Genetic Basis of Cancer Quiz

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Questions and Answers

What is the primary characteristic that defines cancer?

Cancer is characterized by uncontrolled cell division.

How do oncogenes and tumor-suppressor genes differ in relation to cancer?

Oncogenes promote cell division, while tumor-suppressor genes inhibit cell division.

What does it mean for a cancer to be classified as 'metastatic'?

A metastatic cancer has spread to a different site in the body.

Why are most cancers considered clonal in origin?

<p>Most cancers originate from a single cell that undergoes genetic mutations.</p> Signup and view all the answers

What role do radiation and chemical carcinogens play in the development of cancer?

<p>They damage DNA and induce mutations that can lead to cancer.</p> Signup and view all the answers

What are tumor viruses and their significance in cancer research?

<p>Tumor viruses are capable of directly causing cancer in various species, including humans.</p> Signup and view all the answers

What is a 'benign growth' in the context of cancer development?

<p>A benign growth is a non-invasive tumor that has not yet become cancerous.</p> Signup and view all the answers

Can you name a virus that is associated with causing cervical cancer?

<p>Human Papillomavirus (HPV) is associated with causing cervical cancer.</p> Signup and view all the answers

What is the relationship between Epstein-Barr virus and Burkitt lymphoma?

<p>Epstein-Barr virus is a causative agent of Burkitt lymphoma, particularly in immunosuppressed individuals like AIDS patients.</p> Signup and view all the answers

What percentage of human cancers are not induced by viruses?

<p>Approximately 80% of human cancers are not induced by viruses.</p> Signup and view all the answers

How do oncogenes contribute to cancer development?

<p>Oncogenes induce cell transformation and promote uncontrolled cell proliferation, leading to cancer.</p> Signup and view all the answers

What is a proto-oncogene?

<p>A proto-oncogene is a normal gene that, when mutated, can lead to cancer by promoting uncontrolled cell growth.</p> Signup and view all the answers

What role do tumor suppressor genes play in cancer?

<p>Tumor suppressor genes inhibit cell proliferation and tumor development, acting as a safeguard against cancer.</p> Signup and view all the answers

What is the significance of the Rb gene in cancer research?

<p>The Rb gene was the first tumor suppressor gene identified and is crucial for understanding retinoblastoma inheritance.</p> Signup and view all the answers

How does p53 contribute to cell survival in response to DNA damage?

<p>p53 acts as a negative regulator of the cell cycle and induces apoptosis in response to DNA damage.</p> Signup and view all the answers

What distinguishes oncogenes from tumor suppressor genes?

<p>Oncogenes promote cell growth and proliferation, while tumor suppressor genes inhibit these processes.</p> Signup and view all the answers

How does Rb inhibit cell cycle progression?

<p>Rb inhibits progression past the restriction point in G1 by remaining in its active form until it is phosphorylated by Cdk4,6/cyclin D complexes.</p> Signup and view all the answers

What role does p16 play in relation to Cdk4,6/cyclin D complexes?

<p>p16 inhibits the activity of Cdk4,6/cyclin D complexes, thus preventing the phosphorylation and inactivation of Rb.</p> Signup and view all the answers

What is the significance of wild-type p53 in cellular response to DNA damage?

<p>Wild-type p53 is crucial for inducing cell cycle arrest through p21 and triggering apoptosis via proapoptotic proteins like PUMA and Noxa.</p> Signup and view all the answers

Define the difference between oncogenes and tumor suppressor genes.

<p>Oncogenes are mutated genes that promote cancerous growth, while tumor suppressor genes prevent the formation of cancer.</p> Signup and view all the answers

What occurs when a tumor suppressor gene loses function?

<p>Loss-of-function in a tumor suppressor gene allows unregulated cell growth and can lead to cancer development.</p> Signup and view all the answers

List one effect a gain-of-function mutation in a proto-oncogene may have.

<p>A gain-of-function mutation may increase the amount of protein produced by the proto-oncogene.</p> Signup and view all the answers

In what way are ras genes significant in cancer?

<p>Mutations in ras genes, which are proto-oncogenes, lead to a constitutively active Ras protein that promotes cell division.</p> Signup and view all the answers

Identify one type of mutation frequently found in oncogene formation.

<p>One type of mutation is a missense mutation, resulting in a change to an amino acid that alters protein function.</p> Signup and view all the answers

How do the roles of pro-apoptotic Bcl-2 family members influence cancer?

