The smallest bit of genetic material may cause the deadliest of tumours. Researchers have implicated a tiny RNA molecule in the invasive spread of breast cancer — the factor responsible for most deaths from the disease. In 2007, around 179,000 people in the United States will be diagnosed with invasive breast cancer and some 47,000 will probably die. RNA is one of the main players in human genetics; the most well studied type, messenger RNA (mRNA), is vital for translating the code of our DNA, allowing those instructions to be read and used to produce proteins. MicroRNAs — tiny strings of genetic code often just a couple of dozen nucleotides or ‘letters’ long — can block this translation process by binding to mRNAs, stopping the production of proteins. A spate of new research has found these diminutive molecules to be involved in crucial processes of development, metabolism and cell suicide.
Now, a team led by Robert Weinberg at the Massachusetts Institute of Technology’s Whitehead Institute in Cambridge has linked one of these up-and-coming molecules to invasive breast cancers. “I think that these microRNAs are going to be involved ubiquitously in regulating a wide variety of cellular processes, and this is just the tip of the iceberg,” Weinberg says.