Chapter 6 Self-check questions

. All of the following are upstream activators of p53 EXCEPT:

DNA damage, oncogenic activation

Hypoxia and oncogenic activation

Hypoxia and low nucleotide pools

DNA repair and oncogenic activation

. Which one of the following statements is the strict definition of a tumor suppressor gene as stated by Knudson's Hypothesis?

A gene in which a germline mutation leads to cancer in the individual.

A gene in which a germline mutation predisposes individuals to cancer.

A gene inactivated by mutation or epigenetic changes that leads to cancer.

A gene whose product regulates cell numbers.

. Viral protein products interact with p53 and pRB. Identify which one of the following is a correct statement.

Adenovirus E1A, papilloma virus E7 and SV40 LgT activate RB and adenovirus E1B, papilloma virus E6 and SV40 LgT inactivate p53.

Adenovirus E1A, papilloma virus E6 and SV40 LgT inactivate RB and adenovirus E1B, papilloma virus E7 and SV40 LgT inactivate p53.

Adenovirus E1A, papilloma virus E7 and SV40 LgT inactivate RB and adenovirus E1B, papilloma virus E6 and SV40 LgT activate p53.

Adenovirus E1A, papilloma virus E7 and SV40 LgT inactivate RB and adenovirus E1B, papilloma virus E6 and SV40 LgT inactivate p53.

. Which one of the following statements about p53 is false?

It was the first oncogene to be identified.

In the absence of cellular stress, low levels of p53 induce antioxidant activity.

It is a transcription factor that contains four distinct domains, including a DNA binding domain.

The mechanism by which p53 becomes activated is dependent on the nature of the stress signal.

. Which of the following statements about Retinoblastoma is false?

Familial retinoblastoma involves inheriting one germline mutation in the Rb gene and acquiring a second mutation later in life.

In the familial form of the disease, one mutated gene increases the probability that a second mutation will occur.

In sporadic retinoblastoma, mutations occur in both alleles of the Rb gene in the same retinoblast after birth.

The mechanism of action of the Rb gene in cancer does not follow the concept of a tumor suppressor gene described by Knudson's two-hit hypothesis.

. Which of the following does NOT describe p53 mutations in tumor cells:

Most mutations involve single amino acid substitutions

Many mutant p53 mutants are more stable than wildtype protein.

Most occur in the DNA-binding domain.

Most involve nonsense or frameshift mutations that lead to inactivated truncated protein

. What is the role of PTEN (phosphate and tensin homolog) on chromosome 10?

Dephosphorylation of PIP2 to form PIP3.

Dephosphorylation of the membrane lipid PIP3 to form PIP2.

To cause Cowden syndrome.

To remove inhibitory signals and hence induce kinase activity.

. Which of the following therapeutic drugs targets the p53 regulator, MDM2?

Pifithrin-α

Herceptin.

Nutlins.

Vinblastine.

. Which one of the following correctly describes the downstream cell effects of p53 ?

Cell stress, apoptosis, DNA damage, cell cycle arrest.

Cell cycle arrest, apoptosis, DNA repair, inhibition of angiogenesis.

Aberrant growth signals, oncogene activation.

Apoptosis, DNA repair, and cell cycle induction.

. Which of the following statements regarding Li-Fraumeni syndrome is true?

It follows Knudson's two-hit hypothesis.

Patients develop cancer at an old age.

Patients develop multiple primary tumors.

Patients develop retinoblastoma.

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