MRI-visible micellar nanomedicine for targeted drug delivery to lung cancer cells.

Polymeric micelles are emerging as a highly integrated nanoplatform for cancer targeting, drug delivery and tumor imaging applications. In this study, we describe a multifunctional micelle (MFM) system that is encoded with a lung cancer-targeting peptide (LCP), and encapsulated with superparamagnetic iron oxide (SPIO) and doxorubicin (Doxo) for MR imaging and therapeutic delivery, respectively. The LCP-encoded MFM showed significantly increased alpha(v)beta(6)-dependent cell targeting in H2009 lung cancer cells over a scrambled peptide (SP)-encoded MFM control as well as in an alpha(v)beta(6)-negative H460 cell control. (3)H-Labeled MFM nanoparticles were used to quantify the time- and dose-dependent cell uptake of MFM nanoparticles with different peptide encoding (LCP vs SP) and surface densities (20% and 40%) in H2009 cells. LCP functionalization of the micelle surface increased uptake of the MFM by more than 3-fold compared to the SP control. These results were confirmed by confocal laser scanning microscopy, which further demonstrated the successful Doxo release from MFM and accumulation in the nucleus. SPIO clustering inside the micelle core resulted in high T(2) relaxivity (>400 Fe mM(-1) s(-1)) of the resulting MFM nanoparticles. T(2)-weighted MRI images showed clear contrast differences between H2009 cells incubated with LCP-encoded MFM over the SP-encoded MFM control. An ATP activity assay showed increased cytotoxicity of LCP-encoded MFM over SP-encoded MFM in H2009 cells (IC(50) values were 28.3 +/- 6.4 nM and 73.6 +/- 6.3 nM, respectively; p < 0.005). The integrated diagnostic and therapeutic design of MFM nanomedicine potentially allows for image-guided, target-specific treatment of lung cancer.

Mitogenic activity and signaling mechanism of 2-(14,15- epoxyeicosatrienoyl)glycerol, a novel cytochrome p450 arachidonate metabolite.

Arachidonic acid is an essential constituent of cell membranes that is esterified to the sn-2 position of glycerophospholipids and is released from selected phospholipid pools by tightly regulated phospholipase cleavage. Metabolism of the released arachidonic acid by the cytochrome P450 enzyme system (cP450) generates biologically active compounds, including epoxyeicosatrienoic acids (EETs) and hydroxyeicosatetraenoic acids. Here we report that 2-(14,15-epoxyeicosatrienoyl)glycerol (2-14,15-EG), a novel cP450 arachidonate metabolite produced in the kidney, is a potent mitogen for renal proximal tubule cells. This effect is mediated by activation of tumor necrosis factor alpha-converting enzyme (ADAM17), which cleaves membrane-bound transforming growth factor alpha (proTGF-alpha) and releases soluble TGF-alpha as a ligand that binds and activates epidermal growth factor receptor (EGFR). The present studies additionally demonstrate that the structurally related 14,15-EET stimulates release of soluble heparin-binding EGF-like growth factor as an EGFR ligand by activation of ADAM9, another member of the ADAM family. Thus, in addition to the characterization of 2-14,15-EG's mitogenic activity and signaling mechanism, our study provides the first example that two structurally related biologically active lipid mediators can activate different metalloproteinases and release different EGFR ligands in the same cell type to activate EGFR and stimulate cell proliferation.

In vivo off-resonance saturation magnetic resonance imaging of alphavbeta3-targeted superparamagnetic nanoparticles.

Magnetic resonance imaging is a powerful clinical imaging technique that allows for noninvasive tomographic visualization of anatomic structures with high spatial resolution and soft tissue contrast. However, its application in molecular imaging of cancer has been limited by the lack of sensitivity and detection accuracy in depicting the biochemical expression of these diseases. Here, we combine an ultrasensitive design of superparamagnetic polymeric micelles (SPPM) and an off-resonance saturation (ORS) method to enhance the imaging efficacy of tumor biomarkers in vivo. SPPM nanoparticles encoded with cyclic(RGDfK) were able to target the alpha(v)beta(3)-expressing microvasculature in A549 non-small cell lung tumor xenografts in mice. ORS greatly improved tumor detection accuracy over the conventional T(2)*-weighted method by its ability to turn "ON" the contrast of SPPM. This combination of ORS imaging with a tumor vasculature-targeted, ultrasensitive SPPM design offers new opportunities in molecular imaging of cancer.

Identification of novel endogenous cytochrome p450 arachidonate metabolites with high affinity for cannabinoid receptors.

Arachidonic acid is an essential constituent of cell membranes that is esterified to the sn-2-position of glycerophospholipids and is released from selected lipid pools by phospholipase cleavage. The released arachidonic acid can be metabolized by three enzymatic pathways: the cyclooxygenase pathway forming prostaglandins and thromboxanes, the lipoxygenase pathway generating leukotrienes and lipoxins, and the cytochrome P450 (cP450) pathway producing epoxyeicosatrienoic acids and hydroxyeicosatetraenoic acids. The present study describes a novel group of cP450 epoxygenase-dependent metabolites of arachidonic acid, termed 2-epoxyeicosatrienoylglycerols (2-EG), including two regioisomers, 2-(11,12-epoxyeicosatrienoyl)glycerol (2-11,12-EG) and 2-(14,15-epoxyeicosatrienoyl)glycerol (2-14,15-EG), which are both produced in the kidney and spleen, whereas 2-11,12-EG is also detected in the brain. Both 2-11,12-EG and 2-14,15-EG activated the two cannabinoid (CB) receptor subtypes, CB1 and CB2, with high affinity and elicited biological responses in cultured cells expressing CB receptors and in intact animals. In contrast, the parental arachidonic acid and epoxyeicosatrienoic acids failed to activate CB1 or CB2 receptors. Thus, these cP450 epoxygenase-dependent metabolites are a novel class of endogenously produced, biologically active lipid mediators with the characteristics of endocannabinoids. This is the first evidence of a cytochrome P450-dependent arachidonate metabolite that can activate G-protein-coupled cell membrane receptors and suggests a functional link between the cytochrome P450 enzyme system and the endocannabinoid system.

Multifunctional polymeric micelles as cancer-targeted, MRI-ultrasensitive drug delivery systems.

We describe the development of multifunctional polymeric micelles with cancer-targeting capability via alpha(v)beta(3) integrins, controlled drug delivery, and efficient magnetic resonance imaging (MRI) contrast characteristics. Doxorubicin and a cluster of superparamagnetic iron oxide (SPIO) nanoparticles were loaded successfully inside the micelle core. The presence of cRGD on the micelle surface resulted in the cancer-targeted delivery to alpha(v)beta(3)-expressing tumor cells. In vitro MRI and cytotoxicity studies demonstrated the ultrasensitive MRI imaging and alpha(v)beta(3)-specific cytotoxic response of these multifunctional polymeric micelles.