L20- Carcinogenesis: Causes of Cancer Flashcards Preview

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Flashcards in L20- Carcinogenesis: Causes of Cancer Deck (19):
1

What is a carcinogen?

Any agent that significantly increases the risk of developing cancer

2

What are Initiators in terms of carcinogens?

Often Genotoxic i.e. can chemically modify or damage DNA

3

What are promoters in terms of carcinogens?

Often non-genotoxic e.g. induce proliferation and DNA replication

4

What is a complete carcinogen?

“complete” carcinogens can initiate and promote e.g. UV light

5

What is Initiation ?

Mutation induction
-Chemical modification of DNA
-Replication of modified DNA and mis-incorporation by DNA polymerase

6

What can methylation of a CpG site within the promoter region of a gene do?

Can lead to their silencing, a feature found in a number of human cancers (for example the silencing of tumor suppressor genes)

7

Mutations found in oncogenes can lead to:

a gain of function

8

Mutations found in Tumour suppressor Genes (TSGs) can lead to:

lead to a loss of function

9

Metabolic activation of cancer : Direct acting factors works by...

interacting directly with DNA

e.g. oxygen radicals, nitrosomines, UV light, ionising radiation

10

Metabolic activation of cancer: Procarcinogens are...?

Carcinogens that require enzymatic (metabolic) activation before they react with DNA

e.g. aromatic amines, polycyclic aromatic hydrocarbons (PAHs)

11

Name the defences against carcinogenesis..

Dietary antioxidants
Detoxification mechanisms
DNA repair enzymes
Apoptotic response to unrepaired genetic damage
Immune response to infection and abnormal cells

12

What are the Categories of human carcinogens

Chemicals e.g. PAHs, nitrosamines

Infectious agents e.g. human papilloma virus, Helicobacter pylori

Radiation e.g. UV light, radon

Minerals e.g. asbestos, heavy metals

Physiological e.g. oestrogen, androgens

Chronic inflammation – free radicals and growth factors

13

Target tissue of Aflatoxin?

The Liver

14

Target tissue of Asbestos?

Lung pleura

15

Target tissue of X-Rays?

Bone marrow

16

Target tissue of HBV?

The liver

17

Target tissue of HPV?

Cervix

18

Why alcohol is a carcinogen?

increases levels of oestrogen and testosterone

increases uptake of carcinogenic chemicals into cells within the upper GI

reduces levels of folate, needed for accurate DNA replication

can kill surface epithelium leading to unscheduled proliferation

19

Why does Chronic inflammation play an important role in cancer ?

Inflammatory response results in:
- initiation
DNA damage from release of free radicals by immune cells

- promotion
Growth factor induced cell division to repair tissue damage