Aili Suo

MicroRNA profiling of human gastric cancer

MicroRNAs are a group of small non-coding RNAs that modulate gene expression. The de-regulation of microRNA expression has been found in several types of cancer. To study the role of microRNAs in gastric cancer (GC), we analyzed the expression profile of 847 microRNAs in GC from Chinese patients. Total RNA was used for hybridization on the miRCURY LNA Array (v. 11.0), which contains probes specific for 847 human microRNAs. The results from the miRNA microarray analysis were validated by real-time RT-PCR. A total of 24 miRNAs with a more than 2-fold change were differentially expressed between normal gastric tissue and GC. Of these, 22 miRNAs (miR-223, miR-106b, miR-147, miR-34a, miR-130b*, miR-106a, miR-18a, miR-17, miR-98, miR-616*, miR-181a-2*, miR-185, miR-1259, miR-601, miR-196a*, miR-221*, miR-302f, miR-340*, miR-337-3p, miR-520c-3p, miR-575 and miR-138) were significantly up-regulated in GC (P<0.05), whereas only miR-638 and miR-378 were significantly down-regulated in GC (P<0.05) compared to normal gastric tissue. The expression of miR-185 and miR-638, as measured by miRNA microarray analysis, was in agreement with the expression level of these microRNAs found by real-time RT-PCR in the same samples. Our results show that microRNAs are de-regulated in GC, suggesting the involvement of these genes in the development and progression of gastric cancer.

Reduction/pH dual-sensitive PEGylated hyaluronan nanoparticles for targeted doxorubicin delivery.

To minimize the side effect of chemotherapy, a novel reduction/pH dual-sensitive drug nanocarrier, based on PEGylated dithiodipropionate dihydrazide (TPH)-modified hyaluronic acid (PEG-SS-HA copolymer), was developed for targeted delivery of doxorubicin (DOX) to hepatocellular carcinoma. The copolymer was synthesized by reductive amination via Schiffs base formation between TPH-modified HA and galactosamine-conjugated poly(ethylene glycol) aldehyde/methoxy poly(ethylene glycol) aldehyde. Conjugation of DOX to PEG-SS-HA copolymer was accomplished through the hydrazone linkage formed between DOX and PEG-SS-HA, and confirmed by FTIR and (1)H NMR spectra. The polymer-DOX conjugate could self-assemble into spherical nanoparticles (~150 nm), as indicated by TEM and DLS. In vitro release studies showed that the DOX-loaded nanoparticles could release DOX rapidly under the intracellular levels of pH and glutathiose. Cellular uptake experiments demonstrated that the nanoparticles could be efficiently internalized by HepG2 cells. These results indicate that the PEG-SS-HA copolymer holds great potential for targeted intracellular delivery of DOX.

Galactosylated poly(ethylene glycol)-b-poly (l-lactide-co-β-malic acid) block copolymer micelles for targeted drug delivery: preparation and in vitro characterization

Biodegradable galactosylated methoxy poly(ethylene glycol)/poly(l-lactide-co-β-malic acid) (Gal-PEG-b-PLMA) block copolymer micelles were successfully prepared by a solvent diffusion method, and could efficiently encapsulate doxorubicin. The Gal-PEG-b-PLMA micelles before and after doxorubicin loading were characterized by size, morphology, in vitro drug release, and in vitro cytotoxicity in HepG2 cells. Transmission electron microscopy and dynamic light scattering results showed that the empty and doxorubicin-loaded micelles were approximately spherical in shape and had mean sizes of about 72 nm and 85 nm, respectively. In vitro release behavior of doxorubicin from the micelles was pH-dependent, with obviously faster release rates at mildly acidic pH 4.5 and 5.5 compared with physiologic pH 7.4. Methylthiazoletetrazolium assay and flow cytometric analysis indicated that the doxorubicin-loaded galactosylated micelles exhibited a greater growth-inhibitory effect on HepG2 cells than the nongalactosylated doxorubicin-loaded micelles, and induced S phase cell cycle arrest. Confocal laser scanning microscope observations revealed that the galactosylated micelles could be efficiently internalized by HepG2 cells through receptor-mediated endocytosis. The results suggest that Gal-PEG-b-PLMA copolymer micelles are a promising carrier system for targeted drug delivery in cancer therapy.

