Oncogenesis (25) Flashcards
What is not a class of cancer causing agent?
a. Chemical carcinogens
b. UV and ionising radiation
c. Bacterial mutagenesis
d. Viruses
c. Bacterial mutagenesis
What is true about transformation?
a. Cancers arise from un-transformed cells following a clonal pattern
b. Changes cannot be inherited
c. Transformation can prevent immortalisation
d. Changes are genetic and can alter the growth phenotype of a cell
d. Changes are genetic and can alter the growth phenotype of a cell
A feature of transformed cells is:
a. They do not depend on exogenous growth factors
b. Growth can be inhibited in a contact dependent manner
c. Most cell types exhibit anchorage dependence
d. All oncogenic viruses can transform cells in culture
a. They do not depend on exogenous growth factors
What is not a class of oncogene?
a. Growth factors
b. Cyclin dependent kinase repressors
c. Intracellular signal transducers
d. Transcription factors
b. Cyclin dependent kinase repressors
What is a feature of a DNA tumour virus?
a. The viruses are not lytic
b. Transformation involves the inactivation of tumour suppressor genes
c. V-onc usually has a c-onc counterpart
d. Integration is essential and site specific
b. Transformation involves the inactivation of tumour suppressor genes
Exogenous retroviruses:
a. Are transmitted in the germ line
b. Are totally silent
c. Are integrated proviruses
d. Are acquired during life
d. Are acquired during life
Why are most retroviruses that cause cancer replication defective?
a. An oncogene replaces an essential viral gene
b. Coinfection with other viruses leads to competition
c. They have the Src gene as well as gag, pol and env
d. They lose their LTRs during provirus integration
a. An oncogene replaces an essential viral gene
Which virus can cause insertional mutagenesis?
a. Transducing retroviruses
b. Epstein Barr virus
c. Trans-activating retrovirus
d. Cis-activating retrovirus
d. Cis-activating retrovirus
What causes cancer in humans?
a. Transducing retroviruses like Rous sarcoma
b. Cis-activating retrovirus like KoRV
c. Trans-activating retrovirus like HTLV-1
d. Cis-activating retrovirus like MuLV
c. Trans-activating retrovirus like HTLV-1
Human T-cell lymphotrophic virus type 1:
a. Can only be transmitted via the placenta
b. Infects CD4+ T cells
c. Is a cic-activating retrovirus
d. Encodes the regulatory proteins Tat and Rev (Tax and Rex)
b. Infects CD4+ T cells
What is not a feature of Tax?
a. It is a transcription factor which acts on the LTR region of HTLV-1
b. It up-regulates gag, pol , env and some c-onc genes
c. It is up-regulated in late stage leukaemia
d. It activates IL-2 which causes T cell proliferation
c. It is up-regulated in late stage leukaemia
What is NOT involved in the formation of tumours by DNA viruses?
a. Cancer is often due to the viral replication strategy and indirect to the virus itself
b. The virus requires host enzymes which are made during S phase but most cells are in G0 or G1
c. Tumours demonstrate high levels of viral protein expression and episomal viral genomes
d. Transformation occurs during the non-productive stage
c. Tumours demonstrate high levels of viral protein expression and episomal viral genomes
How can HPV cause cancer?
a. Random integration can result in the loss of E2 and constitutive expression of E6 and E7
b. E2 is up-regulated in malignant cells which leads to constitutive E6 and E7 expression
c. The HPV genome exists as a continuously expressed episome in malignant cells
d. Random integration can result in the loss of E6 and E7
a. Random integration can result in the loss of E2 and constitutive expression of E6 and E7
What is true about HBV and liver cancer?
a. HCC arises in 100% of HBV carriers
b. The HBV genome remains episomal, but X is overexpressed in malignant cells
c. HBV X encodes a trans-activating gene that deregulates Src tyrosine kinase following random integration into the host genome
d. Cells infected with HBV have very few mutations as they are constantly being refreshed and regenerated
c. HBV X encodes a trans-activating gene that deregulates Src tyrosine kinase following random integration into the host genome
What transforms B cells to cause clonal expansion and increase the risk of Burkitt’s lymphoma and nasopharyngeal cancer?
a. Hepatitis B virus
b. Hodgkins Lymphoma Virus
c. Human cytomegalovirus
d. Epstein Barr virus
d. Epstein Barr virus
