Severe Combined Immunodeficient Mouse Xenograft Research Articles

BRDT promotes ovarian cancer cell growth

Bromodomain testis-specific factor (BRDT) is a member of the bromodomain and extra-terminal (BET) family proteins. Its expression and potential functions in ovarian cancer were examined. We show that BRDT is overexpressed in human ovarian cancer tissues and in established (CaOV3)/primary ovarian cancer cells. However, its expression is low in ovarian epithelial tissues and cells. Significantly, shRNA-induced silencing or CRISPR/Cas9-mediated knockout of BRDT inhibited ovarian cancer cell growth, viability, proliferation and migration, and induced significant apoptosis activation. Conversely, exogenous overexpression of BRDT, by a lentiviral construct, augmented CaOV3 cell proliferation and migration. In CaOV3 cells expression of two key BRDT target genes, polo-like kinase 1 (PLK1) and aurora kinase C (AURKC), was downregulated by BRDT shRNA or knockout, but upregulated with BRDT overexpression. In vivo, xenograft tumors-derived from BRDT-knockout CaOV3 cells grew significantly slower than control tumors in severe combined immunodeficient (SCID) mice. Furthermore, intratumoral injection of BRDT shRNA lentivirus potently inhibited the growth of primary ovarian cancer xenografts in SCID mice. Downregulation of PLK1 and AURKC was detected in BRDT-knockout and BRDT-silenced tumor tissues. Collectively, BRDT overexpression promotes ovarian cancer cell progression. Targeting BRDT could be a novel strategy to treat ovarian cancer.

The humanin analogue (HNG) prevents temozolomide-induced male germ cell apoptosis and other adverse effects in severe combined immuno-deficiency (SCID) mice bearing human medulloblastoma

Subfertility is a major concern of long-term cancer survivors at the reproductive age. We have previously demonstrated that a potent humanin analogue, HNG, protected chemotherapy-induced apoptosis in germ cells but not cancer cells in a metastatic melanoma allograft model. In this study, we utilized severe combined immuno-deficiency (SCID) mice bearing human medulloblastoma to study the effect of HNG in Temozolomide (TMZ) induced male germ cell apoptosis and white blood cell (WBC) suppression. Human medulloblastoma DAOY cells were injected subcutaneously into the right flank of male SCID mice. Three weeks later, groups of tumor-bearing mice received one of the following treatments: vehicle, HNG, TMZ, or TMZ + HNG. 24 h after last injection, the tumors weights, complete blood counts, liver and spleen weights, male germ cell apoptosis was assessed. HNG did not affect TMZ's significant anti-tumor action. HNG significantly prevented TMZ-induced germ cell apoptosis and attenuated the suppressed total WBC and granulocyte counts in SCID mice with or without TMZ treatment. HNG also attenuated TMZ-induced body weight loss and decrease of spleen and liver weights. In conclusion, HNG ameliorated TMZ-induced germ cell apoptosis; WBC and granulocytes loss; and decreased body/organ weights without compromising the TMZ's anti-cancer action on medulloblastoma xenografts in SCID mice.

FGF9/FGFR2 increase cell proliferation by activating ERK1/2, Rb/E2F1, and cell cycle pathways in mouse Leydig tumor cells.

Fibroblast growth factor 9 (FGF9) promotes cancer progression; however, its role in cell proliferation related to tumorigenesis remains elusive. We investigated how FGF9 affected MA‐10 mouse Leydig tumor cell proliferation and found that FGF9 significantly induced cell proliferation by activating ERK1/2 and retinoblastoma (Rb) phosphorylations within 15 minutes. Subsequently, the expressions of E2F1 and the cell cycle regulators: cyclin D1, cyclin E1 and cyclin‐dependent kinase 4 (CDK4) in G1 phase and cyclin A1, CDK2 and CDK1 in S‐G2/M phases were increased at 12 hours after FGF9 treatment; and cyclin B1 in G2/M phases were induced at 24 hours after FGF9 stimulation, whereas the phosphorylations of p53, p21 and p27 were not affected by FGF9. Moreover, FGF9‐induced effects were inhibited by MEK inhibitor PD98059, indicating FGF9 activated the Rb/E2F pathway to accelerate MA‐10 cell proliferation by activating ERK1/2. Immunoprecipitation assay and ChIP‐quantitative PCR results showed that FGF9‐induced Rb phosphorylation led to the dissociation of Rb‐E2F1 complexes and thereby enhanced the transactivations of E2F1 target genes, Cyclin D1, Cyclin E1 and Cyclin A1. Silencing of FGF receptor 2 (FGFR2) using lentiviral shRNA inhibited FGF9‐induced ERK1/2 phosphorylation and cell proliferation, indicating that FGFR2 is the obligate receptor for FGF9 to bind and activate the signaling pathway in MA‐10 cells. Furthermore, in a severe combined immunodeficiency mouse xenograft model, FGF9 significantly promoted MA‐10 tumor growth, a consequence of increased cell proliferation and decreased apoptosis. Conclusively, FGF9 interacts with FGFR2 to activate ERK1/2, Rb/E2F1 and cell cycle pathways to induce MA‐10 cell proliferation in vitro and tumor growth in vivo.

