Molecular Biology of Cancer Quiz

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Questions and Answers

What type of kinases are referred to as nonreceptor tyrosine kinases?

Kinases that possess receptor sites

Kinases that are found only in the nucleus

Kinases that do not have receptor sites (correct)

Kinases that are exclusively cytoplasmic

Which oncogene is commonly amplified in small cell lung cancers?

BCL2

MDM2

BRAF

MYC (correct)

What is a key function of Myc transcription factors?

Translating oncogenes into proteins

Regulating apoptosis pathways

Inhibiting cell proliferation

Controlling gene expression related to cell proliferation (correct)

Which oncogene produces excessive amounts of Bcl2, affecting apoptosis in non-Hodgkin’s lymphomas?

BCL2 (D) Signup and view all the answers

What cancer is MYCN primarily associated with?

Neuroblastoma (C) Signup and view all the answers

What is the effect of excessive Mdm2 in some human sarcomas?

Inhibition of self-destruct pathways (D) Signup and view all the answers

Which of the following is NOT a member of the MYC gene family?

BRAF (B) Signup and view all the answers

In what type of cancers is the MYC gene frequently amplified aside from small cell lung cancers?

Ovarian and breast cancers (B) Signup and view all the answers

What is the function of the v-mpl oncogene?

It codes for a receptor involved in the Jak-STAT pathway. (D) Signup and view all the answers

Which of the following correctly describes the Ras protein's activation process?

It binds to GTP with the aid of a guanine nucleotide exchange factor. (A) Signup and view all the answers

Which RAS proto-oncogene is most frequently mutated in human cancers?

KRAS (A) Signup and view all the answers

What is the primary amino acid target for the serine and threonine kinases?

Serine and threonine (D) Signup and view all the answers

What is the role of GTPase activating proteins (GAPs) in relation to G proteins?

They convert GTP to GDP, leading to G protein inactivation. (D) Signup and view all the answers

Which type of oncogenes are responsible for point mutations in approximately 30% of all human cancers?

RAS oncogenes (A) Signup and view all the answers

In which type of cancer are HRAS mutations primarily encountered?

Bladder cancers (B) Signup and view all the answers

What is the result of the Ras protein being bound to GDP?

It is in an inactive state. (B) Signup and view all the answers

What is the primary role of transforming growth factor (TGF) in relation to tumor development?

Inhibiting epithelial cell proliferation (A) Signup and view all the answers

Which of the following cancers commonly exhibit loss-of-function mutations in TGF receptors?

Colorectal cancer (D) Signup and view all the answers

The CDKN2A gene is involved in which two cancer regulatory pathways?

Rb pathway and p53 pathway (B) Signup and view all the answers

What percentage of pancreatic cancers are associated with loss-of-function mutations in Smad proteins?

50% (A) Signup and view all the answers

Which of the following statements about BRCA1 and BRCA2 genes is true?

Defects in these genes can cause chromosomal instabilities. (D) Signup and view all the answers

What is the lifetime cancer risk for women who inherit a mutation in one of the BRCA genes for breast cancer?

40% to 80% (A) Signup and view all the answers

Which mechanism of DNA repair is associated with BRCA2?

Homologous recombination (B) Signup and view all the answers

What consequence results from a deletion of both copies of the CDKN2A gene?

Absence of both p16 and ARF proteins (C) Signup and view all the answers

What does the v-sis oncogene produce that leads to uncontrolled cell proliferation?

A mutant form of the growth factor PDGF (B) Signup and view all the answers

How does the v-erb-b oncogene contribute to cancer development?

By altering the EGF receptor to be continuously active (A) Signup and view all the answers

What is a consequence of having multiple copies of the ERBB2 gene?

Increased cell response to growth factors (B) Signup and view all the answers

What type of protein does the v-sis oncogene specifically produce?

Growth factors (B) Signup and view all the answers

Which of the following statements correctly describes the function of the oncogene related to PDGF?

It stimulates uncontrolled cell proliferation (A) Signup and view all the answers

The abnormal EGF receptor produced by the v-erb-b oncogene retains what activity?

Tyrosine kinase activity (B) Signup and view all the answers

In the context of cancer biology, what role do tumor suppressor genes typically play?

They inhibit cell proliferation and tumor growth (A) Signup and view all the answers

What leads to the constancy of activity in the receptor produced by the v-erb-b oncogene?

The lack of an EGF binding site (B) Signup and view all the answers

What role does BRCA1 play in response to DNA damage?

Activates the pathway for repairing double-strand breaks (A) Signup and view all the answers

What is the consequence of a lack of Mad or Bub proteins in cell division?

Creation of aneuploid cells (C) Signup and view all the answers

How do unattached chromosomes signal to prevent premature separation during mitosis?

