Nectin-1 is a marker of thyroid cancer sensitivity to herpes oncolytic therapy

New Insights into Immune Cells and Immunotherapy for Thyroid Cancer

Thyroid cancer (TC) is the most common endocrine malignancy worldwide, and the incidence of TC has gradually increased in recent decades. Differentiated thyroid cancer (DTC) is the most common subtype and has a good prognosis. However, advanced DTC patients with recurrence, metastasis and iodine refractoriness, as well as more aggressive subtypes such as poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC), still pose a great challenge for clinical management. Therefore, it is necessary to continue to explore the inherent molecular heterogeneity of different TC subtypes and the global landscape of the tumor immune microenvironment (TIME) to find new potential therapeutic targets. Immunotherapy is a promising therapeutic strategy that can be used alone or in combination with drugs targeting tumor-driven genes. This article focuses on the genomic characteristics, tumor-associated immune cell infiltration and immune checkpoint expression of different subtypes of TC patients to provide guidance for immunotherapy.

Efficacy of a third-generation oncolytic herpes simplex virus in refractory soft tissue sarcoma xenograft models

Malignant soft tissue tumors, particularly highly malignant leiomyosarcomas, are resistant to chemotherapy and associated with a poor prognosis. T-01, a third-generation genetically modified herpes simplex virus type 1, replicates in tumor cells alone and exerts a cell-killing effect. The current study aimed to investigate the antitumor effect of T-01, which is a novel treatment for leiomyosarcoma. In vitro, six human cell lines and one mouse sarcoma cell line were assessed for T-01 cytotoxicity. In vivo, the efficacy of T-01 was examined in subcutaneously transplanted leiomyosarcoma (SK-LMS-1) cells and subcutaneously or intraperitoneally transplanted mouse sarcoma (CCRF S-180II) cells. Cytokines were assessed using ELISpot assay with splenocytes from the allogeneic models for immunological evaluation. T-01 showed cytotoxicity in all seven cell lines (p < 0.001). In the SK-LMS-1 xenotransplantation model, tumor growth was suppressed by T-01 administration (p = 0.02). In the CCRF S-180II subcutaneous tumor model, bilateral tumor growth was significantly suppressed in the T-01-treated group compared with the control group (p < 0.001). In the peritoneal dissemination model, T-01 treatment caused significant survival prolongation compared with the control (p < 0.01). In conclusion, third-generation genetically modified herpes simplex virus type 1 may be an effective novel therapy against refractory sarcomas.

Oncolytic Viruses in the Therapy of Lymphoproliferative Diseases

Cancer is a leading causes of death. Despite significant success in the treatment of lymphatic system tumors, the problems of relapse, drug resistance and effectiveness of therapy remain relevant. Oncolytic viruses are able to replicate in tumor cells and destroy them without affecting normal, healthy tissues. By activating antitumor immunity, viruses are effective against malignant neoplasms of various nature. In lymphoproliferative diseases with a drug-resistant phenotype, many cases of remissions have been described after viral therapy. The current level of understanding of viral biology and the discovery of host cell interaction mechanisms made it possible to create unique strains with high oncoselectivity widely used in clinical practice in recent years.

Emerging roles of the nectin family of cell adhesion molecules in tumour-associated pathways

Tumour cells achieve maximum survival by modifying cellular machineries associated with processes such as cell division, migration, survival, and apoptosis, resulting in genetically complex and heterogeneous populations. While nectin and nectin-like cell adhesion molecules control development and maintenance of multicellular organisation in higher vertebrates by mediating cell-cell adhesion and related signalling processes, recent studies indicate that they also critically regulate growth and development of different types of cancers. In this review, we detail current knowledge about the role of nectin family members in various tumours. Furthermore, we also analyse the seemingly opposing roles of some members of nectin family in tumour-associated pathways, as they function as both tumour suppressors and oncogenes. Understanding this functional duality of nectin family in tumours will further our knowledge of molecular mechanisms regulating tumour development and progression, and contribute to the advancement of tumour diagnosis and therapy.

