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Molecular pharmaceutics [journal]
- Targeted intracellular delivery of proteins with spatial and temporal control. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 9.
While a host of methods exist to deliver genetic materials or small molecules to cells, very few are available for protein delivery to the cytosol. We describe a modular, light-activated nanocarrier that transports proteins into cells by receptor-mediated endocytosis, and delivers the cargo to the cytosol by light triggered endosomal escape. The platform is based on hollow gold nanoshells (HGN) with poly-histidine tagged proteins attached through an avidity-enhanced, nickel chelation linking layer; here, we used green fluorescent protein (GFP) as a model deliverable cargo. Endosomal uptake of the GFP loaded nanocarrier was mediated by a C-end Rule (CendR) internalizing peptide fused to the GFP. Focused femtosecond pulsed-laser excitation triggered protein release from the nanocarrier and endosome disruption, and the released protein was capable of targeting the nucleoli, a model intracellular organelle. We further demonstrate the generality of the approach by loading and releasing Sox2 and p53. This method for targeting of individual cells, with resolution similar to microinjection, provides spatial and temporal control over protein delivery.
- Targeted PDT Agent Eradicates TrkC Expressing Tumors via Photodynamic Therapy (PDT). [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 9.
This contribution features a small molecule that binds TrkC (tropomyosin receptor kinase C) receptor that tends to be overexpressed in metastatic breast cancer cells but not in other breast cancer cells. A sensitizer for (1)O2 production conjugated to this structure gives 1-PDT for photodynamic therapy. Isomeric 2-PDT does not bind TrkC and was used as a control throughout; similarly, TrkC- cancer cells were used to calibrate enhanced killing of TrkC+ cells. Ex vivo, 1- and 2-PDT where only cytotoxic when illuminated, and 1-PDT, gave higher cell death for TrkC+ breast cancer cells. A 1 h administration-to-illumination delay gave optimal TrkC+/TrkC--photocytotoxicity, and distribution studies showed the same delay was appropriate in vivo. In Balb/c mice, a maximum tolerated dose of 20 mg/kg was determined for 1-PDT. 1- and 2-PDT (single, 2 or 10 mg/kg doses and one illumination, throughout) had similar effects on implanted TrkC- tumors, and like those of 2-PDT on TrkC+ tumors. In contrast, 1-PDT caused dramatic TrkC+ tumor volume reduction (96% from initial) relative to the TrkC- tumors or 2-PDT in TrkC+ models. Moreover, 71% of the mice treated with 10 mg/kg 1-PDT (n = 7) showed full tumor remission and survived until 90 days with no metastasis to key organs.
- Methotrexate-conjugated PEGylated dendrimers show differential patterns of deposition and activity in tumour-burdened lymph nodes after intravenous and subcutaneous administration in rats. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 8.
The current study sought to explore whether the subcutaneous administration of lymph-targeted dendrimers, conjugated with a model chemotherapeutic (methotrexate, MTX), was able to enhance anticancer activity against lymph node metastases. The lymphatic pharmacokinetics and antitumour activity of PEGylated polylysine dendrimers conjugated to MTX [D-MTX(OH)] via a tumour-labile hexapeptide linker was examined in rats and compared to a similar system where MTX was α-carboxyl O-tert-butylated [D-MTX(OtBu)]. The latter has previously been shown to exhibit longer plasma circulation times. D-MTX(OtBu) was well absorbed from the subcutaneous injection site via the lymph, and 3 to 4%/g of the dose was retained by sentinel lymph nodes. In contrast, D-MTX(OH) showed limited absorption from the subcutaneous injection site, but absorption was almost exclusively via the lymph. The retention of D-MTX(OH) by sentinel lymph nodes was also significantly elevated (approximately 30% dose/g). MTX alone was not absorbed into the lymph. All dendrimers displayed lower lymph node targeting after intravenous administration. Despite significant differences in the lymph node retention of D-MTX(OH) and D-MTX(OtBu) after subcutaneous and intravenous administration, the growth of lymph node metastases was similarly inhibited. In contrast, the administration of MTX alone did not significantly reduce lymph node tumour growth. Subcutaneous administration of drug-conjugated dendrimers therefore provides an opportunity to improve drug deposition in downstream tumour-burdened lymph nodes. In this case, however, increased lymph node biodistribution did not correlate well with antitumour activity, possibly suggesting constrained drug release at the site of action.
