Last year an international team led by Cancer Research UK scientists at our Cambridge Research Institute unveiled the results of a huge research project called METABRIC . They used advanced gene sequencing techniques to analyse the patterns of gene activity in breast tumours from thousands of women, revealing the molecular signature of each tumour. The results showed that the disease could be divided into ten distinct subtypes, each with its own characteristics and outlook.

That work was just the beginning of the story. Since then, the researchers, led by Professor Carlos Caldas, have been delving into these subtypes in ever greater depth, trying to figure out what makes them different and how we can tackle each one more effectively.

In a new paper, published in the leading scientific journal Nature , the team took another look at the thousand breast cancer samples from the METABRIC study. But rather than looking at genes that bear the instructions to make proteins in our cells, the researchers focused instead on a set of genes that encode tiny lengths of RNA - a relative of the larger DNA molecules that makes up our genome.

In recent years it has become clear that these short pieces of RNA known as microRNAs, or miRNAs for short - can help to control when and where protein-making genes are switched on or off, and theyre an increasingly hot topic in the world of cancer research .

And now it looks like they may be playing a role in controlling how the immune system responds to certain breast cancers.

Small but powerful

First discovered in the 1990s in tiny worms called nematodes, microRNAs act as molecular switches inside cells, turning genes off when theyre not needed as well as fine-tuning gene activity levels. Theyre made from chopping up much longer strings of RNA a type of molecular messenger in cells.

Many hundreds of different microRNAs have now been identified, and they can recognise and act on individual genes in various ways. And thanks to projects such as ENCODE , we also know theres a lot more in the genome still to be discovered.

Researchers already know that cancer cells contain different levels of microRNAs compared to healthy cells - generally, they tend to be lower - and some types of cancer seem to have a characteristic microRNA fingerprint. This suggests that they could be useful for helping to diagnose or potentially even treat the disease.

Professor Caldas and his team wanted to find out whether the ten distinct subtypes of breast cancer theyd identified in the METABRIC study also had a telltale microRNA signature, and whether this matched up with the particular characteristics of that type.

Continued here:
Genetic "fine-tuners" and breast cancer

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