补体依赖性细胞毒性(CDC)是单克隆抗体(mAb)的重要抗肿瘤机制。然而,曲妥珠单抗,抗HER2单克隆抗体,只施加较小的CDC。膜结合补体调节蛋白(mCRPs)的过表达,抑制CDC,与各种恶性肿瘤有关.这里,我们探讨了三种mCRPs(CD55,CD59和CD46)的表达水平对接受曲妥珠单抗辅助治疗的乳腺癌患者预后的预测作用.我们还在体外研究了mCRP下调对曲妥珠单抗诱导的CDC的影响。65例HER2阳性乳腺癌患者接受含有曲妥珠单抗的辅助治疗,进行回顾性分析。免疫组化检测CD55、CD59和CD46的表达水平。卡方检验,使用Kaplan-Meier生存分析和Cox比例风险模型分析CD55、CD59和CD46表达与预后的关系。HER2阳性SK-Br3和BT-474乳腺癌细胞用各种药物预处理以降低mCRP表达。之后,测量曲妥珠单抗介导的细胞溶解作用。在65名患者中,46.2%高表达CD55,44.6%高表达CD59,44.6%高表达CD46。中位随访时间为47个月(24至75个月)。CD55或CD59过表达患者的复发率高于CD55低表达患者(33.3vs.8.6%;P=0.013)或CD59(31.0vs.11.1%;P=0.046)。同样,CD55或CD59过表达患者的平均无病生存期明显短于CD55低表达患者(56vs.70个月;对数秩检验,P=0.008)或CD59(56vs.69个月;对数秩检验,P=0.033)。多因素分析证实CD55(而非CD59)是复发的独立危险因素(HR=4.757;95%CI,0.985~22.974;P=0.05)。体外,我们发现他莫昔芬抑制SK-Br3和BT-474细胞中CD55的蛋白和mRNA表达水平,但不抑制CD59或CD46.他莫昔芬预处理后,曲妥珠单抗诱导的细胞溶解通过CD55下调得到增强.总之,CD55过度表达是乳腺癌患者术后接受包含曲妥珠单抗的辅助治疗的复发的独立危险因素。联合使用他莫昔芬和曲妥珠单抗治疗HER2阳性乳腺癌可能通过升高的CDC增强曲妥珠单抗的抗肿瘤作用。这值得进一步研究。
Complement-dependent cytotoxicity (CDC) is an important antitumor mechanism of monoclonal antibodies (mAbs). However, trastuzumab, an anti-HER2 mAb, exerts only minor CDC. Overexpression of membrane-bound complement regulatory proteins (mCRPs), which suppress CDC, have been implicated in various malignant tumors. Here, we explored the predictive role of the expression levels of three mCRPs (CD55, CD59 and CD46) in the prognosis of breast cancer cases that underwent adjuvant trastuzumab treatment. We also studied the effect of mCRP downregulation on trastuzumab-induced CDC in vitro. Sixty-five HER2-positive breast cancer patients who received adjuvant therapy containing trastuzumab, were retrospectively analyzed. Levels of CD55, CD59 and CD46 expression were detected by immunohistochemistry. Chi-square test, Kaplan‑Meier survival analysis and a Cox proportional hazards model were used to analyze the association between CD55, CD59 and CD46 expression and prognosis. HER2-positive SK-Br3 and BT-474 breast cancer cells were pretreated with various drugs to reduce mCRP expression. Afterwards, trastuzumab‑mediated cytolytic effects were measured. Among the 65 patients, 46.2% had high expression of CD55, 44.6% had high expression of CD59 and 44.6% had high expression of CD46. The median follow-up duration was 47 months (range from 24 to 75 months). Patients with CD55 or CD59 overexpression had a higher relapse rate than those with low expression of CD55 (33.3 vs. 8.6%; P=0.013) or CD59 (31.0 vs. 11.1%; P=0.046). Similarly, mean disease-free survival of patients with CD55 or CD59 overexpression was significantly shorter than those with a low expression of CD55 (56 vs. 70 months; log-rank test, P=0.008) or CD59 (56 vs. 69 months; log-rank test, P=0.033). Multivariate analysis confirmed that CD55, but not CD59, was an independent risk factor of recurrence (HR=4.757; 95% CI, 0.985-22.974; P=0.05). In vitro, we found that tamoxifen inhibited both the protein and mRNA expression levels of CD55, but not CD59 or CD46 in SK-Br3 and BT-474 cells. After pretreatment of tamoxifen, trastuzumab-induced cytolysis was enhanced through CD55 downregulation. In conclusion, CD55 overexpression is an independent risk factor for recurrence in breast cancer patients receiving postoperative adjuvant therapy containing trastuzumab. Combined use of tamoxifen and trastuzumab for HER2-positive breast cancer treatment may enhance the antitumor effects of trastuzumab by elevated CDC, which warrants further
study.