新的抗原克隆技术可能有助于开发黑素瘤疫苗

生物谷

    最近几年，研究者们已经开发出了一些可帮助免疫系统攻击肿瘤的疫苗。肿瘤疫苗，并非专门设计用于预防癌症，而是用于增强激活免疫反应，对付已经存在的肿瘤。与传统的化疗相比，疫苗的毒性相对较低，而且效能比较高。

    至今为止，直接用于激活机体内最为关键的免疫应答细胞——T辅助细胞的疫苗鲜有被设计成功。尽管在T辅助细胞表面有识别并结合肿瘤抗原的受体，科学家们在分离和克隆抗原上遇到了障碍，整个过程显得非常繁复而又费时，而且往往是收效甚微。

    致力于识别黑素瘤以及其他类型肿瘤中的关键肿瘤抗原，来自美国Wistar研究所的科学家现已开发出一套克隆可被T辅助细胞识别的抗原。而且，Herlyn的研究小组已经采用这套新的克隆技术成功识别出一个新的肿瘤抗原，将之取名为核糖体蛋白L8（ribosomal  protein  L8；RPL8）。有关这项新的克隆技术以及新识别的肿瘤抗原的文章刊登在了4月15日的《Cancer  Research》杂志上。

    资料来源：The  Wistar  Institute

部分英文原文：

Cancer Research 67, 3177-3184, April 1, 2007. doi: 10.1158/0008-5472.CAN-06-3312

Cell, Tumor, and Stem Cell Biology

Mutant V600E BRAF Increases Hypoxia Inducible Factor-1 ${alpha}$ Expression in Melanoma

Suresh M. Kumar1, Hong Yu1, Robin Edwards1, Lianjun Chen1, Steven Kazianis2, Patricia Brafford2, Geza Acs1, Meenhard Herlyn2 and Xiaowei Xu1

1 Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine and 2 The Wistar Institute, Philadelphia, Pennsylvania

Requests for reprints: Xiaowei Xu, Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, PA 19104. Phone: 215-662-6503; Fax: 215-349-5910; E-mail: xug@mail.med.upenn.edu .

Mutations in the BRAF serine/threonine kinase gene are frequently found in cutaneous melanomas. Activation of hypoxia inducible factor-1 ${alpha}$ (HIF-1 ${alpha}$ ) in response to both hypoxic stress and oncogenic signals has important implications in cancer development and progression. Here, we report that mutant BRAFV600E increases HIF-1 ${alpha}$ expression in melanoma cells. Our microarray profiling data in 35 melanoma and melanocyte cell lines showed that HIF-1 ${alpha}$ gene expression was significantly increased in melanomas harboring BRAFV600E mutation. Stable suppression of mutant BRAFV600E or both wild-type and mutant BRAFV600E by RNA interference in melanoma cells resulted in significantly decreased HIF-1 ${alpha}$ expression. Knockdown of mutant BRAFV600E induced significant reduction of cell survival and proliferation under hypoxic conditions, whereas knockdown of both wild-type and mutant BRAFV600E resulted in further reduction. The effects of BRAF knockdown can be rescued by reintroducing BRAFV600E into tumor cells. Transfection of BRAFV600E into melanoma cells with wild-type BRAF induced significantly more hypoxic tolerance. Knockdown of HIF-1 ${alpha}$ in melanoma cells resulted in decreased cell survival under hypoxic conditions. Pharmacologic inhibition of BRAF by BAY 43-9006 also resulted in decreased HIF-1 ${alpha}$ expression. Although HIF-1 ${alpha}$ translational rate was not changed, the protein was less stable in BRAF knockdown cells. In additional, von Hippel-Lindau protein expression was significantly increased in BRAF knockdown cells. Our data show for the first time that BRAFV600E mutation increases HIF-1 ${alpha}$ expression and melanoma cell survival under hypoxic conditions and suggest that effects of the oncogenic V600E BRAF mutation may be partially mediated through the HIF-1 ${alpha}$ pathway. [Cancer Res 2007;67(7):3177–84]