Nectin-1 Expression Correlates with the Susceptibility of Malignant Melanoma to Oncolytic Herpes Simplex Virus In Vitro and In Vivo

Simple Summary

Talimogene laherparepvec (T-VEC), a first-in-class oncolytic herpes simplex virus, improves the outcome of patients suffering from unresectable melanoma, in particular in combination with checkpoint inhibitors. However, a certain percentage of patients does not profit from this treatment, which raises the question of potential biomarkers to predict success or failure of oncolytic herpes viruses. For these purposes, we studied the oncolytic activity of T-VEC in a panel of 20 melanoma cell lines and evaluated the clinical response of 35 melanoma metastases to intralesional T-VEC application. Through these studies, we characterized Nectin-1 as a suitable biomarker predicting 86% and 78% of melanoma regression in vitro and in vivo, respectively. In contrast, other molecules involved in the entry (HVEM) and signal transduction (cGAS, STING) of herpes simplex viruses were not predictive. Altogether, our data support the role of Nectin-1 in pretreatment biopsies to guide clinical decision-making in malignant melanoma and supposedly other tumor entities.

Abstract

Talimogene laherparepvec (T-VEC), an oncolytic herpes simplex virus, is approved for intralesional injection of unresectable stage IIIB/IVM1a melanoma. However, it is still unclear which parameter(s) predict treatment response or failure. Our study aimed at characterizing surface receptors Nectin-1 and the herpes virus entry mediator (HVEM) in addition to intracellular molecules cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) as potential bio-markers for oncolytic virus treatment. In 20 melanoma cell lines, oncolytic activity of T-VEC was correlated with the expression of Nectin-1 but not HVEM, as evaluated via flow cytometry and immunohistochemistry. Knockout using CRISPR/Cas9 technology confirmed the superior role of Nectin-1 over HVEM for entry and oncolytic activity of T-VEC. Neither cGAS nor STING as evaluated by Western Blot and immunohistochemistry correlated with T-VEC induced oncolysis. The role of these biomarkers was retrospectively analyzed for the response of 35 cutaneous melanoma metastases of 21 patients to intralesional T-VEC injection, with 21 (60.0%) of these lesions responding with complete (n = 16) or partial regression (n = 5). Nectin-1 expression in pretreatment biopsies significantly predicted treatment outcome, while the expression of HVEM, cGAS, and STING was not prognostic. Altogether, Nectin-1 served as biomarker for T-VEC-induced melanoma regression in vitro and in vivo.

Oncolytic herpes simplex virus infects myeloma cells in vitro and in vivo

Because most patients with multiple myeloma (MM) develop resistance to current regimens, novel approaches are needed. Genetically modified, replication-competent oncolytic viruses exhibit high tropism for tumor cells regardless of cancer stage and prior treatment. Receptors of oncolytic herpes simplex virus 1 (oHSV-1), NECTIN-1, and HVEM are expressed on MM cells, prompting us to investigate the use of oHSV-1 against MM. Using oHSV-1-expressing GFP, we found a dose-dependent increase in the GFP⁺ signal in MM cell lines and primary MM cells. Whereas NECTIN-1 expression is variable among MM cells, we discovered that HVEM is ubiquitously and highly expressed on all samples tested. Expression of HVEM was consistently higher on CD138⁺/CD38⁺ plasma cells than in non-plasma cells. HVEM blocking demonstrated the requirement of this receptor for infection. However, we observed that, although oHSV-1 could efficiently infect and kill all MM cell lines tested, no viral replication occurred. Instead, we identified that oHSV-1 induced MM cell apoptosis via caspase-3 cleavage. We further noted that oHSV-1 yielded a significant decrease in tumor volume in two mouse xenograft models. Therefore, oHSV-1 warrants exploration as a novel potentially effective treatment option in MM, and HVEM should be investigated as a possible therapeutic target.

