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【drug-news】预防肝癌的新药
Scientists have identified a new compound called CDDO-Im that protects against the development of liver cancer in laboratory animals. Experiments, led by researchers at the Johns Hopkins Bloomberg School of Public Health, show CDDO-Im to be effective at doses 100 times lower than other compounds known to prevent cancer in people. Because of its makeup, the researchers believe CDDO-Im could be particularly effective in preventing cancers with a strong link to inflammation, such as liver, colon, prostate and gastric cancers. It could also play a role in preventing diseases such as neurodegeneration, asthma and emphysema. The findings are featured in the February 15, 2006, issue of the journal Cancer Research.
CDDO-Im is a synthetic compound that belongs to a class of cancer-fighting compounds called triterpenoids under development by Dr. Michael Sporn and other study co-authors at Dartmouth Medical School. It is derived from oleanolic acid, a naturally occurring substance found in many plants. Other oleanolic derivatives are known to reduce tumor growth in animals and humans.
Researchers believe CDDO-Im works by activating Nrf2, a master switch known to direct certain enzymes to stimulate the cell's defense mechanisms and remove harmful chemicals from cells. "Activation of the Nrf2 pathway with CDDO-Im could provide protection against a number of diseases triggered by environmental agents," said Thomas Kensler, PhD, a professor with the Bloomberg School's Department of Environmental Health Sciences and lead author of the study.
In their research, Kensler and his colleagues treated laboratory rats with varying doses of CDDO-Im. Two days after treatment with CDDO-Im, the rats were given aflatoxin, a naturally occurring cancer-causing toxin. CDDO-Im treatment led to an 85 percent reduction in pre-cancerous lesions at the lowest dose of 50 micrograms per rat and a 99 percent reduction at the highest dose of 5 milligrams.
Like other compounds derived from oleanolic acid, CDDO-Im also has strong anti-inflammatory properties, which the researchers say makes it ideally suited to the prevention of certain cancers. "When cells become inflamed, they can produce reactive molecules, called free radicals, that can damage DNA and promote cancer development," explained Kensler. "CDDO-Im can also inhibit cancer formation by interfering with this inflammatory process."
Because it can stimulate the body's defense mechanisms at such low doses, Kensler believes that CDDO-Im is an excellent candidate for cancer prevention in humans. "If this compound can produce such a potent and dramatic reduction in the number of pre-cancerous growths, it should have an equally dramatic impact on the development of actual cancers. This study suggests that we may be on the right track in terms of chemoprevention. It may open the door for a new class of compounds that could prevent a number of diseases," said Kensler.
The National Institute of Environmental Health Sciences and the National Cancer Institute, agencies of the federal National Institutes of Health, provided funding to researchers at the Johns Hopkins Bloomberg School of Public Health for the 认领！
谢谢！ 预防肝癌的新药
科学家发现了一种叫做CDDO-Im的新药，能够预防实验室动物肝癌进展。由约翰霍普金斯公共健康学院的研究人员所进行的实验显示：CDDO-Im较人们熟知的抗癌药 在相差一百倍的低剂量下即可显效。鉴于该药的特点，研究人员认为 CDDO-Im将对与炎症紧密相关的癌症，诸如肝癌、结肠癌、前列腺癌、胃癌等尤为有效，亦可应用于神经变性、哮喘和肺气肿。这项发现登在了癌症研究杂志2006年2月15日上。
CDDO-Im属于三帖类（一种抗癌化合物）Michael Sporn博士及其他达特茅斯医学院的合作者如是说。它源自齐墩果酸——一种存在于多种植物中的物质。其他的齐墩果酸衍生物被认为可以延缓人和动物的肿瘤生长。
研究人员认为，CDDO-Im通过激活Nrf2——类似“总开关”，它作用于特定的酶类以激活细胞防御机制并清除细胞中的有害物质。“CDDO-Im作用下，Nrf2的活化可以抵御环境因素引起的多种疾病，” Thomas Kensler博士，隆伯格环境卫生学院教授 本研究的首作者如是说。
研究中，Kensler及其同事对实验大鼠采用多种剂量施以CDDO-Im，两天后，注入黄曲霉毒素——一种诱发癌症的毒素。结果显示：癌症前损伤在施以最低剂量CDDO-Im时（每只大鼠50微克）减少至85%，在施以最高剂量时（每只大鼠5毫克）减少至99%。
与其他源自齐墩果酸的化合物一样，CDDO-Im也含有较强的抗炎成分，由此，研究人员认为他特别适用于某些癌症。“细胞若有炎症，就会释放不稳定化合物，这种被称为自由基的物质 能破坏DNA引发癌症” Kensler解释道，“CDDO-Im也可以通过干扰这种抗炎机制以阻止癌症形成。”
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作者:admin@医学,生命科学 2011-09-07 05:12
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