1. ✔ ✔ ✔ CHECKPOINTS: STOP OR GO? MITOSIS & Cytokinesis
• DNA checked, repaired
• enough organelles?
MITOSIS & Cytokinesis ✔
• spindle
attached? ✔
duplicate organelles G0
growth
INTERPHASE
INTERPHASE
Protein regulators are molecular signals that may stimulate or halt division, instruct cells to differentiate, or trigger cell death. Errors in the sinaling process can cause too few (hair loss) or too many (tumor) cells. ✔
• SA:V ratio?
• more cells needed?
• adequate room?
replication
Cells Alive
Biointeractive tutorial

2. REGULATING THE CHECKPOINTS:
• proto-oncogenes trigger cell division, direct cell to continue in the cycle turn on the gas!
• tumor-suppressor genes shut down the cycle hit the brakes!
Protein regulators are molecular signals that may stimulate or halt division, instruct cells to differentiate, or trigger cell death. Errors in the sginaling process can cause too few (hair loss) or too many (tumor) cells.
. A consequence of an uncontrolled cell cycle is that the tissue formed from cell division is often non-functional. Without control the growth does not take on the proper form or interact normally with other cell types.
The root cause of the growth is a gene

3. EFFECTS OF MUTATIONS In proto-oncogenes >
• less division therefore too few cells
• more division, creating too many cells, increasing likelihood of mutation
In tumor-suppressor genes >
• loss of inhibition too many cells
creates TUMORS
Protein regulators are molecular signals that may stimulate or halt division, instruct cells to differentiate, or trigger cell death. Errors in the sginaling process can cause too few (hair loss) or too many (tumor) cells.
. A consequence of an uncontrolled cell cycle is that the tissue formed from cell division is often non-functional. Without control the growth does not take on the proper form or interact normally with other cell types.
The root cause of the growth is a gene
Animation 1

4. More division increases likelihood of more mutations
What else causes mutations?

5. Cells stop dividing when they should
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
normal cells
Cells stop dividing when they should
Cells die when damaged
mutation > cell death
cancer cells
Abnormal growth
Abnormal DNA
Cancer arises from a loss of normal growth control. In normal tissues, the rates of new cell growth and old cell death are kept in balance. In cancer, this balance is disrupted. This disruption can result from uncontrolled cell growth or loss of a cell’s ability to undergo cell suicide by a process called“apoptosis.” Apoptosis, or “cell suicide,” is the mechanism by which old or damaged cells normally self-destruct.
NCI Web site:

6. TUMOR DIRECTS MORE GROWTH
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Angiogenesis
TUMOR DIRECTS MORE GROWTH
Tumor that can grow and spread
tumor
angiogenesis
signals
blood vessel
Signal molecules
Tumor angiogenesis is the proliferation of a network of blood vessels that penetrates into cancerous growths, supplying nutrients and oxygen and removing waste products. Tumor angiogenesis actually starts with cancerous tumor cells releasing molecules that send signals to surrounding normal host tissue. This signaling activates certain genes in the host tissue that, in turn, make proteins to encourage growth of new blood vessels.
cell releases signal molecules that cause blood vessels to grow
blood vessels bring in nutrients and removes waste products
NCI Web site:

7. CANCER SPREADS via blood vessels
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Angiogenesis
CANCER SPREADS via blood vessels
tumor breaches organ wall
1. Cancer cells invade surrounding tissues and vessels
Blood vessel
cells lodge, grow in other organs
When patients are diagnosed with cancer, they want to know whether their disease is local or has spread to other locations. Cancer spreads by metastasis, the ability of cancer cells to penetrate into lymphatic and blood vessels, circulate through the bloodstream, and then invade and grow in normal tissues elsewhere.
In large measure, it is this ability to spread to other tissues and organs that makes cancer a potentially life-threatening disease, so there is great interest in understanding what makes metastasis possible for a cancerous tumor.
Metastasis
blood transports cancer cells
NCI Web site:

8. DIFFERENT TYPES OF CANCERS DIFFERENT TYPES OF TREATMENTS
Radiation – use EM waves to disrupt tumor cell DNA
Chemotherapy - toxic chemical cocktail
problem: both therapies kill mitotic cells, cancerous AND healthy
Disrupt signal molecules produced by tumor cells
Block growth of blood vessels to tumors
Use immune system to attack cancer like it does a virus
Vaccines for microbe-caused cancers (HPV)