Different susceptibility of osteosarcoma cell lines and primary cells to treatment with oncolytic adenovirus and doxorubicin or cisplatin

Olfactory receptors impact pathophysiological processes of lung diseases in bronchial epithelial cells

BACKGROUND

Therapeutic options for steroid-resistant non-type 2 inflammation in obstructive lung diseases are limited. Bronchial epithelial cells are key in the pathogenesis by releasing the central proinflammatory cytokine interleukine-8 (IL-8). Olfactory receptors (ORs) are expressed in various cell types. This study examined the drug target potential of ORs by investigating their impact on associated pathophysiological processes in lung epithelial cells.

METHODS

Experiments were performed in the A549 cell line and in primary human bronchial epithelial cells. OR expression was investigated using RT-PCR, Western blot, and immunocytochemical staining. OR-mediated effects were analyzed by measuring 1) intracellular calcium concentration via calcium imaging, 2) cAMP concentration by luminescence-based assays, 3) wound healing by scratch assays, 4) proliferation by MTS-based assays, 5) cellular vitality by Annexin V/PI-based FACS staining, and 6) the secretion of IL-8 in culture supernatants by ELISA.

RESULTS

By screening 100 potential OR agonists, we identified two, Brahmanol and Cinnamaldehyde, that increased intracellular calcium concentrations. The mRNA and proteins of the corresponding receptors OR2AT4 and OR2J3 were detected. Stimulation of OR2J3 with Cinnamaldehyde reduced 1) IL-8 in the absence and presence of bacterial and viral pathogen-associated molecular patterns (PAMPs), 2) proliferation, and 3) wound healing but increased cAMP. In contrast, stimulation of OR2AT4 by Brahmanol increased wound healing but did not affect cAMP and proliferation. Both ORs did not influence cell vitality.

CONCLUSION

ORs might be promising drug target candidates for lung diseases with non-type 2 inflammation. Their stimulation might reduce inflammation or prevent tissue remodeling by promoting wound healing.

In vitro evaluation of doxorubicin release from diopside particles on MG-63 and HF spheroids as a 3D model of tumor and healthy tissues

Local drug delivery systems based on bioceramics ensure safe and effective treatment of bone defects and anticancer therapy. A promising drug delivery scaffold material for bone treatment applications is diopside (CaMgSi2O6) which is bioactive, degradable, and possesses drug-release ability. Currently, in vitro assessment of drug release from biomaterials is performed mostly on a 2D cell monolayer. However, to interpret and integrate biochemical signals, cells need a 3D microenvironment that provides cell-cell and cell-extracellular matrix interactions. In this regard, 3D cell models are gaining popularity. In this work, we proposed the protocol for evaluation of the effect of doxorubicin released from diopside on MG-63 cells and primary human fibroblasts in 3D culture conditions. Tissue spheroids with similar diameters were incubated with doxorubicin-loaded diopside for 72 h, the amount of diopside was calculated in accordance with the required doxorubicin concentration. We demonstrated that doxorubicin is gradually released from diopside and exhibits an activity similar to that of the pure drug at the same total concentration. It is important to note that doxorubicin was more potent on MG-63 spheroids compared to HF spheroids, which confirmed the reliability of spheroids as 3D models of tumor and healthy tissues.

The Development and Characterization of a Next-Generation Oncolytic Virus Armed with an Anti-PD-1 sdAb for Osteosarcoma Treatment In Vitro

Osteosarcoma (OS) is a primary bone malignancy characterized by an aggressive nature, limited treatment options, low survival rate, and poor patient prognosis. Conditionally replicative adenoviruses (CRAds) armed with immune checkpoint inhibitors hold great potential for enhanced therapeutic efficacy. The present study aims to investigate the anti-tumor efficacy of CAV2-AU-M2, a CAV2-based CRAd armed with an anti-PD-1 single-domain antibody (sdAb), against OS cell lines in vitro. The infection, conditional replication, cytopathic effects, and cytotoxicity of CAV2-AU-M2 were tested in four different OS cell lines in two-dimensional (2D) and three-dimensional (3D) cell cultures. CAV2-AU-M2 showed selective replication in the OS cells and induced efficient tumor cell lysis and death. Moreover, CAV2-AU-M2 produced an anti-PD-1 sdAb that demonstrated effective binding to the PD-1 receptors. This study demonstrated the first CRAd armed with an anti-PD-1 sdAb. This combined approach of two distinct immunotherapies is intended to enhance the anti-tumor immune response in the tumor microenvironment.

RNA 5-methylcytosine status is associated with DNMT2/TRDMT1 nuclear localization in osteosarcoma cell lines

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Selected phenotypic features of three osteosarcoma (OS) cell lines were evaluated.

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Redox disequilibrium promoted sustained AKT and ERK1/2 activation.

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Redox imbalance modulated cell death pathways in OS cells.

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Nuclear levels of TRDMT1 methyltransferase were associated with RNA methylation.

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A novel marker for predicting therapy response in OS patients is proposed.

Osteosarcoma (OS) is a pediatric malignant bone tumor with unsatisfying improvements in survival rates due to limited understanding of OS biology and potentially druggable targets. The present study aims to better characterize osteosarcoma U-2 OS, SaOS-2, and MG-63 cell lines that are commonly used as in vitro models of OS. We focused on evaluating the differences in cell death pathways, redox equilibrium, the activity of proliferation-related signaling pathways, DNA damage response, telomere maintenance, DNMT2/TRDMT1-based responses and RNA 5-methylcytosine status. SaOS-2 cells were characterized by higher levels of superoxide and nitric oxide that promoted AKT and ERK1/2 activation thus modulating cell death pathways. OS cell lines also differed in the levels and localization of DNA repair regulator DNMT2/TRDMT1. SaOS-2 cells possessed the lowest levels of total, cytoplasmic and nuclear DNMT2/TRDMT1, whereas in MG-63 cells, the highest levels of nuclear DNMT2/TRDMT1 were associated with the most pronounced status of RNA 5-methylcytosine. In silico analysis revealed potential phosphorylation sites at DNMT2/TRDMT1 that may be related to the regulation of DNMT2/TRDMT1 localization. We postulate that redox homeostasis, proliferation-related pathways and DNMT2/TRDMT1-based effects can be modulated as a part of anti-osteosarcoma strategy reflecting diverse phenotypic features of OS cells.

