Lecture24: Cancer I

Question 1

What is the deadliest form of cancer

Answer 1

Lung cancer

Question 2

What is Cancer

Answer 2

A disease in which an individual mutant clone of cells begin by prospering at the expense of its neighbor cells

Question 3

Properties of cancer cells

Answer 3

• Cells growing out of control
• Become self-sustaining
  
  • do not need signals ot grow
• Release autocrine growth factor signals
• These cells should stop growing with anti-growth signals- but cancer cells ignore them
• Cancer cells ignore apoptosis signals

Question 4

Normal vs. Cancer cells

Answer 4

• Cancer cells require little growth factors
• Normal cells have strong requirement
• Cancer cells become independent of stimulation that is normally required by cells to proliferate
• Cancer cells have decontrolled proliferation

Question 5

What are the two heritable properties of cancer

Answer 5

• Reproduce in defiance of normal restraints on cell division and cell growth
• Invade areas normally reserved for other cells

Question 6

a tumor is considered cancer if it is

Answer 6

malignant (ability to invade surrounding tissues)

Question 7

An abnormal cell that grows (increases in mass) and proliferates (divides) out of control will give rise to a

Answer 7

tumor or neoplastic growth

Question 8

Classification of cancers

Answer 8

• Carcinomas:
  
  • From epithelial cells (most common)
• Sarcomas:
  
  • From Connective tissue and muscle tissue
• Leukemias and Lymphomas:
  
  • From white blood cells and their precursors

Question 9

Adenoma

Answer 9

• Adenoma
  
  • benign epithelial tumor with glandular organization
  • (note a malignant tumor of the same type is adenocarcinoma)

Question 10

Basal cell carcinoma

Answer 10

Cancer of keratinocyte stem cell in skin

Question 11

Melanoma

Answer 11

cancer of pigment cells in skin

Question 12

What is more likely to metastasize Basal-cell carcinoma or malignant melonomas

Answer 12

Basal-cell carcinomas rarely metastasize whereas malignant melonomas metastasize widely

Question 13

What is Metastases

Answer 13

• Invasiveness is property of cancer
• Cancer cells can break loose, enter into blood or lymph, travel to new areas and form secondary tumors

Question 14

Development of Colon Cancer

Answer 14

• Mutation in APC gene (tumor suppressor)
• Cells with APC mutation gain an advantage in growth
• Form polyps
  
  • at this stage the tumor is a benign tumor
• mutation in Ras- becomes a cancer gene
• lose p53 (a tumor suppressor )
• Tumor moves out into blood stream
• Gains capacity to invade
  
  • is now a malignant tumor

Question 15

Do cancer arise form a single heritable cell

Answer 15

• Yes
  
  • (evidence of this is found in the philadelphia chromosome)

Question 16

Philadelphia chromosome

Answer 16

• Translocation between chromosome 9 + 22
• Responsible for chronic myelogenous leukemia

Question 17

What are two types of carcinogens

Answer 17

• Chemical carcinogens
• Radiation (x-rays, UV)

Question 18

What is the best weapon against cancer

Answer 18

early detection

Question 19

What is angiogenesis

Answer 19

Formation of new blood vessels from pre-existing blood vessels

Question 20

What is neovascularization

Answer 20

Formation of new blood vessels basically from scratch

Question 21

High fat/low fiber accounts for ___ % of bowel, pancreas, prostate and breast cancer

Answer 21

37%

Question 22

HIV causes ____ sarcoma

Answer 22

Kaposi’s sarcoma

Question 23

Genes whose alteration frequently results in cancer

Answer 23

Cancer critical genes

Question 24

What are the two broad types of mutations in cancer

Answer 24

• Overactivity mutations
  
  • Gain of function
  • oncogenes
    
    • ​involves single mutaiton event and activation of gene causing proliferation (dominant)
• Underactivity mutations
  
  • loss of function
  • Tumor suppressor genes
    
    • ​involve genes that inhibit growth

Question 25

Genetic causes of cancer

Answer 25

• Mutations of genes that regulate cell proliferation
  
  • overactivity/ gain of function mutation
    
    • Oncogenes
  • Underactivity/loss of function mutation
    
    • Tumor suppressor genes
• Mutation event:
  
  • one gene= no effect
  • second mutaiton causes problems (thus is recessive)

Question 26

What is the third group of genes responsible for cancer

Answer 26

• DNA maintenance genes
  
  • subset of tumor suppressor genes
  • Mutations involve inactivation of caretaker genes that create genomic stability
  • include DNA repair genes, checkpoint genes

Question 27

What is the first human oncogene

Answer 27

Ras

Question 28

What is Ras

Answer 28

• Ras is monomeric GTPase for signal transduction

Question 29

Ras oncogenes

Answer 29

cannot shut off by hydrolyzing GTP to GDP (this is similar to cholera)

Question 30

Activation of proto-oncogenes

Answer 30

• Proto-oncogenes, when activated or overexpressed, can become oncogenes to drive cell proliferation

Question 31

Bcl2 oncogenes

Answer 31

• Bcl2 (promotes survival despite DNA damage)
• overproduction allows cancerous cells to survive and grow
• In cancer cells Bcl2 locus on Chr 18 undergoes a reciprocal translocation with part of Chr 14 gene
  
  • example of rearrangement mutation

Question 32

Question 33

Answer 33

Question 34

Answer 34

Question 35

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Question 37

Question 38