Xiaoyuan Xu

Folic acid conjugated glycol chitosan micelles for targeted delivery of doxorubicin: preparation and preliminary evaluation in vitro

For folate receptor (FR) targeted anticancer therapy, novel folic acid (FA) conjugated cholesterol-modified glycol chitosan (FCHGC) micelles were synthesized and characterized by 1H NMR, dynamic light scattering, transmission electron microscopy, and fluorescence spectroscopy. The degree of substitution was 1.4 FA groups and 7.7 cholesterol groups per 100 sugar residues of glycol chitosan. The critical aggregation concentration of FCHGC micelles in aqueous solution was 0.0169 mg/ml. The doxorubicin (DOX)-loaded FCHGC (DFCHGC) micelles were prepared by an emulsion/solvent evaporation method. The DFCHGC micelles were almost spherical in shape and their size increased from 282 to 320 nm with the DOX-loading content increasing from 4.53 to 11.4%. DOX released from DOX-loaded micelles displayed sustained release behavior. The targeted micelles encapsulated DOX showed significantly greater cytotoxicity against FR-positive HeLa cells than the nontargeted DOX-loaded micelles and free DOX. These results suggested that FCHGC micelles could be a potential carrier for targeted drug delivery.

Development of dual ligand-targeted polymeric micelles as drug carriers for cancer therapy in vitro and in vivo

Chemotherapy is a major therapeutic approach for cancer patients. The action sites of cancer drugs are intracellular compartments including cytoplasm or nucleus. However, targeting drug delivery into the nucleus of specific tumor cells remains a challenging task. Herein, we developed dual-decorated polymeric micelles with folic acid (FA) and a nuclear localization signal (NLS) for specific tumor-targeted drug delivery. Cholesterol-modified glycol chitosan (CHGC) was synthesized. NLS and FA conjugated CHGC (NFCHGC) micelles were constructed. Doxorubicin (DOX) was chosen as a model anticancer drug and coumarin 6 (C6) was used as a hydrophobic fluorescence probe. The drug-loaded polymeric micelles were prepared and characterized. C6-loaded NFCHGC (C6/NFCHGC) showed efficient intracellular trafficking including endosomal/lysosomal escape and nucleus transportation in folate receptor (FR)-positive KB cells investigated by confocal laser scanning microscopy (CLSM). DOX-loaded NFCHGC (DOX/NFCHGC) exhibited stronger cytotoxicity against KB cells than other DOX formulations. Furthermore, blank polymeric micelles displayed low toxicity and good biocompatibility in vivo. DOX/NFCHGC micelles had the strongest anti-tumor efficacy against KB tumor xenograft models in vivo. These findings demonstrated that NFCHGC micelles were deemed as a potential drug nanocarrier for cancer therapy, especially used in FR-positive tumor cells and nucleus-targeting delivery.

MiR-221-induced PUMA silencing mediates immune evasion of bladder cancer cells.

Immune evasion of cancer cells is mainly due to the impaired transduction of apoptotic signals from immune cells to cancer cells, as well as inhibition of subsequent apoptosis signal cascades within the cancer cells. Over the past few decades, the research has focused more on the impaired transduction of the apoptotic signal from immune cells to cancer cells, rather than inhibition of the intracellular signaling pathways. In this study, miR‑221 inhibitor was transfected into bladder cancer cell lines 5637, J82 and T24 to repress the expression of miR‑221. As a result, the repression of miR‑221 on p53 upregulated modulator of apoptosis (PUMA) was abolished, resulting in increased expression of the pro-apoptotic Bax and reduced expression of the anti-apoptotic Bcl-2, which promotes apoptosis of bladder cancer cells. The expression of MMP-2, MMP-9 and VEGF-C were reduced, resulting in reduced invasiveness and infiltration capability of bladder cancer cells, thereby inhibiting the immune evasion of bladder cancer cells.

Gene expression profiling of human bone marrow-derived mesenchymal stem cells during adipogenesis

INTRODUCTION Adipogenesis comprises multiple processes by which mesenchymal stem cells differentiate into adipocytes. To increase our knowledge of the mechanism underlying adipogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs), we performed full-genome gene expression microarray and gene ontology analyses of induced differentiation of hMSCs. MATERIAL AND METHODS Adipogenic differentiation of hMSCs was induced by an adipogenic medium, and total RNA was extracted from undifferentiated hMSCs (day 0) and differentiated adipocytes (day 14). Then microarray hybridization of RNA samples was performed. The GeneChip Operating Software was used to analyze the hybridization data to identify differentially expressed genes, which were performed Gene Ontology categorization and pathway analysis. Pathway-act-network and genes-act-network were built according to the Kyoto Encyclopedia of Genes and Genomes database. Some differentially expressed genes were subjected to qRT-PCR to verify the microarray data. RESULTS We detected a total of 3,821 differentially expressed genes, of which 753 were upregulated and 3,068 downregulated. These genes were well represented in a variety of functional categories, including collagen fibril organization, brown fat cell differentiation, cell division, and S phase of mitotic cell cycle. Subsequently, pathway analysis was conducted, and significant pathways (from top 50) were selected for pathway-act-network analysis, which indicated that the mitogen-activated protein kinase (MAPK) pathway and cell cycle were of high degrees (> 10). Gene-act-network analysis showed that insulin-like growth factor 1 receptor (IGF1R), histone deacetylase 1 (HDAC1), HDAC2, MAPK13, MAPK8, phosphoinositide-3-kinase regulatory subunit 1 (PI3KR1), and PI3KR2 also had high degrees (> 18). CONCLUSIONS Collectively, these data provide novel information and could serve as a basis for future study to clarify the mechanisms underlying adipocyte differentiation of hMSCs.