Comb-like amphiphilic polypeptide-based copolymer nanomicelles for co-delivery of doxorubicin and P-gp siRNA into MCF-7 cells.

A comb-like amphiphilic copolymer methoxypolyethylene glycol-graft-poly(L-lysine)-block-poly(L-phenylalanine) (mPEG-g-PLL-b-Phe) was successfully synthesized. To synthesize mPEG-g-PLL-b-Phe, diblock copolymer PLL-b-Phe was first synthesized by successive ring-opening polymerization of α-amino acid N-carboxyanhydrides followed by the removal of benzyloxycarbonyl protecting groups, and then mPEG was grafted onto PLL-b-Phe by reductive amination via Schiffs base formation. The chemical structures of the copolymers were identified by (1)H NMR. mPEG-g-PLL-b-Phe copolymer had a critical micelle concentration of 6.0mg/L and could self-assemble in an aqueous solution into multicompartment nanomicelles with a mean diameter of approximately 78 nm. The nanomicelles could encapsulate doxorubicin (DOX) through hydrophobic and π-π stacking interactions between DOX molecules and Phe blocks and simultaneously complex P-gp siRNA with cationic PLL blocks via electrostatic interactions. The DOX/P-gp siRNA-loaded nanomicelles showed spherical morphology, possessed narrow particle size distribution and had a mean particle size of 120 nm. The DOX/P-gp siRNA-loaded nanomicelles exhibited pH-responsive release behaviors and displayed accelerated release under acidic conditions. The DOX/P-gp siRNA-loaded nanomicelles were efficiently internalized into MCF-7 cells, and DOX released could successfully reach nuclei. In vitro cytotoxicity assay demonstrated that the DOX/P-gp siRNA-loaded nanomicelles showed a much higher cytotoxicity in MCF-7 cells than DOX-loaded nanomicelles due to their synergistic killing effect and that the blank nanomicelles had good biocompatibility. Thus, the novel comb-like mPEG-g-PLL-b-Phe nanomicelles could be a promising vehicle for co-delivery of chemotherapeutic drug and genetic material.

Co-delivery of doxorubicin and P-glycoprotein siRNA by multifunctional triblock copolymers for enhanced anticancer efficacy in breast cancer cells

Combined treatment of chemotherapeutics and small interfering RNAs (siRNAs) is a promising therapy strategy for breast carcinoma via their synergetic effects. In this study, to improve the therapeutic effect of doxorubicin (DOX), novel triblock copolymers, folate/methoxy-poly(ethylene glycol)-block-poly(l-glutamate-hydrazide)-block-poly(N,N-dimethylaminopropyl methacrylamide) (FA/m-PEG-b-P(LG-Hyd)-b-PDMAPMA), were synthesized and used as a vehicle for the co-delivery of DOX and P-glycoprotein (P-gp) siRNA into breast cancer cells. The triblock copolymers were synthesized by a combination of ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride using cystamine-terminated heterotelechelic PEG derivatives possessing folate or methoxy end groups (FA/m-PEG-Cys) as initiators and reversible addition-fragmentation chain transfer polymerization of N,N-dimethylaminopropyl methacrylamide followed by hydrazinolysis. The successful synthesis of the copolymers was confirmed by 1H NMR and gel permeation chromatography. DOX was covalently conjugated onto the poly(l-glutamate-hydrazide) blocks via a pH-labile hydrazone linkage, and the DOX-conjugated triblock copolymers could self-assemble into nanoparticles in aqueous solutions. P-glycoprotein (P-gp) siRNA was then bound to the cationic poly(N,N-dimethylaminopropyl methacrylamide) (PDMAPMA) blocks through an electrostatic interaction, resulting in the formation of spherical nanocomplexes with an average diameter of 196.8 nm and a zeta potential of +28.3 mV. The in vitro release behaviors of DOX and siRNA from the nanocomplexes were pH- and reduction-dependent, and the release rates were much faster under a reductive acidic condition (pH 5.0, glutathione: 10 mM) simulating the intracellular endo-lysosomal environment of cancer cells compared to physiological conditions. The fast payload release rates were closely related to both the glutathione-triggered detachment of PEG blocks from the nanocomplex surface and the pH-sensitive cleavage of hydrazone linkages. FA-decorated nanocomplexes showed higher cellular uptake efficiency and cytotoxicity against MCF-7 cells than FA-free nanocomplexes, as confirmed by confocal laser scanning microscopy, transmission electron microscopy, MTT and flow cytometry analyses. Our results demonstrated that the multifunctional triblock copolymer-mediated co-delivery of DOX and P-gp siRNA might be a new promising therapeutic strategy for breast cancer treatment.

