Introduction to Cancer Biology
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Questions and Answers

What is the main distinction between invasiveness and metastasis in cancer?

  • Invasiveness involves tumor growth past normal tissue boundaries. (correct)
  • Invasiveness refers to cancer cells spreading to distant sites.
  • Metastasis is the growth of cancer cells within their original site.
  • Metastasis is characterized by localized excessive cell growth.

    • Which type of cancer is typically classified as benign due to its naming convention?

  • Lymphomas
  • Sarcoplasmas
  • Carcinomas
  • Omas (correct)

    • What characterizes dysplasia in tissue architecture?

  • Abnormal cytological changes and disorganization. (correct)
  • Excessive normal cell growth without changes.
  • Replacement of one type of cell layer with another normal type.
  • Complete normalcy of cell structure and function.

    • Stage 3 cancer is associated with what level of survival prognosis?

    <p>15-25%</p> Signup and view all the answers

    Among the following, which cancer type does NOT typically metastasize?

    <p>Gliomas</p> Signup and view all the answers

    What does neoplasia refer to in the context of cancer?

    <p>Abnormal and disorganized cell growth forming distinct masses.</p> Signup and view all the answers

    What is the primary cause of death due to cancer?

    <p>Impaired immune response and resultant infections.</p> Signup and view all the answers

    Which statement accurately defines hyperplasia?

    <p>Increased cell numbers while maintaining normal morphology.</p> Signup and view all the answers

    What is a defining feature of oncogenes that differentiates them from tumor suppressors?

    <p>They are typically mutated to be 'always on' contributing to tumorigenesis.</p> Signup and view all the answers

    Which pathway is primarily modulated by Ras and is involved in cancer signaling?

    <p>Raf-MAPK pathway</p> Signup and view all the answers

    How does Myc contribute to the progression of cancer?

    <p>By promoting cell cycle progression and blocking differentiation.</p> Signup and view all the answers

    Which of the following factors is NOT considered a potential cause of cancer?

    <p>Metabolic activation systems</p> Signup and view all the answers

    The Ames Test is known for its ability to detect what type of mutations?

    <p>Point mutations in prokaryotic cells</p> Signup and view all the answers

    What is a major limitation of the Ames Test?

    <p>It may yield false positives for certain mutagens.</p> Signup and view all the answers

    The concept of monoclonal tumors indicates that these tumors arise from:

    <p>A single mutated precursor cell</p> Signup and view all the answers

    Which cancer type has been associated with the mutation of the N-Ras oncogene?

    <p>Leukemia</p> Signup and view all the answers

    What is the primary mechanism through which oncogenic Myc is activated in cancer?

    <p>Gene amplification or chromosomal translocation</p> Signup and view all the answers

    What does the Two-Hit Hypothesis propose regarding tumor suppression?

    <p>Both copies of a tumor suppressor gene must be inactivated for tumorigenesis.</p> Signup and view all the answers

    What is the role of BH3-only proteins in the apoptotic process?

    <p>They promote apoptosis by binding to pro-survival Bcl-2 proteins.</p> Signup and view all the answers

    How does Akt influence cellular processes in relation to apoptosis?

    <p>It stimulates glucose metabolism and inhibits apoptosis.</p> Signup and view all the answers

    What is a primary consequence of overexpression of pro-survival Bcl proteins?

    <p>Blockade of apoptosis and cell survival promotion.</p> Signup and view all the answers

    Which model describes how p53 differentiates between activating cell cycle arrest and apoptosis?

    <p>p53 interacts more effectively with arrest genes than apoptotic genes.</p> Signup and view all the answers

    What role does Smac/Diablo play in the apoptotic signaling pathway?

    <p>It augments the cytochrome c signal by inhibiting IAP function.</p> Signup and view all the answers

    What is the main consequence of Rb loss-of-function mutations in relation to tumor suppressor activity?

    <p>Accelerated cell cycle progression</p> Signup and view all the answers

    How does the Two-Hit Hypothesis explain the development of hereditary retinoblastoma?

    <p>Both hits must occur in the same retinal cell</p> Signup and view all the answers

    What role does p53 play in cellular response to DNA damage?

    <p>Triggers apoptosis and cell cycle arrest</p> Signup and view all the answers

    What can result from a missense mutation in the p53 gene?

    <p>Formation of a dominant negative protein that can disrupt function</p> Signup and view all the answers

    What is a primary function of the retinoblastoma protein (Rb) in the cell cycle?

