Establishment of hypoxia induction in an in vivo animal replacement model for experimental evaluation of pancreatic cancer

Nanosilver inhibits the progression of pancreatic cancer by inducing a paraptosis-like mixed type of cell death

Silver has been in clinical use since ancient times and silver nanoparticles (AgNPs) have attracted attention in cancer therapy. We investigated the mechanisms by which AgNPs inhibit pancreatic ductal adenocarcinoma (PDAC). AgNPs were synthesized and 3 human PDAC and 2 nonmalignant primary cell lines were treated with AgNPs. MTT, MAPK, colony, spheroid and scratch assays, Western blotting, TEM, annexin V, 7-AAD, and H2DCFDA staining, FACS analysis, mRNA array and bioinformatics analyses, tumor xenograft transplantation, and immunohistochemistry of the treated cells were performed. We found that minimal AgNPs amounts selectively eradicated PDAC cells within a few hours. AgNPs inhibited cell migration and spheroid and colony formation, damaged mitochondria, and induced paraptosis-like cell death with the presence of cytoplasmic vacuoles, dilation of the ER and mitochondria, ROS formation, MAPK activity, and p62 and LC3b expression, whereas effects on the nucleus, DNA fragmentation, or caspases were not detectable. AgNPs strongly decreased tumor xenograft growth without side effects and reduced the expression of markers for proliferation and DNA repair, but upregulated paraptosis markers. The results highlight nanosilver as complementary agent to improve the therapeutic efficacy in pancreatic cancer.

The chorioallantoic membrane as a bio-barrier model for the evaluation of nanoscale drug delivery systems for tumour therapy

In 2010, the European Parliament and the European Union adopted a directive on the protection of animals used for scientific purposes. The directive aims to protect animals in scientific research, with the final goal of complete replacement of procedures on live animals for scientific and educational purposes as soon as it is scientifically viable. Furthermore, the directive announces the implementation of the 3Rs principle: "When choosing methods, the principles of replacement, reduction and refinement should be implemented through a strict hierarchy of the requirement to use alternative methods." The visibility, accessibility, and the rapid growth of the chorioallantoic membrane (CAM) offers a clear advantage for various manipulations and for the simulation of different Bio-Barriers according to the 3R principle. The extensive vascularisation on the CAM provides an excellent substrate for the cultivation of tumour cells or tumour xenografts which could be used for the therapeutic evaluation of nanoscale drug delivery systems. The tumour can be targeted either by topical application, intratumoural injection or i.v. injection. Different application sites and biological barriers can be examined within a single model.

Computational modeling demonstrates that glioblastoma cells can survive spatial environmental challenges through exploratory adaptation

Glioblastoma (GBM) is an aggressive type of brain cancer with remarkable cell migration and adaptation capabilities. Exploratory adaptation-utilization of random changes in gene regulation for adaptive benefits-was recently proposed as the process enabling organisms to survive unforeseen conditions. We investigate whether exploratory adaption explains how GBM cells from different anatomic regions of the tumor cope with micro-environmental pressures. We introduce new notions of phenotype and phenotype distance, and determine probable spatial-phenotypic trajectories based on patient data. While some cell phenotypes are inherently plastic, others are intrinsically rigid with respect to phenotypic transitions. We demonstrate that stochastic exploration of the regulatory network structure confers benefits through enhanced adaptive capacity in new environments. Interestingly, even with exploratory capacity, phenotypic paths are constrained to pass through specific, spatial-phenotypic ranges. This work has important implications for understanding how such adaptation contributes to the recurrence dynamics of GBM and other solid tumors.

A Microdevice Platform Recapitulating Hypoxic Tumor Microenvironments

Hypoxia plays a central role in cancer progression and resistance to therapy. We have engineered a microdevice platform to recapitulate the intratumor oxygen gradients that drive the heterogeneous hypoxic landscapes in solid tumors. Our design features a "tumor section"-like culture by incorporating a cell layer between two diffusion barriers, where an oxygen gradient is established by cellular metabolism and physical constraints. We confirmed the oxygen gradient by numerical simulation and imaging-based oxygen sensor measurement. We also demonstrated spatially-resolved hypoxic signaling in cancer cells through immunostaining, gene expression assay, and hypoxia-targeted drug treatment. Our platform can accurately generate and control oxygen gradients, eliminates complex microfluidic handling, allows for incorporation of additional tumor components, and is compatible with high-content imaging and high-throughput applications. It is well suited for understanding hypoxia-mediated mechanisms in cancer disease and other biological processes, and discovery of new therapeutics.

Radiosensitizing effect of irisquinone on glioma through the downregulation of HIF-1α evaluated by 18F-FDG and 18F-FMISO PET/CT

OBJECTIVE

The aim of this study was to elucidate the radiosensitizing mechanism of irisquinone (IQ) and evaluate the utility of F-fluorodeoxyglucose (F-FDG) and F-fluoromisonidazole (F-FMISO) PET/computed tomography (CT) in assessing the radiosensitizing effect of IQ.

MATERIALS AND METHODS

In an in-vitro experiment, C6 rat glioma cells were treated with IQ, radiation, or both. The viability and radiosensitivity of C6 cells were detected using the MTT assay and clonogenic survival assay. The expression of hypoxia-inducible factor-1α (HIF-1α) was evaluated by real-time PCR and western blot. In an in-vivo experiment, C6 rat glioma cells were implanted into the right flank of rats and treated with IQ, radiation, both, or no treatment. F-FDG and F-FMISO PET/CT images were obtained before and after treatment. The expression of HIF-1α was detected by immunohistochemistry staining.

