40. CANCER

Question 1

1. What is Cancer?

Answer 1

• this is the abnormal proliferation of cells
• they grow in an uncontrolled manner

Question 2

2. What causes Carcinogenesis?

Answer 2

• the abnormal function of the gene regulation systems

Question 3

3. What causes cancer?

Answer 3

• mutations of genes
• these genes are meant to regulate the cell cycle
• tumour viruses can cause cancer
• these are also called Oncogenic Viruses
• they insert their genome into the cellular genome

Question 4

4. List 7 examples of DNA Viruses.

Answer 4

1. Epstein Barr Virus
2. Human Papilloma Virus
3. Hepatitis B Virus
4. Burkitt’s Lymphoma
5. Nasopharyngeal Carcinoma
6. Cervical Carcinoma
7. Hepatocellular Carcinoma

Question 5

5. List 3 examples of RNA Retroviruses?

Answer 5

1. HTLV-I
2. Adult T-cell Leukaemia
3. Lymphoma

Question 6

6. What can be said one type of Oncogenic Retroviruses?

Answer 6

• they are acutely transforming
• they cause viruses by the transduction of the viral
  oncogene

Question 7

7. What does the virus genome contain?

Answer 7

• it contains the oncogene
• it is inserted into the genomes of the cell
• it causes uncontrolled cell proliferation
• leads to carcinogenesis

Question 8

8. What are Non-defective Oncogenic Viruses?

Answer 8

• they are slowly transforming viruses
• they cause tumours
• they do this via Insertional Mutagenesis

Question 9

9. What can be said about the Non-defective virus?

Answer 9

• it does not contain the oncogene
• it inserts itself upstream of c-myc
  (cellular proto oncogene)
• this virus has a strong viral promoter
• this causes uncontrolled cell proliferation
• this results in carcinogenesis

Question 10

10. What are Oncogenes?

Answer 10

• they are genes
• they are found in viral or cellular genomes
• they trigger molecular events
• these lead to cancer

Question 11

11. What do Oncogenes induce?

Answer 11

• they induce uncontrolled cell division
• they promote cancer development

Question 12

12. What are Tumour Suppressor genes?

Answer 12

• they are genes that have a protein product
• their protein product inhibits cell division
• they prevent uncontrolled cell growth
• they prevent cancer

Question 13

13. What are Proto-oncogenes?

Answer 13

• they are the corresponding normal cellular genes
• they are responsible for normal cell growth and
  division

Question 14

14. What happens when a Proto-oncogene undergoes a mutation?

Answer 14

• it can become an oncogene
• this can lead to cancer development

Question 15

15. In which two ways can Proto-Oncogenes be converted to oncogenes?

Answer 15

1. THE MOVEMENT OF THE DNA
   
   • within the genome
   • this includes translocation and transduction
2. AMPLIFICATION OF THE PROTO-ONCOGENE

Question 16

16. What happens when DNA moves within the genome?

Answer 16

• the DNA may be inserted downstream
• it will be inserted with an active promoter
• the transcription of the genes it encodes may increase
• there may also be a viral promoter in the inserted DNA
• this also increases transcription

Question 17

17. What happens when a Proto-Oncogene is amplified?

Answer 17

• there is a increases number of copies of the gene
• there is an increased activation of the MAPK Signalling
  pathway
• increased cellular proliferation

Question 18

18. What does BCR encode for?

Answer 18

• it encodes for a protein that acts as a guanine
  nucleotide
• this becomes an exchange factor for Rho and GTPase
  proteins

Question 19

19. What is ABL1?

Answer 19

• it encodes for the protein Tyrosine Kinase
• this activity is rightly regulated

Question 20

20. What does the BCR-ABL protein have?

Answer 20

• it has unregulated protein tyrosine kinase activity
• this leads to unctonrolled cell division