- Chirality Switching within an Anionic Cell-Penetrating Peptide Inhibits Translocation without Affecting Preferential Entry. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 5.
Multiple substitution of d- for l-amino acids decreases the intracellular uptake of cationic cell penetrating peptides (CPP) in a cell line-dependent manner. We show here that a single d-amino acid substitution can decrease the overall uptake of the anionic, amphipathic CPP, p28, into cancer and histologically matched normal cell lines, while not altering the preferential uptake of p28 into cancer cells. The decrease appears dependent on the position of the d-substitution within the peptide and the ability of the substituted d-amino acid to alter chirality. We also suggest that when d-substitution alters the ratio of α-helix to β-sheet content of an anionic CPP, its translocation across the cell membrane is altered, reducing overall entry. These observations may have a significant effect on the design of future d-substituted analogues of cell penetrating peptides.
- Approaches to Interchain Cysteine-Linked ADC Characterization by Mass Spectrometry. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 17.
Therapeutic antibody-drug conjugates (ADCs) harness the cell-killing potential of cytotoxic agents and the tumor targeting specificity of monoclonal antibodies to selectively kill tumor cells. Recent years have witnessed the development of several promising modalities that follow the same basic principles of ADC based therapies but which employ unique cytotoxic agents and conjugation strategies in order to realize therapeutic benefit. The complexity and heterogeneity of ADCs present a challenge to some of the conventional analytical methods that industry has relied upon for biologics characterization. This current review will highlight some of the more recent methodological approaches in mass spectrometry that have bridged the gap that is created when conventional analytical techniques provide an incomplete picture of ADC product quality. Specifically, we will discuss mass spectrometric approaches that preserve and/or capture information about the native structure of ADCs and provide unique insights into the higher order structure (HOS) of these therapeutic molecules.
- Coencapsulated Doxorubicin and Bromotetrandrine Lipid Nanoemulsions in Reversing Multidrug Resistance in Breast Cancer in Vitro and in Vivo. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 12.
Multidrug resistance has remained a major cause of treatment failure in chemotherapy due to the presence of P-glycoproteins (P-gp) that actively pump drugs from inside the cell to the outside. P-gp inhibitors were developed and coadministered with chemotherapeutic drugs to overcome the effect of efflux pumps thus enhancing the chemosensitivity of therapeutics. Our study aimed at developing a lipid nanoemulsion system for the coencapsulation of doxorubicin (DOX) and bromotetrandrine (W198) to reverse multidrug resistance (MDR) in breast cancer. W198 was a potent P-gp inhibitor, and DOX was selected as a model compound which is a common substrate for P-gp. Coencapsulated DOX and W198 lipid nanoemulsions (DOX/W198-LNs) displayed significantly enhanced cytotoxicity in DOX-resistant human breast cancer cells (MCF-7/ADR) compared with DOX loaded lipid nanoemulsions (DOX-LNs) (p < 0.05), which is due to the enhanced intracellular uptake of DOX in MCF-7/ADR cells. The biodistribution study was performed using a nude mice xenograft model, which demonstrates enhanced tumor uptake of DOX in the DOX/W198-LN treated group. Compared with DOX solution, DOX/W198-LNs showed reduced cardiac toxicity and gastrointestinal injury in rats. Taken together, DOX/W198-LNs represent a promising formulation for overcoming MDR in breast cancer.
- Expression of Drug Transporters and Drug Metabolizing Enzymes in the Bladder Urothelium in Man and Affinity of the Bladder Spasmolytic Trospium Chloride to Transporters Likely Involved in Its Pharmacokinetics. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 10.
