Chapter 8 Self-check questions

. Which one of the following statements correctly describes what happens after WNT ligand binds to Frizzled and LRP?

RAR-RXR heterodimers are formed and associate with HDAC co-repressor complexes, silencing target genes.

Axin and APC form a complex with CKI and GSK3β which then modifies β-catenin for degradation.

Axin is recruited to the phosphorylated co-receptor LRP and this disrupts the APC, CKI, GSK3β complex.

Patched inhibits Smoothened and the pathway is suppressed.

. Evidence that the WNT-signalling pathway is important for self-renewal of stem cells in the adult is:

Tcf gene knock-out mice show lack of stem cells in the intestine.

Gli mutations lead to skin cancer.

APC mutations lead to a lack of stem cells in the intestine.

Tcf gene knock-out mice have an increased rate of colon cancer.

. Polycomb group proteins are known as "guardians of stemness". Which statement about polycomb proteins is true?

They induce genes that promote differentiation.

They trigger the degradation of differentiation regulators.

They repress genes that promote differentiation by epigenetic mechanisms.

They repress genes that promote differentiation directly by binding to target gene promoters.

. Mutations that activate the Hedgehog signaling pathway are characteristic of which one of the following?

Retinoblastoma.

Breast cancer.

Colorectal cancer.

Basal cell carcinoma.

. The Hedgehog signal transduction pathway culminates with the induction of target genes by which transcription factor?

Gli.

β-catenin.

Tcf.

E2F.

. Which one of the following is the correct name for the treatment of acute promyelocytic leukemia by the administration of all-trans retinoic acid?

Differentiation therapy.

Apoptotic therapy.

Anti-angiogenic therapy.

Conventional chemotherapy.

. The chromosomal translocation that is associated with acute promyelocytic leukemia results in the PML-RAR fusion protein. Which statement about how this oncoprotein acts is false?

It acts by disrupting the normal role of PML.

It acts by associating with HDAC with high affinity.

It acts by blocking wild-type receptors and acting in a dominant negative manner.

It acts by inducing the EGF pathway.

. Which one of the following statements regarding cancer stem cells is false?

Cancer stem cells have been identified in many types of cancer.

They are a small fraction of tumor cells that maintain the tumor in a cancerous state.

They represent one in a hundred tumor cells in acute myeloid leukemia.

They express the same cell surface markers as stem cells normally present in the tissue.

. What experimental strategy showed that restoration of APC promotes cell differentiation and re-establishes homeostasis in colorectal cancer in mice?

In vitro mutagenesis of the APC gene

PCR and sequence analysis

Conditional and reversible control of APC gene expression by inducible short hairpin RNAs,

Microinjection of APC protein

. Which one of the following statements about patients with the syndrome, familial adenomatous polyposis is true?

They have a predisposition to basal cell carcinoma and carry a germline mutation in the APC gene.

They have a predisposition to developing colon cancer and carry a germline mutation in the WNT gene.

They have a predisposition to developing colon cancer and carry a germline mutation in the RAR gene.

They have a predisposition to developing colon cancer and carry a germline mutation in the APC gene.

. Which one of the following is NOT a valid strategy for the development of new anti-cancer drugs that target cancer stem cells?

Small molecule inhibitors of Smoothened.

Hedge-hog blocking antibodies.

Tyrosine kinase inhibitors targeted against the Frizzled receptor.

Creation of compounds that mimic cyclopamine.

. Which are NOT features of the models of stem cell division?

Division is asymmetrical giving rise to a stem cell and a more differentiation-committed cell.

Division is intrinsic

Division can give rise to two differentiation-committed cells.

Division can give rise to either two daughter stem cells or one daughter stem cell and and a more differentiation-committed cell depending on space in the stem cell niche.

Quiz Content