Genetics, microRNAs, and the KRAS-variant
Let’s learn more about RNA!
In our last page on Genetics 101, we learned about DNA, genes and how our physical traits are passed on through the chromosomes we get from our biological parents. We learned that inheritable genetic variants in our DNA can be passed on from our biological parents as well.
We also learned how genes are expressed when DNA is turned to RNA in order to make the proteins that make up our bodies, and that variants in our DNA can result in proteins being made incorrectly and can cause cancer.
However, it turns out that not ALL RNAs actually get turned into proteins! These RNAs are called non-coding RNAs, and they actually control how other genes are expressed!
Below we explain the role that these non-coding RNAs can play in the development of cancer, and how the KRAS-variant increases risk of cancer.
MicroRNAs: A type of non-coding RNA
One type of these gene-regulating, non-coding RNAs are called microRNAs. To better understand the role of microRNAs, let's think about our cells as construction sites.
Proteins are the tools that perform vital functions within our cells, like the hammer or the saw, and they are carefully selected based upon the needs of the project. This is where our microRNAs enter the picture. They are the contractors of the project in our cells, overseeing the whole project of cell survival and cell death.
MicroRNAs regulate which protein tools are used and when, as well as how much of each are needed.
How does the KRAS-variant tie into all of this?
The KRAS-variant is an example of a variant, or small change in your DNA. This variant happens to fall in a very important region and can be thought of as a broken landing spot for a very important gene-regulating microRNA, called let-7. Let-7 regulates a key protein, called KRAS, which, when not well-regulated, can cause cancer.
Having the KRAS-variant is like having a contractor ordering the wrong number of hammers, or the wrong type of saw when work needs to be done.
This explains why individuals with the KRAS-variant are at risk for certain cancers, and also respond differently to certain cancer treatments, with some working great, and some not as well.