Podcast
Questions and Answers
What is the primary characteristic of cancer?
What is the primary characteristic of cancer?
- Stable cell mutation rates
- Controlled cell division
- Uncontrolled cell division (correct)
- Uniform cell structure
How many kinds of human cancers have been identified?
How many kinds of human cancers have been identified?
- More than 100 (correct)
- Fewer than 10
- More than 50
- Exactly 100
What does it mean for most cancers to be of clonal origin?
What does it mean for most cancers to be of clonal origin?
- They originate from multiple cells
- They are always benign
- They originate from a single cell (correct)
- They are caused by external factors
Which statement best describes the multistep process of cancer?
Which statement best describes the multistep process of cancer?
Which of the following is NOT a way chemicals contribute to cancer development?
Which of the following is NOT a way chemicals contribute to cancer development?
Which virus is known to cause cervical cancer in humans?
Which virus is known to cause cervical cancer in humans?
What type of cancer is associated with Rous sarcoma virus (RSV)?
What type of cancer is associated with Rous sarcoma virus (RSV)?
Which characteristic defines a malignant cancer?
Which characteristic defines a malignant cancer?
What is the primary type of individual that Burkitt lymphoma occurs in?
What is the primary type of individual that Burkitt lymphoma occurs in?
What percentage of human cancers are estimated to arise from causes other than viruses?
What percentage of human cancers are estimated to arise from causes other than viruses?
Which of the following genes is identified as a prototype tumor suppressor gene?
Which of the following genes is identified as a prototype tumor suppressor gene?
What role do mutations in proto-oncogenes typically play in cancer development?
What role do mutations in proto-oncogenes typically play in cancer development?
Which protein is required for apoptosis induced by DNA damage?
Which protein is required for apoptosis induced by DNA damage?
What is a characteristic of tumor suppressor genes compared to oncogenes?
What is a characteristic of tumor suppressor genes compared to oncogenes?
What is the relationship between oncogenes and proto-oncogenes?
What is the relationship between oncogenes and proto-oncogenes?
Which oncogene was the first to be identified from a retrovirus?
Which oncogene was the first to be identified from a retrovirus?
What role does Rb play in the cell cycle?
What role does Rb play in the cell cycle?
Which protein inhibits Cdk4,6/cyclin D complexes?
Which protein inhibits Cdk4,6/cyclin D complexes?
What type of mutation results in the activation of an oncogene?
What type of mutation results in the activation of an oncogene?
Which of the following is NOT classified as a tumor suppressor gene?
Which of the following is NOT classified as a tumor suppressor gene?
What is the primary function of wild-type p53 in response to DNA damage?
What is the primary function of wild-type p53 in response to DNA damage?
Which characteristic is typical of proto-oncogenes?
Which characteristic is typical of proto-oncogenes?
Which of the following mutations is associated with the Ras protein acting as an oncogene?
Which of the following mutations is associated with the Ras protein acting as an oncogene?
What is the effect of oncogenes on cellular behavior?
What is the effect of oncogenes on cellular behavior?
In the context of tumor suppressors, what does 'loss-of-function' refer to?
In the context of tumor suppressors, what does 'loss-of-function' refer to?
Which protein is a transcription factor that can become an oncogene?
Which protein is a transcription factor that can become an oncogene?
What is the primary function of the NF1 protein in cell division?
What is the primary function of the NF1 protein in cell division?
How does the APC protein affect cell division?
How does the APC protein affect cell division?
What function does p53 serve in cellular processes?
What function does p53 serve in cellular processes?
What is the primary function of BRCA1 and BRCA2 proteins?
What is the primary function of BRCA1 and BRCA2 proteins?
What characterizes tumor-suppressor genes?
What characterizes tumor-suppressor genes?
What is the focus of epigenetics in cellular biology?
What is the focus of epigenetics in cellular biology?
Which of these describes the role of checkpoint proteins?
Which of these describes the role of checkpoint proteins?
What is the primary role of the p53 protein in relation to DNA damage?
What is the primary role of the p53 protein in relation to DNA damage?
In the context of retinoblastoma, what does the 'two-hit' model imply?
In the context of retinoblastoma, what does the 'two-hit' model imply?
What effect does the Rb protein have on the transcription factor E2F?
What effect does the Rb protein have on the transcription factor E2F?
What type of retinoblastoma typically occurs in the late stages of life?
What type of retinoblastoma typically occurs in the late stages of life?
Which of the following accurately describes the process of apoptosis?
Which of the following accurately describes the process of apoptosis?
What typically happens when tumor-suppressor genes like Rb or p53 lose their function?
What typically happens when tumor-suppressor genes like Rb or p53 lose their function?
Caspases are associated with which cellular process?
Caspases are associated with which cellular process?
Which gene was the first human tumor-suppressor gene identified?
Which gene was the first human tumor-suppressor gene identified?
How does the loss of p53 gene function affect cancer progression?