    <p>Preventing the transition from G1 to S phase</p> Signup and view all the answers

    What mechanism primarily regulates p53 activity in response to stress conditions?

    <p>Inhibition of MDM2-mediated degradation</p> Signup and view all the answers

    What is the consequence of the inactivation of the Rb protein in cells?

    <p>Immortalization of cells</p> Signup and view all the answers

    Which of the following is NOT a target gene regulated by p53?

    <p>Thymidylate synthase</p> Signup and view all the answers

    How does cyclin-CDK activity affect Rb?

    <p>It phosphorylates Rb, leading to E2F release</p> Signup and view all the answers

    What cellular event occurs when p53 accumulates in response to DNA damage?

    <p>Activation of DNA repair pathways</p> Signup and view all the answers

    Which kinase is NOT involved in the phosphorylation of p53 that impairs its binding to MDM2?

    <p>PI3K</p> Signup and view all the answers

    What role does p19ARF play in relation to p53 and MDM2?

    <p>It inhibits MDM2.</p> Signup and view all the answers

    Which is a characteristic feature that distinguishes embryonic stem cells from adult stem cells?

    <p>Embryonic stem cells are totipotent.</p> Signup and view all the answers

    Which of the following statements about death receptors is true?

    <p>Death receptors can induce apoptosis in specific target cells.</p> Signup and view all the answers

    What differentiates cancer stem cells from normal stem cells?

    <p>Cancer stem cells may resist traditional treatments more effectively.</p> Signup and view all the answers

    Which of the following best describes the function of FLIP in death receptor signaling?

    <p>Inhibits caspase activation by interfering with FADD.</p> Signup and view all the answers

    Which of the following factors is involved in maintaining the 'stemness' of stem cells?

    <p>Environmental signals from stromal cells.</p> Signup and view all the answers

    What may lead to the transformation of normal stem cells into cancer stem cells?

    <p>Accumulation of mutations.</p> Signup and view all the answers

    Which pathway is characterized by the ligand FasL binding to its receptor to induce apoptosis?

    <p>Extrinsic pathway</p> Signup and view all the answers

    Study Notes

    Introduction to Cancer

    • Cancer is a group of diseases affecting multicellular species.
    • Cancer causes death through organ destruction, infections (due to immune system impairment), cachexia, and hemorrhage.
    • Cancer cells grow through tissue, forming tumors.

    Invasiveness vs. Metastasis

    • Invasiveness: Cancer cells grow beyond normal tissue boundaries, often within connective tissue capsules.
    • Metastasis: Cancer cells spread and grow in new locations. A hallmark of malignancy, although some cancers are highly invasive but don't metastasize (e.g., gliomas, basal cell carcinomas).

    Cancer Types and Terminology

    • Hyperplasia: Excessive cell growth; cells are typically normal.
    • Metaplasia: Replacement of one cell type with another.
    • Dysplasia: Abnormal cells characterized by altered size/shape (nucleus), increased mitosis, and cytoplasmic changes; a transitional state between benign and premalignant.
    • Neoplasia: Abnormal/disorganized growth forming a mass (both malignant and nonmalignant).
    • Anaplasia: Dedifferentiated tumor cells; tissue origin is indistinguishable.
    • "-oma" suffix usually associated with benign tumors.

    Cancer Staging and Prognosis

    • Cancer staging reflects prognosis.
      • Stage 1: High survival (75-90%)
      • Stage 2: Moderate survival (45-55%)
      • Stage 3: Low survival (15-25%)
      • Stage 4: Very low survival (<5%)

    Major Cancer Classifications

    • Carcinoma: Most common; epithelial origin.
    • Sarcoma: Connective/mesenchymal tissue origin.
    • Leukemias/Lymphomas: Blood (hematopoietic) cell origin.
    • Neuroectodermal: Glioblastomas, neuroblastomas, Schwannomas.

    Cancer as a Genetic Disease and Aging

    • Cancer development requires multiple genetic changes.
    • Inherited mutations influence risk, but additional factors are necessary for cancer development.
    • Cancer incidence is strongly correlated with age (e.g., colon cancer).

    Cancer as a Monoclonal Disease

    • Cancer arises from a single mutated cell.
    • Examples: Leiomyomas (uterine wall) and myelomas (B cell precursors).

    Cancer Epidemiology/Causative Factors

    • Viral infections
    • Carcinogens (physical and chemical)
    • Lifestyle factors influence cancer prevalence globally.

