Evaluation of the cytotoxicity of a two photon absorbing fluorescence compound on human HepG2 cells and its application to tracking human hepatic cancer cells in mice

Small organic dyes have been applied widely in fluorescence imaging techniques for biomedical research. We investigated the cytotoxicity of a novel fluorescent dye, trans-4-(N-2-hydroxyethyl-N-ethyl amino)-4'-(dimethyl amino) stilbene (DMAHAS), on human hepatocellular carcinoma (HepG2) cells using methyl thiazolyl tetrazolium(MTT), a neutral red assay, a Coomassie brilliant blue assay, and flow cytometric analysis. Our results showed that DMAHAS had live cell permeability, stable cytosolic localization and no significant cytotoxicity to HepG2 cells. We explored its application further for tumor cell tracking in a human liver tumor xenograft mouse model. Tumor xenografts were examined by fluorescence imaging and conventional histological methods. In addition, a method based on DMAHAS release was developed for tumor-specific cytotoxicity analysis. Our study indicated that DMAHAS is a reliable probe for tumor tracking and fluorescence imaging.

Glucose transporter 2 expression: prevention of streptozotocin-induced reduction in beta-cells with 5-thio-D-glucose

The effect of streptozotocin (STZ) on the glucose transporter 2 (GLUT2) expression in beta-cells was investigated in vitro and in vivo. By Western blot analysis, a gradually decreasing GLUT2 expression was found in islets prepared from C57BL/6 male mice that had received multiple low doses of STZ (MD-STZ) for induction of autoimmune diabetes. Reduction of GLUT2 expression correlated with the number of STZ injections administered and preceded development of hyperglycemia. When hyperglycemia had developed, GLUT2 expression was extremely reduced. In vitro, incubation of isolated islets with STZ resulted in a time- and dose-dependent reduction of beta-cell GLUT2 expression. In vivo, pretreatment of MD-STZ recipients with intraperitoneal injections with 5-thio-D-glucose (5-T-G) just before each of the STZ injections prevented MD-STZ-induced beta-cell GLUT2 reduction and hyperglycemia development. In vitro, preincubation of islet cultures with 5-T-G also prevented STZ-induced GLUT2 reduction. Unlike STZ, equimolar concentrations of methylnitrosourea (MNU), the aglycone moiety of STZ, failed to alter GLUT2 expression in vitro. In conclusion, our data demonstrate that STZ-induced beta-cell GLUT2 reduction was prevented by 5-T-G both in vitro and in vivo in the MD-STZ diabetes model. The noxious effect of STZ on GLUT2 expression is most likely facilitated through its glucose moiety, because MNU lacked to do so. Presumably, in autoimmune MD-STZ diabetes the GLUT2 glucose transporter might be a key target structure for STZ subtoxicity and diabetogenicity, which converge with subsequent immune reactions to beta-cell destruction.

Detection and analysis of Borna disease virus in Chinese patients with neurological disorders

BACKGROUND AND PURPOSE

Borna disease virus (BDV) is a neurotropic RNA virus that is known to cause neurological disturbances in various animal species, potentially even humans. However, the association between BDV infection and human neurological disorders remains unclear.

METHODS

Between August 2005 and March 2006, 65 patients with neurological disorders were enrolled into our study. The presence of BDV p24 RNA from peripheral blood mononuclear cells (PBMCs) was investigated by using nested reverse transcriptase PCR (RT-PCR) assay.

RESULTS

Borna disease virus p24 RNA was detected from PBMCs in six patients with viral encephalitis by using nested RT-PCR assay. However, BDV p24 RNA was not detected in patients with multiple sclerosis or peripheral nerve diseases.

CONCLUSION

There might be possible associations between BDV infection and human viral encephalitis.

Characterisation of fibronectin-mediated FAK signalling pathways in lung cancer cell migration and invasion

Background:

Focal adhesion kinase (FAK) is overexpressed in a variety of cancers, such as breast, colon, prostate, ovary, and lung cancers. However, the mechanism by which extracellular matrix fibronectin stimulates lung cancer cell migration and invasion through FAK remains to be investigated.