Fabrication of PNIPAm-based thermoresponsive hydrogel microwell arrays for tumor spheroid formation

Complex three-dimensional (3D) cell cultures are being increasingly implemented in biomedical research as they provide important insights into complex cancer biology, and cell-cell and cell-matrix interactions in the tumor microenvironment. However, most methods used today for 3D cell culture are limited by high cost, the need for specialized skills, low throughput and the use of unnatural culture environments. We report the development of a unique biomimetic hydrogel microwell array platform for the generation and stress-free isolation of cancer spheroids. The poly N-isopropylacrylamide-based hydrogel microwell array (PHMA) has thermoresponsive properties allowing for the attachment and growth of cell aggregates/ spheroids at 37 °C, and their easy isolation at room temperature (RT). The reversible phase transition of the microwell arrays at 35 °C was confirmed visually and by differential scanning calorimetry. Swelling/ shrinking studies and EVOS imaging established that the microwell arrays are hydrophilic and swollen at temperatures <35 °C, while they shrink and are hydrophobic at temperatures >35 °C. Spheroid development within the PHMA was optimized for seeding density, incubation time and cell viability. Spheroids of A549, HeLa and MG-63 cancer cell lines, and human lung fibroblast (HLF) cell line generated within the PHMAs had relatively spherical morphology with hypoxic cores. Finally, using MG-63 cell spheroids as representative models, a proof-of-concept drug response study using doxorubicin hydrochloride was conducted. Overall, we demonstrate that the PHMAs are an innovative alternative to currently used 3D cell culture techniques, for the high-throughput generation of cell spheroids for disease modeling and drug screening applications.

PRRX1 promotes malignant properties in human osteosarcoma

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PRRX1 is a poor-prognosis marker of human osteosarcoma.

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PRRX1 promotes proliferation, invasion, and drug resistance in human osteosarcoma.

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Forskolin was identified using RNA expression signatures of PRRX1 knockdown.

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Forskolin decreased proliferation and migration in human osteosarcoma.

Paired related homeobox 1 (PRRX1) is a marker of limb bud mesenchymal cells, and deficiency of p53 or Rb in Prrx1-positive cells induces osteosarcoma in several mouse models. However, the regulatory roles of PRRX1 in human osteosarcoma have not been defined. In this study, we performed PRRX1 immunostaining on 35 human osteosarcoma specimens to assess the correlation between PRRX1 level and overall survival. In patients with osteosarcoma, the expression level of PRRX1 positively correlated with poor prognosis or the ratio of lung metastasis. Additionally, we found PRRX1 expression on in 143B cells, a human osteosarcoma line with a high metastatic capacity. Downregulation of PRRX1 not only suppressed proliferation and invasion but also increased the sensitivity to cisplatin and doxorubicin. When 143B cells were subcutaneously transplanted into nude mice, PRRX1 knockdown decreased tumor sizes and rates of lung metastasis. Interestingly, forskolin, a chemical compound identified by Connectivity Map analysis using RNA expression signatures during PRRX1 knockdown, decreased tumor proliferation and cell migration to the same degree as PRRX1 knockdown. These results demonstrate that PRRX1 promotes tumor malignancy in human osteosarcoma.

Sarcoma treatment in the era of molecular medicine

Sarcomas are heterogeneous and clinically challenging soft tissue and bone cancers. Although constituting only 1% of all human malignancies, sarcomas represent the second most common type of solid tumors in children and adolescents and comprise an important group of secondary malignancies. More than 100 histological subtypes have been characterized to date, and many more are being discovered due to molecular profiling. Owing to their mostly aggressive biological behavior, relative rarity, and occurrence at virtually every anatomical site, many sarcoma subtypes are in particular difficult-to-treat categories. Current multimodal treatment concepts combine surgery, polychemotherapy (with/without local hyperthermia), irradiation, immunotherapy, and/or targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of sarcoma subtypes and revealed novel therapeutic targets and prognostic/predictive biomarkers. This review aims at providing a comprehensive overview of the latest advances in the molecular biology of sarcomas and their effects on clinical oncology; it is meant for a broad readership ranging from novices to experts in the field of sarcoma.

High-throughput synthetic rescue for exhaustive characterization of suppressor mutations in human genes

Inherited or acquired mutations can lead to pathological outcomes. However, in a process defined as synthetic rescue, phenotypic outcome created by primary mutation is alleviated by suppressor mutations. An exhaustive characterization of these mutations in humans is extremely valuable to better comprehend why patients carrying the same detrimental mutation exhibit different pathological outcomes or different responses to treatment. Here, we first review all known suppressor mutations' mechanisms characterized by genetic screens on model species like yeast or flies. However, human suppressor mutations are scarce, despite some being discovered based on orthologue genes. Because of recent advances in high-throughput screening, developing an inventory of human suppressor mutations for pathological processes seems achievable. In addition, we review several screening methods for suppressor mutations in cultured human cells through knock-out, knock-down or random mutagenesis screens on large scale. We provide examples of studies published over the past years that opened new therapeutic avenues, particularly in oncology.