<p>Pro-apoptotic Bcl-2 family members like PUMA and Noxa promote apoptosis; their induction may be compromised in cancer, allowing cells to evade death.</p> Signup and view all the answers

How does the protein p16 influence the cell cycle?

<p>p16 negatively regulates cyclin-dependent kinases, controlling the transition from the G1 phase to the S phase of the cell cycle.</p> Signup and view all the answers

What role does the NF1 protein play in cell division?

<p>NF1 stimulates Ras to hydrolyze its GTP to GDP, and loss of NF1 function leads to overactivity of Ras, promoting cell division.</p> Signup and view all the answers

Describe the function of the APC protein in cell signaling.

<p>APC is a negative regulator of a signaling pathway that activates genes promoting cell division.</p> Signup and view all the answers

What is the role of p53 as a checkpoint protein?

<p>p53 acts as a checkpoint sensor of DNA damage, regulating target genes to prevent cell cycle advancement or promote apoptosis.</p> Signup and view all the answers

How do BRCA1 and BRCA2 proteins contribute to DNA repair?

<p>BRCA1 and BRCA2 facilitate DNA repair processes and can promote apoptosis if the damage is irreparable.</p> Signup and view all the answers

What are the two general categories of tumor-suppressor genes?

<p>Tumor-suppressor genes are categorized into those that negatively regulate cell division and those that maintain genome integrity.</p> Signup and view all the answers

Explain the concept of epigenetics.

<p>Epigenetics studies heritable traits that change cell function without altering the DNA sequence.</p> Signup and view all the answers

How do checkpoint proteins maintain genome integrity?

<p>Checkpoint proteins detect genetic abnormalities and prevent the division of cells until issues are resolved.</p> Signup and view all the answers

What is a missense mutation and how can it affect tumor-suppressor genes?

<p>A missense mutation is a change in a DNA sequence that results in the substitution of one amino acid for another in a protein. This can alter the function of tumor-suppressor genes, potentially leading to uncontrolled cell division and cancer.</p> Signup and view all the answers

Define gene amplification and its potential impact on cancer development.

<p>Gene amplification is the process by which a cell increases the number of copies of a particular gene. This can lead to overexpression of proteins that may promote cell division, contributing to cancer progression.</p> Signup and view all the answers

Explain the role of chromosomal translocation in cancer development.

<p>Chromosomal translocation involves the rearrangement of parts between nonhomologous chromosomes, which can lead to the formation of oncogenes or disrupt tumor-suppressor genes. This can result in abnormal cell growth and cancer.</p> Signup and view all the answers

What happens to tumor-suppressor genes when their function is lost?

<p>When tumor-suppressor genes lose their function, the regulation of cell division is impaired, leading to unrestrained cell proliferation and increased cancer risk. This loss can occur through mutations, deletions, or other genetic alterations.</p> Signup and view all the answers

How does the Rb protein regulate cell division?

<p>The Rb protein inhibits the transcription factor E2F, which activates genes necessary for cell cycle progression. By binding to E2F, Rb prevents cells from advancing through the cell cycle.</p> Signup and view all the answers

Describe the two-hit model of retinoblastoma.

<p>The two-hit model posits that retinoblastoma requires two mutations: inherited forms start with one mutation, while non-inherited forms require two mutations occurring later in life. Both scenarios lead to tumor development.</p> Signup and view all the answers

What is the main function of the p53 protein in regards to cancer prevention?

<p>The p53 protein primarily acts as a guardian of the genome by detecting DNA damage and activating pathways for DNA repair, cell cycle arrest, or apoptosis. Its dysfunction can contribute to cancer progression.</p> Signup and view all the answers

Explain the process of apoptosis and its significance in cancer.

<p>Apoptosis is a programmed cell death process that removes damaged or unwanted cells through specific morphological changes, vital for maintaining cellular health and preventing tumorigenesis. Failure of apoptosis can lead to tumor growth.</p> Signup and view all the answers

What are the two categories of tumor-suppressor genes?

<p>The two main categories of tumor-suppressor genes are those that negatively regulate cell division and those that are involved in DNA repair mechanisms. Both are essential for preventing cancer.</p> Signup and view all the answers

How does viral integration contribute to cancer development?

