NIH study reveals new genetic culprit in deadly skin cancerAugust 31, 2009Sequencing work points to new target for melanoma treatment Drawing on the power of DNA sequencing, National Institutes of Health researchers have identified a new group of genetic mutations involved in the deadliest form of skin cancer, melanoma. This discovery is particularly encouraging because some of the mutations, which were found in nearly one-fifth of melanoma cases, reside in a gene already targeted by a drug approved for certain types of breast cancer. In the United States and many other nations, melanoma is becoming increasingly more common. A major cause of melanoma is thought to be sun exposure; the ultraviolet radiation in sunlight can damage DNA and lead to cancer-causing genetic changes within skin cells. In work published in the September issue of Nature Genetics, a team led by Yardena Samuels, Ph.D., of the National Human Genome Research Institute (NHGRI) sequenced the protein tyrosine kinase (PTK) gene family in tumor and blood samples from people with metastatic melanoma. The samples were collected by the study's coauthor Steven Rosenberg, M.D., Ph.D., a leading expert on melanoma and chief of surgery at the National Cancer Institute (NCI). The PTK family includes many genes that, when mutated, promote various types of cancer. However, relatively little had been known about roles played by PTK genes in human melanoma. The NIH study was among the first to use large-scale DNA sequencing to systematically analyze all 86 members of the PTK gene family in melanoma samples. The team's initial survey, which involved samples from 29 melanoma patients, identified mutations in functionally important regions of 19 PTK genes, only three of which had been previously implicated in melanoma. The researchers then conducted more detailed analyses of those 19 genes in samples from a total of 79 melanoma patients. One of the newly implicated genes stood out from the rest. Researchers detected mutations in the ERBB4 gene (also known as HER4) in 19 percent of patients' tumors, making it by far the most frequently mutated PTK gene in melanoma. In addition, researchers found that many ERBB4 mutations were located in functionally important areas similar to those seen in other PTK oncogenes involved in lung cancer, brain cancer and gastric cancer. Next, the researchers moved on to laboratory studies of melanoma cells with ERBB4 mutations. They found that these melanoma cells were dependent on the presence of mutant ERBB4 for their growth. What's more, the melanoma cells grew much more slowly when they were exposed to a chemotherapeutic drug known to inhibit ERBB4. The drug, called lapatinib (Tykerb), was approved by the Food and Drug Administration in 2007 for combination use in breast cancer patients already taking the drug capecitabine (Xeloda). Encouraged by their study results, the researchers are planning a clinical trial using lapatinib in patients with metastatic melanoma harboring ERBB4 mutations. The clinical trial will be conducted under the direction of Dr. Rosenberg at the NIH Clinical Center. "This collaborative study represents an ideal example of how sophisticated genetic analyses can be translated to the benefit of cancer patients," said Dr. Rosenberg. "We have found what appears to be an Achilles' heel of a sizable share of melanomas," said Dr. Samuels, who is an investigator in the Cancer Genetics Branch of the NHGRI's Division of Intramural Research. "Though additional work is needed to gain a more complete understanding of these genetic mutations and their roles in cancer biology, our findings open the door to pursuing specific therapies that may prove useful for the treatment of melanoma with ERBB4 mutations." In addition to ERBB4, the researchers identified two additional PTK genes, FLT1 and PTK2B, with a relatively high rate of mutations in melanoma. Each of these genes was mutated in about 10 percent of the tumor samples studied. NHGRI Scientific Director Eric D. Green, M.D., Ph.D., pointed out how such research is helping to lay the groundwork for the era of personalized medicine. "We envision a day when each cancer patient will have therapies tailored to the specific genetic profile of his or her tumor. Ultimately, this should lead to more effective and less toxic approaches to cancer care," said Dr. Green, who directs the NIH Intramural Sequencing Center, which generated the DNA sequence data for the melanoma study. In addition to NIH scientists, the team included a researcher from the Johns Hopkins Kimmel Cancer Center in Baltimore. In May 2009, Dr. Samuel's group reported in Nature Genetics another large-scale DNA sequencing study of a different group of genes involved in melanoma, the matrix metalloproteinase (MMP) gene family. This earlier study found that one gene, MMP-8, thought to spur cancerous growth actually served to inhibit it. Those findings are now helping to shape melanoma treatment strategies aimed at MMP genes. NIH/National Human Genome Research Institute |
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| Related Melanoma Current Events and Melanoma News Articles Laser therapy can aggravate skin cancer High irradiances of low-level laser therapy (LLLT) should not be used over melanomas. Quarter of a million children in England at risk of skin cancer from sunbeds An estimated quarter of a million 11-17 year olds in England are being put at increased risk of developing malignant melanoma by using sunbeds, warn researchers in a letter to this week's BMJ. Hundreds of genes distinguish patients likely to survive advanced melanoma Although the chances of surviving advanced melanoma aren't very good with current therapies, some patients can live for years with cancer that has spread beyond the skin to other organs. New Notre Dame study provides insights into the molecular basis of tumor cell behavior A new study by a team of researchers led by Crislyn D'Souza-Schorey, associate professor of biological sciences at the University of Notre Dame, sheds light on the molecular basis by which tumor cells modulate their surroundings to favor cancer progression. Switching immunosuppressants reduces cancer risk in kidney Switching to a newer type of immunosuppressant drug may reduce the high rate of skin cancer after kidney transplantation, according to research being presented at the American Society of Nephrology's 42nd Annual Meeting and Scientific Exposition in San Diego, CA. Cancer survivors may not be getting the help they need to stop smoking More than a quarter of cancer survivors who still smoke have not been advised to quit smoking by their health care providers in the last year, according to a study published by researchers at Fox Chase Cancer Center in the current issue of the Journal of General Internal Medicine. Melanoma treatment options 1 step closer A targeted chemotherapy for the treatment of skin cancer is one step closer, after a team of University of Alberta researchers successfully synthesized a natural substance that shows exceptional potential to specifically treat this often fatal disease. Resident physicians seldom trained in skin cancer examination Many resident physicians are not trained in skin cancer examinations, nor have they ever observed or practiced the procedure. New findings on the formation of body pigment The skin's pigment cells can be formed from completely different cells than has hitherto been thought, a new study from the Swedish medical university Karolinska Institutet shows. The results, which are published in the journal Cell, also mean the discovery of a new kind of stem cell. Studying cancer in pet dogs to find new treatments for human patients A team of scientists at the National Cancer Institute (NCI) in Bethesda, USA, says that studying pet dogs with cancer could yield valuable information on how to diagnose and treat human cancers. More Melanoma Current Events and Melanoma News Articles |
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