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Archive - Mar 14, 2011

Jagged2 Binding Drives Metastasis in Lung Cancer Study

Researchers have discovered a new, key component in the spread of lung cancer as well as a likely way to block it with drugs now in clinical trial. The study was published on March 14, 2011, in the Journal of Clinical Investigation. A team led by scientists at The University of Texas MD Anderson Cancer Center found a way to identify metastasis-prone lung cancer cells and then uncovered a mechanism that shifts primary tumor cells into a more deadly type of cell with the capacity to move elsewhere in the body. "We think tumors have to learn how to metastasize because they can't do it initially," said paper senior author Dr. Jonathan Kurie, professor in MD Anderson's Department of Thoracic/Head and Neck Medical Oncology. "Cells change in response to cues from their external environment." About 90 percent of all cancer deaths are caused by metastasis - the spread to, and invasion of, other organs. Lung cancer is the leading cause of cancer-related death in the United States, accounting for more than 157,000 deaths annually. The median five-year survival rate is 3.5%. The researchers found that when a protein called Jagged2 binds externally to Notch, a membrane protein that sticks out through the surface of a cell, it suppresses a microRNA that thwarts metastasis inside the cell. "Jagged2 suppresses miR-200 and drives metastasis as a consequence." Dr. Kurie said. "It's been known for some time that Notch is involved in cancer, but no one really knew how." Two Notch inhibitors are in clinical trial at MD Anderson. "These drugs might suppress the ability of primary tumors to metastasize," Dr. Kurie said. "One question is who is supposed to get these drugs," Dr. Kurie said.

Orchid Lures Prey with Scent of Death

Research led by Dr. Timotheüs van der Niet at the University of KwaZulu-Natal in South Africa shows that the South African orchid Satyrium pumilum lures flies into its flowers by mimicking the smell of rotting flesh. A new study comparing the scent of the orchids with that of roadkill was published online on March 13, 2011, in the Annals of Botany. The orchid S. pumilum is found in sandy, moist conditions near small streams across the Cape floral kingdom of South Africa. The flowers are a puzzle. They don't carry any nectar and even if they did, the spurs that would hold it are the wrong shape to feed any visitors. So how do they attract insects to pollinate their flowers? Dr. Van der Niet said: "We know it's common for orchids to deceive insects into pollinating them. We also know that some plant species can mimic carrion to attract flies. What we didn't know was how successful this was. Mimicry is often a very poor way to pollinate a plant. So we set out to observe the plants in the wild and see if we could work out how they were attracting flies." The team staked out a region of farmland with many of the orchids on it. They then went about finding carrion for a comparison. Dr. Van der Niet said: "We didn't kill creatures to entice the flies. Instead we used dassies (rock hyraxes). They're small animals and they look a little like a guinea pig. You can find them almost anywhere in South Africa, and that means you can also find them as roadkill. So we examined the flies visiting the dead dassies, and compared them to the flies visiting the orchids. Because of the high density of orchids we didn't see many flies visiting the flowers, but on the nearby dassie carcass we caught a lot of flies carrying orchid pollen, providing ample 'smoking gun' evidence of how common this interaction was.

Taking Tamoxifen to Prevent Breast Cancer Can Save Lives

Tamoxifen, taken by certain women as a preventive measure against breast cancer, saves lives and reduces medical costs. That is the conclusion of a new study published online on March 14, 2011, in Cancer, a peer-reviewed journal of the American Cancer Society. The study's results suggest that the benefits of tamoxifen to prevent cancer can sufficiently compensate for its side effects in post-menopausal women under age 55 years who have an increased risk of developing breast cancer. Research has shown that tamoxifen can protect against breast cancer for years after treatment ends, but identifying the group of women who can most benefit from the drug as a cancer preventive agent, without experiencing serious side effects, is a challenge. Side effects of the drug can include pulmonary embolism, endometrial cancer, deep vein thrombosis, and cataracts, as well as hot flashes and early menopause. To investigate those women who would benefit the most from taking tamoxifen as a cancer preventive drug, Dr. Peter Alperin, of Archimedes, Inc., in San Francisco, and his colleagues used a mathematical model to simulate a post-menopausal population under age 55 years in a virtual clinical trial comparing tamoxifen treatment with no treatment. The investigators modeled tamoxifen therapy based on an analysis of four randomized, placebo-controlled cancer prevention trials, and they assessed the effects that tamoxifen would have on women's breast cancer risk for 10 years following the end of treatment. Cancer incidences and survival information were taken from the Surveillance Epidemiology and End Results cancer registry, while factors such as non-cancer disease incidences, quality of life, and costs were taken from the medical literature.