Answer 19

This is the most common radiation that all of us are exposed to. This leads to increased risk of skin cancer.

Question 20

How can infections be carcinogenic?

Answer 20

Directly as it affects the genes in the cell, or indirectly as regeneration of the tissue following chronic inflammation acts as a promoter.

Question 21

How is HPV linked to cervical carcinoma?

Answer 21

HPV expresses E6/7 which inhibit p53 and pRB and so there is no regulation of entry into the cell cycle.

Question 22

What type of carcinogens are hepatitis B/C?

Answer 22

Indirect. They cause chronic liver cell injury and the regeneration acts as a promoter.

Question 23

What is the two hit hypothesis?

Answer 23

Because we have 2 tumour suppressor genes, both need to be mutated for tumour formation and so we need 2 mutations.

Question 24

Why are cancers more common in those with genetic mutations?

Answer 24

If someone has a genetic mutation, then they only need to acquire one more mutation and this is more likely than an individual acquiring 2 mutations.

Question 25

What is a pro-carcinogen?

Answer 25

These are converted by p450 enzymes in the liver to become carcinogens.

Question 26

What is RAS?

Answer 26

This was the first proto-oncogene discovered and is present in 1/3 of all malignant neoplasms.

Question 27

How does RAS work?

Answer 27

It leads to phosphorylation of pRB which then means that cells are pushed into the cell cycle and proliferation is faster.

Question 28

What is the RB gene?

Answer 28

This prevents cell proliferation, however if both alleles pick up a mutation then this allows unrestrained passage past the restriction point.

Question 29

What can protooncogenes encode for?

Answer 29

Intracellular kinases, growth factors, growth factor receptors, plasma membrane signal transducers, transcription factors, cell cycle regulators, apoptosis regulators.

Question 30

What is Xeroderma Pigmentosum?

Answer 30

This is mutations in DNA repair genes.

Question 31

What gene does Xeroderma Pigmentosum commonly affect?

Answer 31

DNA Nucleotide excision repair gene.

Question 32

What is the fate of people with Xeroderma Pigmentosum?

Answer 32

This is an autosomal recessive disorder, and these people will be more susceptible to cancer from a young age.

Question 33

What is HNPCC syndrome?

Answer 33

Hereditary non-polyposis colon cancer syndrome which is an autosomal condition where there is a germ line mutation of the DNA mis-match repair gene.

Question 34

What is affected in familial breast carcinoma?

Answer 34

The BRCA1/2 genes which are important for repairing DNA double strand breaks.

Question 35

What is genetic instability?

Answer 35

This is alterations in genes which lead to accelerated mutation rate found in malignant neoplasms.

Question 36

What are caretaker genes?

Answer 36

These aim to maintain genetic stability.

Question 37

What is cancer progression?

Answer 37

This is the progressive accumulation of mutations of a cell, which occurs over decades.

Question 38

What are the hallmark features of malignant neoplasms?

Answer 38

Malignant neoplasms must show self sufficiency from growth signals, resistance to growth stop signals, ability to induce blood vessels, no limit to number of divisions, apoptosis resistant, ability to invade an metastasise

Question 39

What enzyme is responsible for the ability of cells in a neoplasm to not have a limited number of divisions?

Answer 39

Telomerase. These maintains telomere length.