Enhanced Internalization of Nanoparticles Following Ionizing Radiation Leads to Mitotic Catastrophe in MG-63 Human Osteosarcoma Cells

This study aims to investigate whether ionizing radiation combined with doxorubicin-conjugated iron oxide nanoparticles (NP-DOX) improves the internalization and cytotoxic effects of the nano-carrier-mediated drug delivery in MG-63 human osteosarcoma cells. NP-DOX was designed and synthesized using the co-precipitation method. Highly stable and crystalline nanoparticles conjugated with DOX were internalized in MG-63 cells through macropinocytosis and located in the perinuclear area. Higher nanoparticles internalization in MG-63 cells previously exposed to 1 Gy X-rays was correlated with an early accumulation of cells in G₂/M, starting at 12 h after treatment. After 48 h, the application of the combined treatment led to higher cytotoxic effects compared to the individual treatment, with a reduction in the metabolic capacity and unrepaired DNA breaks, whilst a low percent of arrested cells, contributing to the commitment of mitotic catastrophe. NP-DOX showed hemocompatibility and no systemic cytotoxicity, nor histopathological alteration of the main organs.

Oncolytic adenovirus Ad11 enhances the chemotherapy effect of cisplatin on osteosarcoma cells by inhibiting autophagy

Targeted oncolytic adenoviruses can selectively replicate in cancer cells; combined with traditional chemotherapy drugs, this approach is expected to become an important treatment method for overcoming the current bottleneck of osteosarcoma treatment. Here, we investigate the effect of oncolytic adenovirus Ad11 combined with cisplatin on autophagy in osteosarcoma cells. Immunohistochemistry was used to detect CD46 expression in patients with osteosarcoma. A cytotoxicity assay was employed to detect the killing effect of Ad11, cisplatin and their combination on osteosarcoma cells under different time scenarios. Expression of autophagy proteins Beclin1, ATG3, and LC3A/B under treatment of osteosarcoma cells with Ad11, cisplatin and their combination under different time scenarios was detected by immunofluorescence and western blotting. We found that the oncolytic adenovirus Ad11 synergizes with cisplatin to kill osteosarcoma cells and that the synergistic effect was greatest when cells were first treated with Ad11. This synergy is due to oncolytic adenovirus Ad11-mediated inhibition of autophagy, which enhanced the sensitivity of cells to chemotherapy. In conclusion, this study provides evidence that the oncolytic adenovirus Ad11 can enhance the effect of chemotherapy by inhibiting autophagy. The findings provide a cytological basis for the treatment of osteosarcoma with oncolytic adenovirus combined with cisplatin.

Acquisition of stem associated-features on metastatic osteosarcoma cells and their functional effects on mesenchymal stem cells

BACKGROUND

Osteosarcoma (OS) is the most frequent malignant bone tumor, affecting predominantly children and young adults. Metastases are a major clinical challenge in OS. In this context, 20% of OS patients are diagnosed with metastatic OS, but near 80% of all OS patients could present non-detectable micrometastases at the moment of diagnosis.

METHODS

Osteogenic differentiation; doxorubicin exclusion assay; fluorescence microscopy; RT-qPCR; proteomic analysis.

RESULTS

Our results suggest that metastatic OS cells possess a diminished osteoblastic differentiation potential with a gain of metastatic traits like the capacity to modify intracellular localization of chemodrugs and higher levels of expression of stemness-related genes. On the opposite hand, non-metastatic OS cells possess bone-associated traits like higher osteoblastic differentiation and also an osteoblastic-inducer secretome. OS cells also differ in the nature of their interaction with mesenchymal stem cells (MSCs), with opposites impacts on MSCs phenotype and behavior.

CONCLUSIONS

All this suggests that a major trait acquired by metastatic cells is a switch into a stem-like state that could favor its survival in the pulmonary niche, opening new possibilities for personalized chemotherapeutic schemes.

GENERAL SIGNIFICANCE

Our work provides new insights regarding differences among metastatic and non-metastatic OS cells, with particular emphasis on differentiation potential, multidrug resistance and interaction with MSCs.

Antiproliferative activity of carotenoid pigments produced by extremophile bacteria

Various microorganisms are able to synthesize pigments, which usually present antioxidant properties. The aim of this work was to evaluate the antiproliferative activity of bacterial pigments against cancer cells Neuro-2a, Saos-2 and MCF-7. Pigments were obtained from Deinococcus sp. UDEC-P1 and Arthrobacter sp. UDEC-A13. Both bacterial strains were isolated from cold environments (Patagonia and Antarctica, respectively). Pigments were purified and analyzed by HPLC. Antiproliferative activity was evaluated by 3-4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium (MTT) assay. Deinoxanthin carotenoid obtained from Deinococcus sp. UDEC-P1 was able to reduce significatively the viability of Saos-2 (37.1%), while no effect was observed against MCF-7 and Neuro-2a. Pigments obtained from Arthrobacter sp. UDEC-A13 showed a significant viability reduction of three tumour cells (20.6% Neuro-2a, 26.3% Saos-2 and 13.2% MCF-7). Therefore, carotenoid pigments produced by extremophilic bacteria Deinococcus sp. UDEC-P1 and Arthrobacter sp. UDEC-A13 could be proposed as novel complementary compounds in anticancer chemotherapy.