Oncolytic Virus Therapy with HSV-1 for Hematological Malignancies

Oncolytic herpes simplex virus type 1 (HSV-1) has been investigated to expand its application to various malignancies. Because hematopoietic cells are resistant to HSV-1, its application to hematological malignancies has been rare. Here, we show that the third generation oncolytic HSV-1, T-01, infected and killed 18 of 26 human cell lines and 8 of 15 primary cells derived from various lineages of hematological malignancies. T-01 replicated at low levels in the cell lines. Viral entry and the oncolytic effect were positively correlated with the expression level of nectin-1 and to a lesser extent 3-O-sulfated heparan sulfate, receptors for glycoprotein D of HSV-1, on tumor cells. Transfection of nectin-1 into nectin-1-negative tumor cells made them susceptible to T-01. The oncolytic effects did not appear to correlate with the expression or phosphorylation of antiviral molecules in the cyclic GMP-AMP (cGAS)-stimulator of interferon genes (STING) and PKR-eIF2α pathways. In an immunocompetent mouse model, intratumoral injection of T-01 into lymphoma induced regression of injected, as well as non-injected, contralateral tumors accompanied by abundant infiltration of antigen-specific CD8⁺ T cells. These data suggest that intratumoral injection of oncolytic HSV-1 may be applicable to systemic hematological malignancies. Nectin-1 expression may be the most useful biomarker for optimal efficacy.

Virotherapy as a Potential Therapeutic Approach for the Treatment of Aggressive Thyroid Cancer

Virotherapy is a novel cancer treatment based on oncolytic viruses (OVs), which selectively infect and lyse cancer cells, without harming normal cells or tissues. Several viruses, either naturally occurring or developed through genetic engineering, are currently under investigation in clinical studies. Emerging reports suggesting the immune-stimulatory property of OVs against tumor cells further support the clinical use of OVs for the treatment of lesions lacking effective therapies. Poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC), have a poor prognosis and limited treatment options. Therefore, several groups investigated the therapeutic potential of OVs in PDTC/ATC models producing experimental data sustaining the potential clinical efficacy of OVs in these cancer models. Moreover, the presence of an immunosuppressive microenvironment further supports the potential use of OVs in ATC. In this review, we present the results of the studies evaluating the efficacy of OVs alone or in combination with other treatment options. In particular, their potential therapeutic combination with multiple kinases inhibitors (MKIs) or immune checkpoint inhibitors are discussed.

Saliva enhances infection of gingival fibroblasts by herpes simplex virus 1

Oral herpes is a highly prevalent infection caused by herpes simplex virus 1 (HSV-1). After an initial infection of the oral cavity, HSV-1 remains latent in sensory neurons of the trigeminal ganglia. Episodic reactivation of the virus leads to the formation of mucocutaneous lesions (cold sores), but asymptomatic reactivation accompanied by viral shedding is more frequent and allows virus spread to new hosts. HSV-1 DNA has been detected in many oral tissues. In particular, HSV-1 can be found in periodontal lesions and several studies associated its presence with more severe periodontitis pathologies. Since gingival fibroblasts may become exposed to salivary components in periodontitis lesions, we analyzed the effect of saliva on HSV-1 and -2 infection of these cells. We observed that human gingival fibroblasts can be infected by HSV-1. However, pre-treatment of these cells with saliva extracts from some but not all individuals led to an increased susceptibility to infection. Furthermore, the active saliva could expand HSV-1 tropism to cells that are normally resistant to infection due to the absence of HSV entry receptors. The active factor in saliva was partially purified and comprised high molecular weight complexes of glycoproteins that included secretory Immunoglobulin A. Interestingly, we observed a broad variation in the activity of saliva between donors suggesting that this activity is selectively present in the population. The active saliva factor, has not been isolated, but may lead to the identification of a relevant biomarker for susceptibility to oral herpes. The presence of a salivary factor that enhances HSV-1 infection may influence the risk of oral herpes and/or the severity of associated oral pathologies.

