JUN 06, 2016 02:51 PM PDT

Changes In tRNA Levels Shown to Drive Cancer Metastasis

WRITTEN BY: Carmen Leitch
It’s long been accepted that the human genome instructs our bodies on what proteins to make using molecules called tRNAs. They have seemed to simply be an innocuous participant in a much bigger process without much impact on what happens in a cell. The interaction of tRNA and mRNA is described in the video below.

In new work published in the journal Cell, researchers are challenging the paradigm that tRNA has no other roles or influence on the cell. It appears as though fluctuations in the abundance of tRNAs have a big impact on everything from single cells to disease processes. “We’ve long thought of these molecules as little more than middle men participating in the process of translating proteins,” said Sohail Tavazoie, a physician and Associate Professor at Rockefeller University’s Elizabeth and Vincent Meyer Laboratory of Systems Cancer Biology.

The work has been aided by improved technology, as tRNAs have traditionally been very challenging to analyze. Authors of the paper utilized approaches from next-generation sequencing to devise a new method that allows them to look at tRNA levels in depth.  

Once they found a way to measure the levels of tRNAs, the research team sampled different kinds of tumors, primary and metastatic, from breast cancer patients and compared them to breast tissue samples from healthy people.
                    Samples from non-metastatic (left) and metastatic breast cancer (right) cells showing enhanced expression of a specific gene in metastatic tumors because those cells have increased levels of a tRNA called GluUUC.
Intriguingly, it was found that the amount of two very specific tRNAs was significantly higher in metastatic tumors and cells than it was in both primary tumors that did not metastasize or healthy samples. “There are six different ways to encode for the protein building block arginine,” said Tavazoie. “Yet only one of those - the tRNA that recognizes the codon CGG - was associated with increased metastasis.” The other tRNA that was elevated in metastatic samples was one that recognizes the codon GAA and encodes for glutamic acid.
                              
It was hypothesized that elevated levels of these tRNAs may be what drives metastasis. Using mouse models of non-metastatic primary tumors, the scientists increased the levels of two the tRNAs, and found that these cells became much more invasive and metastatic. To further validate the idea, the inverse experiment was also performed. This time, when the amount of these tRNAs was reduced in metastatic cells, a decrease in the incidence of metastases in the animals was observed, confirming their hypothesis.

So how is the tRNA causing metastasis? The team decided to look at protein levels and see how they varied when levels of the two tRNAs changed.  “We found global increases in many dozens of genes, so we analyzed their sequences and found that the majority of them had significantly increased numbers of these two specific codons,” explained Tavazoie.

From their list of genes that had increased in abundance, they then altered two of them with a ’silent’ mutation. These types of mutations take advantage of the redundancy in the genetic code, and even with a single base pair change will encode for the same amino acid. When they did that, it was observed that elevating tRNA levels no longer resulted in metastasis. Tavazoie commented that “it is remarkable that within a single cell type, synonymous changes in genetic sequence can dramatically affect the levels of specific proteins, their transcripts, and the way a cell behaves.”

Sources: Cell, The Rockefeller University
About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JUL 28, 2018
Cell & Molecular Biology
JUL 28, 2018
Self-organizing Synthetic Tissues are Getting More Complex
All the structures in the body arise from a fertilized cell, and scientists are learning more about how that happens....
JUL 31, 2018
Cell & Molecular Biology
JUL 31, 2018
A Brand New Geometric Shape
Cell use this shape when packing together to form structures....
SEP 22, 2018
Videos
SEP 22, 2018
How Much of the Human Genome is Just Junk DNA?
Once written off as junk, it was suggested that some regions of the genome that don't code for protein act as regulators. But how much?...
SEP 29, 2018
Videos
SEP 29, 2018
CRISPR Technology may Have Serious Drawbacks
The CRISPR gene-editing system has been touted as a miraculous tool, but it has its problems....
OCT 01, 2018
Cell & Molecular Biology
OCT 01, 2018
Revealing How Antibiotics Work Against Bacteria
In a first, researchers have directly observed an antibiotic in action as it disrupted the membrane of a bacterial cell....
OCT 03, 2018
Neuroscience
OCT 03, 2018
Towards Predicting Autism In Pregnancy
Autism is a growing health concern for medical professionals, educators, patients, and family. The latest numbers from the CDC (2014) put the incidence of ...
Loading Comments...