For a cancer tumor to grow, it needs its own blood supply. Now, a new study finds that cancer cells have a way of influencing nearby healthy cells to make them produce more of a protein that supports the growth of blood vessels for the tumor.
The study, published in the journal Current Biology, is the work of scientists from the Institute of Cancer Research (ICR), London, and the Cancer Research UK Beatson Institute in Glasgow - both in the UK.
Co-senior author Dr. Andrew Reynolds, who leads the tumor biology group at the ICR, says:
"Cancers can't gather together the resources they need to grow and spread all by themselves - they need the support of surrounding healthy cells."
New techniques called transcriptomics and proteomics are helping scientists understand more about the molecular processes that go wrong inside cells for cancer to thrive.
They are discovering, for example, that problems can arise in molecules called ribonucleic acid (RNA) that read the instructions held in the cell's DNA and translate them into cell processes, such as production of proteins.
The new study concerns a type of molecule called transfer RNA (tRNA). The authors note that this very common, small RNA is often disregarded in gene studies because it is assumed to be only involved with background cell housekeeping tasks.
"However," they note, "it is now becoming clear that cellular levels of tRNAs are key to the control of gene expression in a number of different contexts."
Unexpected role for transfer RNA
The researchers found that a type of tRNA called initiator methionine tRNA plays an unexpected role in making cells produce a type of collagen protein that promotes blood vessel growth, or angiogenesis, in tumors.
In healthy tissue, cells called fibroblasts make collagen - the main structural protein of the body. In most cases, the type of collagen they make is type 1.
But the researchers found that when they are near tumors, fibroblasts switch from making type 1 collagen to making type 2 - the type that is more suitable for supporting the growth of blood vessels.
The researchers ran various tests on human fibroblasts, mice and also on tumor and normal tissue samples from breast cancer patients.
They found that fibroblast cells that were activated by malignant breast tumors had higher levels of initiator methionine tRNA than normal and they also had higher levels of certain proteins - including type 2 collagen.
The study is important because it highlights the key role played by the environment around a tumor in helping it grow and develop.
It suggests the process of cancer is more than a matter of increasing protein production to make more cells for tumor growth. There is also a subtle alteration of protein production that indirectly allows tumors to solicit their own blood supply.
Dr. Reynolds concludes:
"Our study shows that a specific type of transfer RNA can ramp up production of collagen II protein in fibroblasts, stimulating the blood vessel growth in tumors that promotes cancer growth.
Our results could open up new approaches to treatment, such as drugs that are designed to disrupt cancer's ability to manipulate its environment."
Medical News Today recently learned that fibroblasts could be useful for fighting cancer. Researchers have found a way to transform skin fibroblasts into stem cells that target and destroy brain cancer.