Neoplasia: Additional Concepts and Review

Question 1

LIST THE PHENOTYPIC HALLMARKS OF CANCER.

Answer 1

• Dysregulation of cell proliferation by constitutive activation of growth-stimulatory 
pathways
• Insensitivity to growth inhibitory signals
• Evasion of apoptosis
• Limitless replicative potential
• Angiogenesis
• Invasion & metastasis
• Cellular energetic (Warburg Effect)

Question 2

LIST THREE STEPS IN THE MULTISTAGE CONCEPT OF CANCER.

Answer 2

• Initiation
• Promotion: Dependent on normal pathways
• Progression: Additional changes

Question 3

IDENTIFY INFLAMMATORY DISEASES INVOLVED IN CARCINOGENESIS.

Answer 3

• Generation of oxygenic species
• Cell turnover
• Diseases
  o Ulcerative colitis
  o Chronic pancreatic
  o H. pylori & peptic  ulcers

Question 4

DESCRIBE THE RELATIONSHIP BETWEEN HPV AND CERVICAL CANCER, AND THE RELATIONSHIP BETWEEN HCV AND HEPATOCELLULAR CARCINOMA.

Answer 4

• HPV
o DNA virus
o Types 16 and 18 found in 85% of invasive squamous cell carcinomas of the cervix
o Mechanism
- E7 (HPV) binds to Rb
- E6 (HPV) binds to p53
- Complexes are rapidly degraded so lose DNA error recognition

• HCV

o RNA virus
o Unknown mechanism related to inflammation and repair or
o Viral genome produce inactive tumor suppressor genes in the host

Question 5

STATE THE EVIDENCE THAT THE IMMUNE SYSTEM IS IMPORTANT FOR PREVENTING TUMOR DEVELOPMENT.

Answer 5

• Increased risk of cancer in immunosuppressed transplants

* Increased risk of cancer in older patients, have less active immune system

Question 6

LIST THE IMMUNE CELLS THAT CAN RECOGNIZE CANCER CELLS, AND DESCRIBE THE MECHANISMS OF TUMOR RECOGNITION USED BY EACH ONE.

Answer 6

• B cells
o Produce Abs
• NK cells
o Have receptors that recognize Fc region od Abs bound to the tumor cells
o Absence of MHC class I
• T cells
o Recognize tumor peptides expressed on MHC I

Question 7

LIST THE TYPES OF TUMOR ANTIGENS THAT CAN BE RECOGNIZED BY THE IMMUNE SYSTEM.

Answer 7

• Viral antigen (HTLV, EBV, HPV and HBV)
• Fetal antigens
• Specific mutated proteins that can be expressed on MHC I
• Normal antigens

Question 8

DESCRIBE MECHANISMS BY WHICH THE TUMOR CAN AVOID IMMUNE ATTACK.

Answer 8

• Passive Immune Evasion
o Antigen loss
• Active Immune Suppression
o Cause induction of regulatory T cells
-TGF-beta
-IDO (locally depleted arginine which is need for T cells)
-Myeloid Derived Cells are abundant in tumor cells (recruited by tumor) = immune suppression
-Cells also involved