Oncolytic herpes simplex virus tumor targeting and neutralization escape by engineering viral envelope glycoproteins

Oncolytic herpes simplex viruses (oHSVs) have been approved for clinical usage and become more and more popular for tumor virotherapy. However, there are still many issues for the oHSVs used in clinics and clinical trials. The main issues are the limited anti-tumor effects, intratumor injection, and some side effects. To overcome such challenges, here we review the genetic engineering of the envelope glycoproteins for oHSVs to target tumors specifically, and at the same time we summarize the many neutralization antibodies against the envelope glycoproteins and align the neutralization epitopes with functional domains of the respective glycoproteins for future identification of new functions of the glycoproteins and future engineering of the epitopes to escape from host neutralization.

Enhanced Sensitivity of Patient-Derived Pediatric High-Grade Brain Tumor Xenografts to Oncolytic HSV-1 Virotherapy Correlates with Nectin-1 Expression

Pediatric high-grade brain tumors and adult glioblastoma are associated with significant morbidity and mortality. Oncolytic herpes simplex virus-1 (oHSV) is a promising approach to target brain tumors; oHSV G207 and M032 (encodes human interleukin-12) are currently in phase I clinical trials in children with malignant supratentorial brain tumors and adults with glioblastoma, respectively. We sought to compare the sensitivity of patient-derived pediatric malignant brain tumor and adult glioblastoma xenografts to these clinically-relevant oHSV. In so doing we found that pediatric brain tumors were more sensitive to the viruses and expressed significantly more nectin-1 (CD111) than adult glioblastoma. Pediatric embryonal and glial tumors were 74-fold and 14-fold more sensitive to M002 and 16-fold and 6-fold more sensitive to G207 than adult glioblastoma, respectively. Of note, pediatric embryonal tumors were more sensitive than glial tumors. Differences in sensitivity may be due in part to nectin-1 expression, which predicted responses to the viruses. Treatment with oHSV resulted in prolonged survival in both pediatric and adult intracranial patient-dervied tumor xenograft models. Our results suggest that pediatric brain tumors are ideal targets for oHSV and that brain tumor expression of nectin-1 may be a useful biomarker to predict patient response to oHSV.

Recombinant oncolytic Newcastle disease virus displays antitumor activities in anaplastic thyroid cancer cells

Background

Anaplastic thyroid cancer (ATC) is one of the most aggressive of all solid tumors for which no effective therapies are currently available. Oncolytic Newcastle disease virus (NDV) has shown the potential to induce oncolytic cell death in a variety of cancer cells of diverse origins. However, whether oncolytic NDV displays antitumor effects in ATC remains to be investigated. We have previously shown that the oncolytic NDV strain FMW (NDV/FMW) induces oncolytic cell death in several cancer types. In the present study, we investigated the oncolytic effects of NDV/FMW in ATC.

Methods

In this study, a recombinant NDV expressing green fluorescent protein (GFP) was generated using an NDV reverse genetics system. The resulting virus was named after rFMW/GFP and the GFP expression in infected cells was demonstrated by direct fluorescence and immunoblotting. Viral replication was evaluated by end-point dilution assay in DF-1 cell lines. Oncolytic effects were examined by biochemical and morphological experiments in cultural ATC cells and in mouse models.

Results

rFMW/GFP replicated robustly in ATC cells as did its parent virus (NDV/FMW) while the expression of GFP protein was detected in lungs and spleen of mice intravenously injected with rFMW/GFP. We further showed that rFMW/GFP infection substantially increased early and late apoptosis in the ATC cell lines, THJ-16 T and THJ-29 T and increased caspase-3 processing and Poly (ADP-ribose) polymerase (PARP) cleavage in ATC cells as assessed by immunoblotting. In addition, rFMW/GFP induced lyses of spheroids derived from ATC cells in three-dimensional (3D) cultures. We further demonstrated that rFMW/GFP infection resulted in the activation of p38 MAPK signaling, but not Erk1/2 or JNK, in THJ-16 T and THJ-29 T cells. Notably, inhibition of p38 MAPK activity by SB203580 decreased rFMW/GFP-induced cleavage of caspase-3 and PARP in THJ-16 T and THJ-29 T cells. Finally, both rFMW/GFP and its parent virus inhibited tumor growth in mice bearing THJ-16 T derived tumors.

