爱默力大学 (Emory University)Winship研究所的科学家，发现了一个新的脑部生物标记分子 (biomarker)，据初步的分析结果显示，科学家怀疑这个分子的出现，不但和肿瘤的恶性转移有关，还很可能跟治疗后肿瘤复发的机制，有直接的关系。
据发表在最新一期临床癌症研究 (Clinical Cancer Research)的这篇论文显示，这次研究人员深入的分析了罹患星状细胞瘤 (Astrocytoma)和神经胶质瘤(glioma) 这类脑部恶性肿瘤患者的脑脊液(cerebro spinal fluid) ，结果发现原本用以储存脑部组织，不会出现肿瘤细胞的脑脊液，出现了一个称为水溶性attractin(soluble attractin) 的蛋白质。
这个由 Erwin Van Meir博士所主导的研究小组，利用60 份来自不同时期脑部肿瘤患者的脑脊液，透过蛋白质体的研究方法，比对100 份健康个体的脑脊液，结果居然发现97% 罹患恶性星状细胞瘤(Astrocytoma)的患者，脑脊液中存在着浓度较高的 attractin蛋白，而对于像是第四期恶性星状细胞瘤的患者而言，这个指标分子的浓度，更是高的惊人。
此外研究人员还认为，这个 attractin蛋白很可能是由癌细胞自己所分泌，因此肿瘤一旦转移 attractin 蛋白浓度也跟着变化，参与计划的科学家表示，目前临床上针对脑部肿瘤的患者，极度缺乏非侵入式诊断与追踪病情变化的工具，如今 attractin蛋白的出现，很可能在未来提供一个又快速又准确的诊断与追踪癌细胞的方法。
英文原文：
Newly identified biomarker detects and regulates spread of brain tumors
ATLANTA -- Researchers at Emory University's Winship Cancer Institute have identified a novel biomarker for brain tumors and have uncovered a potential role the marker may play when the tumor spreads or comes back after treatment. The study, 褹ttractin is elevated in the cerebrospinal fluid of patients with malignant astrocytoma and mediates glioma cell migration," is published in the November issue of Clinical Cancer Research.
The biomarker, a protein known as "soluble attractin," is normally absent in the central nervous system (CNS) and is undetectable in cerebral spinal fluid (CSF), unless malignant astrocytomas--the most common form of intracranial tumors--are present in the CNS. The CSF is a liquid that bathes the brain and acts as a reservoir, which can be sampled for analysis of proteins secreted by CNS tumors.
This newfound ability to reliably identify biomarkers for malignant astrocytomas means that physicians will have a new minimally invasive method to track the success of treatments. These biomarkers, singly or in combination, will provide a fingerprint of the disease and be able in the future to better define the disease, predict what kind of treatment to use and allow doctors to monitor how well the tumor responds to treatment.
"Using proteomic analyses of the CSF of patients with brain tumors, we have identified for the first time that attractin levels are elevated in patients with high-grade astrocytoma," says Erwin Van Meir, PhD, professor of neurosurgery and hematology/oncology and lead author of the study. "Because few noninvasive methods are available for monitoring CNS malignancies, there is an urgent need to find reliable indicators."
Van Meir and his colleagues analyzed 60 cerebrospinal fluid or cyst fluid samples from patients with various CNS diseases using proteomics to examine simultaneously all proteins in biological samples. To validate the study's results, attractin levels in a set of 100 normal and tumoral brain samples also were examined. The researchers found elevated attractin levels in 97 percent of malignant astrocytomas, with the highest levels in grade IV tumors.
The grade of a tumor reflects the level of abnormality its cells exhibit and how quickly the tumor is likely to grow and spread and is a predictor of patient outcome. Low-grade tumors are slow growing and show little abnormality, whereas high-grade tumors are highly abnormal and grow and spread quickly, making treatment more difficult. Patients with highly malignant astrocytomas typically have a life expectancy of about one year even after neurosurgery, chemotherapy, and radiation therapy, highlighting the pressing need for more research to develop improved therapies.
Equally important, the researchers also found that attractin plays a key role in the motility of the cancer cells, which influences their ability to spread in the brain, a major cause of recurrence of malignant astrocytoma. Secreted by the tumors themselves, attractin induces cancer cells to migrate, although that mechanism is not well understood. Knowing that attractin modulates the migration and possibly the recurrence of these tumors makes it a promising target for future therapeutic intervention, says Dr. Van Meir. "Our studies suggest that measuring attractin levels in patients with grades II-IV astrocytoma should be explored further as a potential biomarker for monitoring the growth of these tumors or as a potential new target for therapy."
