Combined trastuzumab and paclitaxel treatment better inhibits ErbB-2-mediated angiogenesis in breast carcinoma through a more effective inhibition of Akt than either treatment alone
Combined trastuzumab and paclitaxel treatment better inhibits ErbB-2-mediated angiogenesis in breast carcinoma through a more effective inhibition of Akt than either treatment alone
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作者：
Kos, KS;Zhou, XY;Yu, DH
背景曲妥珠单抗（赫赛汀; Genentech，South San弗朗西斯科，CA）是一种人源化抗ErbB-2单克隆抗体，其已在患有过表达ErbB-2的肿瘤的患者中显示出抗肿瘤功能，特别是与其它化疗剂如紫杉醇（Taxol;布里斯托迈尔斯-施贵宝，普林斯顿，NJ）组合。由于重复给予低剂量化疗（如紫杉醇）证实了体外抗血管生成作用，并且曲妥珠单抗显示出抑制肿瘤异种移植物中的血管生成，因此作者研究了紫杉醇加曲妥珠单抗联合治疗是否能更有效地抑制ErbB-2介导的血管生成反应。通过将ErbB-2过表达的人乳腺癌细胞注射到乳腺脂肪垫中，在37只严重联合免疫缺陷小鼠中建立肿瘤异种移植物。然后用免疫球蛋白（IgG）对照、曲妥珠单抗、紫杉醇或曲妥珠单抗加紫杉醇的组合治疗处理小鼠。评价成瘤性、肺转移和肿瘤微血管密度（MVD）。血管内皮生长因子（VEGF）的分泌，治疗后的内皮细胞迁移，磷酸化Akt的状态进行了评估，在体外，以确定ErbB-2诱导的血管生成的抑制机制。与IgG对照组相比，曲妥珠单抗加紫杉醇联合治疗组小鼠的平均肿瘤体积显著降低（419.5 mm（3）vs. 786.6 mm（3），p < 0.0001）。用曲妥珠单抗治疗的小鼠的平均肿瘤体积为543.9mm3（3），用紫杉醇治疗的小鼠的平均肿瘤体积为574.9mm3（3）。与对照组相比，曲妥珠单抗+紫杉醇组的肿瘤平均MVD也显著降低（30 +/- 8 MVD vs. 44 +/- 12 MVD，P < 0.05）。曲妥珠单抗组的肿瘤MVD为35 +/- 7，与紫杉醇治疗组（35 +/- 9）相似。曲妥珠单抗+紫杉醇组中44%的小鼠有肺转移，而紫杉醇、曲妥珠单抗和对照组中分别有50%、63%和75%的小鼠有肺转移。在体外，用曲妥珠单抗加紫杉醇组合处理的ErbB-2过表达细胞比用曲妥珠单抗、紫杉醇或对照处理的细胞分泌更少的VEGF（分别为185.9 pg/mL对233.2 pg/mL、261.3 pg/mL和286.4 pg/mL）。此外，来自组合组的条件培养基刺激较少的平均内皮细胞迁移（分别为31.0个细胞对47.0个细胞、39.2个细胞和67.5个细胞）。此外，Akt磷酸化促进了VEGF的上调，曲妥珠单抗联合紫杉醇治疗能更有效地降低Akt磷酸化水平。曲妥珠单抗联合紫杉醇治疗比单独治疗更有效地抑制ErbB-2介导的血管生成，这导致更明显的杀肿瘤作用。这种作用可能是通过减少磷酸化Akt介导的。癌症2003;98：1377-85. (C)2003年美国癌症协会。
BACKGROUND. Trastuzumab (Herceptin; Genentech, South San Francisco, CA) is a humanized anti-ErbB-2 monoclonal antibody that has demonstrated antitumor function, especially in combination with other chemotherapies such as paclitaxel (Taxol; Bristol Myers-Squibb, Princeton, NJ), in patients with tumors that overexpress ErbB-2. Because the repeated administration of low-dose chemotherapy, such as paclitaxel, endorsed an antiangiogenic effect in vitro, and because trastuzumab was shown to inhibit angiogenesis in tumor xenografts, the authors investigated whether ErbB-2-mediated angiogenic responses would be inhibited more effectively by the combined treatment of paclitaxel plus trastuzumab.METHODS. Tumor xenografts were established in 37 severe combined immunodeficiency mice by injecting the mammary fat pad with ErbB-2-overexpressing human breast carcinoma cells. Mice then were treated with an immunoglobulin (IgG) control, trastuzumab, paclitaxel, or a combination treatment of trastuzumab plus paclitaxel. Tumorigenicity, lung metastasis, and tumor microvessel density (MVD) were evaluated. Vascular endothelial growth factor (VEGF) secretion, endothelial cell migration after treatment, and the status of phosphorylated Akt were evaluated in vitro to determine mechanisms underlying the inhibition of ErbB-2-induced angiogenesis.RESULTS. Mice treated with the trastuzumab plus paclitaxel combination exhibited significantly reduced mean tumor volumes compared with mice treated with the IgG control (419.5 mm(3) vs. 786.6 mm(3), p < 0.0001). mice treated with trastuzumab had a mean tumor volume of 543.9 mm(3), and mice treated with paclitaxel had a mean tumor volume of 574.9 mm(3). Tumors from the trastuzumab-plus-paclitaxel group also had significantly decreased mean MVD compared with the control (30 +/- 8 MVD vs. 44 +/- 12 MVD, P < 0.05). The trastuzumab group had tumors with a MVD of 35 +/- 7, similar to the paclitaxel-treated group (35 +/- 9). Forty-four percent of the mice in the trastuzumab-plus-paclitaxel group had metastases to the lungs compared with 50%, 63%, and 75% of the mice in the paclitaxel, trastuzumab, and control groups, respectively. In vitro, the ErbB-2-overexpressing cells treated with combined trastuzumab plus paclitaxel secreted less VEGF than the cells treated with trastuzumab, paclitaxel, or control (185.9 pg/mL vs. 233.2 pg/mL, 261.3 pg/mL, and 286.4 pg/mL, respectively). In addition, the conditioned media from the combination group stimulated less mean endothelial cell migration (31.0 cells vs. 47.0 cells, 39.2 cells, and 67.5 cells, respectively). Furthermore, Akt phosphorylation contributed to VEGF up-regulation and Akt phosphorylation was reduced more effectively by combined trastuzumab plus paclitaxel treatment compared with the other treatments.CONCLUSIONS. Combined trastuzumab plus paclitaxel treatment more effectively inhibited ErbB-2-mediated angiogenesis than either treatment alone, which resulted in more pronounced tumoricidal effects. This effect may be mediated via the reduction of phosphorylated Akt. Cancer 2003;98:1377-85. (C) 2003 American Cancer Society.