USP22 transcriptional activity is negatively regulated by the histone deacetylase inhibitor trichostatin A

The ubiquitin‑specific protease 22 (USP22) gene is overexpressed in the majority of types of cancer cells, and has been implicated in tumorigenesis. However, the mechanisms that regulate its expression remain unclear. The results of the present study demonstrated that the expression of USP22 is negatively regulated by trichostatin A (TSA), a classical histone deacetylase inhibitor. Furthermore, TSA was revealed to interfere with the binding of RNA polymerase II to the USP22 promoter, directly suppressing its transcription. In addition, the overexpression of USP22 was observed to attenuate TSA‑induced apoptosis in HeLa cells. To the best of our knowledge, these results provide the first insight into the regulation of the USP22 gene by antitumor drugs and into the mechanisms underlying the anticancer activity of TSA.

Bioinformatics analysis on the differentiation of bone mesenchymal stem cells into osteoblasts and adipocytes

The present study aimed to screen several differentially expressed genes (DEGs) and differentially expressed microRNAs (miRNAs) for two types of mesenchymal stem cell (MSC) differentiation. Bone morphogenetic protein 6 (BMP-6) and dexamethasone were used to induce MSCs towards osteoblastic differentiation or adipocytic differentiation. The t-test in the Bioconductor bioinformatics software tool was used to screen DEGs and differentially expressed miRNAs in the two samples. Subsequent gene ontology (GO) and pathway analyses on the DEGs were performed using the GO and Kyoto Encyclopedia of Genes and Genomes databases, respectively; potential target genes for the screened miRNAs were predicted using the TargetScan database. In addition, an interaction network between the DEGs and miRNAs was constructed. Numerous DEGs and miRNAs were screened during osteoblastic and adipocytic differentiation of MSCs. Important pathways, such as glutathione metabolism, pathogenic Escherichia coli infection and Parkinsons disease, and GO terms, including cytoskeletal protein binding and phospholipase inhibitor activity, were enriched in the screened DEGs from MSCs undergoing osteogenic differentiation and adipocytic differentiation. miRNAs, including miRNA (miR)-382 and miR-203, and DEGs, including neuronal growth regulator 1 (NEGR1), phosphatidic acid phosphatase 2B (PPAP2B), platelet-derived growth factor receptor alpha (PDGFRA), interleukin 6 signal transducer (IL6ST) and sortilin 1 (SORT1), were demonstrated to be involved in osteoblastic differentiation. In addition, the downregulated miRNAs (including miR-495, miR-376a and miR-543), the upregulated miR-106a, the upregulated DEGs, including enabled homolog (ENAH), polypeptide N-acetylgalactosaminyltransferase 1 and acyl-CoA synthetase long-chain family member 1, and the downregulated repulsive guidance molecule family member B and semaphorin SEMA7A were demonstrated to be involved in adipocytic differentiation. The results of the present study suggested that miRNAs (miR-203 and miR-382) and DEGs (NEGR1, PPAP2B, PDGFRA, IL6ST and SORT1) may serve pivotal functions in the osteoblastic differentiation of MSCs, whereas miR-495, which is also involved in osteoblast differentiation and had four targets, including NEGR1, miR-376a, miR-543 and ENAH may have crucial roles in adipocytic differentiation of MSCs.

GABPβ2 expression during osteogenic differentiation from human osteoblast-like Saos-2 cells

The E26 transformation-specific (ETS) family of transcription factors plays an important role in osteogenic differentiation. Whether GA-binding protein β2 (GABPβ2), a member of the ETS family, is involved in osteogenic differentiation has not been previously reported. In the present study, directed differentiation of human osteoblast-like Saos-2 cells was induced and validated by examining alkaline phosphatase (ALP) activity, presence of mineralized nodule and other phenotypic characteristics of the cells on days 0, 3, 6 and 9, thus establishing their osteogenic potential. Real-time PCR revealed that similarly to the bone-specific transcription factor Runx2, the expression of Gabpb2 in Saos-2 cells also peaked on day 3 and was significantly reduced on days 6 and 9. Immunocytochemical staining showed that changes in the immunoreactivity of GABPβ2 also exhibited a similar trend to that of Runx2. Initially, Runx2 was predominantly localized in the nuclei, while GABPβ2 was relatively diffuse. Both exhibited a significant increase in immunoreactivity on day 3, with presence in both the nuclei and cytoplasm. By day 6, both showed a significant decrease in immunoreactivity and were mainly localized in the nuclei. Therefore, we surmise that GABPβ2, as an ETS family member, may play a regulatory role in early osteoblastic differentiation and potentially act in synergy with Runx2.

