Cancer Biology 241: Molecular, Cellular and Genetic Basis of Cancer

Cancer Biology 241:Molecular, Cellular and Genetic

Basis of Cancer

Lectures: Mon and Wed 9-11 AM, CCSR 4105Discussion Section: Friday 9-11AM, TBA

Course Directors: Laura Attardi and Joe LipsickTA: Gabe Quinones

Focus of This Course

• Cancer research

• HOW we know what we know– Key observations and experiments– Historical context– Generalization of key experiments as a basis

for further discoveries

• Learning to read the primary literature

• Learning about experimental methods

Responsibilities and Grading

• Read papers PRIOR to discussion section• Participate actively in discussion sections• Submit original grant proposal on time• Peer review (anonymous) of two grants• Grading

– 50% discussion section participation– 30% grant proposal– 20% grant review

• Honor Code

http://coursework.stanford.edu

http://lane.stanford.edu/index.html

Books

Cancer Biology: The Basics

• Impact of cancer on human population

• Causes of human cancer

• Classification of human cancer

• Experimental approaches to cancer

Leading Causes of Death in U.S.Death Rate

0

200

400

600

800

1000

1200

1400

1600

1950 1960 1970 1980 1990 2000

Year

De

ath

s p

er

10

0,0

00

TotalHeartCancerStrokeAccident

from CDC

Change in Causes of Death

* Age-adjusted to the 2000 US standard population.Source: US Mortality Volume 1950, National Vital Statistics Report, 2002, Vol. 50, No. 15.

586.8

180.5

48.160.923.7

200.9193.7

258.2

0

100

200

300

400

500

600

HeartDiseases

CerebrovascularDiseases

Pneumonia/Influenza

Cancer

1950

2000

Rate Per 100,000

Invasive Cancer versus Age

0

500

1000

1500

2000

2500

3000

3500

<1

1-4

5-9

10-1

4

15-1

9

20-2

4

25-2

9

30-3

4

35-3

9

40-4

4

45-4

9

50-5

4

55-5

9

60-6

4

65-6

9

70-7

4

75-7

9

80-8

4

85+

Age at Diagnosis (Years)

per

100,

000

data from National Cancer Institutehttp://www.cdc.gov/cancer/npcr/uscs/report/

Cancers by Type in U.S.

from American Cancer Society

Cancer Death Rates in U.S.

MALE FEMALE

from American Cancer Society

From Suffrage to Suffering

Enough S’nuff – The Sot Weed Factor

1761 – Sir John Hill notes that snuff causes nasal cancer

Human Migration and Cancer

from Rubin and Farber, Pathology

Same Virus, Different Outcomes

EBV

Mononucleosis Burkitt’s LymphomaNasopharyngealCancer

Immune Suppression Malaria AIDS Organ Transplants

Dietary Factors

Known Causes of Human Cancer• Chemical Exposure

– Tobacco smoke– Environmental (PCBs)– Occupational (coal tar,

asbestos, aniline dye)– Diet (aflatoxin)

• Radiation (UV, ionizing)• Infection

– Viruses (EBV, hepatitis B, papilloma)

– Bacteria (Helicobacter)• Inherited familial cancer

syndromes

Diagnosis of NeoplasiaSymptoms Weight loss Rectal bleeding Persistent cough

Screening Pap smear Mammogram Occult blood

Incidental Radiology > ~1 gm (109 cells)

Biopsy

Histopathology

Staging

Autopsy

The Vocabulary

• Hyperplasia – increased number of cells• Hypertrophy – increased size of cells• Dysplasia – disorderly proliferation• Neoplasia – abnormal new growth• Anaplasia – lack of differentiation • Tumor – originally meant any swelling,

but now equated with neoplasia• Metastasis –growth at a distant site

Colonic Polyps

from Rubin and Farber, Pathology

Histology of Colonic Polyps

from Kinzler and Vogelstein, Cell 1996

Colon Cancer

from WebPath

Classification of Neoplasms

• Benign Tumor (-oma)– Adenoma (“adeno-” means gland-like)– Fibroma– Lipoma (“lipo-” means fat)

• Malignant Cancer (carcinoma or sarcoma)– Adenocarcinoma– Fibrosarcoma (“sar-” means fleshy)– Liposarcoma– Leukemia and Lymphoma

Carcinoma vs Sarcoma

EPITHELIUM => CARCINOMA

MESENCHYMAL ORIGIN=> SARCOMA

fibroblasts blood vessels blood cells muscle adipocytes (fat) bone cartilage

Basal Lamina

Collagen

Types of Epithelia

from Junqueira, et al.,Basic Histology

Epithelial Origin of Glands

from Poirier and Dumas,Review of Medical Histology

The Prognosis

“It’s tough to make predictions, especially about the future.”

