Tumor suppressor genes are also known as antioncogenes or loss-of-function genes.
Types of Tumor Suppressor Genes
Tumor suppressor genes come in three main types.
Tumor suppressor genes are easier to describe by using an analogy.
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It can get highly technical and confusing, so it may help to think of cells as cars.
Each cell has an accelerator and brakes.
In normal cars, both are working fine.
Multiple processes double-check they stay in balance so the car both moves along steadily, but doesn’t crash.
Cancer begins with a series of mutations in genes.
Genes function as a blueprint for making proteins with different functions.
Some mutations are no big dealthey ride along quietly and don’t mess with anything.
They’re called passenger mutations.
Then we come to driver mutations.
In other words, the accelerator has to be stuck to the floor AND the brakes have to malfunction.
More time allows for more mutations.
In general, oncogenes aredominant.
Take, for example, brown eyes.
Tumor suppressor genes, in contrast, tend to berecessive.
Examples of tumor suppressor genes are the BRCA1/BRCA2 genes, otherwise known as the “breast cancer genes.”
However, not everyone with the gene develops breast cancer.
This recessive nature is what is referred to in the “2 hit hypothesis” of cancer.
Of note is that having “2 hits” alone is not enough to lead to cancer.
These types of tumor suppressor genes can be thought of as “gatekeeper” genes.
Yet some tumor suppressor genes function in more of a caretaker role.
In the examples below, Rb, APC, and p53 function as gatekeepers.
History
Tumor suppressor genes were first identified among children with retinoblastoma.
The University of Texas has atumor suppressor gene databasethat lists many of these genes.
Some cancer treatments work to stimulate cells to commit suicide.
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