Insulin protects apoptotic cardiomyocytes from hypoxia/reoxygenation injury through the sphingosine kinase/sphingosine 1-phosphate axis.

Objective Experimental and clinical studies have shown that administration of insulin during reperfusion is cardioprotective, but the mechanisms underlying this effect are still unknown. In this study, the ability of insulin to protect apoptotic cardiomyocytes from hypoxia/reoxygenation injury using the sphingosine kinase/sphingosine 1-phosphate axis was investigated. Methods and Results Rat cardiomyocytes were isolated and subjected to hypoxia and reoxygenation. [γ-32P] ATP was used to assess sphingosine kinase activity. Insulin was found to increase sphingosine kinase activity. Immunocytochemistry and Western blot analysis showed changes in the subcellular location of sphingosine kinase 1 from cytosol to the membrane in cardiomyocytes. Insulin caused cardiomyocytes to accumulate of S1P in a dose-dependent manner. FRET efficiency showed that insulin also transactivates the S1P1 receptor. TUNEL staining showed that administration of insulin during reoxygenation could to reduce the rate of reoxygenation-induced apoptosis, which is a requirement for SphK 1 activity. It also reduced the rate of activation of the S1P receptor and inhibited hypoxia/reoxygenation-induced cell death in cardiomyocytes. Conclusion The sphingosine kinase 1/sphingosine 1-phosphate/S1P receptor axis is one pathway through which insulin protects rat cardiomyocytes from apoptosis induced by hypoxia/reoxygenation injury.

γ‑secretase inhibitor inhibits bladder cancer cell drug resistance and invasion by reducing epithelial‑mesenchymal transition

A previous study by our group demonstrated that the expression levels of Notch 1 and Jagged 1 in bladder cancer cells was significantly lower compared with those in normal bladder mucosa, while the expression levels of Notch 1 and Jagged 1 in invasive bladder cancer were higher compared with those in superficial bladder cancer. The present study investigated the effect of the Notch signaling pathway on the drug resistance and invasiveness of bladder cancer cells. It was demonstrated that complete inhibition of the Notch signaling pathway induced significant morphological changes and inhibited cell proliferation and migration (P<0.05). Reverse transcription quantitative polymerase chain reaction and western blot analyses revealed that the mRNA and protein expression levels of E-cadherin were upregulated (P<0.05) and the mRNA and protein expression levels of N-cadherin, vimentin and α-smooth muscle actin were downregulated (P<0.05). The present study concluded that complete inhibition of the Notch signaling pathway inhibited cell proliferation and invasion, and reduced drug resistance in bladder cancer cells, a phenomenon which may be associated with the inhibition of the epithelial-mesenchymal transition.

SIKVAV-Modified Chitosan Hydrogel as a Skin Substitutes for Wound Closure in Mice

Skin wound healing is a complex and dynamic process that involves angiogenesis and growth factor secretion. Newly formed vessels can provide nutrition and oxygen for skin wound healing. Growth factors in skin wounds are important for keratinocytes and fibroblasts proliferation, epithelialization, extracellular matrix remodeling, and angiogenesis, which accelerate skin wound healing. Therefore, treatment strategies that enhance angiogenesis and growth factors secretion in skin wounds can accelerate skin wound healing. This study investigated the effects of a SIKVAV (Ser-Ile-Lys-Val-Ala-Val) peptide-modified chitosan hydrogel on skin wound healing. Hematoxylin and eosin (H&E) staining demonstrated that the SIKVAV-modified chitosan hydrogel accelerated the re-epithelialization of wounds compared with that seen in the negative and positive controls. Masson’s trichrome staining showed that more collagen fibers were deposited in the skin wounds treated with the SIKVAV-modified chitosan hydrogel than in the negative and positive controls. Immunohistochemistry assays demonstrated that more myofibroblasts were deposited and more angiogenesis occurred in skin wounds treated with the SIKVAV-modified chitosan hydrogel than in the negative and positive controls. In addition, ELISA assays showed that the SIKVAV-modified chitosan hydrogels promoted the secretion of growth factors in skin wounds. Taken together, these results suggest that the SIKVAV-modified chitosan hydrogel has the potential to be developed as synthesized biomaterials for the treatment of skin wounds.