Monitoring of tumor burden invivo by optical imaging in a xenograft SCID mouse model: evaluation of two fluorescent proteins of the GFP-superfamily.

Mouse models of human-malignant-melanoma (MM) are important tools to study tumor dynamics. The enhanced green fluorescent protein (EGFP) is widely used in molecular imaging approaches, together with optical scanners, and fluorescence imaging. Currently, there are no data available as to whether other fluorescent proteins are more suitable. The goal of this preclinical study was to analyze two fluorescent proteins of the GFP superfamily under real-time invivo conditions using fluorescence reflectance imaging (FRI). The human melanoma cell line MeWo was stable transfected with one plasmid: pEGFP-C1 or pDsRed1-N1. We investigated two severe combined immunodeficiency (SCID)-mice groups: A (solid xenografts) and B (xenografts as metastases). After three weeks, the animals were weekly imaged by FRI. Afterwards the mice were euthanized and metastases were imaged in situ: to quantify the cutis-dependent reduction of emitted light, we compared signal intensities obtained by metastases invivo with signal intensities obtained by in situ liver parenchyma preparations. More than 90% of cells were stable transfected. EGFP-/DsRed-xenograft tumors had identical growth kinetics. Invivo the emitted light by DsRed tumors/metastases was much brighter than by EGFP. DsRed metastases were earlier (3 vs. 5 weeks) and much more sensitive detectable than EGFP metastases. Cutis-dependent reduction of emitted light was greater in EGFP than in DsRed mice (tenfold). Autofluorescence of DsRed was lower than of EGFP. We established an invivo xenograft mouse model (DsRed-MeWo) that is reliable, reproducible, and superior to the EGFP model as a preclinical tool to study innovative therapies by FRI under real-time invivo conditions.

Augmented expression of RUNX1 deregulates the global gene expression of U87 glioblastoma multiforme cells and inhibits tumor growth in mice.

Glioblastoma multiforme is the most common and aggressive primary brain tumor in adults. A mesenchymal phenotype was associated with tumor aggressiveness and poor prognosis in glioblastoma multiforme patients. Recently, the transcription factor RUNX1 was suggested as a driver of the glioblastoma multiforme mesenchymal gene expression signature; however, its independent role in this process is yet to be described. Here, we assessed the role of RUNX1 in U87 glioblastoma multiforme cells in correspondence to its mediated transcriptome and genome-wide occupancy pattern. Overexpression of RUNX1 led to diminished tumor growth in nude and severe combined immunodeficiency mouse xenograft tumor model. At the molecular level, RUNX1 occupied thousands of genomic regions and regulated the expression of hundreds of target genes, both directly and indirectly. RUNX1 occupied genomic regions that corresponded to genes that were shown to play a role in brain tumor progression and angiogenesis and upon overexpression led to a substantial down-regulation of their expression level. When overexpressed in U87 glioblastoma multiforme cells, RUNX1 down-regulated key pathways in glioblastoma multiforme progression including epithelial to mesenchymal transition, MTORC1 signaling, hypoxia-induced signaling, and TNFa signaling via NFkB. Moreover, master regulators of the glioblastoma multiforme mesenchymal phenotype including CEBPb, ZNF238, and FOSL2 were directly regulated by RUNX1. The data suggest a central role for RUNX1 as master regulator of gene expression in the U87 glioblastoma multiforme cell line and mark RUNX1 as a potential target for novel future therapies for glioblastoma multiforme.

Targeting Nonsquamous Nonsmall Cell Lung Cancer via the Proton-Coupled Folate Transporter with 6-Substituted Pyrrolo[2,3-d]Pyrimidine Thienoyl Antifolates.

