LECTURE 2 + 3: Experimental Approaches to Cancer Flashcards

(69 cards)

1
Q

slides i haven’t finished

A

3.7, 3.30, 4.5

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2
Q

Hallmarks of cancer importance

A

cancer isn’t a single disease
collection of diseases w similar characteristics
unification factors
enable therapeutic treatment

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3
Q

Tumours by tissue of origin:
blood cells (B, T, myeloid…)

A

hematopoietic

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4
Q

Tumours by tissue of origin:
epithelial cells (lung, breast…)

A

carcinoma

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5
Q

Tumours by tissue of origin:
connective tissues (muscle, bone…)

A

sarcoma

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6
Q

Tumours by tissue of origin:
nervous system (glio-, retino-blastomas…)

A

Neuroectodermal

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7
Q

Tumours by tissue of origin:
small cell lung cancer, melanoma

A

Non-neuroectodermal

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8
Q

Cancer tumors are divided into ____ and ______ tumors

A

liquid, solid

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9
Q

Totally liquid tumors

A

Leukemia

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10
Q

What is leukemia?

A

excessive proliferation of circulating cells
usually white blood cells (leukocytes)
totally liquid

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11
Q

Semi-solid/liquid tumors

A

Lymphoma

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12
Q

What is lymphoma?

A

elevated numbers of lymphocytes in the peripheral blood
also present as solid masses in lymph
nodes (often multi-focal)

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13
Q

Solid tumors

A

Lumps - localized cell proliferation
Found/associated with a multicellular organ
Spread around the body by metastasis

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14
Q

Why are leukemias and solid tumours treated differently?

A

Leukemias can’t be surgically removed
Etiology of the cancers is different

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15
Q

Most prevalent & deadly cancer

A

carcinomas (cancers of the epithelium)

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16
Q

Leading sites of new cancer and deaths (male)

A

Prostate, lung & bronchus, urinary bladder, colon & rectum, pancreas (deaths)

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17
Q

Leading sites of new cancer and deaths (female)

A

breast, lung & bronchus, uterine corpus, colon & rectum, pancreas (deaths)

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18
Q

basement membrane

A

cell-free matrix between epithelial cells and connective tissue

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19
Q

malignant cancer

A

disruption of the basement membrane

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20
Q

degrees of malignancy

A

normal -> hyperplasia -> dysplasia -> cancer
cancer only when it breaks past the basement membrane

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21
Q

malignant growth

A
  • break past the basement membrane
  • invade adjacent tissue
  • enter blood and lymph
  • metastasis
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22
Q

Approaches to Studying Cancer

A

Observational (Human/Patient)
- epidemiological
- genomic
- clinical

Experimental (hypothesis driven)
- carcinogens
- tissue culture assays
- mouse cancer models

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23
Q

Approaches to Studying Cancer: Epidemiology

what are the different ways we study it?

A
  1. Age incidence curves
  2. Cancer risk factors
  3. Incidence in different populations
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24
Q

Approaches to Studying Cancer: Epidemiology - Age incidence curves

what do you learn from the curves?

