Neurosurgery：癌症干细胞也是脑瘤病根
生物谷报道：干细胞是维持生物细胞活力的源泉，但是这种具有特殊功能的细胞却可以在身体中起到有害作用，尤其实在癌症的生长和扩散中起到重要作用。在一个肿瘤的疯狂分裂的细胞中，来自美国Weill Connell医学院的研究人员定位到了癌症干细胞。目前，研究人员正在进一步研究这些细胞，希望有一天能够战胜恶性脑癌。
John A. Boockvar博士解释说，一些患者的脑瘤对化疗有响应，但另外一些则没有反应。他们认为癌症干细胞就是这种状况的背后原因。
Boockvar博士正在捕捉和分类这些干细胞一确定他们如何对特定药物作出反应。这些信息的获得将有助于更精确、更具特异性的癌症诊断，从而能够采用适合个体病人的药物治疗方案。研究人员在2008年1月的Neurosurgery杂志上公布了用于获得正常神经干细胞和脑瘤衍生干细胞的技术。
研究人员表示，对脑瘤干细胞的分类目录将成为患者诊断的强大工具。而且，还有助于位科学界创建一个信息库，以帮助科研人员了解脑瘤如何形成和检测、开发新药物。
为了阻止大脑中癌症干细胞的生长，Boockvar博士正在研究使用两只已有的抗癌药物的效果。这两种药物分别为肺癌、胰腺癌药物Tarceva和用于治疗结肠癌的Avastin。
这些试验的初步结果显示，一些患者的癌症被消除，而另外一些则有抗药性。Boockvar博士相信，这些患者的药物抗性可能归咎于一类干细胞的反弹。
Boockvar博士表示，确定患者的癌症干细胞特征将有助于选择适合患者个体的药物治疗方案。
许多年前，美国密歇根大学癌症中心就已经假设，癌症可能是来自于干细胞。因为从肿瘤发生的条件来看，干细胞的确是癌变基因的理想萌生处和持久的载体。首先肿瘤发生在某个细胞上需要这个细胞具有不断分裂的能力,而且该细胞的基因突变不会因为组织更新而丢失；其次，发生基因突变的肿瘤细胞必须能保持在体内，这样看来，高度分化的组织特异性细胞不会是肿瘤的始作俑者，因为它们终究会走向凋亡，而具有长久活力的干细胞很可能是肿瘤发生的元凶。
多伦多大学的约翰迪克和同事们1997年率先在白血病中找到癌症干细胞。2003年，斯坦福大学的迈克尔克拉克博士发现可以用细胞表面的标记蛋白将肿瘤细胞分成两类，将两类蛋白分别注入老鼠的乳腺中，第一类肿瘤细胞（有标记蛋白）虽然只占整个细胞数量的极小部分，但却能引起肿瘤发生，第二类肿瘤细胞占整个细胞的绝大多数，却不能引起肿瘤发生。继续重复上述实验，可以发现有蛋白标记的第一类肿瘤细胞在每一代都可以引起新的肿瘤发生。进一步研究发现，这些细胞类似于成体干细胞，有着分裂增殖，自我更新，以及分化成其他细胞的能力，因此被命名为肿瘤干细胞。2004年，多伦多大学的彼得德克斯博士在人类脑肿瘤中找到与干细胞相似的细胞。2005年，佛罗里达大学的帕克
英文原文：
Cancer Stem Cells May Be At The Root Of Brain Tumors
ScienceDaily (Dec. 24, 2007) — Stem cells -- popularly known as a source of biological rejuvenation -- may play harmful roles in the body, specifically in the growth and spread of cancer. Amongst the wildly dividing cells of a tumor, scientists have located cancer stem cells. Physician-scientists from Weill Cornell Medical College are studying these cells with hopes of combating malignant cancers in the brain.
"Some patients' brain tumors respond to chemotherapy and some don't," says Dr. John A. Boockvar, the Alvina and Willis Murphy Assistant Professor of Neurological Surgery and head of the Brain Tumor Research Group at NewYork-Presbyterian Hospital/Weill Cornell Medical Center. "We believe cancer stem cells may be the cause."
Dr. Boockvar is capturing and classifying these cancer stem cells in order to determine how they react to certain available drug therapies. Doing so will lead to more accurate and specific cancer diagnosis, allowing for tailored drug treatments. Results explaining the techniques used to harvest normal neural and brain-tumor-derived stem cells will be described in the January 2008 edition of the journal Neurosurgery.
"Cataloging brain tumor stem cells will be an enormous tool for patient diagnosis," explains Dr. Boockvar, "but it will also help to create a library of knowledge for the scientific community to understand how brain tumors form and to test and develop new drugs."
To stave off cancer stem cell growth in the brain, Dr. Boockvar is studying the use of two drugs already available for cancer treatment. Tarceva -- approved for the treatment of lung and pancreatic cancer -- works by stopping the growth and spread of cancer cells. Avastin -- approved for the treatment of colorectal cancers -- is also being studied for inhibiting cancer cell growth and works by stopping the growth of blood vessels (angiogenesis) that feed the tumor.
Preliminary results from these trials have shown that some patients' cancers are wiped out, whereas others remain resistant. Dr. Boockvar believes that these patients' drug resistance might be due to a class of stem cells resilient to available treatments. Finding biomarkers that distinguish these stem cells from those that are destroyed by known drugs might help researchers formulate new drugs.
"Determining a patient's cancer stem cell profile will take a lot of the guessing out of choosing a course of treatment," says Dr. Boockvar. "It will save money, medical resources and precious time for the patient."
Adapted from materials provided by New York- Presbyterian Hospital/Weill Cornell Medical Center.
- 众说风云 (已有0条评论)