How does the loss of p53 gene function affect cancer progression?
Which of the following best describes how tumor-suppressor genes function?
Which of the following best describes how tumor-suppressor genes function?
Which mechanisms can alter gene expression without changing the DNA sequence?
Which mechanisms can alter gene expression without changing the DNA sequence?
How can epigenetic changes indirectly contribute to disease?
How can epigenetic changes indirectly contribute to disease?
What type of chromatin modification is commonly abnormal in cancer cells?
What type of chromatin modification is commonly abnormal in cancer cells?
What can result from mutations in genes encoding chromatin-modifying proteins?
What can result from mutations in genes encoding chromatin-modifying proteins?
Which cancer is associated with mutations in DNA methyltransferase?
Which cancer is associated with mutations in DNA methyltransferase?
What is a common environmental agent associated with lung cancer?
What is a common environmental agent associated with lung cancer?
Which environmental agent is linked to multiple myeloma and lymphoma?
Which environmental agent is linked to multiple myeloma and lymphoma?
Which modification is made by histone acetyltransferase?
Which modification is made by histone acetyltransferase?
What is a key feature of epigenetic changes caused by environmental agents?
What is a key feature of epigenetic changes caused by environmental agents?
Which type of histone modification is linked to breast cancer?
Which type of histone modification is linked to breast cancer?
Which treatment is being explored to target epigenetic changes in cancer?
Which treatment is being explored to target epigenetic changes in cancer?
What is a potential outcome of chromatin remodeling in cancer cells?
What is a potential outcome of chromatin remodeling in cancer cells?
Which cancer type is NOT commonly associated with mutations in histone methyltransferase?
Which cancer type is NOT commonly associated with mutations in histone methyltransferase?
Flashcards
Cancer Definition
Cancer Definition
Uncontrolled cell division resulting in a genetic disease at the cellular level.
Cancer Origin
Cancer Origin
Most cancers begin from a single cell, making a clonal growth.
Cancer Process
Cancer Process
A multi-step process, starting as a benign growth and becoming malignant through genetic changes.
Cancer Stages
Cancer Stages
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Cancer Causes (Radiation)
Cancer Causes (Radiation)
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Cancer Causes (Carcinogens)
Cancer Causes (Carcinogens)
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Tumor Viruses
Tumor Viruses
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Cancer Classifications
Cancer Classifications
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Oncogenes
Oncogenes
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Proto-oncogenes
Proto-oncogenes
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Tumor Suppressor Genes
Tumor Suppressor Genes
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Rb gene
Rb gene
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p53 gene
p53 gene
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Cell Transformation
Cell Transformation
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Retroviruses
Retroviruses
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Viral Oncogenes
Viral Oncogenes
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Rb protein function
Rb protein function
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Cdk4/6-cyclin D complex
Cdk4/6-cyclin D complex
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p16 function
p16 function
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p53 function
p53 function
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Ras protein
Ras protein
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Gain-of-function mutation
Gain-of-function mutation
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Mutations triggering oncogenesis
Mutations triggering oncogenesis
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E2F Inhibition
E2F Inhibition
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p16 Role
p16 Role
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APC Role
APC Role
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BRCA1 & BRCA2 Role
BRCA1 & BRCA2 Role
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Genome Integrity
Genome Integrity
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Epigenetics
Epigenetics
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Epigenetic Mechanisms
Epigenetic Mechanisms
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DNA Methylation
DNA Methylation
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Histone Modification
Histone Modification
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Epigenetics and Disease
Epigenetics and Disease
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Cancer and Epigenetics
Cancer and Epigenetics
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Mutations in Chromatin-Modifying Proteins
Mutations in Chromatin-Modifying Proteins
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Environmental Agents and Epigenetics
Environmental Agents and Epigenetics
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5-azacytidine and Decitabine
5-azacytidine and Decitabine
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Epigenetic Changes in Cancer (Direct)
Epigenetic Changes in Cancer (Direct)
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Epigenetic Changes in Cancer (Consequence)
Epigenetic Changes in Cancer (Consequence)
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Epigenetic Changes in Cancer (Indirect)
Epigenetic Changes in Cancer (Indirect)
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Examples of Environmental Agents
Examples of Environmental Agents
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Epigenetics and Cancer Treatment
Epigenetics and Cancer Treatment
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Missense mutation
Missense mutation
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Gene amplification
Gene amplification
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Chromosomal translocation
Chromosomal translocation
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Viral integration
Viral integration
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What is the 'two-hit' model?
What is the 'two-hit' model?
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How does Rb protein regulate cell division?
How does Rb protein regulate cell division?
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What is the role of p53 in DNA damage?
What is the role of p53 in DNA damage?
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What is apoptosis?
What is apoptosis?
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What is the function of caspases?
What is the function of caspases?
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Study Notes
Genetic Basis of Cancer
- Cancer is a disease of uncontrolled cell division, a genetic disease at the cellular level.