A double-network poly(Nɛ-acryloyl l-lysine)/hyaluronic acid hydrogel as a mimic of the breast tumor microenvironment

UNLABELLED To mimic the structure of breast tumor microenvironment, novel double-network poly(Nɛ-acryloyl L-lysine)/hyaluronic acid (pLysAAm/HA) hydrogels were fabricated by a two-step photo-polymerization process for in vitro three-dimensional (3D) cell culture. The morphology, mechanical properties, swelling and degradation behaviors of pLysAAm/HA hydrogels were investigated. The growth behavior and function of MCF-7 cells cultured on the hydrogels and standard 2D culture plates were compared. The results showed that pLysAAm/HA hydrogels had a highly porous microstructure with a double network and that their mechanical properties, swelling ratio and degradation rate depended on the degree of methacrylation of HA. The results of in vitro studies revealed that the pLysAAm/HA hydrogels could support MCF-7 cell adhesion, promote cell proliferation, and induce the diversification of cell morphologies and overexpression of VEGF, IL-8 and bFGF. The MCF-7 cells cultured on 3D hydrogels showed significantly increased migration and invasion abilities as compared to 2D-cultured cells. Preliminary in vivo results confirmed that the 3D culture of MCF-7 cells resulted in greater tumorigenesis than their 2D culture. These results indicate that the pLysAAm/HA hydrogels can provide a 3D microenvironment for MCF-7 cells that is more representative of the in vivo breast cancer. STATEMENT OF SIGNIFICANCE Traditional 2D cell cultures cannot ideally represent their in vivo physiological conditions. In this work, we reported a method for preparing double-network poly(Nɛ-acryloyl L-lysine)/hyaluronic acid hydrogel, and demonstrated its suitability for use in mimicing breast tumor microenvironment. Results showed the prepared hydrogels had controllable mechanical properties, swelling ratio and degradation rate. The MCF-7 cells cultured in hydrogels expressed much higher levels of pro-angiogenic growth factors and displayed significantly enhanced migration and invasion abilities. The tumorigenic capability of MCF-7 cells pre-cultured in 3D hydrogels was enhanced significantly. Therefore, the novel hydrogel may provide a more physiologically relevant 3D in vitro model for breast cancer research. To our knowledge, this is the first report assessing a HA-based double-network hydrogel used as a tumor model.

Preparation and in vitro characterization of biomorphic silk fibroin scaffolds for bone tissue engineering

In bone tissue engineering, a qualified scaffold should provide a three-dimensional porous structure mimicking the extracellular matrix of bone except good biological properties. In this study, biomorphic silk fibroin (SF) scaffolds were fabricated from cane by an innovative biotemplating-negative mold process. The physicochemical properties, in vitro enzymatic degradation behavior and biocompatibility of the biomorphic SF scaffolds were investigated. The results showed that the scaffolds well inherited the original porous morphology of cane, and possessed good mechanical stability. The scaffolds had a compressive modulus of 1.56 ± 0.08 MPa and a porosity of 82.73%, and exhibited a bimodal pore size distribution (15 and 172 μm). The degradation ratio of the SF scaffolds increased with prolonging degradation time and reached 29% within 21 days when exposed to 1.0 U/mL collagenase IA. The in vitro cytocompatibility evaluation indicated that the scaffolds could support cell attachment, proliferation, and osteogenic differentiation of osteoblast-like MC3T3-E1 cells, as assessed by SEM, fluorescent staining, MTT, and ALP activity assays. The results indicated the potential of biomorphic SF scaffolds for bone tissue engineering.

Proteome analysis of the effects of sorafenib on human hepatocellular carcinoma cell line HepG2.