Monitoring the effects of doxorubicin on 3D-spheroid tumor cells in real-time

Recently, increasing numbers of cell culture experiments with 3D spheroids presented better correlating results in vivo than traditional 2D cell culture systems. 3D spheroids could offer a simple and highly reproducible model that would exhibit many characteristics of natural tissue, such as the production of extracellular matrix. In this paper numerous cell lines were screened and selected depending on their ability to form and maintain a spherical shape. The effects of increasing concentrations of doxorubicin (DXR) on the integrity and viability of the selected spheroids were then measured at regular intervals and in real-time. In total 12 cell lines, adenocarcinomic alveolar basal epithelial (A549), muscle (C2C12), prostate (DU145), testis (F9), pituitary epithelial-like (GH3), cervical cancer (HeLa), HeLa contaminant (HEp2), embryo (NIH3T3), embryo (PA317), neuroblastoma (SH-SY5Y), osteosarcoma U2OS, and embryonic kidney cells (293T), were screened. Out of the 12, 8 cell lines, NIH3T3, C2C12, 293T, SH-SY5Y, A549, HeLa, PA317, and U2OS formed regular spheroids and the effects of DXR on these structures were measured at regular intervals. Finally, 5 cell lines, A549, HeLa, SH-SY5Y, U2OS, and 293T, were selected for real-time monitoring and the effects of DXR treatment on their behavior were continuously recorded for 5 days. A potential correlation regarding the effects of DXR on spheroid viability and ATP production was measured on days 1, 3, and 5. Cytotoxicity of DXR seemed to occur after endocytosis, since the cellular activities and ATP productions were still viable after 1 day of the treatment in all spheroids, except SH-SY5Y. Both cellular activity and ATP production were halted 3 and 5 days from the start of the treatment in all spheroids. All cell lines maintained their spheroid shape, except SHSY-5, which behaved in an unpredictable manner when exposed to toxic concentrations of DXR. Cytotoxic effects of DXR towards SH-SY5Y seemed to cause degradation of the extracellular matrix, since all cells were dismantled from the spheroid upon cell death. On the other hand, 293T spheroids revealed retarded cellular activity and ATP productions upon DXR treatment throughout the experiment. Since 293T was the embryonic kidney cells, the fast clearance or neutralizations could have made them resistant towards DXR. In conclusion, the same degree of sensitivity from the 2D system did not translate to a 3D culture system, resulting in higher IC50 values than the 2D system. The varying sensitivities and tolerances to drugs could be better understood with a 3D cell culture system.

Real-time monitoring of cisplatin cytotoxicity on three-dimensional spheroid tumor cells

Three-dimensional (3D) cell cultivation is a powerful technique for monitoring and understanding diverse cellular mechanisms in developmental cancer and neuronal biology, tissue engineering, and drug development. 3D systems could relate better to in vivo models than two-dimensional (2D) cultures. Several factors, such as cell type, survival rate, proliferation rate, and gene and protein expression patterns, determine whether a particular cell line can be adapted to a 3D system. The 3D system may overcome some of the limitations of 2D cultures in terms of cell–cell communication and cell networks, which are essential for understanding differentiation, structural organization, shape, and extended connections with other cells or organs. Here, the effect of the anticancer drug cisplatin, also known as cis-diamminedichloroplatinum (II) or CDDP, on adenosine triphosphate (ATP) generation was investigated using 3D spheroid-forming cells and real-time monitoring for 7 days. First, 12 cell lines were screened for their ability to form 3D spheroids: prostate (DU145), testis (F9), embryonic fibroblast (NIH-3T3), muscle (C2C12), embryonic kidney (293T), neuroblastoma (SH-SY5Y), adenocarcinomic alveolar basal epithelial cell (A549), cervical cancer (HeLa), HeLa contaminant (HEp2), pituitary epithelial-like cell (GH3), embryonic cell (PA317), and osteosarcoma (U-2OS) cells. Of these, eight cell lines were selected: NIH-3T3, C2C12, 293T, SH-SY5Y, A549, HeLa, PA317, and U-2OS; and five underwent real-time monitoring of CDDP cytotoxicity: HeLa, A549, 293T, SH-SY5Y, and U-2OS. ATP generation was blocked 1 day after addition of 50 μM CDDP, but cytotoxicity in HeLa, A549, SH-SY5Y, and U-2OS cells could be visualized only 4 days after treatment. In 293T cells, CDDP failed to kill entirely the culture and ATP generation was only partially blocked after 1 day. This suggests potential CDDP resistance of 293T cells or metabolic clearance of the drug. Real-time monitoring and ATP measurements directly confirmed the cytotoxicity of CDDP, indicating that CDDP may interfere with mitochondrial activity.

Oxidative stress induced by low-dose doxorubicin promotes the invasiveness of osteosarcoma cell line U2OS in vitro

Reactive oxygen species (ROS) are known to mediate doxorubicin (DOX)-induced apoptosis and are the major cause of DOX toxicity. We introduce a novel in vitro phenomenon of osteosarcoma (OS) cell line caused by low-dose DOX-induced oxidative stress. Human osteosarcoma cell line U2OS was used for the experiments. Hydrogen peroxide (H2O2) and the antioxidant compound N-acetylcysteine (NAC) were used to investigate the involvement of oxidative stress. In proliferation assays, low dose of DOX (below 200 nM) did not affect U2OS proliferation significantly for up to 48 h. In Matrigel(TM) invasion assay, DOX increased the invasiveness of U2OS at around 100 nM, which is a subclinical concentration. Quantitative real-time polymerase chain reaction and gelatin zymography showed increased MMP-9 expression and increased MMP-9 enzymatic activity, respectively, in the presence of DOX doses that increased the invasiveness of U2OS. H2O2, a representative source of ROS, also increased the invasiveness of U2OS as DOX did, with similar patterns. However, when the cells were pre-treated with NAC, no DOX- or H2O2-mediated increase of invasiveness or MMP-9 expression was evident. The results suggest that oxidative stress induced by low-dose DOX promotes the invasiveness of osteosarcoma cell line U2OS in vitro, through MMP-9 induction.

In vitro screen of a small molecule inhibitor drug library identifies multiple compounds that synergize with oncolytic myxoma virus against human brain tumor-initiating cells

BACKGROUND

Brain tumor-initiating cells (BTICs) are stem-like cells hypothesized to form a disease reservoir that mediates tumor recurrence in high-grade gliomas. Oncolytic virotherapy uses replication-competent viruses to target and kill malignant cells and has been evaluated in clinic for glioma therapy with limited results. Myxoma virus (MyxV) is a safe and highly effective oncolytic virus (OV) in conventional glioma models but, as seen with other OVs, is only modestly effective for patient-derived BTICs. The objective of this study was to determine whether MyxV treatment against human BTICs could be improved by combining chemotherapeutics and virotherapy.

