Basic Biology of Cancer
Basic Biology of Cancer
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REAP Senior Health February 10, 2016
Normal development starting with a fertilized egg
All DNA available
Embryo – at the stage of an undifferentiated ball of cells
Parts of the DNA strand are covered, making them inactive.
Proteins are formed and released to allow signaling between cells.
Receptors formed on cell surfaces to receive the signaling proteins.
A “ladder” of proteins created to carry the signal from cell surface to inside the nucleus.
Parts of the DNA strand are clumped up in little balls, inactivating that portion which is covered.
The signals received are of two types – activators and suppressors.
As a result of receiving an activator signal, proteins covering the DNA expose a part of it, thereby
activating it to make RNA or a protein. The portion activated is called a gene.
A suppressor signal causes protein to cover a gene, inactivating it.
Differentiation of Embryo
A consensus is reached amongst cell as to which end will be the head and the tail and cells send
controlling signals to adjacent cells to create a recognizable animal.
The embryo goes through stages where parts – gills and a tail for example – are no longer
needed and the cells in these parts get a signal to die off – apoptosis.
When an organ has reached an appropriate size, the cells receive signals to stop dividing.
DNA repair
The DNA in one cell, if straightened out, would be about two yards long.
Formed into 2 x 46 chromosomes = 92 strands, your DNA is crammed together inside the
nucleus and is exposed to destructive forces by being in close contact and by radiation and the
toxins we ingest. There are thousands of DNA breaks a day in each of our cells.
There is a constant repair of broken or improperly crossed strands of DNA.
If the DNA in a cell is so gummed up that it can’t be repaired, the repair protein opens a
chemical pathway to kill the cell – apoptosis.
Angiogenesis
As cells grow in a cluster, they become starved for food and oxygen and send out signals to
nearby blood vessels to send a branch in their direction
Innate immune system
We are all acquainted with the acquired immune system – active by viruses, bacteria, etc.
The innate system monitors the cells in our bodies and kills cells that have developed
abnormalities.
One part, the DNA repair system was mentioned above.
Basic Biology of Cancer
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The other part is white blood cells that patrol the entire body and identify abnormalities on the
surface of cells that, if allowed to persist, would cause problems. Once identified as abnormal,
the cell is either directly destroyed or given a signal to turn itself off and die.
Cancer develops when cells mutate so they have combinations of:
1. DNA Activators locked on, promoting cell growth
2. DNA Suppressors locked on the off position, promoting cell growth
3. DNA Repair Proteins inactivated
4. The ability to ignore signals for cell death – apoptosis
5. The ability to defeat or fool the Innate Immune System
6. The continued ability to have blood vessels grow in their direction - angiogenesis
7. Multiple mutations have to occur in one cell for it to become malignant and able to spread
Having a hereditary mutation, BRCA (BReast CAncer) for example, means that a cell has one less
mutation to go through before it becomes malignant.
Targeted Cancer Therapy attempts to block one of the steps above that the cancer cell uses to survive
and spread.