cancer week 2
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Questions and Answers

What is the primary function of tumor suppressor genes?

  • To enhance cell migration and invasion
  • To promote cell proliferation and growth
  • To induce apoptosis in abnormal cells
  • To inhibit cell growth and division (correct)

    • DNA repair mechanisms are only important for cancer cells.

    False

    Oncogenes are genes that normally inhibit cell growth and division.

    False

    Match the following tumor suppressor genes with their associated types of cancer:

    <p>TP53 = Various types of cancer BRCA1 and BRCA2 = Breast and ovarian cancer PTEN = Breast, prostate, and brain cancer</p> Signup and view all the answers

    What is the result of the accumulation of mutations in a cell?

    <p>Cancer development</p> Signup and view all the answers

    What is the role of oncogenes in normal cell growth and development?

    <p>To promote cell growth and division</p> Signup and view all the answers

    What is the result of genetic instability in cancer cells?

    <p>The accumulation of additional mutations and the development of more aggressive cancer cells</p> Signup and view all the answers

    Cancer stem cells are thought to be responsible for the initiation and maintenance of tumors.

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

    Tumor suppressor genes are normally involved in promoting cell growth and division.

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

    Explain the difference btw a proto-oncogene and an oncogene

    <p>An oncogene is a mutated gene that has the potential to cause cancer. Before an oncogene becomes mutated, it is called a proto-oncogene, and it plays a role in regulating normal cell division. Cancer can arise when a proto-oncogene is mutated, changing it into an oncogene and causing the cell to divide and multiply uncontrollably.</p> Signup and view all the answers

    Why is DNA important for cells?

    <p>It contains code for building specific proteins that control how cells function</p> Signup and view all the answers

    What 3 instructions does DNA provide for cells in terms of their function?

    <p>How often cells grow, divide, and how long they live for</p> Signup and view all the answers

    What are all cancers associated with?

    <p>Altered genetic expression</p> Signup and view all the answers

    What happens within a cell that can initiate cancer

    <p>1 or more genes in a cell mutates</p> Signup and view all the answers

    How do mutated genes affecting proteins contribute to cancer?

    <p>Abnormal proteins in cells provide different instructions for cell regulation and control, which may permit cells to multiply uncontrollably and become cancerous</p> Signup and view all the answers

    What is the primary purpose of normal cell division?

    <p>Both A and B</p> Signup and view all the answers

    What are the three stages of interphase?

    <p>Gap 1 (G1), Synthesis (S), and Gap 2 (G2)</p> Signup and view all the answers

    What is the result of mitosis?

    <p>Two daughter cells with the same number of chromosomes</p> Signup and view all the answers

    What is the purpose of checkpoints in mitosis?

    <p>To ensure that each phase is completed correctly before moving on to the next one</p> Signup and view all the answers

    What is the primary function of cell division checkpoints?

    <p>To ensure the cell cycle progresses correctly and maintain genomic integrity</p> Signup and view all the answers

    Match the following cell division checkpoints with their primary functions:

    <p>G1 Checkpoint = Checks for DNA damage and availability of resources to support division G2 Checkpoint = looks for errors during DNA replication M checkpoint = looks to ensure all sister chromosomes are attached to miotic spindles, or are in a good position, to be duplicated Post-Mitotic Checkpoint = Checks for presence of DNA damage or mutations, and abnormalities in chromosome number or structure.</p> Signup and view all the answers

    Match the cell cycle stage to its function

    <p>G1 = (1) DNA synthesis ceases (2) RNA, protein synthesis, and cell growth occur S-phase = DNA synthesis occurs. Gives rise to 2 separate sets of chromosomes G2 = Is the pre-miotic phase where DNA synthesis ceases and RNA &amp; protein synthesis continues M-phase = the phase of cellular division or mitosis</p> Signup and view all the answers

    When a checkpoint fails, what 4 things may occur?