<p>Viral integration can lead to the insertion of viral oncogenes into host cell genomes, potentially inactivating tumor-suppressor genes or activating oncogenes. This disruption can result in uncontrolled cell growth and cancer.</p> Signup and view all the answers

What are DNA methylation and histone modification, and how do they differ from mutations?

<p>DNA methylation and histone modification are epigenetic changes that alter gene expression without modifying the DNA sequence, whereas mutations involve changes to the nucleotide sequence.</p> Signup and view all the answers

Describe one way in which epigenetic changes can be associated with human disease.

<p>Epigenetic changes can directly contribute to disease symptoms by altering gene expression patterns related to the disease.</p> Signup and view all the answers

What is a potential effect of mutations in genes encoding chromatin-modifying proteins?

<p>Mutations can lead to either inhibition or increased function of chromatin-modifying proteins, significantly affecting gene expression.</p> Signup and view all the answers

List two cancers commonly associated with histone acetyltransferase mutations.

<p>Colorectal cancer and breast cancer are commonly associated with mutations in histone acetyltransferase.</p> Signup and view all the answers

How do environmental agents affect chromatin-modifying proteins?

<p>Environmental agents can alter the functions of chromatin-modifying proteins, potentially leading to epigenetic changes that are associated with cancer.</p> Signup and view all the answers

What role do polycyclic aromatic hydrocarbons play in cancer development?

<p>Polycyclic aromatic hydrocarbons are environmental agents that can cause epigenetic changes associated with multiple cancer types, including lung and breast cancer.</p> Signup and view all the answers

Identify one drug being researched for its potential effects on epigenetic changes in cancer.

<p>5-azacytidine is a drug being researched for its ability to inhibit DNA methylation in cancer cells.</p> Signup and view all the answers

What is the function of the SWI/SNF complex in chromatin remodeling?

<p>The SWI/SNF complex alters the positions of histones, influencing the accessibility of DNA for transcription.</p> Signup and view all the answers

Explain the significance of histone demethylase in cancer.

<p>Histone demethylase removes methyl groups from histones, potentially leading to abnormal gene expression patterns associated with cancers such as multiple myeloma.</p> Signup and view all the answers

Why may epigenetic changes be considered indirect in some cases?

<p>Epigenetic changes may be indirect if a third factor, such as a toxic agent, influences both the disease and the epigenetic alterations.</p> Signup and view all the answers

What potential outcomes can arise from increased function of chromatin-modifying proteins?

<p>Increased function of chromatin-modifying proteins can lead to enhanced gene expression and contribute to oncogenesis.</p> Signup and view all the answers

How can the association between epigenetics and cancer be identified?

<p>Research can identify this association through the observation of specific epigenetic changes in cancer cells and their correlation with clinical outcomes.</p> Signup and view all the answers

In terms of epigenetics, what are the implications of histone phosphorylation?

<p>Histone phosphorylation can influence gene expression by altering chromatin structure, which is associated with cancers like medulloblastoma.</p> Signup and view all the answers

Discuss how a disease can cause epigenetic changes.

<p>Disease symptoms may arise first, leading to cellular stress that triggers epigenetic alterations as an adaptive response.</p> Signup and view all the answers

Flashcards

Cancer

A disease characterized by uncontrolled cell division; a genetic disease at the cellular level.

Cancer Cell Clonal Origin

Cancer originates from a single cell, which divides to form a mass of identical cancer cells.

Multistep Cancer Development

Cancer develops in stages, starting with a benign growth that progresses to cancerous growth through genetic changes.

Malignant Cancer

Cancer that invades surrounding tissues. This type is highly aggressive.

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Metastatic Cancer

Cancer that has spread to different parts of the body.

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Oncogenes

Genes that promote cell division and uncontrolled cell growth.

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Tumor Suppressor Genes

Genes that prevent uncontrolled cell growth and regulate cell division.

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Cancer-Causing Agents

Substances, like radiation and certain chemicals, that damage DNA and increase the risk of mutation leading to cancer.

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Proto-oncogenes

Normal genes that can mutate and become oncogenes, driving cancer.

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Rb gene

A key tumor suppressor gene, often mutated in cancers.

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p53 gene

Crucial tumor suppressor gene that triggers cell death if DNA is damaged.

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Cell transformation

The process where a normal cell becomes a cancer cell.

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Mutations (oncogenes)

Changes in the genetic code of oncogenes that cause them to become overactive.