Conclusion

Taken together, these data indicate that both the recombinant reporter virus rFMW/GFP and its parent virus NDV/FMW, display oncolytic activities in ATC cells in vitro and in vivo and suggest that oncolytic NDV may have potential as a novel therapeutic strategy for ATC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4522-3) contains supplementary material, which is available to authorized users.

Activity of roniciclib in medullary thyroid cancer

Altered cyclin-dependent kinase activity is observed in many human malignancies. Cyclin-dependent kinases that promote cell cycle progression may be promising targets in the treatment of cancer. The therapeutic effects of roniciclib, a cyclin-dependent kinase inhibitor for medullary thyroid cancer were investigated in the present study. Roniciclib inhibited medullary thyroid cancer cell proliferation in a dose-dependent manner. Roniciclib induced caspase-3 activity and contributed to apoptosis. Cell cycle progression was arrested in the G2 phase. In vivo, roniciclib treatment retarded the growth of tumors of medullary thyroid cancer xenografts. In addition, roniciclib in combination with sorafenib was more effective than either single treatment in a xenograft model. No morbidity was observed in animals treated with single roniciclib therapy and combination treatment of roniciclib and sorafenib. These data provide a rationale for clinical assessment of using roniciclib in the treatment of patients with medullary thyroid cancer.

Third-generation oncolytic herpes simplex virus inhibits the growth of liver tumors in mice

Multimodality therapies are used to manage patients with hepatocellular carcinoma (HCC), although advanced HCC is incurable. Oncolytic virus therapy is probably the next major breakthrough in cancer treatment. The third-generation oncolytic herpes simplex virus type 1 (HSV-1) T-01 kills tumor cells without damaging the surrounding normal tissues. Here we investigated the antitumor effects of T-01 on HCC and the host's immune response to HCC cells. The cytopathic activities of T-01 were tested in 14 human and 1 murine hepatoma cell line in vitro. In various mouse xenograft models, HuH-7, KYN-2, PLC/PRF/5 and HepG2 human cells and Hepa1-6 murine cells were used to investigate the in vivo efficacy of T-01. T-01 was cytotoxic to 13 cell lines (in vitro). In mouse xenograft models of subcutaneous, orthotopic and peritoneal tumor metastasis in athymic mice (BALB/c nu/nu), the growth of tumors formed by the human HCC cell lines and hepatoblastoma cell line was inhibited by T-01 compared with that of mock-inoculated tumors. In a bilateral Hepa1-6 subcutaneous tumor model in C57BL/6 mice, the growth of tumors inoculated with T-01 was inhibited, as was the case for contralateral tumors. T-01 also significantly reduced tumor growth. T-01 infection significantly enhanced antitumor efficacy via T cell-mediated immune responses. Results demonstrate that a third-generation oncolytic HSV-1 may serve as a novel treatment for patients with HCC.

Neuroblastomas vary widely in their sensitivities to herpes simplex virotherapy unrelated to virus receptors and susceptibility