    <p>(1) this mistake is quickly fixed (2) a cell mutation occurs resulting in the production of an abnormal protein or enzyme. (3) A cell mutation occurs near or around the proto-oncogene turning on cell division when not required (4) cell mutation occurs near or around tumor suppressor gene resulting in an inability to stop uncontrolled cell division</p> Signup and view all the answers

    Purpose of p53 gene and implications of its mutations

    <p>Is a tumor suppressor gene. Mutations in p53 renders cells unable to induce apoptotic machinery in response to detecting other genetic mutations. This increase survival of cancer cells.</p> Signup and view all the answers

    Purpose of RB1 gene and implications of mutations

    <p>makes RB protein that works to prevent cells dividing too fast or uncontrollably. If theres a mutation in this gene, theres a greater chance that cells themselves will start dividing more rapidly and uncontrollably</p> Signup and view all the answers

    Name the 3 main categories of genes that contribute to cancer development

    <p>(1) Tumor suppressor genes (2)Proto-oncogenes (3) DNA repair genes</p> Signup and view all the answers

    Match the gene to its function

    <h1>Tumor supressor gene = work to slow down cell proliferation, repair DNA mutations or signal apoptosis Proto-oncogene = responsible for stimulating healthy growth and division of cells and halting cell death DNA repair gene = work to correct errors in DNA replication (most function as tumor suppressor genes)</h1> Signup and view all the answers

    Name the 4 factors that contribute to cell mutations

    <p>Heredity, age, mutagens (chemicals, radiation, virsues), and carcingoens (tobacco smoke, alcohol)</p> Signup and view all the answers

    What are clinical manifestations?

    <p>Are the direct effects of a disease on the body (how the disease makes you feel). Independent from side effects associated with treatment or intervention</p> Signup and view all the answers

    Define what a local effect is

    <p>effects the primary tumor on surrounding local cells, tissues, and structures</p> Signup and view all the answers

    Define what a systemic effect is

    <p>effects not directly related to the primary location of a tumor or its metasteses</p> Signup and view all the answers

    Name a few clinical manifestations of cancer

    <p>(1) pain: pressure on nearby nerves (2) fever (3) fatigue (4)immunosupression (5)bone marrow suppression (6)cancer cachexia</p> Signup and view all the answers

    What are the 2 ways in which cancer is staged?

    <ol> <li>TNM system 2. A numbered system</li> </ol> Signup and view all the answers

    Explain the TNM system

    <p>Is a method of staging cancer in which it is given a number 0-4 based on tumor size, 0-2 for node involvement, and 0,1,or X for metastatic spread</p> Signup and view all the answers

    Explain the numbered cancer staging system

    <p>Stage 0= ‘in-situ’ cancer meaning the cells are still in place where they started. Stage 1= small spread into nearby tissues. No spread to lymph nodes or other body areas. Stage 2&amp;3= means it is larger or has spread into nearby tissues or lymph nodes. Stage 4= cancer has spread to other areas of the body (metastatic cancer)</p> Signup and view all the answers

    Study Notes

    Tumor Suppressor Genes

    • Definition: Genes that normally inhibit cell growth and division, preventing tumor formation
    • Function:
      • Regulate cell cycle progression
      • Induce apoptosis (programmed cell death) in abnormal cells
      • Repair DNA damage
    • Examples:
      • TP53 (most frequently mutated tumor suppressor gene in human cancer)
      • BRCA1 and BRCA2 (associated with breast and ovarian cancer)
      • PTEN (associated with various types of cancer, including breast, prostate, and brain cancer)
    • Inactivation of tumor suppressor genes can lead to uncontrolled cell growth and tumor formation

    DNA Repair Mechanisms

    • Importance: Maintenance of genome stability and prevention of mutations
    • Types of DNA damage:
      • Single-strand breaks
      • Double-strand breaks
      • Oxidative damage
      • Alkylation
    • Repair mechanisms:
      • Nucleotide excision repair (NER)
      • Base excision repair (BER)
      • Mismatch repair (MMR)
      • Homologous recombination (HR)
      • Non-homologous end joining (NHEJ)
    • Defects in DNA repair mechanisms can increase the risk of cancer