Pemetrexed (PMX) is a 5-substituted pyrrolo[2,3-d]pyrimidine antifolate used for therapy of nonsquamous nonsmall cell lung cancer (NS-NSCLC). PMX is transported by the reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT). Unlike RFC, PCFT is active at acidic pH levels characterizing the tumor microenvironment. By real-time reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry, PCFT transcripts and proteins were detected in primary NS-NSCLC specimens. In six NS-NSCLC cell lines (A549, H1437, H460, H1299, H1650, and H2030), PCFT transcripts and proteins were detected by real-time RT-PCR and western blots, respectively. 6-Substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolates related to PMX [compound 1 (C1) and compound 2 (C2), respectively] are selective substrates for PCFT over RFC. In the NS-NSCLC cell lines, both [(3)H]PMX and [(3)H]C2 were transported by PCFT. C1 and C2 inhibited proliferation of the NS-NSCLC cell lines; A549, H460, and H2030 cells were more sensitive to C1 than to PMX. C1 and C2 inhibited glycinamide ribonucleotide formyltransferase in de novo purine nucleotide biosynthesis. When treated at pH 6.8, which favors PCFT uptake, C1 and C2 inhibited clonogenicity of H460 cells greater than PMX; PMX inhibited clonogenicity more than C1 or C2 at pH 7.2, which favors RFC transport over PCFT. Knockdown of PCFT in H460 cells resulted in decreased [(3)H]PMX and [(3)H]C2 transport and decreased growth inhibition by C1 and C2, and to a lesser extent by PMX. In vivo efficacy of C1 was seen toward H460 tumor xenografts in severe-combined immunodeficient mice. Our results suggest that 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolates offer significant promise for treating NS-NSCLC by selective uptake by PCFT.

Cancer and embryo expression protein 65 promotes cancer cell growth and metastasis.

Cancer and embryo expression protein 65 (CEP65) is a centrosomal protein that is expressed at relatively high levels in embryonic tissue and different cancerous tissues, but its role in tumorigenesis remains unknown. In the present study, CEP65 was stably expressed in AGS gastric cancer cells. CEP65 was found to promote cell growth in the MTT assay and to enhance cell migration and invasion in Transwell chamber assays. To validate results from the in vitro experiments, CEP65 was stably expressed in BICR-H1 breast cancer cells through adenovirus-mediated transduction. By inoculating BICR-H1 cells on chick chorioallantoic membrane (CAM), it was found that CEP65 promotes cell growth on the CAM and increases cell metastasis to the lungs of the chicken. By utilizing a xenograft severe combined immunodeficiency mouse model, CEP65 was also found to accelerate BICR-H1 cell growth and metastasis to the lungs. Furthermore, it was shown that CEP65 increases matrix metalloproteinase (MMP)2 activity in zymographic assays, however, microarray screening and reverse transcription polymerase chain reaction validation revealed that CEP65 had no effect on the expression levels of MMP2 or MMP9, but decreased the expression levels of metastasis-associated genes, TIMP2, RAP and VTN. Taken together, the results of the present study demonstrated the oncogenic function of CEP65 in promoting cancer cell growth and metastasis.

The novel immunotoxin HM1.24-ETA' induces apoptosis in multiple myeloma cells.

Despite new treatment modalities, the clinical outcome in a substantial number of patients with multiple myeloma (MM) has yet to be improved. Antibody-based targeted therapies for myeloma patients could make use of the HM1.24 antigen (CD317), a surface molecule overexpressed on malignant plasma cells and efficiently internalized. Here, a novel immunotoxin, HM1.24-ETA′, is described. HM1.24-ETA′ was generated by genetic fusion of a CD317-specific single-chain Fv (scFv) antibody and a truncated variant of Pseudomonas aeruginosa exotoxin A (ETA′). HM1.24-ETA′ inhibited growth of interleukin 6 (IL-6)-dependent and -independent myeloma cell lines. Half-maximal growth inhibition was observed at concentrations as low as 0.3 nM. Target cell killing occurred via induction of apoptosis and was unaffected in co-culture experiments with bone marrow stromal cells. HM1.24-ETA′ efficiently triggered apoptosis of freshly isolated/cryopreserved cells of patients with plasma cell leukemia and MM and was active in a preclinical severe combined immunodeficiency (SCID) mouse xenograft model. Importantly, HM1.24-ETA′ was not cytotoxic against CD317-positive cells from healthy tissue (monocytes, human umbilical vein endothelial cells). These results indicate that CD317 may represent a promising target structure for specific and efficient immunotoxin therapy for patients with plasma cell tumors.