METHODS

A 73-compound library of drug candidates in clinical use or preclinical development was screened to identify compounds that sensitize human BTICs to MyxV treatment in vitro, and synergy was evaluated mathematically in lead compounds using Chou-Talalay analyses. The effects of combination therapy on viral gene expression and viral replication were also assessed.

RESULTS

Eleven compounds that enhance MyxV efficacy were identified, and 6 were shown to synergize with the virus using Chou-Talalay analyses. Four of the synergistic compounds were shown to significantly increase viral gene expression, indicating a potential mechanism for synergy. Three highly synergistic compounds (axitinib, a VEGFR inhibitor; rofecoxib, a cyclooxygenase-2 inhibitor; and pemetrexed, a folate anti-metabolite) belong to classes of compounds that have not been previously shown to synergize with oncolytic viruses in vitro.

CONCLUSIONS

This study has identified multiple novel drug candidates that synergistically improve MyxV efficacy in a preclinical BTIC glioma model.

miR-382 inhibits osteosarcoma metastasis and relapse by targeting Y box-binding protein 1

Lung metastasis and relapse in osteosarcoma (OS) patients indicate poor prognosis. Here, we identified significantly decreased expression of miR-382 in highly metastatic OS cell lines and relapsed OS samples compared to their parental cell lines and primary OS samples, respectively. In addition, our clinical data showed that the miR-382 expression level was inversely associated with relapse and positively associated with metastasis-free survival in OS patients. The overexpression of miR-382 suppressed epithelial-mesenchymal transition (EMT) and metastasis. This overexpression also decreased the cancer stem cell (CSC) population and function in OS cells. In contrast, inhibition of miR-382 stimulated EMT and metastasis and increased CSC population in OS cells. In addition, our in vivo experiments showed that the overexpression of miR-382 inhibited CSC-induced tumor formation, and the combination of miR-382 with doxorubicin prevented disease relapse in OS patients. Furthermore, we demonstrated that miR-382 exerted its tumor-suppressing potential by directly targeting Y box-binding protein 1 (YB-1) in OS. Taken together, our findings suggest that miR-382 functions as a tumor suppressor function and that the overexpression of miR-382 is a novel strategy to inhibit tumor metastasis and prevent CSC-induced relapse in OS.

The oncolytic adenovirus Δ24-RGD in combination with cisplatin exerts a potent anti-osteosarcoma activity

Osteosarcoma is the most common malignant bone tumor in children and adolescents. The presence of metastases and the lack of response to conventional treatment are the major adverse prognostic factors. Therefore, there is an urgent need for new treatment strategies that overcome both of these problems. Our purpose was to elucidate whether the use of the oncolytic adenovirus Δ24-RGD alone or in combination with standard chemotherapy would be effective, in vitro and in vivo, against osteosarcoma. Our results showed that Δ24-RGD exerted a potent antitumor effect against osteosarcoma cell lines that was increased by the addition of cisplatin. Δ24-RGD osteosarcoma treatment resulted in autophagy in vitro that was further enhanced when combined with cisplatin. Of importance, administration of Δ24-RGD and/or cisplatin, in novel orthotopic and two lung metastatic models in vivo resulted in a significant reduction of tumor burden meanwhile maintaining a safe toxicity profile. Together, our data underscore the potential of Δ24-RGD to become a realistic therapeutic option for primary and metastatic pediatric osteosarcoma. Moreover, this study warrants a future clinical trial to evaluate the safety and efficacy of Δ24-RGD for this devastating disease.

Superhydrophobic chips for cell spheroids high-throughput generation and drug screening

We suggest the use of biomimetic superhydrophobic patterned chips produced by a benchtop methodology as low-cost and waste-free platforms for the production of arrays of cell spheroids/microtissues by the hanging drop methodology. Cell spheroids have a wide range of applications in biotechnology fields. For drug screening, they allow studying 3D models in structures resembling real living tissues/tumors. In tissue engineering, they are suggested as building blocks of bottom-up fabricated tissues. We used the wettability contrast of the chips to fix cell suspension droplets in the wettable regions and evaluated on-chip drug screening in 3D environment. Cell suspensions were patterned in the wettable spots by three distinct methods: (1) by pipetting the cell suspension directly in each individual spot, (2) by the continuous dragging of a cell suspension on the chip, and (3) by dipping the whole chip in a cell suspension. These methods allowed working with distinct throughputs and degrees of precision. The platforms were robust, and we were able to have static or dynamic environments in each droplet. The access to cell culture media for exchange or addition/removal of components was versatile and opened the possibility of using each spot of the chip as a mini-bioreactor. The platforms' design allowed for samples visualization and high-content image-based analysis on-chip. The combinatorial analysis capability of this technology was validated by following the effect of doxorubicin at different concentrations on spheroids formed using L929 and SaOs-2 cells.

Association of oncolytic adenoviruses with chemotherapies: an overview and future directions

Oncolytic adenoviruses have been used in different preclinical and clinical studies, showing their capacity to kill tumor cells without major adverse events. However, these studies also underline the limitations of this approach. The efficacy of oncolytic adenoviruses is hampered by their limited ability to transduce some tumor types, their lack of selectivity, and their poor dissemination within tumors. In addition, the host immune response may limit oncolytic adenovirus efficacy. Combining oncolytic adenoviruses with chemotherapeutics constitutes an appealing strategy to increase their potency. The first part of this review describes the molecular basis of oncolytic adenoviruses, their use in preclinical studies and clinical trials, their limitations, and strategies to circumvent these limitations. The second part will focus on studies combining oncolytic adenoviruses with chemotherapeutic drugs, including standard chemotherapeutic drugs, molecularly targeted drugs, and other drugs that have been combined with oncolytic adenoviruses. Finally, based on these studies, we describe future directions and general rules that could be followed to identify chemotherapeutic drugs displaying additive/synergistic effects when combined with oncolytic adenoviruses.