    Cell Signaling Pathways

    • Definition: Complex networks of molecular interactions that regulate cellular processes
    • Key pathways involved in cancer:
      • PI3K/AKT pathway (cell survival and growth)
      • RAS/MAPK pathway (cell proliferation and differentiation)
      • JAK/STAT pathway (cell growth and differentiation)
      • WNT/β-catenin pathway (cell proliferation and differentiation)
    • Deregulation of cell signaling pathways can lead to uncontrolled cell growth and tumor formation

    Cellular Mutations

    • Definition: Changes in DNA sequence that can affect gene function
    • Types of mutations:
      • Point mutations (single nucleotide changes)
      • Frameshift mutations (insertions or deletions leading to altered reading frame)
      • Chromosomal mutations (changes in chromosome number or structure)
    • Consequences of mutations:
      • Activating mutations (gain of function)
      • Inactivating mutations (loss of function)
      • Dominant-negative mutations (interference with normal gene function)
    • Accumulation of mutations can lead to cancer development

    Oncogenes

    • Definition: Genes that have the potential to cause cancer when mutated or overexpressed
    • Function:
      • Promote cell proliferation and growth
      • Inhibit apoptosis
      • Enhance cell migration and invasion
    • Examples:
      • RAS oncogenes (associated with various types of cancer)
      • MYC oncogene (associated with Burkitt lymphoma and other cancers)
      • HER2 oncogene (associated with breast cancer)
    • Activation of oncogenes can lead to uncontrolled cell growth and tumor formation

    Tumor Suppressor Genes

    • Tumor suppressor genes regulate cell growth and division, preventing tumor formation
    • They regulate cell cycle progression, inducing apoptosis in abnormal cells and repairing DNA damage
    • Examples of tumor suppressor genes include TP53, BRCA1, BRCA2, and PTEN
    • Inactivation of tumor suppressor genes can lead to uncontrolled cell growth and tumor formation

    DNA Repair Mechanisms

    • DNA repair mechanisms maintain genome stability and prevent mutations
    • Types of DNA damage include single-strand breaks, double-strand breaks, oxidative damage, and alkylation
    • Repair mechanisms include nucleotide excision repair, base excision repair, mismatch repair, homologous recombination, and non-homologous end joining
    • Defects in DNA repair mechanisms increase the risk of cancer

    Cell Signaling Pathways

    • Cell signaling pathways are complex networks of molecular interactions regulating cellular processes
    • Key pathways involved in cancer include PI3K/AKT, RAS/MAPK, JAK/STAT, and WNT/β-catenin
    • Deregulation of cell signaling pathways leads to uncontrolled cell growth and tumor formation

    Cellular Mutations

    • Cellular mutations are changes in DNA sequence affecting gene function
    • Types of mutations include point mutations, frameshift mutations, and chromosomal mutations
    • Consequences of mutations include activating mutations, inactivating mutations, and dominant-negative mutations
    • Accumulation of mutations leads to cancer development

    Oncogenes

    • Oncogenes are genes that can cause cancer when mutated or overexpressed
    • Oncogenes promote cell proliferation and growth, inhibit apoptosis, and enhance cell migration and invasion
    • Examples of oncogenes include RAS, MYC, and HER2
    • Activation of oncogenes leads to uncontrolled cell growth and tumor formation

    Genetic Mechanisms of Cancer

    Oncogenes

    • Promote cell growth and division
    • Normally involved in cell growth and development
    • Can become mutated or overexpressed, contributing to cancer
    • Examples: HER2, RAS, MYC

    Tumor Suppressor Genes

    • Inhibit cell growth and division, acting as a "brake" to prevent uncontrolled cell growth
    • Normally prevent cancer
    • When mutated or deleted, can contribute to cancer
    • Examples: TP53, BRCA1, BRCA2