The cationic, water-soluble quaternary trospium chloride (TC) is incompletely absorbed from the gut and undergoes wide distribution but does not pass the blood-brain barrier. It is secreted by the kidneys, liver, and intestine. To evaluate potential transport mechanisms for TC, we measured affinity of the drug to the human uptake and efflux transporters known to be of pharmacokinetic relevance. Affinity of TC to the uptake transporters OATP1A2, -1B1, -1B3, -2B1, OCT1, -2, -3, OCTN2, NTCP, and ASBT and the efflux carriers P-gp, MRP2 and MRP3 transfected in HEK293 and MDCK2 cells was measured. To identify relevant pharmacokinetic mechanisms in the bladder urothelium, mRNA expression of multidrug transporters, drug metabolizing enzymes, and nuclear receptors, and the uptake of TC into primary human bladder urothelium (HBU) cells were measured. TC was shown to be a substrate of OATP1A2 (Km = 6.9 ± 1.3 μmol/L; Vmax = 41.6 ± 1.8 pmol/mg·min), OCT1 (Km = 106 ± 16 μmol/L; Vmax = 269 ± 18 pmol/mg·min), and P-gp (Km = 34.9 ± 7.5 μmol/L; Vmax = 105 ± 9.1 pmol/mg·min, lipovesicle assay). The genetic OATP1A2 variants *2 and *3 were loss-of-function transporters for TC. The mRNA expression analysis identified the following transporter proteins in the human urothelium: ABCB1 (P-gp), ABCC1-5 (MRP1-5), ABCG2 (BCRP), SLCO2B1 (OATP2B1), SLCO4A1 (OATP4A1), SLC22A1 (OCT1), SLC22A3 (OCT3), SLC22A4 (OCTN1), SLC22A5 (OCTN2), and SLC47A1 (MATE1). Immuno-reactive P-gp and OATP1A2 were localized to the apical cell layers. Drug metabolizing enzymes CYP3A5, -2B6, -2B7 -2E1, SULT1A1-4, UGT1A1-10, and UGT2B15, and nuclear receptors NR1H3 and NR1H4 were also expressed on mRNA level. TC was taken up into HBU cells (Km = 18.5 ± 4.8 μmol/L; Vmax = 106 ± 11.3 pmol/mg·min) by mechanisms that could be synergistically inhibited by naringin (IC50 = 10.8 (8.4; 13.8) μmol/L) and verapamil (IC50 = 4.6 (2.8; 7.5) μmol/L), inhibitors of OATP1A2 and OCT1, respectively. Affinity of TC to OCT1 and P-glycoprotein may be the reason for incomplete oral absorption, wide distribution into liver and kidneys, and substantial intestinal and renal secretions. Absence of brain distribution may result from affinity to P-gp and a low affinity to OATP1A2. The human urothelium expresses many drug transporters and drug metabolizing enzymes that may interact with TC and other drugs eliminated into the urine.
- Dendrimer Nanocarriers for Transport Modulation across Models of the Pulmonary Epithelium. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 2.
The purpose of this study was to determine the effect of PEGylation on the interaction of poly(amidoamine) (PAMAM) dendrimer nanocarriers (DNCs) with in vitro and in vivo models of the pulmonary epithelium. Generation-3 PAMAM dendrimers with varying surface densities of PEG 1000Da were synthesized and characterized. The results revealed that the apical to basolateral transport of DNCs across polarized Calu-3 monolayers increases with an increase in PEG surface density. DNC having the greatest number of PEG groups (n=25) on their surface traversed at a rate tenfold greater than its non-PEGylated counterpart, in spite of their larger size. This behavior was attributed to a significantly reduction in charge density upon PEGylation. We also observed that PEGylation can be used to modulate cellular internalization. The total uptake of PEG-free DNC into polarized Calu-3 monolayers was 12% (w/w) vs. 2% (w/w) for that with 25 PEGs. Polarization is also shown to be of great relevance in studying this in vitro model of the lung epithelium. The rate of absorption of DNCs administered to mice lungs increased dramatically when conjugated with 25 PEG groups, thus supporting the in vitro results. The exposure obtained for the DNC with 25PEG was determined to be very high, with peak plasma concentrations reaching 5 μg.mL-1 within 3h. The combined in vitro and in vivo results shown here demonstrate that PEGylation can be potentially used to modulate the internalization and transport of DNCs across the pulmonary epithelium. Modified dendrimers thereby may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation - using the lung as pathway to the bloodstream, for systemic delivery.
