Yangde Zhang

Reversion of multidrug resistance by co-encapsulation of doxorubicin and curcumin in chitosan/poly(butyl cyanoacrylate) nanoparticles

Co-encapsulated doxorubicin (DOX) and curcumin (CUR) in poly(butyl cyanoacrylate) nanoparticles (PBCA-NPs) were prepared with emulsion polymerization and interfacial polymerization. The mean particle size and mean zeta potential of CUR-DOX-PBCA-NPs were 133 ± 5.34 nm in diameter and +32.23 ± 4.56 mV, respectively. The entrapment efficiencies of doxorubicin and curcumin were 49.98 ± 3.32% and 94.52 ± 3.14%, respectively. Anticancer activities and reversal efficacy of the formulations and various combination approaches were assessed using 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyltetrazolium bromide assay and western blotting. The results showed that the dual-agent loaded PBCA-NPs system had the similar cytotoxicity to co-administration of two single-agent loaded PBCA-NPs (DOX-PBCA-NPs+CUR-PBCA-NPs), which was slightly higher than that of the free drug combination (DOX+CUR) and one free drug/another agent loaded PBCA-NPs combination (DOX+CUR-PBCA-NPs or CUR+DOX-PBCA-NPs). The simultaneous administration of doxorubicin and curcumin achieved the highest reversal efficacy and down-regulation of P-glycoprotein in MCF-7/ADR cell lines, an MCF-7 breast carcer cell line resistant to adriamycin. Multidrug resistance can be enhanced by combination delivery of encapsulated cytotoxic drugs and reversal agents.

miR-203 reverses chemoresistance in p53-mutated colon cancer cells through downregulation of Akt2 expression

In this study, we explored miR-203s role in the chemoresistance of colon cancer. We found that overexpression of miR-203 significantly decreased cell proliferation and survival, and induced cell apoptosis in the p53-mutated colon cancer cells. Importantly, miR-203 overexpression increased the cytotoxic role of paclitaxel in the p53-mutated colon cancer cells, but not in the p53 wild-type cells. We further demonstrated that the tumor suppressive role of miR-203 was mediated by negatively regulating Akt2 protein expression through mRNA degradation. The inhibition of Akt2 activity downregulated the protein expression of its downstream molecules involved in chemoresistance, such as MTDH and HSP90 genes. Also, overexpression of miR-203 decreased anti-apoptotic gene Bcl-xL expression and increased apoptotic proteins Bax and active caspase-3 levels. Our study is the first to identify the tumor suppressive role of overexpressed miR-203, describe its associated signaling pathways, and highlight the role of miR-203 in chemoresistance.

Overexpression of miR-22 reverses paclitaxel-induced chemoresistance through activation of PTEN signaling in p53-mutated colon cancer cells

Chemoresistance is a key cause of treatment failure in colon cancer. MiR-22 is a tumor-suppressing microRNA. To explore whether miR-22 is an important player in the development of chemoresistance in colon cancer, we overexpressed miR-22 and subsequently tested its role in cell proliferation, apoptosis, survival, and associated signaling in p53-mutated HT-29 and HCT-15 cells, and p53 wild-type HCT-116 cells. We further investigated the role of miR-22 on cytotoxicity of paclitaxel in both the p53-mutated and p53 wild-type colon cancer cells. Results showed that HT-29 and HCT-15 cells were resistant to paclitaxel-induced cytotoxicity, which normally inhibits cell proliferation and survival, and induces apoptosis. Conversely, HCT-116 was relatively sensitive to the cytotoxicity of paclitaxel. Overexpression of miR-22 significantly decreased cell proliferation and survival, and induced cell apoptosis in the p53-mutated colon cancer cells, but played no role in the p53 wild-type cells. Importantly, miR-22 overexpression enhanced the cytotoxic role of paclitaxel in p53-mutated HT-29 and HCT-15 cells, but not in p53 wild-type HCT-116 cell. We further demonstrated that the tumor-suppressive role of miR-22 in p53-mutated colon cancer cells was mediated by upregulating PTEN expression, which negatively regulated Akt phosphorylation at Ser473 and MTDH expression, and subsequently increased Bax and active caspase-3 levels. Our study is the first to identify the tumor-suppressive role of miR-22 and its associated signaling in the p53-mutated colon cancer cells and highlighted the chemosensitive role of miR-22.