Although most high-risk neuroblastomas are responsive to chemotherapy, relapse is common and long-term survival is less than 40%, underscoring the need for more effective treatments. We evaluated the responsiveness of 12 neuroblastoma cell lines to the Δγ₁34.5 attenuated oncolytic HSV, Seprehvir (HSV1716), which is currently used in pediatric phase I trials. We found that entry of Seprehvir in neuroblastoma cells is independent of the expression of nectin-1 and the sum of all four known major HSV entry receptors. We observed varying levels of sensitivity and permissivity to Seprehvir, suggesting that the cellular anti-viral response, not virus entry, is the key determinant of efficacy with this virus. In vivo, we found significant anti-tumor efficacy following Seprehvir treatment, which ranged from 6/10 complete responses in the CHP-134 model to a mild prolonged median survival in the SK-N-AS model. Taken together, these data suggest that anti-tumor efficacy cannot be solely predicted based on in vitro response. Whether or not this discordance holds true for other viruses or tumor types is unknown. Our results also suggest that profiling the expression of known viral entry receptors on neuroblastoma cells may not be entirely predictive of their susceptibility to Seprehvir therapy.

Pediatric medulloblastoma xenografts including molecular subgroup 3 and CD133+ and CD15+ cells are sensitive to killing by oncolytic herpes simplex viruses

BACKGROUND

Childhood medulloblastoma is associated with significant morbidity and mortality that is compounded by neurotoxicity for the developing brain caused by current therapies, including surgery, craniospinal radiation, and chemotherapy. Innate therapeutic resistance of some aggressive pediatric medulloblastoma has been attributed to a subpopulation of cells, termed cancer-initiating cells or cancer stemlike cells (CSCs), marked by the surface protein CD133 or CD15. Brain tumors characteristically contain areas of pathophysiologic hypoxia, which has been shown to drive the CSC phenotype leading to heightened invasiveness, angiogenesis, and metastasis. Novel therapies that target medulloblastoma CSCs are needed to improve outcomes and decrease toxicity. We hypothesized that oncolytic engineered herpes simplex virus (oHSV) therapy could effectively infect and kill pediatric medulloblastoma cells, including CSCs marked by CD133 or CD15.

METHODS

Using 4 human pediatric medulloblastoma xenografts, including 3 molecular subgroup 3 tumors, which portend worse patient outcomes, we determined the expression of CD133, CD15, and the primary HSV-1 entry molecule nectin-1 (CD111) by fluorescence activated cell sorting (FACS) analysis. Infectability and cytotoxicity of clinically relevant oHSVs (G207 and M002) were determined in vitro and in vivo by FACS, immunofluorescent staining, cytotoxicity assays, and murine survival studies.

RESULTS

We demonstrate that hypoxia increased the CD133+ cell fraction, while having the opposite effect on CD15 expression. We established that all 4 xenografts, including the CSCs, expressed CD111 and were highly sensitive to killing by G207 or M002.

CONCLUSIONS

Pediatric medulloblastoma, including Group 3 tumors, may be an excellent target for oHSV virotherapy, and a clinical trial in medulloblastoma is warranted.

Progress in oncolytic virotherapy for the treatment of thyroid malignant neoplasm

Thyroid malignant neoplasm develops from follicular or parafollicular thyroid cells. A higher proportion of anaplastic thyroid cancer has an adverse prognosis. New drugs are being used in clinical treatment. However, for advanced thyroid malignant neoplasm such as anaplastic thyroid carcinoma, the major impediment to successful control of the disease is the absence of effective therapies. Oncolytic virotherapy has significantly progressed as therapeutics in recent years. The advance is that oncolytic viruses can be designed with biological specificity to infect, replicate and lyse tumor cells. Significant advances in virotherapy have being achieved to improve the accessibility, safety and efficacy of the treatment. Therefore, it is necessary to summarize and bring together the main areas covered by these investigations for the virotherapy of thyroid malignant neoplasm. We provide an overview of the progress in virotherapy research and clinical trials, which employ virotherapy for thyroid malignant neoplasm as well as the future prospect for virotherapy of thyroid malignant neoplasms.