“To Serve and Protect”: Enzyme Inhibitors as Radiopeptide Escorts Promote Tumor Targeting

Radiolabeled octreotide analogs are most successfully being applied today in clinical cancer imaging and treatment. Propagation of this paradigm to other radiopeptide families has been greatly hampered by the inherent poor metabolic stability of systemically administered peptide analogs. We hypothesized that the in vivo coadministration of specific enzyme inhibitors would improve peptide bioavailability and hence tumor uptake. Through single coinjection of the neutral endopeptidase inhibitor phosphoramidon (PA), we were able to provoke remarkable rises in the percentages of circulating intact somatostatin, gastrin, and bombesin radiopeptides in mouse models, resulting in a remarkable increase in uptake in tumor xenografts in mice. The peptide conjugates [DOTA-Ala(1)]SS14 (DOTA-Ala-Gly-c[Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys]-OH), PanSB1 (DOTA-PEG2-dTyr-Gln-Trp-Ala-Val-βAla-His-Phe-Nle-NH2), and DOTA-MG11 (DOTA-dGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2) were labeled with (111)In by 20 min of heating at an acidic pH. Metabolic stability was studied with high-performance liquid chromatography analysis of blood samples collected 5 min after the injection of the test radiopeptide alone or with PA into mice. Biodistribution was studied after injection of each (111)In-labeled radiopeptide alone or after coinjection of PA in tumor-bearing severe combined immunodeficient (SCID) mice. The amount of intact [(111)In-DOTA-Ala(1)]SS14 detected in the mouse circulation at 5 min after the injection of PA increased impressively-from less than 2% to 86%-whereas the uptake in AR4-2J xenografts rose from less than 1 percentage injected dose per gram of tissue (%ID/g) to 14 %ID/g at 4 h after injection. Likewise, the coadministration of PA resulted in a marked increase in the amount of circulating intact (111)In-PanSB1-from 12% to 80%-at 5 min after injection, and radioligand uptake in human PC-3 xenografts in SCID mice escalated from less than 4 %ID/g to greater than 21 %ID/g at 4 h after injection. In a similar manner, the coadministration of PA resulted in an equally impressive increase in intact [(111)In-DOTA]MG11 levels in the mouse bloodstream-from less than 5% to 70%-at 5 min after injection, leading to a remarkable increase in radiotracer uptake-from 2 %ID/g to greater than 15 %ID/g-in both AR4-2J tumors and A431(CCKR+) tumors (i.e., tumors induced by A431 cells transfected to stably express the human cholecystokinin subtype 2 receptor) in mice at 4 h after injection. This effect was well visualized by SPECT/CT imaging of AR4-2J tumor-bearing mice at 4 h after injection. The results of this study clearly demonstrate that the coadministration of key enzyme inhibitors can effectively prolong the survival of radiolabeled peptides in the circulation, securing their safe transit to the target. This strategy clearly provoked an unprecedented increase in radiolabel accumulation in tumor xenografts in mice; this increase might translate into higher diagnostic sensitivity or improved therapeutic efficacy of radiopeptide drugs in cancer patients. Hence, our findings provide exciting new opportunities for the application of biodegradable (radio)peptide drugs of either natural or synthetic origin as well as for the rationale design of analogs that are stable in vivo.

Therapeutic targeting malignant mesothelioma with a novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate via its selective uptake by the proton-coupled folate transporter

We examined whether the novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate, compound 2, might be an effective treatment for malignant pleural mesothelioma (MPM), reflecting its selective membrane transport by the proton-coupled folate transport (PCFT) over the reduced folate carrier (RFC). HeLa sublines expressing exclusively PCFT (R1-11-PCFT4) or RFC (R1-11-RFC6) and H2452 MPM cells were assayed for transport with [(3)H]compound 2. [(3)H]Polyglutamate metabolites of compound 2 were measured in R1-11-PCFT4 and H2452 cells. In vitro cell proliferation assays and colony formation assays were performed. Inhibition of glycinamide ribonucleotide formyltransferase (GARFTase) was assayed by nucleoside protection assays and in situ GARFTase assays with [(14)C]glycine. In vivo efficacy was established with early- and advanced-stage H2452 xenografts in severe-combined immunodeficient (SCID) mice administered intravenous compound 2. [(3)H]Compound 2 was selectively transported by PCFT and was metabolized to polyglutamates. Compound 2 selectively inhibited proliferation of R1-11-PCFT4 cells over R1-11-RFC6 cells. H2452 human MPM cells were sensitive to the antiproliferative effects of compound 2. By colony-forming assays with H2452 cells, compound 2 was cytotoxic. Compound 2 inhibited GARFTase in de novo purine biosynthesis. In vivo efficacy was confirmed toward early- and advanced-stage H2452 xenografts in SCID mice administered compound 2. Our results demonstrate potent antitumor efficacy of compound 2 toward H2452 MPM cells in vitro and in vivo, reflecting its efficient membrane transport by PCFT, synthesis of polyglutamates, and inhibition of GARFTase. Selectivity for non-RFC cellular uptake processes by tumor-targeted antifolates such as compound 2 presents an exciting new opportunity for treating solid tumors.

