Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, 336 College of Pharmacy South, Athens, GA 30602, USA.
Integr Biol (Camb). 2013 Jan;5(1):172-82. doi: 10.1039/c2ib20108a.
Secretory phospholipase A(2) (sPLA(2)) cleave phospholipids at sn-2 ester bonds, releasing lysophospholipids and fatty acids, and are over expressed in several pathologies, including inflammation, arthritis, sepsis and breast and prostate cancers. Herein we evaluated the therapeutic activity of liposomes engineered to be responsive to different sPLA(2) isoforms compared to clinically used long-circulating (pegylated) sterically stabilized liposomes (SSL) in vitro and in vivo, and assessed differences in roles of sPLA(2) in the mechanism of uptake and delivery of these nanoparticles. Exposing sPLA(2) responsive liposomes (SPRL) to sPLA(2) increased the release of intraluminal entrapped contents in a time-dependent manner that was inhibited by the sPLA(2) inhibitor LY3117273. Treatment of prostate cancer cells with doxorubicin encapsulated in SSL and SPRL resulted in cytotoxicity in LNCaP, DU-145 and PC-3 cells lines comparable to free drug. Interestingly, cytotoxicity was not altered by sPLA(2) inhibition. Tracking of drug and liposome delivery using fluorescence microscopy and flow cytometry, we demonstrated that drug uptake was liposome-dependent, as encapsulation of doxorubicin in SPRL resulted in 1.5 to 2-fold greater intracellular drug levels compared to SSL. Liposome uptake was cell-dependent and did not correlate to doxorubicin uptake; however, doxorubicin uptake was generally greatest in PC-3 cells, followed by DU-145 cells and then LNCaP cells. In almost all cases, uptake of one of our formulations, SPRL-E, was greater than SSL. The therapeutic activity of SPRL in vivo was demonstrated using a mouse xenograft model of human prostate cancer, which showed that doxorubicin entrapped within SPRL decreased tumor growth compared to SSL, suggesting that SPRL are more effective at slowing tumor growth than a SSL formulation similar to the FDA approved DOXIL™. Collectively, these data show the therapeutic activity of SPRL compared to SSL, yield insights into the mechanisms of action of these nanoparticles and suggest that SPRL could be useful for treatment of other pathologies that over express sPLA(2).
分泌型磷脂酶 A(2)（sPLA(2)）在 sn-2 酯键处切割磷脂，释放溶血磷脂和脂肪酸，并在多种病理状态下过度表达，包括炎症、关节炎、脓毒症以及乳腺癌和前列腺癌。在此，我们评估了与临床上使用的长循环（聚乙二醇化）立体稳定脂质体（SSL）相比，针对不同 sPLA(2) 同工型进行工程设计的脂质体的治疗活性，在体外和体内评估了 sPLA(2) 在这些纳米颗粒摄取和递送上的作用机制中的差异。暴露于 sPLA(2) 的响应性脂质体（SPRL）以时间依赖性方式增加腔内包裹内容物的释放，该释放被 sPLA(2) 抑制剂 LY3117273 抑制。用 SSL 和 SPRL 包封的多柔比星处理前列腺癌细胞导致 LNCaP、DU-145 和 PC-3 细胞系的细胞毒性与游离药物相当。有趣的是，sPLA(2) 抑制并未改变细胞毒性。通过荧光显微镜和流式细胞术跟踪药物和脂质体的递送，我们证明药物摄取依赖于脂质体，因为将多柔比星包封在 SPRL 中导致与 SSL 相比细胞内药物水平增加 1.5 至 2 倍。脂质体摄取依赖于细胞，与多柔比星摄取无关；然而，多柔比星摄取通常在 PC-3 细胞中最大，其次是 DU-145 细胞，然后是 LNCaP 细胞。在几乎所有情况下，我们的一种制剂 SPRL-E 的摄取都大于 SSL。通过人前列腺癌的小鼠异种移植模型证明了 SPRL 在体内的治疗活性，结果表明，与 SSL 相比，包封在 SPRL 中的多柔比星降低了肿瘤生长，这表明 SPRL 比与 FDA 批准的 DOXIL™ 相似的 SSL 制剂更有效地减缓肿瘤生长。总之，这些数据显示了 SPRL 与 SSL 相比的治疗活性，深入了解了这些纳米颗粒的作用机制，并表明 SPRL 可能对治疗其他过度表达 sPLA(2) 的病理状态有用。
