Physical Carcinogens and Proto-oncogenes Quiz

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Questions and Answers

What is the term used to describe the ability to notice distinct characteristics of cancer cells from other surrounding tissues?

  • Malignancy
  • Differentiation (correct)
  • Metastasis
  • Benignity

Which type of cancer originates from melanocytes?

  • Leukemia
  • Sarcoma
  • Melanoma (correct)
  • Lymphoma

What occurs when a damaged DNA cannot be repaired in normal cells exposed to mutagens?

  • Benign transformation
  • Inhibition of Apoptosis
  • Mutation (correct)
  • Activation of Tumor Suppressor Genes

Which class of substances are alkylating agents and aromatic hydrocarbons examples of?

<p>Mutagens (A)</p> Signup and view all the answers

What is the main consequence of the inhibition of apoptosis in carcinoma cells?

<p>Cells divide uncontrollably (D)</p> Signup and view all the answers

In carcinogenesis, what do mutagens lead to after damaging the DNA in normal cells?

<p>Activation of Oncogenes (D)</p> Signup and view all the answers

What is a characteristic of an ideal tumor marker?

<p>High sensitivity (C)</p> Signup and view all the answers

Which of the following is NOT a way to promote apoptosis in cancer cells?

<p>Increasing DNA repair mechanisms (A)</p> Signup and view all the answers

Which genetic mutation can lead to uncontrolled cell division?

<p>Insertion of promoter (A)</p> Signup and view all the answers

Which chemical compound is known to cause Hepatic Carcinoma?

<p>Aflatoxin B1 (A)</p> Signup and view all the answers

Which virus is associated with causing Kaposi’s sarcoma?

<p>Epstein-Barr Virus (EBV) (A)</p> Signup and view all the answers

How do ideal tumor markers respond to treatment?

<p>Decreased levels (B)</p> Signup and view all the answers

Which type of genes are responsible for slowing down cell division, repairing DNA mutations, and promoting apoptosis?

<p>Tumor suppressor genes (A)</p> Signup and view all the answers

What is the primary function of tumor suppressor genes when they are not mutated?

<p>Inhibit cell division (A)</p> Signup and view all the answers

Which type of mutation results in a loss or reduction in the function of tumor suppressor genes?

<p>Point mutation (A)</p> Signup and view all the answers

What is the role of proto-oncogenes in normal cells?

<p>Promote cell division (C)</p> Signup and view all the answers

What type of gene conversion can result in proto-oncogenes becoming oncogenes?

<p>Point mutation (B)</p> Signup and view all the answers

Which characteristic is NOT commonly associated with an ideal tumor marker?

<p>Relatively long half-life (C)</p> Signup and view all the answers

What is a key feature of tumor markers that are produced by the body in response to tumor cells?

<p>Presence in plasma and body fluids (C)</p> Signup and view all the answers

What is the primary purpose of utilizing tumor markers in cancer diagnosis?

<p>To support diagnosis as a laboratory test (A)</p> Signup and view all the answers

What does the inhibition of tumor suppressor genes primarily result in?

<p>Promotion of cell division (D)</p> Signup and view all the answers

What is the consequence of mutations in proto-oncogenes that convert them into oncogenes?

<p>Growth and division of cells (D)</p> Signup and view all the answers

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Study Notes

Physical Carcinogens

  • X-ray, Gamma ray, and UV ray can cause:
    • Formation of pyrimidine dimers
    • Apurinic sites with consequent break in DNA
    • Formation of free radicals and superoxides leading to DNA break and somatic mutations
    • Increase risk of leukemia in childhood if exposed during fetal life

Proto-Oncogenes and Oncogenes

  • Proto-oncogenes are responsible for the synthesis of:
    • Growth factors
    • Transcription factors
    • Receptor factors
    • Proteins for gene expression
  • Proto-oncogenes can be converted to oncogenes through:
    • Point mutation
    • Chromosomal translocation
    • Gene amplification
  • Examples of oncogenes:
    • jun (Transcription Factor)
    • fos (Transcription Factor)
    • myc (DNA Binding Protein)
    • ras (GTPase)
    • rat (Protein Kinase)
    • abl (Tyrosine Kinase)
    • sis (Platelet-Derived Growth Factor)

Tumor Suppressor Genes (Anti-Oncogenes/Recessive Oncogenes)

  • Normal genes that:
    • Slow down cell division
    • Repair DNA mutations
    • Responsible for apoptosis
  • Mutation can result in loss or reduction of function, allowing cells to grow abnormally and cause cancer
  • Examples of tumor suppressor genes:
    • RB1 (Retinoblastoma Gene 1)
    • P53 (Phosphoprotein)
    • WT (Wilm's Tumor)
    • FAP (Familial Adenomatous Polyposis)
    • BRCA (Breast cancer gene)

Tumor Markers

  • Biochemical indicators of the presence of a tumor
  • Produced by tumor cells (tumor-derived) or by the body in response to tumor cells (tumor-associated)
  • Detected in plasma and body fluids such as urine, CSF, and pleural fluid
  • Characteristics of an ideal tumor marker:
    • Specific production in premalignant or malignant tissue
    • Early in the progression of disease
    • Sensitive and produced at detectable levels in all patients with a specific malignancy
    • Expression in an organ site-specific manner
    • Evidence of presence in bodily fluids obtained non-invasively
    • Levels related quantitatively to tumor volume, biological behavior, and disease progression
    • Relatively short half-life, reflecting temporal changes in tumor burden and response to therapy

Cancer

  • Types of cancer classified by origin:
    • Epithelial (Carcinoma)
    • Blood cells (Leukemia)
    • Lymphatics (Lymphoma)
    • Connective Tissue (Sarcoma)
    • Melanocyte (Melanoma)

Carcinogenesis

  • Normal cells exposed to chemicals, viruses, or radiation can damage DNA
  • Damaged DNA can be repaired, but failure to repair leads to mutation
  • Mutation can lead to:
    • Activation of oncogenes
    • Inhibition of tumor suppressor genes
    • Inhibition of apoptosis

Etiology (Mutagens)

  • Substances that increase the rate of mutation, enhancing the incidence of cancer
  • Examples of mutagens:
    • Chemicals:
      • Alkylating Agents
      • Aromatic Hydrocarbons
      • Aromatic Amines
      • Nitroso Compounds
    • Viruses:
      • HPV (human papillomavirus)
      • HSV (herpes simplex virus)
      • HBV (hepatitis B virus)
      • HCV (hepatitis C virus)
      • HIV (human immunodeficiency virus)
      • HTLV (human T-lymphotropic virus type 1)
      • EBV (Epstein-Barr Virus)

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