A novel PEGylation of chitosan nanoparticles for gene delivery

CS (chitosan) has emerged as a promising non‐viral vector for gene delivery because of its ability to form complexes with pDNA (plasmid DNA) and enhance its transport across cellular membranes through endocytosis. Complexes of CS and pDNA may improve transfection efficiency; however, they are not capable of sustained DNA release and prolonging gene transfer. In order to achieve prolonged delivery of CS–DNA complexes, we prepared CS NP (nanoparticle) and CS–DNA complexes. α‐Methoxy‐ω‐succinimidylpoly(ethylene glycol) was then conjugated to the surface of CS–DNA complexes using an active ester scheme; finally, the potential of PEGylation [poly(ethylene glycol)ylation] of CS NP as a non‐viral gene‐delivery vector to transfer exogenous genes in vitro and in vivo were examined. Electrophoretic analysis suggested that CS NPs could protect the DNA from nuclease degradation. The pDNA carried by CS NPs could enter and be expressed in HepG2 cells. However, the transfection efficiency was very low and the highest dose of DNA transferred was 1.6 μg. The transfection activities of CS–DNA–PEG were preserved and a higher dose (2.4 μg) of pDNA was transferred. This indicated that the transfection efficiency of the PEGylated complexes had been improved. In vivo experiments also showed that CS–DNA–PEG complexes mediated higher gene expression in tissues than did CS–DNA complexes, and that gene expression in tumours induced by CS–DNA–PEG complexes was the highest of all. These results suggested that PEGylation of CS–DNA complexes improves non‐viral gene delivery in vitro or in vivo and has the potential to deliver therapeutic genes directly into hepatoma tissues.

Overexpression of EphA2, MMP-9, and MVD-CD34 in hepatocellular carcinoma: Implications for tumor progression and prognosis

Aim:  To investigate the expression of erythropoietin‐producing hepatocellular (Eph)A2 receptor, matrix metalloproteinase (MMP)‐9, and angiogenesis in hepatocellular carcinoma (HCC), in order to reveal their expression correlations with tumor invasion, metastasis, and prognosis.

In vitro and in vivo antitumoral action of metformin on hepatocellular carcinoma

Aims:  Metformin is a biguanide that has been widely used to treat type 2 diabetes. Several studies have shown that metformin is also effective in treating cancer, including hepatocellular carcinoma (HCC). The objective of this study was to evaluate the antitumor effects of metformin in HCC, and to investigate the potential molecular target(s) of metformin‐mediated antitumor activity.

Panning and Identification of a Colon Tumor Binding Peptide from a Phage Display Peptide Library

Tumor-targeting therapy can be an efficacious way to cure a malignant tumor in clinical trials. Phage display is a molecular diversity technology that allows the presentation of a large number of peptides or proteins on the surface of filamentous phage for various applications. In this study, we report on using phage display to generate peptide libraries that bind to colon cancer tissues. To accomplish this, we developed a screening protocol that contained 3 rounds of in vitro positive panning on colon cancer cells (SW480) and 2 rounds of subtractive screening in vitro on normal human intestinal epithelial cells with a phage display-7 peptide library. After several rounds of panning, both phage titer and recovery efficiency were significantly improved. Through a cell-based enzyme-linked immunosorbent assay, immunofluorescence, in vivo binding assay, immunocytochemical staining, and immunohistochemical staining, peptide CP15 (VHLGYAT) was demonstrated to be the most effective peptide in targeting tumor cells (SW480 and HT29 cells) and tumor tissues but not the normal human intestinal epithelial cells and control colon tissue. These studies suggest that peptide CP15 may be a promising lead candidate in the development of a useful colon tumor diagnostic and targeted drug delivery agent. (Journal of Biomolecular Screening 2007:429-435)

Role of bile salt in regulating Mcl-1 phosphorylation and chemoresistance in hepatocellular carcinoma cells

BackgroundGlycochenodeoxycholate (GCDA) is one of the major human bile salts. Bile salts stimulate cell survival and proliferation through the mitogen-activated protein kinase, but the downstream signaling mechanism(s) remains enigmatic. Mcl-1 is an antiapoptotic molecule of the Bcl2 family that is extensively overexpressed in tumor tissues of patients with hepatocellular carcinoma (HCC).ResultsHere we found that exposure of HepG2 cells to GCDA results in activation of ERK1 and ERK2 and phosphorylation of Mcl-1 in a PD98059 (MEK inhibitor)-sensitive manner. GCDA stimulates Mcl-1 phosphorylation in cells expressing WT but not T163A Mcl-1 mutant, indicating that GCDA-induced Mcl-1 phosphorylation occurs exclusively at the T163 site in its PEST region. GCDA-induced Mcl-1 phosphorylation at T163 enhances the half-life of Mcl-1. Treatment of HepG2 cells with GCDA facilitates Mcl-1 dissociation from Mule (a physiological Mcl-1 ubiquitin E3 ligase). Specific depletion of Mcl-1 from HepG2 cells by RNA interference increases sensitivity of HepG2 cells to chemotherapeutic drugs (i.e. cisplatin and irinotecan). In addition to activation of the ERK/Mcl-1 survival pathway, GCDA can also induce dose-dependent apurinic/apyrimidinic (AP) sites of DNA lesions, which may partially neutralize its survival activity.ConclusionOur findings suggest that bile salt may function as a survival agonist and/or potential carcinogen in the development of HCC. Molecular approaches that inactivate Mcl-1 by blocking its T163 phosphorylation may represent new strategies for treatment of HCC.