Resveratrol Reduces Prostate Cancer Growth and Metastasis by Inhibiting the Akt/MicroRNA-21 Pathway

The consumption of foods containing resveratrol produces significant health benefits. Resveratrol inhibits cancer by reducing cell proliferation and metastasis and by inducing apoptosis. These actions could be explained by its ability to inhibit (ERK-1/2), Akt and suppressing the levels of estrogen and insulin growth factor -1 (IGF-1) receptor. How these processes are manifested into the antitumor actions of resveratrol is not clear. Using microarray studies, we show that resveratrol reduced the expression of various prostate-tumor associated microRNAs (miRs) including miR-21 in androgen-receptor negative and highly aggressive human prostate cancer cells, PC-3M-MM2. This effect of resveratrol was associated with reduced cell viability, migration and invasiveness. Additionally, resveratrol increased the expression of tumor suppressors, PDCD4 and maspin, which are negatively regulated by miR-21. Short interfering (si) RNA against PDCD4 attenuated resveratrol’s effect on prostate cancer cells, and similar effects were observed following over expression of miR-21 with pre-miR-21 oligonucleotides. PC-3M-MM2 cells also exhibited high levels of phospho-Akt (pAkt), which were reduced by both resveratrol and LY294002 (a PI3-kinase inhibitor). MiR-21 expression in these cells appeared to be dependent on Akt, as LY294002 reduced the levels of miR-21 along with a concurrent increase in PDCD4 expression. These in vitro findings were further corroborated in a severe combined immunodeficient (SCID) mouse xenograft model of prostate cancer. Oral administration of resveratrol not only inhibited the tumor growth but also decreased the incidence and number of metastatic lung lesions. These tumor- and metastatic-suppressive effects of resveratrol were associated with reduced miR-21 and pAkt, and elevated PDCD4 levels. Similar anti-tumor effects of resveratrol were observed in DU145 and LNCaP prostate cancer cells which were associated with suppression of Akt and PDCD4, but independent of miR-21.These data suggest that resveratrol’s anti-tumor actions in prostate cancer could be explained, in part, through inhibition of Akt/miR-21 signaling pathway.

CSPG4 as a Target of Antibody-Based Immunotherapy for Malignant Mesothelioma

Malignant mesothelioma (MM) is an aggressive cancer, resistant to current therapies. Membrane chondroitin sulphate proteoglycan 4 (CSPG4), which has been successfully targeted in melanoma and breast cancer, was found highly expressed in MM, but not in normal mesothelium. Therefore, we explored CSPG4 as a suitable target for monoclonal antibody (mAb)-based immunotherapy for MM. We assayed adhesion, motility, invasiveness, wound-healing, apoptosis, and anchorage-independent growth of MM cells on cell cultures. CSPG4 expression and signaling was studied by immunoblotting. The growth of MM severe combined immunodeficient (SCID) mice xenografts induced by PPM-Mill cells, engineered to express the luciferase reporter gene, was monitored by imaging, upon treatment with CSPG4 mAb TP41.2. Animal toxicity and survival were assayed in both tumor inhibition and therapeutic experiments. CSPG4 was expressed on 6 out of 8 MM cell lines and in 25 out of 41 MM biopsies, with minimal expression in surrounding healthy cells. MM cell adhesion was mediated by CSPG4-dependent engagement of ECM. Cell adhesion was inhibited by mAb TP41.2 resulting in decreased phosphorylation of focal adhesion kinase (FAK) and AKT, reduced expression of cyclin D1 and apoptosis. Moreover, mAb TP41.2 significantly reduced MM cell motility, migration, and invasiveness, and inhibited MM growth in soft agar. In vivo, treatment with mAb TP41.2 prevented or inhibited the growth of MM xenografts in SCID mice, with a significant increase in animal survival. These results establish the safety of CSPG4 mAb-based immunotherapy and suggest that CSPG4 mAb-based immunotherapy may represent a novel approach for the treatment of MM.

