Abstract #1573: Nanoparticle-mediated targeting of MAPK signaling predisposes tumor to chemotherapy
Authors: Sudipta Basu, Rania Harfouche, Shivani Soni, Geetanjali Chimote, Shiladitya Sengupta
Journal: Cancer Research (2009)

One of the recent advances in cancer chemotherapy is the use of nanotechnology to improve the efficacy of cytotoxic agents. However, with the increased molecular understanding of cancer progression, there is an increasing shift towards targeted therapy. For example, the mitogen-activated protein kinase (MAPK) cascade, a key intracellular signaling pathway, is deregulated in most human tumors, and is a key therapeutic target. RAS mutations are found in 30% of all cancer, and are in particular common in pancreatic cancer (90%), colon cancer (50%) and were overexpressed in 25% of breast cancer cell lines, while RAF mutations are prevalent in melanomas (63%), ovarian cancer (36%). The aim of the study is nanoparticle-mediated targeting of this pathway can optimize cancer chemotherapy. In this study, we integrated a PLGA-based nanoparticle with an extensively characterized inhibitor of PD98059, to perturb the MAPK signaling pathway. A limitation of PLGA as a carrier is the linear aspect of the polymer, which results in a 1:1 molar loading ratio with the drug, resulting in low loading efficiency. To overcome this limitation we developed a hexadentate-variant of PLGA by chemical synthesis, and engineered nanoparticles by emulsion-solvent evaporation with a 20-fold increase in drug loading. Electron microscopy revealed the size (80-140 nm diameter) and morphology of the nanoparticles. The physicochemical release kinetics of PD98059 from the nanoparticles in different hypoxic cell lysates showed a sustained release of PD98059. We evaluated the anticancer effects of the PD98059-nanoparticle as compared with free PD98059 in a series of in vitro cytotoxicity assays using MTS assays. We used three different cancer cell lines for this study, the B16/F10 melanoma cells, the MDA231 breast cancer cells and Lewis lung carcinoma cells. Study indicated that MDA231 was resistant to PD98059-nanparticle, while B16/F10 was most susceptible. We also developed fluorescently labelled nanoparticles to study the uptake mechanism. The fluorescent nanoparticles were taken up by cancer cells through endocytosis. The Western analysis showed that PD98059 loaded nanoparticles inhibited the phosphorylation of downstream extracellular signal regulated kinase (ERK). We demonstrate that nanoparticle-targeted MAPK inhibition blocks proliferation of B16/F10 melanoma, and Lewis Lung carcinoma cells and induces apoptosis in vitro by FACS analysis. Administration of the PD98059-loaded nanoparticles in B16/F10 melanoma-bearing mouse inhibited tumor growth in vivo as compared with free PD98059. Furthermore, when combined with cisplatin, nanoparticle-PD98059 exerted a dramatically improved synergistic anticancer activity in vivo. Our study, for the first time, shows the targeting of signal transduction pathways using nanoparticles can result in improved anticancer effect.  Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 1573.