Retinoblastoma cells lack receptors.Retinoblastoma Retinoblastoma Definition Retinoblastoma is a malignant tumor of the retina that occurs predominantly in young children. Description The eye has three layers, the sclera, the choroid, and the retina. cells lack receptors Researchers seeking to uncover the biochemical defect behind retinoblastoma, a hereditary cancer of the eye, have found that retinoblastoma tumor cells lack a class of chemical receptors involved in inhibiting growth. The exact function of the so-called transforming growth factor-beta 1 (TGF-beta 1) receptors, first characterized in 1985, is still not well understood. Scientists suspect, howevcer, that the receptors--located on the surface of some cells--are important in regulating cell proliferation. In some cases they appear to protect against the effects of cancer-causing genes, or oncogenes oncogenes 1. genes carried by tumor viruses that are directly and solely responsible for the neoplastic transformation of host cells. Many oncogenes function after integration into the DNA of the host cell and some up-regulate normal downstream host cell genes to cause neoplasia. . As reporte in the April 8 SCIENCE, researchers at the Weizmann Institute of Science The Weizmann Institute of Science (מכון ויצמן למדע) is a world-renowned institute of higher learning and research in Rehovot, Israel. in Rehovot, Israel, The White-head Institute for Biomedical Research Biomedical research (or experimental medicine), in general simply known as medical research, is the basic research or applied research conducted to aid the body of knowledge in the field of medicine. in Cambridge, Mass., and the University of Massachusetts Medical School UMMS is ranked fourth in primary care education among the nation’s 125 medical schools in the 2006 U.S.News & World Report annual guide, “America’s Best Graduate Schools”. UMMS is also a major center for research. in Worcester tested the responses of retinoblastoma tumor cells and normal retinal cells to various growth-inhibiting factors. When the tumor cells proved insensitive to the growth inhibitor TGF-beta 1, they tested the cells for TGF-beta 1 receptors. None was found. "Loss of TGF-beta 1 receptors, which is a rare event even among tumor cells, may represent one mechansm through which these cells escape from negative control and form retinoblastoma," the researchers report. Scientists discovered years ago that retinoblastoma involves the failure of a particular gene, the RB gene, to function properly. Little is known about the protein normally coded for by the RB gene, although it is blieved to act directly on DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. . It is possible, the new report concludes, that the RB protein might directly affect the expression of TGF-beta 1 receptors. Alternatively, it might interact with the receptors in a way that affects receptor structure and function, allowing cell proliferation and tumor formation. "Righ now we can't really draw a link," says Sela Cheifetz, a Whitehead Institute Founded in 1982, the Whitehead Institute for Biomedical Research is a non-profit research and teaching institution located in Cambridge, Massachusetts. The Whitehead Institute was founded as a fiscally independent entity from Massachusetts Institute of Technology, and its members researcher and coauthor of the report. "The apparent lack of TGF-beta receptors may not be the direct cause of the these cells being tumorogenic, but rather might be a consequence." More research needs to be done, she says, to find out exactly what the RB gene product is and its role in cell growth. |
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