- Human cancers are categorized by the cell type that becomes cancerous; more than 100 types have been identified.
- Most cancers arise from a single cell, a clonal growth.
- Cancer development is a multistep process, starting as a benign, non-invasive growth, then progressing with genetic changes to become cancerous.
- Cancer can be staged based on its invasiveness; malignant is invasive, and metastatic spreads to a different body site.
Characteristics of Cancer
- Most cancers originate from a single cell with clonal growth.
- Cancer cells divide repeatedly forming a growth.
- Cancer begins as a benign growth, not invasive.
- Cancer's multi-step process involves additional genetic changes leading to cancerous growth.
- Cancers are staged based on:
- Malignant, meaning invasive, and spreading to surrounding tissues
- Metastatic, meaning spread to different sites in the body.
Causes of Cancer
- Radiation and many chemical carcinogens cause damage to DNA, leading to mutations.
- Other chemical carcinogens stimulate cell proliferation, contributing to cancer development.
- Viruses can cause cancer in humans and other species.
- Members of several families of tumor viruses directly cause cancer in both experimental animals and humans.
Tumor Viruses
- Specific virus families cause specific types of human cancers:
- DNA viruses: Hepatitis B viruses, SV40 and polyomaviruses, Papillomaviruses, Adenoviruses, Herpesviruses
- RNA viruses: Hepatitis C virus, Retroviruses
Oncogenes
- Specific genes called oncogenes cause cell transformation, providing insights into cancer's molecular basis.
- Studies of viral oncogenes led to the discovery of cellular oncogenes, involved in non-virus-induced cancers.
- The key link between viral and cellular oncogenes was identified through retroviruses.
- The first oncogene identified was the src gene of Rouse sarcoma virus. -Further studies have identified more than two dozen distinct oncogenes in various retroviruses.
- Proto-oncogenes are normal genes that can mutate into oncogenes, causing cancer. -Mutations in proto-oncogenes are typically dominant, where a mutated gene product promotes cancer. -Oncogenes are mutated forms of proto-oncogenes, that are either overexpressed or are mutated in structure, resulting in the promotion of cancer.
Tumor Suppressor Genes
- Tumor suppressor genes are involved in controlling cell growth, acting to inhibit proliferation and tumor development.
- The Rb gene, a prototypical tumor suppressor gene is identified by studies of retinoblastoma inheritance patterns.
- Loss or inactivation of Rb and other tumor suppressors, including p53, lead to numerous human cancers.
- Tumor suppressor proteins act as inhibitors of cell proliferation and cell survival. -Rb, INK4, p53 proteins negatively regulate cell cycle progression. -p53 is essential in apoptosis, induced by DNA damage or other stimuli. Inactivation enhances tumor cell survival.
Rb Protein
- Rb protein controls cell division, regulating the transcription factor E2F. -Phosphorylation of Rb by cyclin-dependent kinases causes detachment from E2F. This allows E2F and therefore activating cell cycle genes. -Binding of Rb to E2F inhibits its function, and prevents the cell from progressing through the cell cycle. -In the absence of a functional Rb protein, cells can progress through the cell cycle continually.
p53
- p53 is a tumor suppressor gene involved in determining cell damage.
- If DNA damage is detected, p53 promotes cellular pathways, activating DNA repair, halting cell division, and inducing apoptosis (programmed cell death).
- About 50% of human cancers are connected with p53 gene defects.
Apoptosis
- Apoptosis is a process of programmed cell death, involving cell shrinkage, chromatin condensation, and DNA degradation.
- Caspases are proteases in apoptosis that act like "executioners".
- In apoptosis, the cell breaks down into vesicles, and the immune system eventually removes them.
Epigenetics
- Epigenetics is the study of heritable changes in gene expression that occur without changes to the underlying DNA sequence.
- Epigenetic mechanisms such as DNA methylation and histone modifications alter gene expression without changing the DNA sequence.
- Epigenetic factors are also linked to cancer.
Epigenetic Changes in Cancer
- Several chromatin modifications, DNA methylation, histone modification, chromatin remodeling are abnormal in cancer cells.
- Mutations in genes encoding chromatin-modifying proteins can cause inhibition, or increased function, influencing gene expression patterns.
- Environmental agents can alter chromatin modifying protein functions.
Environmental Agents that Alter Chromatin Modifying Proteins
- Some environmental agents directly alter chromatin-modifying protein functions.
- Scientists are still investigating whether epigenetic changes from environmental agents cause cancer.
- Various examples of environmental agents associated with cancer and epigenetic changes are listed in a table.
Cancer Treatments Aimed at Epigenetic Changes
- Researchers are researching drugs to affect DNA methylation and covalent histone modifications, to inhibit cancer cells.
- 5-azacytidine and decitabine are DNA methyltransferase inhibitors and are effective in diseases such as leukemia. However, mechanisms aren't entirely understood.
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