30 Questions
What is the main difference between a proto-oncogene and an oncogene?
A proto-oncogene is a normal cellular gene, while an oncogene is a viral gene product.
What is the main function of oncogenic viruses in cancer development?
They induce transformation of cells through their gene products.
What is genome instability and mutation in the context of cancer?
A hallmark of cancer, characterized by uncontrolled cell growth.
How do cancer cells avoid the immune system?
By evading the immune system through various mechanisms.
What is the term for a gene that can induce transformation of cells?
Oncogene
What is the main characteristic of the fourth stage of cancer (Stage IV)?
Cancer has spread to other sites in the body.
What is the term for the process of overcoming senescence and crisis, allowing indefinite cell division?
Immortalization
What is the term for the adoption of a fully cancerous phenotype?
Transformation
What is the main function of the hallmarks of cancer framework?
To understand the underlying principles of cancer development.
Who discovered the Rous sarcoma virus, a retrovirus that can cause cancer in chickens?
Peyton Rous
What is the primary function of p53 and pRB in cells?
To regulate cell cycle progression and induce cell death when damage cannot be repaired
How do most oncogenic viruses stimulate proliferative signaling?
By targeting key canonical pathways such as PI3K-AKT-mTOR, MAPK, Notch, and WNT
What is the role of apoptosis in tissue homeostasis?
To maintain tissue function and prevent cell death
Why do oncogenic viruses block apoptosis?
To prevent cell death due to innate immune signaling and damage responses
How do oncogenic viruses evade immune destruction of infected cells?
By blocking innate immune pathways and adaptive immune responses
What is the result of genome instability and mutation in host cells?
The development of cancer
How do some oncogenic viruses alter the expression of host genes?
By integrating their genome into the host cell genome
What is the result of chronic infection by some viruses such as HBV and HCV?
The creation of an environment that facilitates cell growth and division as well as mutation
What is the role of p53 in cancer development?
It is mutated in ~50% of cancers
What is the hallmark of cancer that is enabled by the integration of viral genomes into the host cell genome?
Genome instability and mutation
What percentage of human cancers are caused by viral infections?
15-17%
What is a characteristic of oncogenic viruses?
They can establish persistent infections
What is a hallmark of cancer?
Uncontrollable growth and spread of abnormal cells
Which of the following is NOT a type of cancer?
Bacteria
What is the primary mechanism by which oncogenic viruses promote cancer?
By promoting the action of viral proteins on the cell
Which of the following viruses is NOT an oncogenic virus?
Influenza virus
What is a common property of oncogenic viruses?
They are all transmitted between humans
What is the primary reason why cancer is deadly?
Uncontrollable growth and spread of abnormal cells
Which of the following is a type of infectious disease associated with cancer?
All of the above
What is the name of the process by which cancer cells evade the immune system?
Immune system evasion
Study Notes
Hallmarks of Cancer
- There are eight hallmarks of cancer, which are common traits of most cancers
- These hallmarks include:
- Sustained proliferative signaling
- Evading growth suppressors
- Resisting cell death
- Enabling replicative immortality
- Inducing angiogenesis
- Activating invasion and metastasis
- Deregulating cellular energetics
- Evading immune destruction
- Tumor-promoting inflammation
- Most oncogenic viruses induce at least four of these hallmarks through their gene products
Oncogenic Viruses
- Seven oncogenic viruses of humans have been identified
- These viruses are from different families:
- Herpesviridae (EBV and KSHV)
- Papillomaviridae (HPV)
- Polyomaviridae (MCPyV)
- Hepadenaviridae (HBV)
- Flaviviridae (HCV)
- Retroviridae (HTLV-1)
Characteristics of Oncogenic Viruses
- Not a lot in common among the seven oncogenic viruses
- However, they are all transmitted between humans (not zoonotic) and can establish persistent infections
- Cancer is not necessary for replication, and viruses have not evolved to cause cancer
- Cancer is a by-product of viral proteins acting on cells to promote replication and transmission
Types of Cancer
- Cancers can be classified by their primary site of origin (e.g., breast, liver, lung)
- Cancers can also be classified by tissue type:
- Carcinomas (epithelial origin, most common type)
- Sarcomas (supportive or connective tissue)
- Myelomas (plasma cells of bone marrow)
- Leukemias (bone marrow, site of blood cell production)
- Lymphomas (glands or nodes of the lymphatic system)
Burden of Cancer
- Every sixth death in the world is from cancer
- About 40% of people will be diagnosed with cancer at some point in their lives
- 15-17% of all human cancers are caused by viral infections
Explore the key characteristics of cancer, including sustained proliferative signaling, evading growth suppressors, and resisting cell death. Delve into the role of genome instability and tumor-promoting inflammation.
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