Neoplasms

BENIGN MALIGNANT

NON-INVASIVE INVASIVE / METASTATIC

~well-defined borders ~irregular borders

~well differentiated ~poorly differentiated

~regular nuclei ~irregular, larger nuclei

~rare mitoses ~more frequent and/ or abnormal mitoses

Cytology (cells)

from NCI

Benign vs Malignant Histology (tissue)

Leiomyomaof Uterus

Leiomyosarcomaof Uterus

from WebPath

Predictors of Behavior

• Grade – How bad do the cells look?

• Stage – Where has the cancer spread?– Tumor– Nodes (Lymph)– Metastases

Grading Cancer

Grade 1 welldifferentiated

Grade 2 moderatelydifferentiated

Grade 3 poorlydifferentiated

Grade 4 anaplastic

adapted from WebPath

Staging Colon Cancer

from Rubin and Farber, Pathology

Duke’s A 5 yr survival > 90%

Duke’s B 5 yr survival 55% to 85%

Duke’s C 5 yr survival 20% to 55%

Duke’s D 5 yr survival < 5%

Metastases

• Seeding body cavities

• Lymphatic drainage to lymph nodes

• Hematogenous via blood vessels

Cancer Arises from Single Cells

1858 – Rudolf Virchow proposes that “omnis cellula e cellula”.All cells come from cells.

Metastatic cancer cells resemble the primary.All cells of a cancer come from a single cell.

metastatic adenocarcinoma within lymphatic vessel in lung (WebPath)

Cancer Arises from Single Cells

• Cancers are usually clonal in origin.– X-inactivation studies in human cancer

• Transformation can be observed in cell culture.

Tumor Clonality by X-Inactivation

Heterozygous Female Zygote

Random Inactivation of X Chromosomes During Early Development Malignancy

Monoclonal Tumor [single G6PD isoenyzme]

Polyclonal Tumor [two G6PD isoenzymes]

AB

AB

X XA B

OR

Tumor Clonality as a Diagnostic

• Immunoglobulin and TCR genes rearrange

• Rearrangements are unique in each cell

• Rearrangements display allelic exclusion

Clonality of Lymphoid Proliferation

Cell Type Benign Malignant

B Lymphocyte Ig Light ChainHeterogeneity

Ig Kappa or Lambda Only

Plasma Cells Heterogeneous Ig Electrophoresis

Monoclonal IgSpike

T Lymphocyte Heterogeneous Variable Regions

HomogeneousVariable Regions

Cancer: Selection for Single-Cell Survival in a Multi-Cellular Organism

• Cells must make critical decisions.– Stem cell renewal– Differentiation– Growth / quiescence– Death

• Things can go wrong at all of these levels.

Decisions Cells Must Make

Growth Fraction

Experimental tumors

  L1210 (mouse) 86 0.5

  B16 (mouse) 55 1.9

  LL (mouse) 38 2.9

  DMBA (rat) 10 7.4

Human tumors

  Embryonal carcinoma 90 27

  Lymphoma (high grade) 90 29

  Squamous cell carcinoma 25 58

  Adenocarcinoma

Normal Human Bone Marrow

6

35

83

--

Growth Fraction DoublingFraction (%) Time (days)

What Makes the Water Level Rise?

US Army Corps of Engineers

Good luck will rub off…

when you shake hands with me!

1775 – Percival Pott discovers “occupational cancer” of scrotum in chimney sweeps and in hands of gardeners who spread coal tar

Coal Tar Causes Skin Cancer

1891 -- Katsusabura Yamagiwa shows that coal tarcauses skin cancer when painted on rabbits’ ears.

Radiation Causes Cancer

1908 – Clunet shows that X-rays cause cancer in animals.

X-Rays Are Mutagens

Carcinogens Are Mutagens

• X-rays are carcinogenic

• X-rays cause mutations

• Therefore, carcinogens are mutagens?

• Puzzle: Ames test for mutagens in Salmonella scores some by not all carcinogens

Modified Ames Test for Carcinogens

What About Hormones?

Estrogens and Androgens Score Negatively in Ames Tests

Promoter-Initiator Model

Time

Initiator

Promoter

Cancer

Cancer

No Cancer

No Cancer

1940s -- Berenblum and Shubik develop model of carcinogenesis by painting polycyclic aromatic hydrocarbons and croton oil on mouse skin.

Initiators and Promoters

• Tumor Initiators = Mutagens– X rays– Ultraviolet Light– DNA alkylating agents

• Tumor Promoters = Proliferation Inducers– Phorbol Esters (croton oil)– Inflammation (hepatitis)– Estrogens and Androgens– Epstein-Barr Virus

Cancer is a Genetic Disease

• Somatic mutations occur in most cancers.

• Inherited germline mutations occur in rare familial cancer syndromes.

• Increases in mutation rate or genomic instability increase frequency of cancer.

• Aneuploidy is a hallmark of cancer cells.

• Genetic selection at the level of single cells.

Genetic Theory of Cancer

IF by Bill Brinkley

Theodor Boveri, 1914

dispermic fertilization in sea urchin

normal cancer

How Many Genetic Changes?

Nordling, 1953

Which Genetic Changes?