YM155 Reverses Cisplatin Resistance in Head and Neck Cancer by Decreasing Cytoplasmic Survivin Levels

Cisplatin is one of the commonly used chemotherapeutic drugs for the treatment of head and neck squamous cell carcinoma (HNSCC). However, acquisition of cisplatin resistance is common in patients with HNSCC, and it often leads to local and distant failure. In this study, we showed that survivin expression is significantly upregulated in HNSCC primary tumors and cell lines. In addition, survivin levels were significantly higher in human papilloma virus-negative patients that normally respond poorly to cisplatin treatment. Survivin expression was further increased in cisplatin-resistant cells (CAL27-CisR) as compared with its parent cells (CAL27). Therefore, we hypothesized that targeting of survivin in HNSCC could reverse the resistant phenotype in tumor cells, thereby enhancing the therapeutic efficacy of cisplatin. We used both in vitro and in vivo models to test the efficacy of YM155, a small molecule survivin inhibitor, either as a single agent or in combination with cisplatin. YM155 significantly decreased survivin levels and cell proliferation in a dose-dependent manner. In addition, YM155 pretreatment significantly reversed cisplatin resistance in cancer cells. Interestingly, YM155 treatment altered the dynamic localization of survivin in cells by inducing a rapid reduction in cytoplasmic survivin, which plays a critical role in its antiapoptotic function. In a severe combined immunodeficient mouse xenograft model, YM155 significantly enhanced the antitumor and antiangiogenic effects of cisplatin, with no added systemic toxicity. Taken together, our results suggest a potentially novel strategy to use YM155 to overcome the resistance in tumor cells, thereby enhancing the effectiveness of the chemotherapy in HNSCC.

Cancer Cell Secretion of the DAMP Protein HMGB1 Supports Progression in Malignant Mesothelioma

Human malignant mesothelioma is an aggressive and highly lethal cancer that is believed to be caused by chronic exposure to asbestos and erionite. Prognosis for this cancer is generally poor because of late-stage diagnosis and resistance to current conventional therapies. The damage-associated molecular pattern protein HMGB1 has been implicated previously in transformation of mesothelial cells. Here we show that HMGB1 establishes an autocrine circuit in malignant mesothelioma cells that influences their proliferation and survival. Malignant mesothelioma cells strongly expressed HMGB1 and secreted it at high levels in vitro. Accordingly, HMGB1 levels in malignant mesothelioma patient sera were higher than that found in healthy individuals. The motility, survival, and anchorage-independent growth of HMGB1-secreting malignant mesothelioma cells was inhibited in vitro by treatment with monoclonal antibodies directed against HMGB1 or against the receptor for advanced glycation end products, a putative HMGB1 receptor. HMGB1 inhibition in vivo reduced the growth of malignant mesothelioma xenografts in severe-combined immunodeficient mice and extended host survival. Taken together, our findings indicate that malignant mesothelioma cells rely on HMGB1, and they offer a preclinical proof-of-principle that antibody-mediated ablation of HMBG1 is sufficient to elicit therapeutic activity, suggesting a novel therapeutic approach for malignant mesothelioma treatment.

Modeling Human Choroidal Melanoma Xenograft Growth in Immunocompromised Rodents to Assess Treatment Efficacy

To evaluate potential treatments of primary uveal melanoma in rodent xenograft models, it is necessary to track individual tumor growth during treatment. Previously, high-frequency ultrasound (HF-US) was used to measure tumor volume in nude rats for up to 2 weeks. This study tests the hypothesis that HF-US can be used to repeatedly measure tumor volume for at least a month in both nude rat and severe combined immunodeficiency (SCID) mouse xenograft models of human uveal melanoma, with the goal of modeling tumor growth to evaluate treatment efficacy. C918 human uveal melanoma spheroids were implanted in the choroids of six nude rats and six severe combined immunodeficiency mice. OCM-1 human uveal melanoma spheroids were implanted in six nude rats. Every 4-7 days thereafter for up to 5 weeks, HF-US images of the tumor-bearing eye were captured every 100 or 250 μm. Tumor areas were measured on each image and integrated to calculate volume. Tumor growth was modeled using a logistic curve, and parameters characterizing growth, including the time to reach a target volume (t(T)), were evaluated as potential measures of treatment efficacy. Tumor volume could be measured for up to 5 weeks in all models, and the logistic curve described the growth well. The parameter t(T) was shown to be a suitable endpoint to evaluate treatments. HF-US is a practical method to track uveal melanoma growth in the same nude rat or SCID mouse for up to a month. Such growth data can be used to evaluate treatments in these xenograft models.