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Viral oncogenes

Oncogenes found in viruses and involved in cancer.

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Missense mutation

A change in a single DNA base pair that results in a different amino acid being incorporated into a protein.

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Gene amplification

An increase in the number of copies of a gene.

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Chromosomal translocation

A rearrangement of genetic material between non-homologous chromosomes.

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Viral integration

The insertion of viral DNA into the host cell's genome.

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What is a tumor suppressor gene?

A gene whose normal function is to prevent the uncontrolled growth of cells. They act as brakes on cell division.

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How does the Rb protein inhibit cell division?

The Rb protein binds to a transcription factor called E2F, preventing E2F from activating genes needed for cell cycle progression.

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What is Apoptosis?

Programmed cell death. It's a controlled process of cell self-destruction.

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Function of p53 protein

The p53 protein detects DNA damage and initiates repair mechanisms. If repair fails, it triggers cell cycle arrest or apoptosis.

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What happens when tumor suppressor genes are inactivated?

When tumor suppressor genes are inactivated, cell division control is lost, leading to uncontrolled cell growth and cancer development.

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How do tumor suppressor genes prevent cancer?

They regulate cell division and apoptosis. They act as "gatekeepers" protecting the genome from mutations that can lead to cancer.

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Restriction Point (G1)

A crucial checkpoint in the cell cycle, ensuring proper cell growth and DNA integrity before entering S phase (DNA replication).

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Rb Protein

A tumor suppressor protein that inhibits progression through the restriction point, preventing uncontrolled cell division.

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Cdk4/6-Cyclin D Complex

A protein complex that promotes passage through the restriction point by phosphorylating and inactivating Rb.

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p16

A tumor suppressor protein that inhibits the activity of Cdk4/6-Cyclin D complex, preventing uncontrolled cell division.

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p53

A tumor suppressor protein that plays a crucial role in cell cycle arrest and apoptosis (programmed cell death) in response to DNA damage.

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p21

A Cdk inhibitor protein that is induced by p53, leading to cell cycle arrest in response to DNA damage.

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PUMA and Noxa

Pro-apoptotic proteins induced by p53, triggering apoptosis (controlled cell death) in response to severe DNA damage.

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Mutation Effects on Proto-Oncogenes

Mutations in proto-oncogenes can lead to increased protein production, altered protein activity, or expression in inappropriate cell types, all contributing to uncontrolled growth.

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Ras Protein

A GTPase involved in signaling pathways that regulate cell growth. Mutations in the Ras gene can lead to the formation of an oncogene.

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E2F Inhibition's Role

E2F inhibition prevents the transcription of genes crucial for DNA replication and cell division.

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p16's Role

The protein kinase p16 acts as a negative regulator of cyclin-dependent kinases, controlling the transition from the G1 phase to the S phase of the cell cycle.

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NF1's Action

NF1 protein stimulates Ras to hydrolyze GTP to GDP, essentially turning off Ras.

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Loss of NF1 Function

A loss of NF1 function leads to overactive Ras, which promotes cell division and can contribute to cancer development.

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APC's Function

APC acts as a negative regulator of a pathway that activates genes promoting cell division.

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Genome Integrity

Maintaining genome integrity refers to cellular mechanisms that prevent mutations or stop mutant cells from dividing or surviving.

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Checkpoint Proteins & DNA Repair

Checkpoint proteins detect genetic abnormalities and prevent cell division, while DNA repair enzymes fix errors in the genetic code.

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p53's Role

p53 acts as a sensor of DNA damage, regulating genes to control cell cycle progression and promote apoptosis if necessary.

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Epigenetics

Changes in gene expression without altering the DNA sequence. Think of it like adding sticky notes to your DNA to change how genes are read.

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Epigenetic Changes and Disease

Alterations in gene expression due to epigenetics can contribute to disease development through direct involvement, subsequent changes, or indirect associations via a third factor.

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Epigenetic Changes in Cancer

Cancer cells often exhibit abnormal epigenetic modifications, including DNA methylation, histone modifications, and chromatin remodeling, contributing to uncontrolled cell growth.

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Mutations in Chromatin-Modifying Proteins

Mutations in genes that encode chromatin-modifying proteins can lead to either inhibition or increased function of these proteins, ultimately affecting gene expression patterns.