- Compression-Induced Crystallization of Amorphous Indomethacin in Tablets: Characterization of Spatial Heterogeneity by Two-Dimensional X-ray Diffractometry. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 9.
Tablets of amorphous indomethacin were compressed at 10, 25, 50, or 100 MPa using either an unlubricated or a lubricated die and stored individually at 35 °C in sealed Mylar pouches. At selected time points, tablets were analyzed by two-dimensional X-ray diffractometry (2D-XRD), which enabled us to profile the extent of drug crystallization in tablets, in both the radial and axial directions. To evaluate the role of lubricant, magnesium stearate was used as "internal" and/or "external" lubricant. Indomethacin crystallization propensity increased as a function of compression pressure, with 100 MPa pressure causing crystallization immediately after compression (detected using synchrotron radiation). However, the drug crystallization was not uniform throughout the tablets. In unlubricated systems, pronounced crystallization at the radial surface could be attributed to die wall friction. The tablet core remained substantially amorphous, irrespective of the compression pressure. Lubrication of the die wall with magnesium stearate, as external lubricant, dramatically decreased drug crystallization at the radial surface. The spatial heterogeneity in drug crystallization, as a function of formulation composition and compression pressure, was systematically investigated. When formulating amorphous systems as tablets, the potential for compression induced crystallization warrants careful consideration. Very low levels of crystallization on the tablet surface, while profoundly affecting product performance (decrease in dissolution rate), may not be readily detected by conventional analytical techniques. Early detection of crystallization could be pivotal in the successful design of a dosage form where, in order to obtain the desired bioavailability, the drug may be in a high energy state. Specialized X-ray diffractometric techniques (2D; use of high intensity synchrotron radiation) enabled detection of very low levels of drug crystallization and revealed the heterogeneity in crystallization within the tablet.
- Efficacious Gene Silencing in Serum and Significant Apoptotic Activity Induction by Survivin Downregulation Mediated by New Cationic Gemini Tocopheryl Lipids. [JOURNAL ARTICLE]
- Mol Pharm 2014 Dec 1.
Non-viral gene delivery offers cationic liposomes as promising instruments for the delivery of double-stranded RNA (ds RNA) molecules for successful sequence-specific gene silencing (RNA interference). The efficient delivery of siRNA (small interfering RNA) to cells while avoiding the unexpected side effects is an important prerequisite for the exploitation of the power of this excellent tool. We present here, six new tocopherol based cationic gemini lipids, which induce substantial gene knockdown without any obvious cytotoxicity. All the efficient co-liposomal formulations derived from each of these geminis and a helper lipid, dioleoyl phosphatidyl ethanolamine (DOPE) were well characterized using physical methods such as atomic force microscopy (AFM) and dynamic light scattering (DLS). Zeta potential measurements were conducted to estimate the surface charge of these formulations. Flow cytometric analysis showed that the optimized co-liposomal formulations could transfect anti-GFP siRNA efficiently in three different GFP expressing cell lines, viz. HEK 293T, HeLa and Caco-2 significantly better than a potent commercial standard Lipofectamine 2000 (L2K) both in the absence and presence of serum (FBS). Notably, the knockdown activity of co-liposomes of gemini lipids was not affected even in the presence of serum (10% and 50% FBS) while it dropped down for L2K significantly. Observations under a fluorescence microscope, RT-PCR and western blot analysis substantiated the flow cytometry results. The efficient cellular entry of labeled siRNA in GFP expressing cells as evidenced from confocal microscopy put forward these gemini lipids among the potent lipidic carriers for siRNA. The efficient transfection capabilities were also profiled in a more relevant fashion while performing siRNA transfections against survivin (an anti-apoptotic protein) which induced substantial apoptosis. Furthermore, the survivin downregulation improved the therapeutic efficacy levels of an anticancer drug, doxorubicin significantly. In short, the new tocopherol based gemini lipids appear to be highly promising for achieving siRNA mediated gene knockdown in various cell lines.