Translating clinical activity and gene expression signatures of etanercept and ciclosporin to the psoriasis xenograft SCID mouse model

The psoriasis xenograft severe combined immunodeficiency (SCID) mouse model is used in drug discovery to obtain preclinical proof-of-principle of new antipsoriatic drug candidates. Validation of this model by antipsoriatic therapeutic agents in clinical use is important to understand its utility as well as its limitations. The effects of the clinically efficacious antitumour necrosis factor-α biologics have not yet been demonstrated in the psoriasis xenograft SCID mouse model. To investigate the effect of etanercept and to explore the time-dependent changes induced by ciclosporin on psoriatic biomarkers at the gene expression level in the psoriasis xenograft SCID mouse model. Xenografted SCID mice were treated either with etanercept and vehicle for 2 weeks or with ciclosporin and vehicle for 2 and 4 weeks, respectively. Treatment-induced changes in the psoriatic grafts were assessed by gene expression analysis and compared with published clinical microarray data. The grafts were further evaluated by histology and immunohistochemistry. Etanercept induced normalization of gene expression, which correlated with a significant reduction in epidermal thickness as well as a decrease in the number of proliferative cells. Anti-inflammatory activity induced by ciclosporin preceded the reduction in epidermal hyperplasia. Comparison of the etanercept- and ciclosporin-induced gene expression signatures with clinical microarray data showed significant correlations. Efficacy of etanercept and ciclosporin could be translated to the psoriasis xenograft SCID mouse model.

IL-6 Promotes Head and Neck Tumor Metastasis by Inducing Epithelial–Mesenchymal Transition via the JAK-STAT3-SNAIL Signaling Pathway

Epithelial-mesenchymal transition (EMT) is a key process in tumor metastatic cascade that is characterized by the loss of cell-cell junctions and cell polarity, resulting in the acquisition of migratory and invasive properties. However, the precise molecular events that initiate this complex EMT process in head and neck cancers are poorly understood. Increasing evidence suggests that tumor microenvironment plays an important role in promoting EMT in tumor cells. We have previously shown that head and neck tumors exhibit significantly higher Bcl-2 expression in tumor-associated endothelial cells and overexpression of Bcl-2 alone in tumor-associated endothelial cells was sufficient to enhance tumor metastasis of oral squamous cell carcinoma in a severe combined immunodeficient (SCID) mouse model. In this study, we show that endothelial cells expressing Bcl-2 (EC-Bcl-2), when cocultured with head and neck tumor cells (CAL27), significantly enhance EMT-related changes in tumor cells predominantly by the secretion of IL-6. Treatment with recombinant IL-6 or stable IL-6 overexpression in CAL27 cells or immortalized oral epithelial cells (IOE) significantly induced the expression of mesenchymal marker, vimentin, while repressing E-cadherin expression via the JAK/STAT3/Snail signaling pathway. These EMT-related changes were further associated with enhanced tumor and IOE cell scattering and motility. STAT3 knockdown significantly reversed IL-6-mediated tumor and IOE cell motility by inhibiting FAK activation. Furthermore, tumor cells overexpressing IL-6 showed marked increase in lymph node and lung metastasis in a SCID mouse xenograft model. Taken together, these results show a novel function for IL-6 in mediating EMT in head and neck tumor cells and increasing their metastatic potential.

