A brand of fatal cancer is its ability to spread like a windblown fire to other parts of the body. Today, scientists have identified an enzyme that can link the ability of a tumor to spread with an abnormality in the integrated self-destruct mechanism in all cells. The discovery, reported in Nature tomorrow , may help scientists better understand how aggressive the cancer cells reproduce more tumors.
Normal cells divide enough to replace others that have aged. But when a decrepit cell ignores commands the body to self-destruction, it can continue to divide, eventually forming a tumor. But for tumor cells to spread - a process called metastasis - they need more specific skills. After leaving the main tumor, cells must evade the body's defenses and penetrate tissues. Scientists have investigated the genes and proteins that provide cells with these deadly talents; Recently, they began to find evidence that certain enzymes involved in programmed cell death, or apoptosis, can also allow cancer cells to strike on their own.
Now Adi Kimchi molecular geneticist at the Weizmann Institute of Science in Rehovot, Israel, and colleagues identified an enzyme called DAP-kinase, which seems to strengthen this link. When DAP kinase is missing, the cells ignore the molecular signals that control the cells to kill themselves. To better understand how the enzyme is involved in tumor development, Kimchi and his colleagues searched various types of cell lines from mouse lung cancer. They noticed a fascinating pattern: the enzyme is absent in aggressive, spreads rapidly cell lines, and present in the tamer ones. When the team inserted the DAP kinase gene in aggressive cancer cells and injected into healthy mice, the cancer does not spread as easily as it did in mice with cancer cells without enzymes.
The connection makes sense, Kimchi said, since a break of cancer cell ignores a variety of immune signals that should trigger his death. His team is now screening patients for tumor samples with several types of cancer - including breast cancer and leukemia - to see if the enzyme is missing. The discovery, she said, could eventually lead to gene therapy for particularly pernicious cancers. DAP-kinase, is a researcher Eric Stanbridge agreement on the cancer of the University of California, Irvine, perhaps "still a target for testing" for possible gene therapies.
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