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59 Cards in this Set
- Front
- Back
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What are the family of viruses that have been found to cause cancer?
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Papillomaaviridae
Hepadnaviridae Herpesviridae Poxiviridae |
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Describe the mechanism of transformation for small DNA viruses.
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induces S phase genes
Extend life of cell Block action of normal regulatory proteins Often tumor suppressor genes |
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describe the mechanism of Large DNA viruses
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interact with extra-cellular growth factors or intracellular signaling systems
Results in perpetual cellular replication Encode homologs of cellular genes involved in signaling |
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True or False
Tumor Suppressor genes are often deleted or damaged in cancer cells |
True
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True or False
50% of human tumors have p53 gene inactivated |
True
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what does p53 do in the cell?
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p53 regulates G1 to S phase in the cell cycle
Active p53 inhibits progression from G1 to S phase |
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what is the function of pRb?
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the pRb protein is a cell cycle regulator
it inhibits cells moving from G1 to S phase |
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how do Polymaviruses cause cancer?
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these viruses also encode proteins that interfere with tumor suppressor factors
SV40 makes the larger T antigen which interferes with both pRb and p53 |
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what produces SV40? what does it do?
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Polymaviruses
-makes the larger T antigen which interferes with both pRb and p53 |
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Is there a vaccine for HPV?
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Yes
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what types of HPV cause cervical carcinoma?
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HPV types 16, 18, and 31
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How does HPV act on the cell to cause cancer?
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Two viral proteins, E6 and E7 maintain cells in S phase for virus replication and can immortalize cells
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what is the function of protein E7 in the HPV virus?
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Protein E7 interferes with pRb while protein E6 interferes with p53
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E7: pRb
E6: _____ |
p53
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what type of cell will the EBV infect?
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EBV in a gammaherpesvirus that infects limited set of cells bearing the CD21 molecule
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what type of cells is EBV limited to?
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B-lymphocytes and a few types of epithelial cells
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what main proteins does EBV viral DNA produce?
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EBNA-1
+LMP1 |
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what does LMP stand for in EBV?
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Latent membrane protein
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what is a fatal lymphoma of the head or neck caused by a virus?
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Burkitt's Lymphoma
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what do the lymphoma cells of Burkitt's lymphoma exhibit in its genome?
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the lymphoma cell exhibits a chromosomal translocation (t8:14) which is relocation of c-myc
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If the immune system is well intact will a Burkitt's lymphoma occur?
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NO
loss of immune surveillance is necessary for this disease to develop |
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what are the 3 forms of Burkitt's lymphoma?
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Ednemic Form
Sporadic Form AIDS form |
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What type of co-infection is required for the formation of Endemic form of Burkitt's Lymphoma?
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requires co-infetion with Plasmodium falciparum (malaria)
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True or False
50% of cells found in an AIDS form of a Burkitt's lymphoma have EBV DNA present. |
True
loss of immune surveillance due to HIV infection |
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what virus subset has been found to cause Hodgkin's disease (lymphoma)?
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EBV
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what is the etiological agent of Kaposi's Sarcoma?
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HHV-8
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Describe the pathogenesis in the mechanism of HHV-8
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multifactorial viral neoplasia that is not well understood
not an aggressive tumor due to lack of immune competence |
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What type of co-infection is required for the formation of Endemic form of Burkitt's Lymphoma?
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requires co-infetion with Plasmodium falciparum (malaria)
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True or False
50% of cells found in an AIDS form of a Burkitt's lymphoma have EBV DNA present. |
True
loss of immune surveillance due to HIV infection |
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what virus subset has been found to cause Hodgkin's disease (lymphoma)?
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EBV
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what is the etiological agent of Kaposi's Sarcoma?
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HHV-8
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Describe the pathogenesis in the mechanism of HHV-8
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multifactorial viral neoplasia that is not well understood
not an aggressive tumor due to lack of immune competence |
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Is the HHV-8 caused tumor an aggressive tumor?
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NO
not an aggressive tumor and the overt disease is due to lack of immune competence |
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what is described as " hit and run" transformation?
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proposed mechanism for HSV (1 & 2) of a small part of the genome is a rearrangement of cellular genes
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Is there a vaccine for Hepatits B?
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YES
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what type of cancer does Hepatitis B cause?
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a member of the Hepadnaviridae family that causes a persistent infection of the liver
-there is a long incubation period before cancer develops -Chronic HBV infection and increased proliferation of hepatocytes predisposes the patient to PHC -Hepatocellular Carcinoma is a multifactorial disease |
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How do viruses cause cancer?
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viruses encode proteins that perturb normal cellular regulation
-these proteins can upregulate cellular growth factors and disrupt regulatory brakes this is a multistep/multifacotrial process |
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define oncogenesis
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mechanism of the development of cancer
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define Neoplasm
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an abnormal new growth
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define Retinoblastoma
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a cancer of the retina
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Sarcoma
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a cancer of fibroblasts
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How many kinds of RNA viruses are there?
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three kinds of RNA viruses
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What are the three RNA viruses?
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Retroviruses & Hepatitis C (Flavivirus)
1. Non-acute transforming retroviruses 2. Acute transforming retroviruses 3. Trans-activating retroviruses |
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Human T-cell Leukemia is causes by what type of virus
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Trans-acting retroviruses
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Avian Sarcoma virus is caused by what type of virus
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Acute transforming retroviruses
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Murine leukemia virus is caused by what type of virus
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Non-Acute transforming retrovirus
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Are Non-acute transforming Retroviruses responsible for cancer in humans?
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NO
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do acute transforming retroviruses cause cancer in humans?
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NO
these viruses are uncommon in nature and do NOT cause cancer in humans |
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how long is the incubation period until cancer is developed by an acute transforming retrovirus?
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weeks
-the virus is defective and required a helper virus |
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what does the oncogen version of C-ras have transformed in it from the normal C-ras?
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The oncogene version, v-ras has a change in codon for aa-12
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what type of cancer may be linked to Prostate Cancer?
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gamma retrovirus
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what type of virus is uncommon in nature but causes cancer in humans?
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Trans activating Tumor Viruses
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what type of virus is considered a trans activating tumor virus?
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Retroviris
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How long is the incubation period for a trans activating tumor virus to cause cancer?
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The incubation period until cancer develops is years
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How do trans activating tumor viruses act on the cell to cause cancer?
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The action of viral regulatory proteins on cellular genes immortalizes or transforms the cell
-the virus is replication competent -the virus transforms a subset of lymphocytes -after a long incubation period there will be numerous immortalized T-cells |
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When does Adult T-cell Leukemia occur?
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occurs when an aggressive clone is generated by the trans activating tumor viruses
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Describe the mechanism of HTLV Transformation.
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1. Retrovirus carries an accessory gene, tax
2. tax may activate several cellular genes and initiate an autostimulating IL-2 loop |
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what family does Hepatits C virus belong to?
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Flaviviridae
(+) ssRNA genome -infection with virus predisposes patients to primary hepatocellular carcinoma |
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What is the mechanism of transformation for HCV?
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HCV persistently infects hepatocytes
It causes continual destruction and regeneration of liver tissue Continual induction of cell growth in the presence of an active immune response may lead to cancer |
