This article will explain how cancer cells and normal, healthy cells are different.
It covers the basic differences between cancer cells and normal cells, like how they grow and communicate.
Growth
Normal cells stop growing (reproducing) when enough cells are present.
© Verywell, 2017.
In contrast, cancer cells dont stop growing when there are enough cells present.
Cancer cells reproduce rapidly before they have had a chance to mature.
This continued replication often results in a tumor (a cluster of cancer cells) being formed.
Each gene in the body carries a blueprint that codes for a different protein.
Some of these proteins are growth factorschemicals that tell cells to grow and divide.
In response, the cells continue to grow.
Normal cells respond to signals sent from other nearby cells that say, youve reached your boundary.
When normal cells hear these signals they stop growing.
Cancer cells do not respond to these signals.
Homeostasis is one area where normal cells and cancer cells are very different.
Cancer cells are either not repaired or do not undergo apoptosis.
Stickiness
Normal cells secrete substances that make them stick together in a group.
Spread
Normal cells stay in the area of the body where they belong.
For example, lung cells remain in the lungs.
Appearance
Under a microscope, normal cells and cancer cells may look quite different.
The nucleus appears both larger and darker than normal cells.
The reason for the darkness is that the nucleus of cancer cells contains excess DNA.
Up close, cancer cells often have an abnormal number ofchromosomesthat are arranged in a disorganized fashion.
Maturation
Normal cells mature.
Cancer cells, because they grow rapidly and divide before cells are fully mature, remain immature.
Doctors use the termundifferentiatedto describe immature cells (in contrast to differentiated to describe more mature cells.)
The degree of maturation of cells corresponds to the grade of cancer.
Cancers are graded on a scale from 1 to 3 with 3 being the most aggressive.
Some of the newerimmunotherapy medicationsaddress this aspect of cancer cells.
For example, normalwhite blood cellshelp fight off infections.
The same can be true of substances produced.
For example, normal thyroid cells produce thyroid hormones.
Cancerous thyroid cells (thyroid cancer) may not produce thyroid hormone.
Blood Supply
Angiogenesisis the process by which cells attract blood vessels to grow and feed the tissue.
Cancer cells undergo angiogenesis even when growth is not necessary.
How Do Cells Become Cancerous?
There are proteins in the body that regulate cell growth.
YourDNAcarries genes that are the blueprint for proteins produced in the body.
Some of these proteins are growth factorschemicals that tell cells to divide and grow.
Other proteins work to stop (suppress) growth.
Sometimes, the proteins are abnormal and function differently.
Normally, roughly three billion cells divide in the body every single day.
Evading Growth Suppressors
Normal cells are controlled by growth (tumor) suppressors.
There are three main types of tumor suppressor genes that code for proteins that suppress growth.
Mutations that result in any of these tumor suppressor genes being inactivated allow cancer cells to grow unchecked.
Cancer cells ignore these cells and invade nearby tissues.
Benign (noncancerous) tumors have a fibrous capsule.
They may push up against nearby tissues but they do not invade/intermingle with other tissues.
Cancer cells, in contrast, dont respect boundaries and invade tissues.
This results in the fingerlike projections that are often noted on radiologic scans of cancerous tumors.
Many types of cancer cells produce their energy through glycolysisdespite the presence of oxygen(Warburg phenomenon).
Thus, the reasoning behind hyperbaric oxygen therapy is flawed.
Sometimes hyperbaric oxygen may induce cancer growth.
Mortality/Immortality
Normal cells are mortal, that is, they have a lifespan.
One of the limitations to growth in normal cells is the length of the telomeres.
Every time a cell divides, the telomeres get shorter.
When the telomeres become too short, a cell can no longer divide and the cell dies.
Cancer cells have figured out a way to renew telomeres so that they can continue to divide.
An enzyme called telomerase works to lengthen the telomeres so that the cell can divide indefinitelyessentially becoming immortal.
There are several theories about why cancers may recur.
This is an active area of research, and extremely important.
Genomic Instability
Normal cells have normal DNA and a normal number of chromosomes.
Some of these are driver mutations, meaning they drive the transformation of the cell to be cancerous.
Many of the mutations are passenger mutations, meaning they dont have a direct function for the cancer cell.
Can Cancer Cells Differ From Other Cancer Cells?
Scientists still don’t understand how cancer cells can seemingly hide for years or decades and then reappear.
There is not one step, but rather many, that are currently being addressed in different ways.
In addition, cancer isn’t a single disease, but rather hundreds of different diseases.
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