Cancer Symposium Keynote Speech
Nobel Laureate Phillip Sharp, PhD, Gives Keynote Speech at BIDMC's Cancer Symposium
Date: 10/24/2008
BIDMC Contact: Zineb Marchoudi
Phone: (617) 667-7305
Email: zmarchou@bidmc.harvard.edu
Nobel Laureate Phillip Sharp, PhD, Institute Professor at the Koch Institute for Integrative Cancer Research at MIT, won the Nobel Prize in Physiology or Medicine in 1993 for his discovery of introns, which are regions of DNA that sit between the codes that translate into proteins.
In his keynote lecture at the close of the first day of the BIDMC Cancer Symposium Wednesday, Sharp presented evidence connecting microRNAs, single strands of DNA found inside these non-coding introns, with the development of cancer.
MicroRNAs regulate the expression of genes. When things go wrong and microRNAs fail to regulate genes involved in cell growth, cancer may develop.
Sharp put microRNAs into historical context, going back to the discovery of DNA over a half century ago. Back then, researchers focused their efforts on understanding the flow of information from DNA to a living biological system. As more and more genetic intermediaries were discovered – messenger RNA, transfer RNA, and ribosomal RNA, which all play roles in translating DNA into proteins – the question changed, he said. Researchers became interested in understanding the regulation of the flow of data from DNA to the biological system.
That regulation, it turns out, is very complex. For instance, small interfering RNA has the power to silence genes. Similarly, microRNA binds to genes to regulate them.
“Over half of all messages are regulated by microRNAs,” said Sharp, emphasizing the “extensive nature” of microRNA regulation.
Normally, microRNAs control the expression of genes after transcription. Genes governing cells that normally proliferate, such as B or T cells, have fewer places for microRNAs to bind and suppress growth and proliferation. In cells that don’t normally replicate and spread, there are larger regions for microRNA binding, and therefore more opportunities for microRNA to suppress that growth.
When microRNA doesn’t function properly, normally quiescent cells (those that are not dividing) lose this layer of control. The result can be unbridled cell growth and proliferation. Sharp presented several studies that have connected dysfunctional microRNAs with the development of cancer. In one study, researchers found microRNAs that regulate genes important in the development of small-cell lung cancer. Another connected the loss of certain microRNAs with prostate cancer.
According to Sharp, it isn’t yet clear whether microRNAs are involved early on in the genesis of tumors. But, he said, “MicroRNAs are part of the picture of the development of cancer.”
