Hellrung Daniel J, Kisselev Serguei, Link Charles J
Iowa Cancer Research Foundation, Urbandale, IA 50322, USA.
Cancer Immunol Immunother. 2007 Jan;56(1):25-34. doi: 10.1007/s00262-006-0163-5. Epub 2006 Apr 13.
The use of alpha(1,3)galactosyltransferase (alphaGT) as a method of inducing hyperacute rejection of tumors has been gaining interest recently. However, the approach is based in part on the sensitivity of each tumor line to the effects of complement lysis. Tumors expressing complement resistance factors such as membrane cofactor (CD46), decay accelerating factor (CD55) and protectin (CD59) have been shown to be more resistant to complement mediated lysis. Anchored to the membrane by a glycosylphosphoinositol moiety (GPI-anchored), CD55 and CD59 can be cleaved by Bacillus thuringiensis phosphatidylinositol-specific phospholipase C (PIPLC). Complement resistant A549 human lung carcinoma cells were engineered to express both the murine alphaGT gene and the B. thuringiensis PIPLC gene to alleviate complement resistance and enhance alphagal-mediated cancer killing. The PIPLC native signal sequence was replaced with the human epidermal growth factor signal sequence, EGFssPIPLC, to induce secretion from A549. Expression of EGFssPIPLC resulted in complete removal of CD55 and CD59 while sparing the non-GPI-anchored CD46. Results demonstrated that A549 cells transduced with two recombinant retroviral vectors carrying the alphaGT and EGFssPIPLC genes expressed high levels of alphagal epitope and exhibited a 5-fold increase in sensitivity to anti-alphagal mediated complement lysis.
使用α(1,3)半乳糖基转移酶（αGT）作为诱导肿瘤超急性排斥反应的方法最近受到了关注。然而，该方法部分基于每个肿瘤细胞系对补体溶解作用的敏感性。已证明表达补体抗性因子如膜辅因子（CD46）、衰变加速因子（CD55）和保护素（CD59）的肿瘤对补体介导的溶解更具抗性。CD55和CD59通过糖基磷脂酰肌醇部分（GPI锚定）锚定在膜上，可被苏云金芽孢杆菌磷脂酰肌醇特异性磷脂酶C（PIPLC）切割。对补体抗性的A549人肺癌细胞进行工程改造，使其表达鼠αGT基因和苏云金芽孢杆菌PIPLC基因，以减轻补体抗性并增强α半乳糖介导的癌症杀伤作用。将PIPLC天然信号序列替换为人表皮生长因子信号序列EGFssPIPLC，以诱导A549细胞分泌。EGFssPIPLC的表达导致CD55和CD59完全去除，而不影响非GPI锚定的CD46。结果表明，用携带αGT和EGFssPIPLC基因的两种重组逆转录病毒载体转导的A549细胞表达高水平的α半乳糖表位，并且对抗α半乳糖介导的补体溶解的敏感性增加了5倍。
