Pagnan G, Montaldo P G, Pastorino F, Raffaghello L, Kirchmeier M, Allen T M, Ponzoni M
Laboratory of Oncology, G. Gaslini Children's Hospital, Genoa, Italy.
Int J Cancer. 1999 Apr 12;81(2):268-74. doi: 10.1002/(sici)1097-0215(19990412)81:2<268::aid-ijc17>3.0.co;2-1.
Melanoma is a highly malignant and increasingly common neoplasm. Because metastatic melanoma remains incurable, new treatment approaches are needed. Immunoliposomes have been previously shown to enhance the selective localization of immunoliposome-entrapped drugs to solid tumors with improvements in the therapeutic index of the drugs. Previously, we reported that the synthetic retinoid fenretinide (HPR) is an inducer of apoptosis in neuroblastoma (NB) cells, sharing the neuroectodermal origin with melanoma cells. HPR is a strong inducer of apoptosis also in melanoma cells, although at doses 10-fold higher than those achievable clinically. Thus, our purpose was to investigate the in vitro potentiation of its cytotoxic effect on melanoma cells in combination with long-circulating GD2-targeted immunoliposomes. GD2 is a disialoganglioside extensively expressed on tumors of neuroectodermal origin, including melanoma. Murine anti-GD2 antibody (Ab) 14.G2a and its human/mouse chimeric variant ch14.18 have been ligated to sterically stabilized liposomes by covalent coupling of Ab to the polyethylene glycol (PEG) terminus. Ab-bearing liposomes showed specific, competitive binding to and uptake by various melanoma cell lines compared with liposomes bearing non-specific isotype-matched Abs or Ab-free liposomes. Cytotoxicity was evaluated after 2 hr treatment, followed by extensive washing and 72 hr incubation. This treatment protocol was designed to minimize non-specific adsorption of liposomes to the cells, while allowing for maximum Ab-mediated binding. When melanoma cells were incubated with 30 microM HPR entrapped in anti-GD2 liposomes, a significant reduction in cellular growth was observed compared to free HPR, entrapped HPR in Ab-free liposomes or empty liposomes. Cytotoxicity was not evident in tumor cell lines of other origins that did not express GD2. Growth of NB cells was also inhibited by immunoliposomes with entrapped HPR.
黑色素瘤是一种高度恶性且日益常见的肿瘤。由于转移性黑色素瘤仍然无法治愈，因此需要新的治疗方法。免疫脂质体先前已被证明可增强包封于免疫脂质体中的药物在实体瘤中的选择性定位，同时提高药物的治疗指数。此前，我们报道合成视黄酸芬维A胺（HPR）是神经母细胞瘤（NB）细胞凋亡的诱导剂，它与黑色素瘤细胞具有共同的神经外胚层起源。HPR也是黑色素瘤细胞凋亡的强诱导剂，尽管其剂量比临床可达到的剂量高10倍。因此，我们的目的是研究其与长循环的GD2靶向免疫脂质体联合使用时对黑色素瘤细胞的体外细胞毒性增强作用。GD2是一种二唾液酸神经节苷脂，在包括黑色素瘤在内的神经外胚层起源的肿瘤上广泛表达。通过将鼠抗GD2抗体（Ab）14.G2a及其人/鼠嵌合变体ch14.18与聚乙二醇（PEG）末端共价偶联，将其连接到空间稳定的脂质体上。与携带非特异性同型匹配抗体或无抗体脂质体相比，携带抗体的脂质体显示出对各种黑色素瘤细胞系的特异性、竞争性结合和摄取。在2小时处理后评估细胞毒性，随后进行大量洗涤并孵育72小时。该处理方案旨在使脂质体对细胞的非特异性吸附最小化，同时允许最大程度的抗体介导结合。当黑色素瘤细胞与包封于抗GD2脂质体中的30 microM HPR孵育时，与游离HPR、包封于无抗体脂质体中的HPR或空脂质体相比，观察到细胞生长显著降低。在不表达GD2的其他起源的肿瘤细胞系中未观察到细胞毒性。包封有HPR的免疫脂质体也抑制了NB细胞的生长。