Conditionally replicative adenovirus-based mda-7/IL-24 expression enhances sensitivity of colon cancer cells to 5-fluorouracil and doxorubicin

BACKGROUND

Multiple drug resistance (MDR) greatly limits the efficacy of chemotherapy for colon cancer. An adenovirus armed with Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24; abbreviated to 'IL-24' here) was shown to reverse the MDR of colon cancer cells to oxaliplatin and doxorubicin. However, the relatively low expression level of IL-24 mediated by a replication-deficient adenoviral vector hindered its clinical application.

METHODS

To enhance IL-24-dependentreversion of the MDR phenotype, we utilized a conditionally replicative adenoviral vector, AdBB-IL24, to express IL-24 at a high level for more efficient MDR reversion.

RESULTS

An enzyme-linked immunosorbent assay (ELISA) suggested conditionally replicative adenoviral vector-mediated IL-24 expression was elevated in comparison with that of a replication-deficient adenoviral vector, Ad-IL24. AdBB-IL24 was shown to reverse MDR in colon cancer cells more potently than Ad-IL24. The AdBB-IL24-induced MDR reversion was linked to reduced P-glycoprotein (Pgp) and breast cancer resistance protein 1 (BCRP1) expression. Consistently, 5-fluorouracil and doxorubicin induced more apoptosis in AdBB-IL24-infected colon cancer cells compared with that in the Ad-IL24-infected cells. A cell viability assay showed that AdBB-IL24 could enhance the growth-inhibitory effect of 5-fluorouracil and doxorubicin on colon cancer cells more effectively than Ad-IL24 in vitro. In a mouse model, we also found that the combination of 5-fluorouracil and doxorubicin with AdBB-IL24 completely inhibited the growth of colon cancer cells.

CONCLUSION

We here provide evidence supporting conditionally replicative adenoviral vector-based gene therapy as a powerful strategy to enhance mda7/IL-24-dependent MDR reversion of colon cancer cells.

Endothelin-1 promotes osteosarcoma cell invasion and survival against cisplatin-induced apoptosis

BACKGROUND

Endothelin-1 (ET-1) participates in a wide range of cancer-relevant processes including cell proliferation, inhibition of apoptosis, matrix remodeling, bone deposition, and metastases. Although ET-1 reportedly promotes osteosarcoma (OS) cell invasion, suggesting an important role of ET-1 in OS metastasis, the role of ET-1 in OS remains unclear.

QUESTION/PURPOSES

We asked whether (1) ET-1 expression is associated with the malignancy of OS, (2) ET-1 enhances the cell invasion ability of OS, and (3) ET-1 promotes OS cell survival against apoptotic stress.

METHODS

We cultured primary OS specimens from 22 patients with Stages II (OS-II) and III (OS-III) in real-time quantitative RT-PCR and ELISA to compare ET-1 expression. We used Transwell(®) cell invasion assays (in triplicate) to assess the invasion ability of cells in the presence or absence of exogenous ET-1 and/or ET receptor antagonists. We compared cell apoptosis rate among the cells treated with cisplatin in the presence or absence of exogenous ET-1 and/or ET receptor antagonists. We used OS cell line MG-63 in all experiments as a reference.

RESULTS

Real-time quantitative RT-PCR and ELISA showed OS-III cells had greater ET-1 expression than OS-II cells at the mRNA and the secreted protein levels. Transwell(®) cell invasion assays showed OS-III cells had a greater migrated cell number than OS-II cells, which could be abrogated by ET(A) receptor antagonist BQ123 (100 pmol/L), but not ET(B) receptor antagonist BQ788 (1 μmol/L); exogenous ET-1 dose-dependently promoted OS cell migration, which could be inhibited by BQ123 (100 pmol/L). Cisplatin (10 nmol/L) induced less apoptosis in OS-III cells than in OS-II cells; exogenous ET-1 dose-dependently promoted OS cell survival against cisplatin-induced apoptosis; both effects were reversed by BQ123 (1 μmol/L), but not BQ788 (1 μmol/L).

CONCLUSIONS

Increased ET-1 expression appears to be associated with increased malignancy of OS. ET-1 promotes OS cell invasion and survival against cisplatin-induced apoptosis through the ET(A) receptor.

CLINICAL RELEVANCE

The ET-1/ET(A) pathway may represent an important target for treating OS, because blocking the ET(A) receptor with a selective antagonist can inhibit OS cell invasion and potentiate a chemotherapeutic agent's effect on OS.

Novel quinazoline HMJ-30 induces U-2 OS human osteogenic sarcoma cell apoptosis through induction of oxidative stress and up-regulation of ATM/p53 signaling pathway

Human osteogenic sarcoma is the most common primary bone tumor. Despite of the success of frontline therapy, about 40% of patients have disease progression and further therapy is palliative and toxic. In this study, we developed a novel quinazoline HMJ-30 to investigate the cell growth inhibition and apoptotic responses in U-2 OS human osteogenic sarcoma cells. Our results demonstrated that HMJ-30 significantly reduced cell viabilities of U-2 OS, HOS, and 143B cells in a dose-dependent manner, but it exhibited low cytotoxicity in normal hFOB cells. HMJ-30 induced DNA damage and apoptosis in U-2 OS cells as revealed by morphologic changes, comet assay and DAPI staining. Immuno-staining, colorimetric assays, and Western blotting analyses indicated that activities of caspase-8, caspase-9, and caspase-3 and the levels of Bcl-2 family-related proteins (Bcl-2, Mcl-1, Bax, BAD, and t-Bid) were altered in HMJ-30-treated U-2 OS cells. Pretreatment of cells with caspase-8, -9, and -3 specific inhibitors significantly reduced the cell growth inhibition. HMJ-30-induced apoptosis was mediated through both death-receptor and mitochondria-dependent apoptotic pathways in U-2 OS cells. HMJ-30 induced early phosphorylation of p53(Ser18) was through the activation of ataxia telangiectasia mutated (ATM) in U-2 OS cells. The cell growth inhibition by HMJ-30 was substantially attenuated either by the pre-incubation of U-2 OS cells with N-acetylcysteine (NAC, an antioxidant) and caffeine (an ATM kinase inhibitor) or by p53 knockdown via RNAi. In conclusion, ROS dependent-ATM/p53 signaling pathway is involved in HMJ-30-induced apoptosis in U-2 OS cells.