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Epigenetic Changes in Cancer: DNA Methylation

Mutations in genes that encode DNA methyltransferases, the enzymes responsible for attaching methyl groups to DNA, can contribute to abnormal methylation patterns in cancer.

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Epigenetic Changes in Cancer: Histone Modification

Mutations in histone-modifying enzymes, such as histone acetyltransferases, methyltransferases, demethylases, and kinases, can lead to aberrant histone modifications, altering gene expression in cancer.

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Epigenetic Changes in Cancer: Chromatin Remodeling

Alterations in chromatin remodeling complexes, such as SWI/SNF, can disrupt chromatin structure and affect gene expression, contributing to cancer development.

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Environmental Agents and Epigenetics

Certain environmental factors, such as pollutants and toxic substances, can directly alter the functions of chromatin-modifying proteins, potentially influencing the development of cancer.

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Epigenetic Cancer Treatments

Inhibition of DNA methylation and histone modifications is a promising approach to target cancer cells. Drugs like 5-azacytidine and decitabine are examples of DNA methyltransferase inhibitors showing potential in leukemia treatment.

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How do epigenetic changes contribute to cancer?

Epigenetic changes can lead to inappropriate gene expression, promoting uncontrolled cell growth, invasion, and metastasis. It is also important to note that epigenetic alterations can be influenced by environmental factors, which may contribute to cancer development.

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What are the main types of epigenetic modifications in cancer?

Three major categories of epigenetic modifications are commonly affected in cancer: DNA methylation, histone modifications, and chromatin remodeling. Each type alters the accessibility and expression of genes.

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How do mutations in chromatin-modifying proteins contribute to cancer?

Mutations in genes encoding enzymes that modify chromatin can alter the function of these enzymes, leading to inappropriate epigenetic modifications. This can either enhance or suppress gene expression, potentially causing cancer development.

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What are some examples of environmental agents that can alter epigenetics?

Environmental factors like pollutants, tobacco smoke, endocrine disruptors, and heavy metals can directly influence the function of chromatin-modifying proteins, leading to epigenetic changes that may contribute to cancer development.

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What are the potential therapeutic strategies based on targeting epigenetic changes in cancer?

Drugs aimed at inhibiting DNA methylation and histone modifications, like 5-azacytidine and decitabine, are being investigated for their potential as cancer treatments. These drugs try to restore normal gene expression patterns to control cancer cell growth.

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Study Notes

Genetic Basis of Cancer

  • Cancer is a disease characterized by uncontrolled cell division.
  • It is a genetic disease at the cellular level.
  • Human cancers are classified by the type of cell that becomes cancerous.
  • More than 100 types of human cancer have been identified.

Characteristics of Cancer

  • Most cancers originate from a single cell, and the growth is clonal.
  • Cancer cell division produces two cancerous cells.
  • Cancer is a multistep process.
  • It begins as a non-invasive benign growth.
  • Additional genetic changes lead to cancerous growth.
  • Cancers can be staged as malignant or metastatic.
  • Malignant tumors are invasive, invading surrounding tissue.
  • Metastatic tumors move to different sites in the body.

Causes of Cancer

  • Radiation and many chemical carcinogens damage DNA and induce mutations.
  • Other chemical carcinogens stimulate cell proliferation to contribute to cancer development.
  • Viruses, including tumor viruses, cause cancer in both humans and other species.

Tumor Viruses

  • Members of several animal virus families, called tumor viruses, cause cancer.
  • They are capable of causing cancer in experimental animals and humans.

Tumor Viruses Table

  • DNA Genomes:
    • Hepatitis B viruses - Liver cancer.
    • SV40 and polyomavirus - None
    • Papillomaviruses - Cervical carcinoma
    • Adenoviruses - None
    • Herpesviruses - Burkitt's lymphoma, nasopharyngeal, carcinoma, Kaposi's sarcoma.
  • RNA Genomes:
    • Hepatitis C virus - Liver cancer
    • Retroviruses - Adult T-cell leukemia

Table 22.7 Examples of Viruses That May Cause Cancer

  • Retroviruses (RSV) - Cause sarcomas in chickens

  • Hardy-Zuckerman-4 feline sarcoma virus - Cause sarcomas in cats

  • DNA viruses (Hepatitis B, SV40, polyomavirus) - Cause liver cancer in several species including humans

  • Papillomavirus - Causes benign tumors and malignant carcinomas in several species including humans; causes cervical cancer in humans

  • Herpesvirus - Causes carcinoma in frogs and T-cell lymphoma in chickens. A human herpesvirus (Epstein-Barr virus) is a causative agent in Burkitt lymphoma, which occurs primarily in immunosuppressed individuals such as AIDS patients.

