Researchers at Yale have identified a potential therapeutic target for cancer in the form of a micro RNA (miRNA) gene that cancer cells, but not normal cells, are dependent on for survival. Inactivating the miRNA causes cancer cell death and tumour regression.

It is known that the micro RNA called miR-21 is in abundance and active in most types of cancer, and has been termed an ‘oncomiR’.

Professor Frank Slack and colleagues at Yale Cancer Centre demonstrated that cancer cells are dependent on miR-21 for survival and rapidly die when it is not present. This phenomenom, termed ‘oncomiR addiction’, means that despite the multiple genes involved in the development and growth of a tumour, tumours regression occurs when miR-21 is inactivated.

This 'oncomiR addiction' means that miR-21 is a powerful therapeutic target for many cancers. The study was the first to demonstrate that miR-21 was acting as an oncomiR, and that cancer cells could be ‘addicted’ to an oncomiR.

miRNA are a recently-discovered class of small Ribonucleic acid molecules that are not involved in protein-coding but act as negative gene regulators. They are known to be abundant and to regulate many genetic pathways.

'Our understanding of ‘oncogene addiction’ in cancer has major potential to change the way we target and treat cancer, with a new emphasis on targeting and inactivating microRNAs', said Professor Thomas Lynch, Director of Yale Cancer Center.

This study identifies a new therapeutic target – inactivation of miR-21 – for future cancer drug development. 'If we show that a cancer is addicted to a particular gene, it means that we have a prime target to attack and treat it with drugs,' Professor Slack said.