B/06

Question 1

What are tumor suppressor genes?

Answer 1

Genes needed for control of cell growth

Question 2

Mechanisms of tumor suppressor gene inactivation (5)

Answer 2

• loss of heterozygosity
• mutation of allele : missense / STOP codon
• epigenetic
• transdominance
• haploinsufficiency

Question 3

Epigenetic modification of tumor suppressor gene

Answer 3

hypermethylation of promoter silences transcription

Question 4

What is transdominance?

Answer 4

1 gene is mutated, the other isn’t - mutated protein silences the “normal” protein

Question 5

Tumor suppressor gene inactivation in hereditary cancers

Answer 5

One mutated allele is present in the family and the other one happens sporadically

Question 6

Tumor suppressor gene inactivation in sporadic cancers

Answer 6

Requires two mutations to silence the gene on both alleles

Question 7

WT1 gene function, hereditary neoplasm and sporadic neoplasm

Answer 7

• regulates nuclear transcription

- causes Wilms tumor in both cases

Question 8

What is specific to the tumor suppressor gene inactivation mechanism?

Answer 8

You need to have BOTH alleles silenced for an oncogenic effect

Question 9

Rb gene function, hereditary and sporadic neoplasms

Answer 9

• regulates cell cycle
• hereditary : retinoblastoma
• sporadic : retinoblastoma, lung cancer

Question 10

p53 gene function, hereditary and sporadic neoplasms

Answer 10

• cell cycle block and apoptosis
• hereditary : li-fraumeni syndrome
• sporadic : most human cancers

Question 11

APC gene function, hereditary and sporadic neoplasms

Answer 11

• beta katenin block
• hereditary : melanoma
• sporadic : colon cancer