Researchers from Israel to the US to Korea took part in an effort to map the mutation in melanoma - one of the deadliest cancers
Prof. Yardena Samuels took part in an international effort to map the melanoma genome
Prof. Yarden Samuels of the Weizmann Institute’s Molecular Cell Biology Department is a part of the Cancer Atlas group that recently produced the melanoma genome map. Hundreds of researchers from Australia, the US, Canada, Russia, Germany, Italy, Poland, China and Korea participated in the effort. “This has been the most in-depth mapping yet,” says Samuels. After a careful selection process, 333 melanoma samples were included in the study, and the screening was conducted using six different platform technologies, going beyond the bounds of simple gene sequencing to explore how the various genes are expressed, how they interact and which proteins they produce.
Each sample required a second, non-cancerous sample from the same patient for comparison, and several of the samples afforded comparisons of genes from the patients’ early tumors to those that had metastasized. In addition to the sequencing of protein-coding genes, some of the samples had their entire genome sequenced, which could prove in the future to be an “unexplored goldmine of information on what makes cancer tick,” says Samuels. RNA and microRNA, as well as protein expression assays, were included. The latter screens added further dimensions to the gene map – creating a “landscape” that can help researchers understand not just the genes, but the pathways, intersections and cancer-causing diversions associated with them.
“The study was intensive, and it has paid off,” says Samuels. For one thing, it showed, for the first time, that melanomas can be divided into four distinct groups, according to a main mutation. Now melanoma researchers will be able to focus on understanding exactly how the different mutations lead to cancer, and physicians may eventually gain better tools for diagnosing the disease and tailoring treatments to individual cases. The first type, occurring in a mutation “hotspot,” is known as BRAF, and it tends to appear in younger people, in whom the cancer is fairly aggressive. The second is known as RAS. BRAF and RAS protein products lie in the same pathway so that BRAF and RAS mutations are mutually exclusive: A patient will have one or the other, but not both. The third is called NF1, and this mutation was found in older patients. The fourth group, called “triple wild type,” had none of the three most common mutations.
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