Combining conditionally replicating adenovirus-mediated gene therapy with chemotherapy: a novel antitumor approach

Despite significant improvements in diagnosis and innovations in the therapy of specific cancers, effective treatment of neoplastic diseases still presents major challenges. Recent studies have shown that conditionally replicating adenoviruses (CRAds) not only have the ability to destroy cancer cells but may also be potential vectors for the expression of therapeutic genes. Several studies in animal models have demonstrated that the combination of CRAds-mediated gene therapy and chemotherapy has greater therapeutic benefit than either treatment modality alone. In this review, an overview of specifications for a novel antitumor approach combining CRAd-gene therapy and chemotherapy is provided and recent progress in this field is discussed.

The topoisomerase II inhibitor voreloxin causes cell cycle arrest and apoptosis in myeloid leukemia cells and acts in synergy with cytarabine

BACKGROUND

Topoisomerase II is essential for the maintenance of DNA integrity and the survival of proliferating cells. Topoisomerase II poisons, including etoposide and doxorubicin, inhibit enzyme-mediated DNA ligation causing the accumulation of double-stranded breaks and have been front-line drugs for the treatment of leukemia for many years. Voreloxin is a first-in-class anti-cancer quinolone derivative that intercalates DNA and inhibits topoisomerase II. The efficacy and mechanisms of action of voreloxin in acute myeloid leukaemia were addressed in this study.

DESIGN AND METHODS

Primary acute myeloid leukemia blasts (n = 88) and myeloid cell lines were used in vitro to study voreloxin through viability assays to assess cell killing and synergy with other drugs. Apoptosis and cell cycling were assessed by flow cytometry. DNA relaxation assays were utilized to determine that voreloxin was active on topoisomerase II.

RESULTS

The mean lethal dose 50% (LD(50)) (± standard deviation) of voreloxin for primary acute myeloid leukemia blasts was 2.30 μM (± 1.87). Synergy experiments between voreloxin and cytarabine identified synergism in 22 of 25 primary acute myeloid leukemia samples tested, with a mean combination index of 0.79. Apoptosis was shown to increase in a dose-dependent manner. Furthermore, voreloxin was active in the p53-null K562 cell line suggesting that the action of voreloxin is not affected by p53 status. The action of voreloxin on topoisomerase II was confirmed using a DNA relaxation assay.

CONCLUSIONS

Voreloxin may provide an interesting addition to the cache of drugs available for the treatment of acute myeloid leukemia, a disease with a poor long-term survival. In addition to its potent action as a single agent in dividing cells, the synergy we demonstrated between voreloxin and cytarabine recommends further investigation of this topoisomerase II inhibitor.

Combinatory cytotoxic effects produced by E1B-55kDa-deleted adenoviruses and chemotherapeutic agents are dependent on the agents in esophageal carcinoma

We examined possible combinatory antitumor effects of replication-competent type 5 adenoviruses (Ad) lacking E1B-55kDa molecules (Ad-delE1B55) and chemotherapeutic agents in nine human esophageal carcinoma cells. Ad-delE1B55 produced cytotoxic effects on all the carcinoma cells and the cytotoxicity is not directly linked with the p53 status of the tumors or with the infectivity to respective tumors. A combinatory treatment with Ad-delE1B55 and an anticancer agent, 5-fluorouracil (5-FU), mitomycin C or etoposide, produced greater cytotoxic effects than that with either the Ad or the agent. Administration of 5-FU could minimally inhibit the viral replication and a simultaneous treatment with the Ad and 5-FU achieved better cytotoxicity than sequential treatments. We also confirmed the antitumor effects by the combination of Ad-delE1B55 with 5-FU in vivo. Cisplatin, however, did not achieve the combinatory effects in most of the cells tested. These data indicate that the Ad-delE1B55 produce combinatory antitumor effects with a chemotherapeutic agent irrespective of the administration schedule, but the effects depend on an agent in esophageal carcinoma.

Armoring CRAds with p21/Waf-1 shRNAs: the next generation of oncolytic adenoviruses

Conditionally replicating adenoviruses (CRAds) represent a promising modality for the treatment of neoplastic diseases, including Prostate Cancer. Selectively replicating viruses can be generated by placing a tissue or cancer-specific promoter upstream of one or more of the viral genes required for replication (for example, E1A, E1B). We have previously reported multiple cellular processes that can attenuate viral replication, which in turn compromises viral oncolysis and tumor kill. In this study, we investigated the importance of the cyclin-dependent kinase inhibitor p21/Waf-1, on viral replication and tumor growth. To our knowledge, this is the first report describing the importance of p21/Waf-1shRNA on the induction of an androgen responsive element (ARE) based promoter driving the E1A gene. As a proof of concept, the study emphasizes the use of RNA interference technology to overcome promoter weaknesses for tissue-specific oncolytic viruses, as well as the cellular inhibitor pathways on viral life cycle. Using RNA interference against p21/Waf-1, we were able to show an increase in viral replication and viral oncolysis of prostate cancer cells. Similarly, CRAd viruses that carry p21/Waf-1 shRNA (Ad5-RV004.21) were able to prevent tumor outgrowth that resulted in a marked increase in the mean survival time of tumor-bearing mice compared with CRAd without p21/Waf-1 shRNA (Ad5-RV004). In studies combining Ad5-RV004.21 with Adriamycin, a suprar-additive effect was observed only in CRAds that harbor shRNA against p21/Waf-1. Taken together, these findings of enhanced viral replication in prostate cancer cells by using RNA interference against the cdk inhibitor p21/Waf-1 have significant implications in the development of prostate-specific CRAd therapies.