Clinical significance of microRNA-93 downregulation in human colon cancer.

Aim MicroRNA-93 (miR-93) has been shown to suppress proliferation and colony formation of colon cancer stem cells. The aim of this study was to examine the expression pattern and prognostic value of miR-93 in patients with colon cancer. Materials and methods A quantitative real-time PCR analysis was carried out to detect the expression levels of miR-93 in 138 paired samples of tumoral and nontumoral colon tissues diagnosed with colon cancer. Associations of miR-93 expression with clinicopathological parameters and survival were also examined. Results miR-93 expression was significantly decreased in tumoral compared with nontumoral colon tissues (P<0.001). Low miR-93 expression was significantly correlated with advanced tumor stage (P=0.02), positive nodal metastasis (P=0.006), and positive distant metastases (P=0.01). In addition, Kaplan–Meier survival analysis by Cox regression showed that low miR-93 expression [hazard ratio (HR), 10.2; 95% confidence interval (CI), 1.9–42.8, P=0.003] was associated closely with poor overall survival in patients with colon cancer. Moreover, multivariate analysis showed that miR-93 decreased expression (HR, 4.3; 95% CI, 0.8–17.2, P=0.02), advanced tumor stage (HR, 3.1; 95% CI, 0.2–13.9, P=0.04), positive nodal metastasis (HR, 4.1; 95% CI, 0.7–16.8, P=0.02), and positive distant metastases (HR, 3.7; 95% CI, 0.5–14.1, P=0.03) were independent risk factors for overall survival in patients with colon cancer. Conclusion Our data show for the first time that the downregulation of miR-93 was significantly correlated with unfavorable clinicopathologic features and short overall survival in patients with colon cancer, suggesting that decreased expression of miR-93 be used as a novel prognostic factor for this disease.

Prognostic Value of Matrix Metalloproteinase-1/ Proteinase-Activated Receptor-1 Signaling Axis in Hepatocellular Carcinoma

Matrix metalloproteinase-1 (MMP-1) is proposed to be involved in both tumor cell invasion and metastasis. MMP-1 proteolytically activates protease activated receptor-1 (PAR-1), which also plays an important role in tumor development and progression. However, it is currently unknown whether MMP-1 activation of PAR-1 has relevance to the progression of hepatocellular carcinoma (HCC). To address this problem, we investigate the clinicopathological and prognostic value of MMP-1/PAR-1 signaling axis in HCC. Immunohistochemistry assay was used to determine the expression of MMP-1 and PAR-1 proteins in normal and HCC tissues. The correlations of MMP-1 and PAR-1 expression with clinicopathological parameters were assessed by Chi-squared test. Patient survival and their differences were determined by Kaplan-Meier method and log-rank test. Cox regression was adopted for multivariate analysis of prognostic factors. MMP-1 and PAR-1 immunoreactivities were negative or low in normal liver tissues, but high in HCC tissues. PAR-1 expression was significantly correlated with that of MMP-1 (r = 0.896, p < 0.0001). The overexpression of MMP-1 and PAR-1 was significantly associated with recurrence, TNM staging and portal vein invasion of HCC. Patients with high MMP-1 and PAR-1 expression had significantly poorer overall survival (OS) (both P < 0.001) and disease-free survival (DFS) (both P < 0.001) when compared with patients with the low expression of MMP-1 and PAR-1. On multivariate analysis, MMP-1 and PAR-1 expression patterns were found to be independent prognostic factors for OS (both P < 0.001) and DFS (both P < 0.001). Our results suggest for the first time that the MMP-1/PAR-1 signaling axis might be applied as a novel marker for the prediction of recurrence and metastasis potency and a significant indicator of poor prognosis for patients with HCC.