Sorafenib Enhances the Antitumor Effects of Chemoradiation Treatment by Downregulating ERCC-1 and XRCC-1 DNA Repair Proteins

Head and neck squamous cell carcinoma remains a challenging clinical problem because of the persisting high rate of local and distant failure due to the acquisition of chemo- and radioresistance. In this study, we examined if treatment with sorafenib, a potent inhibitor of Raf kinase and VEGF receptor, could reverse the resistant phenotype in tumor and tumor-associated endothelial cells, thereby enhancing the therapeutic efficacy of currently used chemoradiation treatment. We used both in vitro and in vivo models to test the efficacy of sorafenib either as a single agent or in combination with chemoradiation. Sorafenib, as a single agent, showed antitumor and angiogenesis properties, but the effects were more pronounced when used in combination with chemoradiation treatment. Sorafenib significantly enhanced the antiproliferative effects of chemoradiation treatment by downregulating DNA repair proteins (ERCC-1 and XRCC-1) in a dose-dependent manner. In addition, combination treatment significantly inhibited tumor cell colony formation, tumor cell migration, and tumor cell invasion. Combination treatment was also very effective in inhibiting VEGF-mediated angiogenesis in vitro. In a severe combined immunodeficient mouse xenograft model, combination treatment was very well tolerated and significantly inhibited tumor growth and tumor angiogenesis. Interestingly, following combination treatment, low-dose sorafenib treatment alone was highly effective as a maintenance regimen. Taken together, our results suggest a potentially novel strategy to use sorafenib to overcome chemo- and radioresistance in tumor and tumor-associated endothelial to enhance the effectiveness of the chemoradiation therapy.

Increased efficacy of doxorubicin delivered in multifunctional microparticles for mesothelioma therapy

New and effective treatment strategies are desperately needed for malignant mesothelioma (MM), an aggressive cancer with a poor prognosis. We have shown previously that acid-prepared mesoporous microspheres (APMS) are nontoxic after intrapleural or intraperitoneal (IP) administration to rodents. The purpose here was to evaluate the utility of APMS in delivering chemotherapeutic drugs to human MM cells in vitro and in two mouse xenograft models of MM. Uptake and release of doxorubicin (DOX) alone or loaded in APMS (APMS-DOX) were evaluated in MM cells. MM cell death and gene expression linked to DNA damage/repair were also measured in vitro. In two severe combined immunodeficient mouse xenograft models, mice received saline, APMS, DOX or APMS-DOX injected directly into subcutaneous (SC) MM tumors or injected IP after development of human MMs peritoneally. Other mice received DOX intravenously (IV) via tail vein injections. In comparison to DOX alone, APMS-DOX enhanced intracellular uptake of DOX, MM death and expression of GADD34 and TP73. In the SC MM model, 3× weekly SC injections of APMS-DOX or DOX alone significantly inhibited tumor volumes, and systemic DOX administration was lethal. In mice developing IP MMs, significant (p < 0.05) inhibition of mesenteric tumor numbers, weight and volume was achieved using IP administration of APMS-DOX at one-third the DOX concentration required after IP injections of DOX alone. These results suggest APMS are efficacious for the localized delivery of lower effective DOX concentrations in MM and represent a novel means of treating intracavitary tumors.

TRAIL and Doxorubicin Combination Induces Proapoptotic and Antiangiogenic Effects in Soft Tissue Sarcoma In vivo

Novel therapeutic approaches for complex karyotype soft tissue sarcoma (STS) are crucially needed. Consequently, we assessed the efficacy of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), in combination with chemotherapy, on local and metastatic growth of human STS xenografts in vivo. TRAIL was evaluated alone and combined with low-dose doxorubicin in two human STS severe combined immunodeficient mouse xenograft models using fibrosarcoma (HT1080; wild-type p53) and leiomyosarcoma (SKLMS1; mutated p53), testing for effects on local growth, metastasis, and overall survival. Magnetic resonance imaging was used to evaluate local growth and bioluminescence was used to longitudinally assess lung metastases. Tissues were evaluated through immunohistocemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining for treatment effects on tumor cell proliferation, apoptosis, angiogenesis, angiogenic factors, and TRAIL receptor expression. Quantitative real-time polymerase chain reaction (QRTPCR) angiogenesis array was used to assess therapy-induced gene expression changes. TRAIL/doxorubicin combination induced marked STS local and metastatic growth inhibition in a p53-independent manner. Significantly increased (P < 0.001) host survival was also demonstrable. Combined therapy induced significant apoptosis, decreased tumor cell proliferation, and increased TRAIL receptor (DR4 and DR5) expression in all treated tumors. Moreover, decreased microvessel density was observed, possibly secondary to increased expression of the antiangiogenic factor CXCL10 and decreased proangiogenic interleukin-8 cytokine in response to TRAIL/doxorubicin combination, as was also observed in vitro. Given the urgent need for better systemic approaches to STS, clinical trials evaluating TRAIL in combination with low-dose chemotherapy are potentially warranted.