In a recently published paper in the Cancer Cell journal, researchers report a genetic event called “RNA editing” to be responsible for drug sensitivity in cancer patients. The findings may explain why some cancer patients react better to treatment and live longer than others. The study is entitled “The Genomic Landscape and Clinical Relevance of A-to-I RNA Editing in Human Cancers“, and was led by an international team of scientists at The University of Texas MD Anderson Cancer Center.
Cancer relies on an abnormal process of cell growth and the ability to travel and invade other parts of the body. The latter, ultimately leads to destruction of the involved tissues and formation of malignant tumors. There are over 100 different identified forms of cancer affecting human organs and tissues, such as the lungs, breast, brain, digestive system, skin, and kidneys, among others. While practically no symptoms appear at early stages of cancer, at advanced stages of the disease, patients usually suffer from a number of signs and symptoms that depend on the type of cancer and the affected body parts. While 5–10% of cancers are associated with inherited genetics, the majority of them are caused by environmental factors such as chemicals, diet, infections, radiation, and hormones. Being responsible for approximately 13% of all deaths each year, cancer is considered the leading cause of death in the developed world and second leading cause of death in the developing world.
From the therapeutic standpoint, depending on the cancer type, location, stage of progression, as well as the person’s health and wishes, several treatment options are available. This includes chemotherapy and treatments based on radiation, hormones, and surgery, each with a variable success rate with respect to survival and relieve of symptoms. On the other hand, studies have suggested that sensitivity to treatment, and hence survival rate, depend not only on the type of therapy but also on the patient’s tolerability and sensitivity to treatment. To help predict drug sensitivity and patient survival, cancer specialists have studied genetic mutations and DNA copy changes to gain in-depth understanding, however, without significant results.
The recent study performed at MD Anderson Cancer Center shed new insights into understanding the biological reasons behind sensitivity to anticancer drugs. In other words, it answers the question of why some cancer patients respond better to treatment, whereas others not. In this study, the research team analyzed genetic data of 6,226 samples from patients suffering from 17 different cancers taken from The Cancer Genome Atlas.
The results offered new information on RNA editing events in tumors tissues in comparison to normal tissues. RNA editing is the process in which genetic information is altered in the RNA molecule. This RNA editing mechanism, long considered rare in humans and other vertebrates, is now recognized as a common event in the human genome. The results led the scientists to propose that RNA editing may selectively influence the sensitivity of patients to anticancer drugs.
“If a protein is only highly edited in the tumor proteins, but not in normal proteins, then it’s possible that a specific drug could be designed to inhibit the edited mutant protein,” said the study’s co-senior author Dr. Han Liang in a news release. “Previous studies have focused on DNA mutations and mainly focused on RNA editing in normal tissues. The role of RNA editing in human cancers is only beginning to emerge from those early studies of individual patient samples in a few cancer types.”
“The larger scale Cancer Genome Atlas study provided the information needed to alter proteins or RNA sequences that may act as “drivers” for prognostic biomarkers or therapeutic targets. RNA editing adds another layer of complexity in the quest to predict patient survivability and suggest new therapies” added Dr. Liang.
In summary, the findings highlighted RNA editing as a novel valuable avenue to explore concerning cancer therapeutics. In the study, a number of clinically relevant events related to RNA editing have been identified, and future analysis should provide new details about cancer mechanisms, biomarkers, and novel therapies.