Methods:

The signalling pathways in fibronectin-mediated lung cancer cell migration and invasion were examined using western blotting. The metastasis function was detected by wound healing, migration and invasion assays. Further, RNA interference and kinase inhibitors were also used to study the downstream signals.

Results:

In this study, we examined the FAK signalling pathways in relation to calpain-2 and RhoA in fibronectin-mediated lung cancer cell migration and invasion. We found that A549 lung epithelial cells stimulated by fibronectin showed increased phosphorylation of FAK and its downstream targets, Src, ERK1/2, phosphatidylinositol 3′-kinase (PI3K), and Akt. Consistent with this observation, depletion of FAK by siRNA resulted in the inhibition of Src, ERK1/2, PI3K, and Akt activity. In addition, the Src inhibitor, PP2, blocked the phosphorylation of FAK, ERK1/2, PI3K, and Akt. Conversely, inhibition of MEK1/2 using PD98059 reduced the expression of matrix metalloproteinase-9 (MMP9) and calpain-2. The PI3K inhibitor, LY294002, further blocked the expression of MMP9 and RhoA. Inhibition of both MEK1/2 and PI3K caused reduced cell migration and invasion.

Conclusion:

Our data suggest that fibronectin-mediated activation of FAK that leads to lung cancer metastasis could occur through ERK or PI3K/Akt regulation of MMP9/calpain-2 or MMP9/RhoA activity, respectively.

ORAOV1-A correlates with poor differentiation in oral cancer

Oral cancer overexpressed 1 (ORAOV1) is a crucial oncogene in oral squamous cell carcinoma (OSCC). In this study, we have identified a novel splice variant of ORAOV1, designated as ORAOV1-A. To study the potential role of ORAOV1-A in OSCC, we tested its expression in 7 OSCC cell lines, as well as in 19 normal oral tissue samples and 47 OSCC tissue samples. The expression of ORAOV1-A was detectable in 6 out of 7 OSCC cell lines tested. In OSCC tissue samples, the expression frequency of ORAOV1-A (51.1%) was much higher than that in normal samples (10.5%). Notably, an inverse correlation was found between the expression frequency of ORAOV1-A and the degree of differentiation in OSCC (P = 0.0017). In conclusion, our results suggested that ORAOV1-A may play a functional role in the tumorigenesis of OSCC, and ORAOV1-A expression may serve as an adjunctive prognostic indicator for persons with OSCC.

Induction stage-dependent expression of vascular endothelial growth factor and aquaporin-1 in diethylstilbestrol-treated rat pituitary

The anterior pituitary gland undergoes tumourigenic changes in response to oestrogen treatment in several breeds of rats. We administered diethylstilbestrol (DES) to female Wistar rats and assessed whether the expression of vascular endothelial growth factor (VEGF) and aquaporin-1 (AQP-1) was altered at different time points following DES administration. In vivo magnetic resonance imaging (MRI) scans showed that the mass index corresponding to the mid-sagittal area of DES-treated pituitary was significantly higher than the vehicle-controlled pituitary (p<0.01) at three specific time points, accompanied by a significant reduction in body weight. Haematoxylin and eosin (HE) staining and immunohistochemical analysis demonstrated that during early stages of induction, DES increased cell proliferation and sprouting of endothelial cells, and VEGF expression transitioned from a vessel-surrounding pattern to a diffuse pattern. During later stages, angiogenesis was predominant, and VEGF expression decreased. In contrast to the early abundant expression of VEGF, endothelial expression of AQP- 1 increased during later stages. Our data indicated a dynamic scenario of biological alterations in DES-treated pituitary tissue, in which VEGF and AQP-1 exert their functions at different stages of induction, and we provide novel insights into understanding oestrogen-related tumourigenesis in the anterior pituitary gland.