    DNA Damage and Repair

    • DNA damage occurs through environmental factors (e.g. UV radiation, carcinogens) or errors during DNA replication
    • Cells have mechanisms to repair DNA damage
    • Failure to repair DNA damage leads to mutations and contributes to cancer
    • Types of DNA damage: point mutations, insertions, deletions, chromosomal translocations

    Epigenetic Modifications

    • Chemical changes to DNA or histone proteins that affect gene expression
    • Can be inherited or acquired through environmental factors
    • Examples: DNA methylation, histone acetylation, microRNA regulation
    • Can contribute to cancer by silencing tumor suppressor genes or activating oncogenes

    Genetic Instability

    • Increased rate of mutations and genetic changes in cancer cells
    • Leads to accumulation of additional mutations and development of more aggressive cancer cells
    • Caused by defects in DNA repair mechanisms, telomere shortening, or other factors

    Tumor Development

    • Multistep process involving accumulation of genetic and epigenetic changes
    • Involves activation of oncogenes and inactivation of tumor suppressor genes
    • Influenced by environmental factors, such as carcinogens and hormones

    Cancer Stem Cells

    • Subpopulation of cancer cells with stem cell-like properties
    • Thought to initiate and maintain tumors
    • Can be resistant to chemotherapy and radiation, leading to relapse

    Normal Cell Division

    Overview

    • Normal cell division, also known as mitosis, is crucial for growth, development, and tissue repair in multicellular organisms.
    • It involves the process of a eukaryotic cell dividing into two daughter cells.

    Phases of Mitosis

    • Interphase involves cell growth, DNA replication, and preparation for cell division, consisting of three stages: Gap 1 (G1), Synthesis (S), and Gap 2 (G2).
    • Prophase involves chromatin condensation, breakdown of the nuclear envelope, and formation of the mitotic spindle.
    • Metaphase involves chromosomes lining up at the center of the cell, attached to the spindle fibers.
    • Anaphase involves sister chromatids separating and moving to opposite poles of the cell.
    • Telophase involves the nuclear envelope reforming around each set of chromosomes, and chromatin decondensing.
    • Cytokinesis involves the cytoplasm dividing, and the cell splitting into two daughter cells.

    Key Features

    • Each daughter cell receives a complete set of chromosomes identical to the parent cell.
    • Mitosis maintains the same number of chromosomes in the daughter cells as in the parent cell.
    • It occurs in somatic cells, not in gametes (eggs and sperm).

    Regulation of Mitosis

    • Checkpoints regulate the progression of mitosis to ensure each phase is completed correctly before moving on to the next one.
    • Cyclin-dependent kinases (CDKs) and cyclins regulate the progression of the cell cycle.

    Cell Division Checkpoints

    • Cell division checkpoints are regulatory mechanisms that ensure the cell cycle progresses correctly, preventing errors and maintaining genomic integrity.

    G1 Checkpoint

    • Also known as the restriction point, occurs in the G1 phase, after cell growth and before DNA replication.
    • Checks for DNA damage, cell size and growth, and availability of nutrients and growth factors.
    • Halts cell cycle if issues are detected, and cell undergoes repair or apoptosis (programmed cell death).

    G2 Checkpoint

    • Occurs in the G2 phase, after DNA replication and before mitosis.
    • Checks for completeness and accuracy of DNA replication, presence of DNA damage, and proper chromosome condensation and spindle formation.
    • Halts cell cycle if issues are detected, and cell undergoes repair or apoptosis.

    Spindle Checkpoint (Metaphase-Anaphase Transition)

    • Occurs in the metaphase phase, before anaphase.
    • Checks for proper attachment of chromosomes to spindle fibers and alignment of chromosomes at the metaphase plate.
    • Halts cell cycle if issues are detected, and cell undergoes apoptosis.

    Post-Mitotic Checkpoint (Apoptosis)

    • Occurs after mitosis, in the G1 phase of the next cell cycle.
    • Checks for presence of DNA damage or mutations, and abnormalities in chromosome number or structure.
    • If issues are detected, cell undergoes apoptosis.

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