Characterization and comparison of the properties of sarcoma cell lines in vitro and in vivo

To expand the available tools for investigating human sarcomas, we characterized the primary properties of 22 common, uncommon, and newly characterized sarcoma cell lines representing eight different histological subtypes. Throughout the characterization process we noticed that in vitro markers and assays are poor indicators of tumorigenicity and that generated xenografts often bear little resemblance to the original histopathology. In vitro properties examined included morphology, proliferation rate, cell cycle characteristics, invasiveness, and immunohistochemical expression of p53 and phospho-AKT. In vivo properties examined included days to tumor formation in NOD/SCID mice, xenograft morphology in several locations and immunohistochemical expression of Ki67, p53 and phospho-AKT. We believe that such an in depth comparison of a large cohort of sarcoma cell lines will be useful in both designing and interpreting experiments aimed at elucidating both the molecular biology and efficacy of therapeutic agents in sarcomas. However, that data generated also suggests a small set of sarcoma cell lines may be inappropriate for generalizations regarding biological behavior of specific sarcoma subtypes. Integration of functional genomics or other more sophisticated assays of cell lines may help bridge the differences in vitro and in vivo.

Evaluation of adenovirus capsid labeling versus transgene expression

Adenoviral vectors have been utilized for a variety of gene therapy applications. Our group has incorporated bioluminescent, fluorographic reporters, and/or suicide genes within the adenovirus genome for analytical and/or therapeutic purposes. These molecules have also been incorporated as capsid components. Recognizing that incorporations at either locale yield potential advantages and disadvantages, our report evaluates the benefits of transgene incorporation versus capsid incorporation. To this end, we have genetically incorporated firefly luciferase within the early region 3 or at minor capsid protein IX and compared vector functionality by means of reporter readout.

Intelligent design: combination therapy with oncolytic viruses

Metastatic cancer remains an incurable disease in the majority of cases and thus novel treatment strategies such as oncolytic virotherapy are rapidly advancing toward clinical use. In order to be successful, it is likely that some type of combination therapy will be necessary to have a meaningful impact on this disease. Although it may be tempting to simply combine an oncolytic virus with the existing standard radiation or chemotherapeutics, the long-term goal of such treatments must be to have a rational, potentially synergistic combination strategy that can be safely and easily used in the clinical setting. The combination of oncolytic virotherapy with existing radiotherapy and chemotherapy modalities is reviewed along with novel biologic therapies including immunotherapies, in order to help investigators make intelligent decisions during the clinical development of these products.

Immunotherapy for osteosarcoma: genetic modification of T cells overcomes low levels of tumor antigen expression

Human epidermal growth factor receptor 2 (HER2) is expressed by the majority of human osteosarcomas and is a risk factor for poor outcome. Unlike breast cancer, osteosarcoma cells express HER2 at too low, a level for patients to benefit from HER2 monoclonal antibodies. We reasoned that this limitation might be overcome by genetically modifying T cells with HER2-specific chimeric antigen receptors (CARs), because even a low frequency of receptor engagement could be sufficient to induce effector cell killing of the tumor. HER2-specific T cells were generated by retroviral transduction with a HER2-specific CAR containing a CD28.zeta signaling domain. HER2-specific T cells recognized HER2-positive osteosarcoma cells as judged by their ability to proliferate, produce immunostimulatory T helper 1 cytokines, and kill HER2-positive osteosarcoma cell lines in vitro. The adoptive transfer of HER2-specific T cells caused regression of established osteosarcoma xenografts in locoregional as well as metastatic mouse models. In contrast, delivery of nontransduced (NT) T cells did not change the tumor growth pattern. Genetic modification of T cells with CARs specific for target antigens, expressed at too low a level to be effectively recognized by monoclonal antibodies, may allow immunotherapy to be more broadly applicable for human cancer therapy.

The Werner syndrome protein functions in repair of Cr(VI)-induced replication-associated DNA damage

Werner syndrome is a premature aging disorder characterized by cancer predisposition that is caused by loss of the Werner syndrome protein (WRN) helicase/exonuclease DNA repair protein. Hexavalent chromium is an environmental carcinogen and genotoxicant that is associated with respiratory cancers and induces several forms of DNA damage, including lesions that interfere with DNA replication. Based on the evidence that WRN protein facilitates repair of stalled and collapsed replication forks, we hypothesized that WRN functions in the cellular response to and recovery from Cr(VI)-induced genotoxicity and genomic instability. Here we report that human cells deficient in WRN protein are hypersensitive to Cr(VI) toxicity, and exhibit a delayed reduction in DNA breaks and stalled replication forks, indicated by gammaH2AX foci, during recovery from Cr(VI) exposure. Cr(VI)-induced WRN protein translocation from the nucleoli into nucleoplasmic foci in S-phase cells, and these foci colocalized with gammaH2AX foci indicating WRN responds to replication-associated DNA damage. As further evidence that Cr(VI) triggers stalled DNA replication, we observed Cr(VI) treatment induced an accumulation of cells in S-phase that exhibited high levels of gammaH2AX foci. Therefore, these data demonstrate a novel role for WRN protein in cellular protection against the environmental genotoxicant Cr(VI) and further provide evidence that Cr(VI) induces DNA replicative stress which has implications for aging and cancer.

Utilizing RNA interference to enhance cancer drug discovery

With the development of RNA interference (RNAi) libraries, systematic and cost-effective genome-wide loss-of-function screens can now be carried out with the aim of assessing the role of specific genes in neoplastic phenotypes, and the rapid identification of novel drug targets. Here, we discuss the existing applications of RNAi in cancer drug discovery and highlight areas in this process that may benefit from this technology in the future.