By transmitting a ‘wait’ signal that inhibits the anaphase-promoting complex (B) Signup and view all the answers

What is the function of the anaphase-promoting complex during cell division?

To degrade cohesin proteins holding chromatids together (A) Signup and view all the answers

Which of the following statements is true regarding the Mad and Bub proteins?

They bind to unattached chromosomes and inhibit the anaphase-promoting complex (D) Signup and view all the answers

What triggers the onset of anaphase?

Breakdown of cohesin proteins by separase (A) Signup and view all the answers

What happens when chromosomes are not properly attached to the mitotic spindle?

A signal prevents anaphase initiation (B) Signup and view all the answers

What is the potential outcome of mutations in BRCA1 or BRCA2 genes?

Increased susceptibility to DNA damage from carcinogenic agents (B) Signup and view all the answers

What type of mutations do proto-oncogenes undergo to potentially lead to cancer?

Gain-of-function mutations (D) Signup and view all the answers

Which of the following is a characteristic of tumor suppressor genes?

They can be lost or inactivated through random mutations. (D) Signup and view all the answers

What is the phenomenon called when the normal copy of a tumor suppressor gene on one chromosome is disrupted?

Loss of heterozygosity (D) Signup and view all the answers

What role do 'gatekeeper' tumor suppressor genes play in cancer prevention?

They control cell proliferation and survival. (D) Signup and view all the answers

Which mechanism is NOT associated with loss of heterozygosity?

Chromosomal aberration (B) Signup and view all the answers

What is the primary function of caregiver tumor suppressor genes?

They maintain genome integrity. (A) Signup and view all the answers

What happens to the Rb protein in its normal state?

It binds to E2F transcription factor. (D) Signup and view all the answers

Which cyclin-dependent kinase is amplified in certain sarcomas?

CDK4 (B) Signup and view all the answers

Signup and view all the answers

Study Notes

Cancer Biology: Tumor Suppressor Genes

Lecture 9, First Semester, 2024/2025 Academic Year
Topics covered include the discovery of cellular oncogenes, how cellular oncogenes arise, oncogene signaling pathways, tumor suppressor gene discovery, and tumor suppressor gene examples.
The lecture also delves into various types of proteins produced by oncogenes, focusing on growth factors, receptor proteins, plasma membrane G proteins, intracellular protein kinases, and transcription factors, with examples of specific oncogenes like v-sis, v-erb-b, and RAS, and tumor suppressor genes such as BCL2, MDM2, PTEN, TGFß, CDKN2A, BRCA1 and BRCA2.
Tumor suppressor genes typically lead to cancer through loss-of-function mutations.
Proto-oncogenes undergo gain-of-function mutations that lead to cancer.
Tumor suppressor genes can undergo loss-of-function mutations that lead to cancer.
Loss of heterozygosity is discussed as a mechanism for disrupting tumor suppressor genes.
The RB protein prevents E2F from activating the transcription of genes needed for DNA replication, holding the cell in a non-proliferating state. Phosphorylation of the Rb protein is triggered by growth factors.
p53 is a crucial protein, called the "guardian of the genome", that protects cells from the effects of DNA damage.
The p53 protein activates the ATM kinase, leading to its phosphorylation and blocking its interaction with Mdm2 for subsequent events to trigger apoptosis or cell cycle arrest.
Individuals with a mutated p53 gene can exhibit an elevated cancer risk, termed Li-Fraumeni syndrome.
p53 gene mutations are common in various cancers.
The APC gene and the related Wnt signaling pathway are discussed as crucial in colon cancer development.
The PI3K-Akt pathway and the function of the PTEN gene are also explained, highlighting how the disruption of this pathway can lead to enhanced cell proliferation.
The TGFß gene is a key regulator of cell proliferation, often inactivated in various cancers.
Mutations in the CDKN2A gene can lead to the production of alternative proteins, impacting cell cycle regulation and potentially leading to cancer development.
The BRCA1 and BRCA2 genes are involved in DNA repair, and mutations in these genes can increase the risk of breast and ovarian cancer.
The mitotic spindle checkpoint and its role in preventing premature chromosome separation are discussed, emphasizing the consequences of faulty checkpoint function as a driver of cancer.
In some cancers, stepwise accumulation of mutations in tumor suppressor and oncogene genes is associated with increasingly aggressive behavior
Lastly, the lecture introduces laboratory methods for cancer diagnosis, including protein purification and mass spectrometry to identify proteomic patterns.

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Description

Test your knowledge on the role of oncogenes, kinases, and transcription factors in cancer biology. This quiz covers important concepts related to nonreceptor tyrosine kinases, MYC gene family, and their functions in various cancers. Assess your understanding of key molecular mechanisms driving tumorigenesis.