Sorafenib is a multi-target oral anticancer drug used as first-line treatment for patients with advanced human hepatocellular carcinoma (HCC). But the exact mechanism of sorafenib involved in HCC treatment is not clear yet. In this study, a comparative proteomic approach was performed to identify novel sorafenib-related proteins in HCC. Proteomes of HepG2 cells treated with sorafenib and the control (without sorafenib) were obtained by two-dimensional differential gel electrophoresis. Comprehensive analysis of proteins was focused on total protein spots to filtrate the different protein spots between the two groups. The differentially expressed proteins were identified by peptide mass fingerprinting with high-performance liquid chromatography–tandem mass spectrometry. Then, Western blot and immunohistochemistry were used to verify the expression of some candidate proteins. Results indicated that 19 protein spots were differentially expressed with significant changes, including 6 up-regulated proteins and 13 down-regulated proteins. It was confirmed by Western blot that expressions of Annexin A1 and cyclophilin A were down-regulated in sorafenib-treated HCC cell lines. Immunohistochemical study revealed their oncogenic role in HCC tissues. These observations might be novel findings leading to bring new insights into the exact mechanism of sorafenib and identify possible therapeutic targets.

Novel hydroxyethyl chitosan/cellulose scaffolds with bubble-like porous structure for bone tissue engineering

Hydrogels fabricated from natural polysaccharides may serve as ideal scaffolds for tissue engineering because of their similarity to the extracellular matrices. In this study, novel hydrogel scaffolds with bubble-like porous structure were prepared from hydroxyethyl chitosan (HECS) and cellulose (CEL) by a combination of chemical crosslinking, particle-leaching using silicon dioxide particles as porogen and freeze-drying method. The morphology, compression stress-strain curves, wettability, and swelling and rheological behaviors of the HECS/CEL scaffolds were characterized by SEM, mechanical test, contact angle measurement and rheometer. HECS/CEL scaffolds had good comprehensive performances and could reach equilibrium swelling state in water within 20s. The results from in vitro biocompatibility evaluated using SEM, live/dead cell viability and MTT assays demonstrated that the HECS/CEL scaffolds could well support the attachment, spreading and proliferation of osteoblastic MC3T3-E1 cells and showed good biocompatibility. Therefore, the novel HECS/CEL scaffolds may be promising for bone tissue engineering applications.

A reduction-dissociable PEG-b-PGAH-b-PEI triblock copolymer as a vehicle for targeted co-delivery of doxorubicin and P-gp siRNA

To enhance the therapeutic efficacy of doxorubicin (DOX) to breast cancer cells, a multifunctional triblock copolymer, poly(ethylene glycol)-block-poly(L-glutamic acid γ-hydrazide)-block-polyethylenimine (PEG-b-PGAH-b-PEI) having a cleavable disulfide linkage between blocks, was developed as a vehicle for targeted co-delivery of DOX and P-glycoprotein (P-gp) siRNA into MCF-7/ADR cells. The PGAH blocks were used to chemically conjugate DOX molecules via hydrazone bonds, while the PEI blocks could complex siRNA through electrostatic interactions. A tumor-targeting agent, folic acid (FA), was attached to the distal ends of the PEG blocks to specifically bind to the folate receptors overexpressed in MCF-7/ADR cells. The DOX-conjugated copolymer would self-assemble in aqueous solutions into cationic nanomicelles, which could condense siRNA to form nanomicelleplexes with an average particle size of ∼194 nm and a positive zeta potential of >+10 mV. The nanomicelleplexes exhibited sustained drug release profiles, and the release rates of DOX and siRNA from the nanomicelleplexes in a reductive acidic environment (pH 5.0 + 10 mM glutathione) were much faster than those under physiological conditions (pH 7.4). FA-decorated nanomicelleplexes were more efficiently internalized by MCF-7/ADR cells via folate-receptor-mediated endocytosis and exhibited a higher cytotoxic effect on MCF-7/ADR cells in comparison with FA-undecorated nanomicelleplexes. Furthermore, the synergistic effects of DOX and P-gp siRNA in inhibiting cell proliferation and inducing apoptosis in MCF-7/ADR cells were achieved by the FA-targeted co-delivery system. The triblock copolymer itself had a low cytotoxicity. These results indicate that the triblock copolymer could serve as an ideal tumor-targeting vehicle for simultaneous delivery of drugs and siRNA in breast cancer therapy.