cancer notes f06
TRANSCRIPT
-
8/10/2019 Cancer Notes F06
1/20
Characteristics of Cancer Cells
Obituary brings to light the tragedy of one localfamily (at ALE section of Website)
1. Have lost the genetic ability to stop dividing
Cancer is heritable
Cancer cells give rise to cancer
cells
2. Immortal
3. Not subject to contact inhibition
4. Metastasize:Spread into other tissues5. Are Dedifferentiated
less specialized than the cell it came from)
-
8/10/2019 Cancer Notes F06
2/20
Mitosis:division ofthe nucleus
Cytokinesis:division ofcytoplasm
Daughtercells
M-phase
Interphase =
G1, S, G2
S-phase
G2-phase G1-phase
Prep.for division:organelles
duplicate
Cell growth +normal cell
activities
Synthesis of DNA
(chromosomes replicate)
Cellsdivide
The Cell Cycle
-
8/10/2019 Cancer Notes F06
3/20
Regulation of Cell Division
What evidence in your own life do you havethat cell division is regulatedby your body?
Left ear is about same size as right ear.
A cut your finger heals, but the skin doesn't justkeep growing!
What normally controls cell division?
-
8/10/2019 Cancer Notes F06
4/20
Contact Inhibition
Cells do not normally grow or divide when incontact w/ other Cells
E.g. Cultured cells in a petri dish
will divide until they form a layer one cell thickand then stop when make contact w/ other cells.
Called contact inhibition of cell growth.
Cells also migrate in culture.
Stop moving when touch other cells due to contactinhibition of cell movement.
-
8/10/2019 Cancer Notes F06
5/20
Contact inhibitiondoes not occur in Cancerous Cells
Cancerous cells continue growing andmoving when they touch other cells.
They pile up and they migrate to other parts ofthe body -- the cancer spreads.
Growth Factors
made of protein
Chemical messages that control the cell cycle
How do we know the cell cycle is under geneticcontrol?
1 N l ll th
-
8/10/2019 Cancer Notes F06
6/20
1. Normal cell growth
2. Basal cell carcinoma
Both daughtercells divideActively dividing cells
(basal cells)
Only one daughterCell divides
Onedaughterdifferentiat
es
-
8/10/2019 Cancer Notes F06
7/20
Growth control in a normal cell
Signaling cellGrowth factor (sonic hedgehog)
Growth factor binds to receptor
Receptor sets off a signalcascade to nucleus
target cell entersS-phase and divides,
eventually repairingwound
target cell
Nucleus
-
8/10/2019 Cancer Notes F06
8/20
1. Cell mightproduceits owngrowthfactor
Several ways to get faulty growth control in a cancer cell
2. Mutant receptor might turnon even without
binding growth factor
3. Signal cascade mightoccur even without triggerfrom receptor
In each case, cancer cellenters S phase anddivides inappropriately,causing a tumor
-
8/10/2019 Cancer Notes F06
9/20
Growth Factors:Stimulate Cell Division
Diffuse through the body, sometimes a longway, bathing many different cells
Bind to Membrane Receptors, like a keyfitting into a lock. stimulate a pathway inside cell that leads to cell
division.
Each receptor binds to a different growthfactor.
Different cell types are stimulated bydifferent growth factors.
-
8/10/2019 Cancer Notes F06
10/20
Cancer: Its all in the Genes
Proto-oncogenes:
Genes that code for growth factors
Active in actively dividing tissues (e.g. skin) Sometimes mutate into......
Oncogenes:
genes that cause cancer produce too much growth factor
Over stimulate mitosis
Oncogenes are rarely inherited.....Why?
-
8/10/2019 Cancer Notes F06
11/20
Tumor Suppressor Genes
Tumor Suppressor Genes Code for Proteins that turn off mitosis
e.g. p53 gene
p53 Gene Codes for a protein that stops the cell cycle
after G1
Half of all cancers involve p53
One mutant Tumor Suppressor Genedoes not cause cancer....Why?
-
8/10/2019 Cancer Notes F06
12/20
p53: A Tumor Suppresser Gene
How many p53 genes did you inherit? Why?
How many p53 genes need to mutate before acell becomes cancerous? Why?
-
8/10/2019 Cancer Notes F06
13/20
BRCA 1:Breast Cancer Susceptibility Gene
BRCA 1 is a Tumor Suppresser gene
If a women inherits BRCA 1 she has a
80 to 90%chance of developing breast cancer
40 to 50%chance of ovarian cancer.
Why arent the percentages 100%?
Why are the percentages much lower for theaverage woman?
-
8/10/2019 Cancer Notes F06
14/20
The Role of theEnvironment in Causing Cancer
Certain Viruses, toxins, or Radiation may leadto a p53 mutation
A 2nd p53 mutation may lead to one of thefollowing cancers
Cancer of the....
Bladder, blood, brain, breast, colon, esophagus,
liver, lung, spleen, thyroid, etc.
h
-
8/10/2019 Cancer Notes F06
15/20
Therapeutic Strategies:Attack Actively Dividing Cells
Since cancer is uncontrolled cell division, alltreatments involve the cell cycle.
Phase-specific chemotherapies Prevent cells from entering S-phase
Block the S-phase
Block the M-phase (mitosis)
-
8/10/2019 Cancer Notes F06
16/20
Phase-specific Chemotherapies
1. Prevent cells from entering the S-phase
Block Growth factor receptors on cell membranewith antibody (e.g. Herceptin)
2. Block the S phase
Methotrexate and other chemotherapeutic drugsblock DNA synthesis
3. Block or stop mitosis
Taxol: interferes with the movement of thechromosomes along spindle fibers
-
8/10/2019 Cancer Notes F06
17/20
Cells Affected by Chemotherapy
May affect all rapidly dividing cells
Which cells divide rapidly?
Hair follicle cells Skin cells
Cells lining digestive tract
Blood stem cells Divide to produce???
So.... what would be the side effects?
-
8/10/2019 Cancer Notes F06
18/20
Side Effects of Chemotherapy
Baldness
Unable to heal wounds
Destroy lining of digestive tract nausea and severe bacterial infection
Decrease Blood cell Production
RBCsAnemia WBCsdecreased ability to fight infections and
kill cancer cells
H
-
8/10/2019 Cancer Notes F06
19/20
How toLower your Cancer Risks
Eat plenty of fiber
Fiber speeds passage through digestive tract
Do not smoke
Drink alcohol in moderation or not at all
Exercise regularly
Do not become overweight Limit dietary fat
Limit sun exposure or use sunscreen (SPF 30)
Learn to recognize the warning signs of cancer
-
8/10/2019 Cancer Notes F06
20/20