Effective and safe delivery of anticancer agents is among the major challenges in cancer therapy. The majority of anticancer agents are toxic to normal cells, have poor bioavailability, and lack in vivo stability. Recent advancements in nanotechnology provide safe and efficient drug delivery systems for successful delivery of anticancer agents via nanoparticles. The physicochemical and functional properties of the nanoparticle vary for each of these anticancer agents, including chemotherapeutics, nucleic acid-based therapeutics, small molecule inhibitors, and photodynamic agents. The characteristics of the anticancer agents influence the design and development of nanoparticle carriers. This review focuses on strategies of nanoparticle-based drug delivery for various anticancer agents. Recent advancements in the field are also highlighted, with suitable examples from our own research efforts and from the literature.

Successful chemotherapeutic intervention for management of lung cancer requires an efficient drug delivery system. Gold nanoparticles (GNPs) can incorporate various therapeutics; however, GNPs have limitations as drug carriers. Nano-sized cellular vesicles like exosomes (Exo) can ferry GNP-therapeutic complexes without causing any particle aggregation or immune response. In the present study, we describe the development and testing of a novel Exo-GNP-based therapeutic delivery system -‘nanosomes’- for lung cancer therapy. This system consists of GNPs conjugated to anticancer drug doxorubicin (Dox) by a pH-cleavable bond that is physically loaded onto the exosomes (Exo-GNP-Dox). The therapeutic efficacy of Dox in nanosomes was assessed in H1299 and A549 non-small cell lung cancer cells, normal MRC9 lung fibroblasts, and Dox-sensitive human coronary artery smooth muscle cells (HCASM). The enhanced rate of drug release under acidic conditions, successful uptake of the nanosomes by the recipient cells and the cell viability assays demonstrated that nanosomes exhibit preferential cytotoxicity towards cancer cells and have minimal activity on non-cancerous cells. Finally, the underlying mechanism of cytotoxicity involved ROS-mediated DNA damage. Results from this study mark the establishment of an amenable drug delivery vehicle and highlight the advantages of a natural drug carrier that demonstrates reduced cellular toxicity and efficient delivery of therapeutics to cancer cells.

BackgroundThe stromal cell derived factor (SDF)-1/chemokine receptor (CXCR)-4 signaling pathway plays a key role in lung cancer metastasis and is molecular target for therapy. In the present study we investigated whether interleukin (IL)-24 can inhibit the SDF-1/CXCR4 axis and suppress lung cancer cell migration and invasion in vitro. Further, the efficacy of IL-24 in combination with CXCR4 antagonists was investigated.MethodsHuman H1299, A549, H460 and HCC827 lung cancer cell lines were used in the present study. The H1299 lung cancer cell line was stably transfected with doxycycline-inducible plasmid expression vector carrying the human IL-24 cDNA and used in the present study to determine the inhibitory effects of IL-24 on SDF-1/CXCR4 axis. H1299 and A549 cell lines were used in transient transfection studies. The inhibitory effects of IL-24 on SDF1/CXCR4 and its downstream targets were analyzed by quantitative RT-PCR, western blot, luciferase reporter assay, flow cytometry and immunocytochemistry. Functional studies included cell migration and invasion assays.Principal FindingsEndogenous CXCR4 protein expression levels varied among the four human lung cancer cell lines. Doxycycline-induced IL-24 expression in the H1299-IL24 cell line resulted in reduced CXCR4 mRNA and protein expression. IL-24 post-transcriptionally regulated CXCR4 mRNA expression by decreasing the half-life of CXCR4 mRNA (>40%). Functional studies showed IL-24 inhibited tumor cell migration and invasion concomitant with reduction in CXCR4 and its downstream targets (pAKTS473, pmTORS2448, pPRAS40T246 and HIF-1α). Additionally, IL-24 inhibited tumor cell migration both in the presence and absence of the CXCR4 agonist, SDF-1. Finally, IL-24 when combined with CXCR4 inhibitors (AMD3100, SJA5) or with CXCR4 siRNA demonstrated enhanced inhibitory activity on tumor cell migration.ConclusionsIL-24 disrupts the SDF-1/CXCR4 signaling pathway and inhibits lung tumor cell migration and invasion. Additionally, IL-24, when combined with CXCR4 inhibitors exhibited enhanced anti-metastatic activity and is an attractive therapeutic strategy for lung metastasis.

The CXCR4 chemokine receptor plays an important role in cancer cell metastasis. The CXCR4 antagonist, AMD3100, has limited efficacy in controlling metastasis. HuR, an RNA-binding protein, regulates CXCR4 in cancer cells. We therefore investigated whether targeting HuR using a siRNA-based nanoparticle plus AMD3100 would suppress CXCR4 and inhibit lung cancer metastasis. We treated human H1299 lung cancer cell with HuR-specific siRNA contained in a folate-targeted lipid nanoparticle (HuR-FNP) plus AMD3100, and compared this with AMD3100 alone, HuR-FNP alone and no treatment. HuR-FNP plus AMD3100 treatment produced a G1 phase cell-cycle arrest and reduced cell viability above and beyond the effects of AMD3100 alone. HuR and CXCR4 mRNA and protein expression levels were markedly reduced in all treatment groups. Phosphorylated (p) AKTS473 protein was also reduced. P27 protein expression increased with HuR-FNP and combination treatment. Promoter-based reporter studies showed that the combination inhibited CXCR4 promoter activity more than did either treatment alone. Cell migration and invasion was significantly reduced with all treatment; the combination provided the most inhibition. Reduced matrix metalloprotease (MMP) -2 and -9 expression was associated with reduced invasion in all treatment groups. Thus, we found that combined HuR and CXCR4 targeting effectively controlled lung cancer metastasis.

Tumor-associated M2-macrophages are one of the most abundant immunosuppressive cell types in the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME). However, the molecular mechanisms responsible for the generation of M2macrophages are unclear. Here, we demonstrated that overexpression of DCLK1-isoform2 in AsPC1 and MIA PaCa2 cells resulted in the polarization of M1-macrophages toward an M2 phenotype via secreted chemokines/cytokines. These M2-macrophages enhanced parental PDAC cell migration, invasion, and selfrenewal, and this was associated with increased expression of Snail and Slug. We observed distinct expression of Dclk-iso-form2, marked infiltration of M2-macrophages, and a marginal increase of CD8 þ T cells in 20-week-old KPCY mice pancreas compared with 5 weeks old. Utilizing an autochthonous mouse model of pancreatic adenocarcinoma, we observed distinct immunoreactive Dclk1 and arginase1 in tissues where CD8 þ T-cell infiltration was low and observed a paucity of DCLK1 and arginase1 staining where CD8 þ T-cell infiltration was high. Finally, we found that DCLK1-isoform2 tumor-educated M2macrophages inhibit CD8 þ T-cell proliferation and granzyme-B activation. Inhibition of DCLK1 in an organoid coculture system enhanced CD8 þ T-cell activation and associated organoid death. We conclude that DCLK1-isoform2 is a novel initiator of alternate macrophage activation that contributes to the immunosuppression observed in the PDAC TME. These data suggest that tumor DCLK1-isoform2 may be an attractive target for PDAC therapy, either alone or in conjunction with immunotherapeutic strategies.