  • The majority (approximately 80%) of human cancers do not appear to be induced by viruses. They result from other causes, such as radiation and chemicals.

Genes, Oncogenes

  • Cancer results from alterations in critical regulatory genes that control cell proliferation, differentiation, and survival.
  • Specific genes (called oncogenes) induce cell transformation providing insights into cancer's molecular basis.
  • Studies of viral oncogenes led to the identification of cellular oncogenes, involved in non-virus-caused cancers.
  • Retroviral oncogenes, such as the src gene of Rous sarcoma virus (RSV), were identified in early studies.

Proto-Oncogenes

  • Proto-oncogenes are genes normally causing normal cells to become cancerous when mutated.
  • Mutations in proto-oncogenes are typically dominant.
  • The mutated form of a proto-oncogene is called an oncogene.
  • Oncogenes are abnormal or mutated forms of corresponding proto-oncogenes.

Tumor Suppressor Genes

  • Tumor suppressor genes function as the opposite side of cell growth control. They normally inhibit cell proliferation and tumor development.
  • Tumor suppressor gene Rb was identified, along with p53, in studies of retinoblastoma inheritance.
  • Loss or mutational inactivation of Rb and other tumor suppressor genes, contributes to many human cancers.
  • The encoded proteins of tumor suppressor genes act as inhibitors of cell proliferation or survival..

Functions of Tumor Suppressor Gene Products

  • Rb, INK4, and p53 proteins are negative regulators of the cell cycle progression.
  • P53 is required for apoptosis induced by DNA damage or other stimuli, so its inactivation contributes to enhanced tumor cell survival.

Rb Protein Regulates Cell Division

  • The Rb protein suppresses the proliferation of cancer cells.
  • Rb regulates transcription factor E2F, which activates genes necessary for cell cycle progression.
  • Rb binding to E2F inhibits its activity and prevents cell progression through the cell cycle.
  • In the absence of functional Rb, a cell can always progress through the cell cycle.

p53

  • The p53 gene is a tumor suppressor gene discovered after Rb.
  • Approximately 50% of human cancers have defects in the p53 gene.
  • The p53 protein is a primary determinant of a cell's response to DNA damage.
  • It activates genes that promote DNA repair, arrest cell division, and induce apoptosis.

Apoptosis

  • Apoptosis is programmed cell death involving cell shrinkage, chromatin condensation, and DNA degradation.
  • It is facilitated by proteases known as caspases.
  • In apoptosis, the cell fragments into small vesicles.
  • Immune system cells later phagocytose these vesicles.

Epigenetics

  • Epigenetics is the study of heritable traits that happen without changes in the DNA sequence, but affect cell function.
  • Epigenetic factors can contribute to cancer.
  • DNA methylation and histone modification are examples of epigenetics mechanisms that alter gene expression without altering the underlying DNA sequence.

Epigenetic Changes Common in Cancer Cells

  • Several chromatin modifications are abnormal in cancer cells, such as DNA methylation, covalent histone modifications, and chromatin remodeling.

Environmental Agents that Alter Chromatin-Modifying Proteins

  • Some environmental agents directly alter chromatin-modifying proteins.
  • For some agents, an association with cancer is causative.
  • Whether other influences are truly causative is not yet known for all agents.

Cancer Treatments Aimed at Epigenetic Changes

  • Researchers are investigating drugs to inhibit cancer by affecting DNA methylation or covalent histone modifications.
  • 5-azacytidine and decitabine, which are DNA methyltransferase inhibitors, have shown some promise in leukemia treatment.

Mutations Changing Proto-Oncogenes to Oncogenes

  • Four common types of mutations change proto-oncogenes to oncogenes: missense mutation, gene amplification, chromosomal translocation, and viral integration.

Oncogenes vs Tumor Suppressor Genes

  • Genes involved in cancers are classified as either oncogenes or tumor suppressor genes.
  • Oncogenes have a mutated gene that promotes cancerous growth by overexpression.
  • Tumor suppressor genes regulate processes that control cancer, stopping or hindering cancer by preventing it. -Loss in function occurs in tumor suppressor genes, causing cancerous growth.

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