RESULTS

In the in-vitro experiment, the results of the MTT assay showed that the half-inhibition concentration (IC50) of IQ for normoxic and hypoxic C6 tumor cells was 17.2 and 21.0 nmol/l, respectively. Clonogenic survival assay showed that IQ could improve the radiosensitivity of both normoxic and hypoxic C6 tumor cells. When the concentration of irradiation was 20% IC50 (4.2 nmol/l), the sensitive enhancement ratio of normoxic and hypoxic C6 tumor cells was 1.18 and 1.33, respectively. The mRNA and protein expression levels of HIF-1α decreased significantly when treated with IQ plus radiation compared with the other groups.In the in-vivo experiment, 24 or 48 h after different treatments, the maximum standardized uptake values (SUVmax) of F-FDG or F-FMISO uptake decreased in the radiation group and the IQ plus radiation group, whereas these values increased in the control and IQ groups. The SUVmax of F-FDG or F-FMISO uptake in IQ plus radiation group were lower than those of the radiation group (t=3.28, 2.62, P<0.05). However, there was no significant decrease in tumor volumes in the radiation group and the IQ plus radiation treatment group early after treatment.Immunohistochemistry staining showed that there were significant differences in the expression of HIF-1α in the four groups (F=87.1, P<0.01). The SUVmax of both F-FDG and F-FMISO uptake showed a significant correlation with the expression of HIF-1α. F-FMISO provided a higher correlation coefficient with HIF-1α than F-FDG (r=0.93, 0.82, P<0.01).

CONCLUSION

The present experiments indicated that IQ enhanced the radiosensitivity of C6 rat glioma cells both in vitro and in vivo. The primary mechanism of this radiosensitizing effect involves the downregulation of HIF-1α. F-FDG and F-FMISO PET/CT were sensitive and noninvasive for monitoring the early radiosensitizing effect of IQ. Meanwhile, F-FMISO PET/CT provided more information on the changes in tumor hypoxic status.

Protective effect of salidroside against bone loss via hypoxia-inducible factor-1α pathway-induced angiogenesis

Hypoxia-inducible factor (HIF)-1α plays a critical role in coupling angiogenesis with osteogenesis during bone development and regeneration. Salidroside (SAL) has shown anti-hypoxic effects in vitro and in vivo. However, the possible roles of SAL in the prevention of hypoxia-induced osteoporosis have remained unknown. Two osteoblast cell lines, MG-63 and ROB, were employed to evaluate the effects of SAL on cell viability, apoptosis, differentiation and mineralization in vitro. Rats subjected to ovariectomy-induced bone loss were treated with SAL in vivo. Our results showed that pre-treatment with SAL markedly attenuated the hypoxia-induced reductions in cell viability, apoptosis, differentiation and mineralization. SAL down-regulated HIF-1α expression and inhibited its translocation; however, SAL increased its transcriptional activity and, consequently, up-regulated vascular endothelial growth factor (VEGF). In vivo studies further demonstrated that SAL caused decreases in the mineral, alkaline phosphatase (ALP), and BGP concentrations in the blood of ovariectomized (OVX) rats. Moreover, SAL improved the trabecular bone microarchitecture and increased bone mineral density in the distal femur. Additionally, SAL administration partially ameliorated this hypoxia via the HIF-1α-VEGF signalling pathway. Our results indicate that SAL prevents bone loss by enhancing angiogenesis and osteogenesis and that these effects are associated with the activation of HIF-1α signalling.

Ultrasound-mediated destruction of oxygen and paclitaxel loaded lipid microbubbles for combination therapy in hypoxic ovarian cancer cells

We synthesized oxygen and paclitaxel (PTX) loaded lipid microbubbles (OPLMBs) for ultrasound mediated combination therapy in hypoxic ovarian cancer cells. Our experiments successfully demonstrated that ultrasound induced OPLMBs destruction significantly enhanced the local oxygen release. We also demonstrated that OPLMBs in combination with ultrasound (300 kHz, 0.5 W/cm(2), 15s) yielded anti-proliferative activities of 52.8 ± 2.75% and cell apoptosis ratio of 35.25 ± 0.17% in hypoxic cells at 24h after the treatment, superior to other treatment groups such as PTX only and PTX-loaded MBs (PLMBs) with or without ultrasound mediation. RT-PCR and Western blot tests further confirmed the reduced expression of HIF-1α and MDR-1/P-gp after ultrasound mediation of OPLMBs. Our experiment suggests that ultrasound mediation of oxygen and drug-loaded MBs may be a useful method to overcome chemoresistance in the hypoxic ovarian cancer cells.

Hypoxia induced epithelial-mesenchymal transition and vasculogenic mimicry formation by promoting Bcl-2/Twist1 cooperation

Hypoxia plays a pivotal role in tumor progression. The functions of hypoxia and subsequent Bcl-2/Twist1 activation in epithelial-mesenchymal transition (EMT) and vasculogenic mimicry (VM) formation are currently unclear. This study aimed to investigate the role of Bcl-2/Twist1 cooperation in hypoxia-induced EMT and VM formation. In in vitro experiments, we found that hypoxia resulted in co-overexpression of Bcl-2 and Twist1, facilitated Twist1 nuclear translocation and promoted EMT and VM formation. Co-overexpression of Bcl-2 and Twist1 under normoxia could also induce EMT and promote VM formation. Furthermore, blocking Bcl-2 or Twist1 attenuated the effects of hypoxia on EMT progress and VM formation in hepatocellular carcinoma cells. In in vivo experiments, the mechanism by which hypoxia promoted Bcl-2 and Twist1 co-overexpression and induced EMT process and VM formation was demonstrated using murine xenograft models. These results above suggest that hypoxia could activate the cooperation of Bcl-2 and Twist1, Bcl-2 plays an important role in assisting Twist1 nuclear translocation which could change the expression of a wide range of genes and lead to the induction of EMT and VM formation.