A
  • cancer risk increases with age (curve steeper with age)
  • cancer results from multiple events that accumulate over your life (at least 5-6 independent random events)
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25
Why is cancer not subject to forces of evolutionary selection?
Post-reproductive age disease
26
Approaches to Studying Cancer: Epidemiology - Risk Factors what are the top risk factors?
Tobacco use >>>obesity>>pathogens >>>> physical inactivity, diet > alcohol > reproductive factors > UV light > environmental pollutants
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Cigarettes and lung cancer
- lots of smoking after WW1, WW2 - 30-35 year lag - lung cancer rates peak in 1990 in the US
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Approaches to Studying Cancer: Incidence in different populations genetic vs environmental factors
environmental factors outweigh genetic factors for most cancers eg. incidence of prostate (10x) , breast (10x) and stomach (5x) in Hawaiian-Japanese immigrants adopt rates of Hawaiians, not Japanese
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Approaches to Studying Cancer: Genomic Studies what is the goal of the genomic studies
survey the entire genome for transcriptional changes and changes at the DNA level (point mutations, insertions, deletions)
30
no of base pairs in human genome
3 billion
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cancer genome sequencing allows us to identify
MIRA mutations insertions/deletions rearrangements amplifications
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next gen sequencing technology
explain what it is
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challenges of genomic studies
tumor heterogeneity 1. mixture of cell types (immune cells, fibroblasts, endothelial cells, neoplastic cells) 2. diversity of neoplastic cells (clones)
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solution to tumor heterogeneity
single cell analysis
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Approaches to Studying Cancer: Clinical Studies phases
Phase 1: SAFETY - small groups, 50 - how the agent affects the body - safe dosage Phase 2: EFFECTIVENESS - medium group, 200 - is the agent effective against the disease Phase 3: BETTER THAN STANDARD - large group, 2000 - randomized trial
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Pharmacokinetics (PK)
Time course of *drug concentration* in body, usually monitored in blood
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Pharmacodynamics (PD)
Time course of activity of drug in *target tissue*, e.g. cancer
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Therapeutic Index
Dose range of drug that is therapeutically active against cancer without being highly toxic
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Biomarkers
Molecules, cells, phenotypes that are identified as predictive of responsiveness to drug
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Carcinogen
Agents that contribute to tumor formation
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Cancers associated with occupation
1. Radium girls - radium in watches increased risk of multiple cancers 2. Chimney sweeps increased risk of skin cancers of scrotum 3. Silver ore miners increased risk of lung cancer 4. Tobacco snuff users increased risk of nasal cancer 5. X-ray technicians increased risk of cancers 6. Shipbuilders exposed to asbestos increased risk of mesothelioma 7. Smokers increased risk of lung cancer
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Yamagiwa and Ichikawa (1915)
First successful induction of cancer by a specific agent Induced cancer in the skin of rabbit ears by painting them with coal tar repeatedly for hundreds of days
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Ames Test: Goal/ Accomplishments
Approach: compare carcinogenicity to mutagenicity in bacteria Confirmed carcinogens are mutagens (altered DNA, genetic alteration)!!
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Ames Test: Procedure
- Suspected carcinogen + homogenized rat liver - *metabolic* activation by rat liver enzymes - add to Salmonella with mutation that prevents synthesis of histidine - mutagens revert defective gene, so bacterial colonies grow
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Approaches to Studying Cancer: Experimental - 2D cell cultures title card no question
title card no question
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Hayflick Limit
max 60 doublings of *normal* cells in cell culture, they always hit senescence due to telemore shortening
47
normall cells in tissue culture
Finite lifespan (extra serum and media = extended survival, but they eventually die) always reach senescence
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HeLa cells
First immortal human-cell line (cervical cancer)
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Cell culture consists of __, __ , ___
cells, medium, substrate
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Cell Culture: Cells
1. Fibroblasts (cells generally of mesenchymal origin that make extracellular matrix) 2. Epithelial cells are harder to grow
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Cell Culture: Medium
Contains salts, energy source (glucose), amino acids, vitamins, buffer (CO2/HCO3–) and growth factors (in serum) Eg. DMEM, RPMI
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Cell Culture: Substrate
Surface on which cells are grown on Cells are plated and adhere to treated plastic/glass Most cell types are anchorage-dependent (adhere to plastic) for growth and proliferation Undergoes treatment to become more hydrophilic to facilitate cell attachment
53
Properties of normal cells in tissue culture
1. GO Growth arrest in low serum - growth factor signalling required for proliferation 2. STOP Contact inhibition - cellular growth & division stops due to contact with other cells 3. DIE Anchorage dependent growth - epithelial cells require attachment for survival
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Properties of cancer cells in tissue culture
1. Growth factor independent growth 2. Loss of contact inhibition (they grow on top of each other) 3. Anchorage independent growth
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Assays to measure cell transformation (for cancer)
gold standard: tumorigenesis in nude mice in vitro - Growth factor independent growth => Serum indepndent growth - Loss of contact inhibition => focus forming assay - Anchorage independent growth => soft agar assay - immortalization => infinite proliferation
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focus
group of cells clustered together
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soft agar assay
used to test for anchorage independent growth base agar matrix cell suspension + agar matrix formation of cell colonies counted using colorimetric detection (MTT soln)
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hallmarks of cancer seen in cell culture assays
S - sustaining proliferative Signaling A D - resisting cell Death I - replicative Immortality S - evading growth Suppresors M
59
pros of using cell culture to study cancer
* use of animals reduced * Homogenous cell population, same growth requirements * Control of the extracellular environment * Minimize interference from other biological molecules that may occur in vivo * Screens for cancer-causing genes (Lec. 4) or for cancer therapies
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cons of using cell culture to study cancer
* Impossible to re-create in vivo environment * Remove interaction with other cells, hormones, support structures (ECM) that would be present in vivo (the tumor microenvironment) * Artificial conditions could cause cells to de-differentiate or change phenotyp
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Lecture 3
Breakpoint go stretch :D
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Approaches to Studying Cancer: Experimental - Mouse Models what are the different types of mouse models?
GSOX GEMMs Syngeneic Orthotopic Xenograft
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Syngeneic mouse model
Transplant tumor cells from mouse to mouse
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Xenograft
Transplant tumor cells from **human** to **mouse** Grafts from human primary tumors or cell lines Have to be injected into an immuno deficient mouse
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Orthotopic
Transplant tumor cells into their native location Can be both xenograft and syngeneic
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GEMMs
Genetically engineered mouse models arise in situ
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Nude mice
FOXN1 mutation Blocks development of thymus (and hair) => no T cells Tumors easy to monitor
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SCID mice
Severe Combined Immunodeficiency (SCID) Can't complete VDJ recombination (DNA-PK mutation) and lack T or B cells
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Limitations of Mouse Models
- Different lifespans (2 vs 80) - Different size - Different physiology - Different metabolic response (PK) - Fewer mutations required (mice fibroblasts require ~2 mutations - Different tumors from same deficiencies (p53 mice -> sarcomas, p53 humans -> carcinomas) - Less metastasis