    Ames Test

    • The Ames test measures the frequency of back mutations in Salmonella strains requiring histidine.
    • Strengths include simplicity, sensitivity to mutagens, and use of metabolic activation.
    • Limitations include prokaryotic system, inherent false positives/negatives, and limited scope, missing non-mutagenic carcinogens.

    Hallmarks of Cancer

    • Cancer cells exhibit characteristic features, like uncontrolled growth, resistance to cell death, and ability to metastasize.
    • Tumor biology is influenced by surrounding stromal tissues. Understanding stromal influences is important for treatment.

    Oncogenes (Lecture 2)

    • Oncogenes cause uncontrolled growth through gain-of-function mutations.
    • Tumor suppressor genes are inactivated by loss-of-function mutations.

    Proto-oncogene Transformation Mechanisms

    • Quantitative: Gene amplification (e.g., MYC, HER2).
    • Qualitative: Point mutations (e.g., RAS).

    RAS Protein

    • RAS is a small GTP-binding protein involved in many signaling pathways, like the MAP kinase pathway.
    • Mutations in RAS, lock it in an "on" state, leading to cancer.
      • It is found in several cancer types, including pancreatic, lung, and colon cancers.

    MYC Protein

    • MYC is a transcription factor regulating cell growth and proliferation.
    • Aberrant expression (amplification or translocation) can drive oncogenesis.
    • Myc is implicated in a multitude of cancers.

    MAP Kinase Pathway Components and Cancer

    • Mutated components of the MAP kinase pathway can contribute to cancer, including ERBB2/HER2, RAF, and NF-1.

    Targeted Therapies for Oncogenes

    • Therapy targeting the activity of RAS and MYC is a primary focus. Often involves small molecule inhibitors to limit activity.

    Tumor Suppressors (Lecture 3)

    • LOH (Loss of Heterozygosity): Loss of one copy of a tumor suppressor gene.
    • Two-Hit Hypothesis: Usually requires the inactivation of both alleles of a tumor suppressor gene to develop a tumor. This highlights the importance of both genes.

    RB Protein and its Function

    • RB plays a crucial role in regulating the cell cycle by controlling the restriction point, and is often inactivated in cancer.
    • RB normally prevents cells from passing to the next phase and becoming cancerous, blocking E2F gene transcription.

    P53 Protein and its Function

    • P53 is a key tumor suppressor, acting as a "guardian angel" by inducing cell cycle arrest or apoptosis in response to stress, like DNA damage.
    • It's frequently inactivated or mutated in cancer, allowing unchecked cell growth.

    P53 Activation and Regulation

    • P53 levels are normally kept low through quick degradation.
    • Stress leads to accumulation of p53 for proper cellular response.
    • MDM2 is an oncoprotein that interacts with and regulates p53 levels.

    Cancer Stem Cells (Lecture 4)

    • Stem cells are characterized by self-renewal and the ability to differentiate into various cell types.
    • Cancer stem cells are a subset of abnormal cells within a tumor that can proliferate and maintain the cancer.

    Distinguishing Cancer Stem Cells

    • Cancer stem cells often possess distinct surface markers (e.g., CD44, CD24) compared to typical cancer cells using FACS to distinguish.
    • Cancer stem cells are more resistant to traditional cancer therapies and often drive tumor recurrence.

    Apoptosis and Cancer (Lecture 5)

    • Apoptosis: Programmed cell death.
    • Necrosis: Uncontrolled cell death.

    Pathways of Apoptosis

    • Intrinsic (Mitochondrial) Pathway: Activated by cellular stress, involving Bcl-2 family proteins (Bax, Bak, Bcl-2) that regulate mitochondrial membrane integrity.
    • Extrinsic (Death Receptor) Pathway: Activated by external signals (ligands binding specific receptors). The receptor pathway relays information to activate the caspase proteins involved in apoptosis.

    Warburg Effect

    • Cancer cells have increased glucose uptake and metabolic activity, driving glycolysis instead of oxidative phosphorylation in situations of abundant glucose.

    p53's Role in Apoptosis vs. Arrest

    • p53 can induce apoptosis when stress is severe, or cell cycle arrest in those situations of milder stress. Which pathway p53 activates depends on the level of stress faced by the cell.

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    Description

    This quiz covers the fundamentals of cancer biology, including its definitions, types, and key terms related to cancer progression. Understand the differences between invasiveness and metastasis, as well as various terminologies such as hyperplasia and dysplasia. Test your knowledge on how cancer affects multicellular organisms.

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