Assessment of oncolytic HSV efficacy following increased entry-receptor expression in malignant peripheral nerve sheath tumor cell lines

Limited expression and distribution of nectin-1, the major herpes simplex virus (HSV) type-1 entry-receptor, within tumors has been proposed as an impediment to oncolytic HSV (oHSV) therapy. To determine whether resistance to oHSVs in malignant peripheral nerve sheath tumors (MPNSTs) was explained by this hypothesis, nectin-1 expression and oHSV viral yields were assessed in a panel of MPNST cell lines using γ134.5-attenuated (Δγ134.5) oHSVs and a γ134.5 wild-type (wt) virus for comparison. Although there was a correlation between nectin-1 levels and viral yields with the wt virus (R=0.75, P =0.03), there was no correlation for Δγ134.5 viruses (G207, R7020 or C101) and a modest trend for the second-generation oHSV C134 (R=0.62, P=0.10). Nectin-1 overexpression in resistant MPNST cell lines did not improve Δγ134.5 oHSV output. While multistep replication assays showed that nectin-1 overexpression improved Δγ134.5 oHSV cell-to-cell spread, it did not confer a sensitive phenotype to resistant cells. Finally, oHSV yields were not improved with increased nectin-1 in vivo. We conclude that nectin-1 expression is not the primary obstacle of productive infection for Δγ134.5 oHSVs in MPNST cell lines. In contrast, viruses that are competent in their ability to counter the antiviral response may derive benefit with higher nectin-1 expression.

The control of anaplastic thyroid carcinoma cell lines by oncolytic poxviruses

BACKGROUND AND SIGNIFICANCE

Anaplastic thyroid cancer (ATC) is rare, but its clinical presentation is often dramatic and aggressive and is nearly uniformly fatal. Oncolytic viral therapy is a potential strategy to improve outcomes for patients suffering with this disease.

METHODS

Seven established ATC cell lines were infected with a panel of poxviruses to identify which virus had the most potential as an oncolytic agent. These included myxoma, vaccinia, and tanapox viruses, all modified to express green fluorescence protein (GFP). Viral proliferation was assessed by fluorescence and viral amplification. The effect on cell line growth was assessed by the Presto Blue metabolic assay and a live-dead assay. A replication assay was performed to assess the production of infectious progeny. An additional five ATC cell lines were tested using the assays described above for susceptibility to vaccinia virus.

RESULTS

ATC cell lines were differentially susceptible to each virus. Vaccinia virus was superior to myxoma and tanapox viruses for the control of anaplastic thyroid cancer in vitro. Although subsequent investigation using an expanded panel of cell lines revealed differential susceptibility to vaccinia virus, effective control of cell proliferation was still achieved using higher titers.

CONCLUSIONS

Vaccinia virus was the most potent of the tested poxviruses and was highly effective in controlling proliferation and inducing cell death in ATC cell lines. The efficacy of these viruses offers hope for improving outcomes for patients suffering with ATC.

Epithelial-mesenchymal transition enhances response to oncolytic herpesviral therapy through nectin-1

Cancers exhibiting epithelial-mesenchymal transition (EMT) are associated with aggressive behavior and increased metastatic potential. Therapies that are able to target EMT would have significant clinical value. Nectin-1 is a cell surface herpes simplex virus type 1 (HSV-1) receptor that also forms a component of intercellular adherens junctions, which are typically disrupted in EMT. To explore relationships between HSV-1 sensitivity and EMT, we generated cell lines with a stable EMT phenotype from human follicular thyroid cancer (WRO82-1) through E-cadherin silencing with short hairpin RNA (shEcadWRO). HSV-1 viral attachment and gene expression were both enhanced in shEcadWRO as compared with shControl. Immunoblotting and immunostaining revealed enhanced nectin-1 expression by shEcadWRO. Receptor-blocking assays demonstrated that increased herpesviral entry into shEcadWRO as compared with shControl was mediated predominantly through nectin-1. Colocalization of green fluorescent protein-tagged HSV-1 and tdTomato-tagged nectin-1 confirmed an increase in viral attachment to nectin-1 in shEcadWRO. Cell viability assays demonstrated increased susceptibility of shEcadWRO to HSV-1 oncolysis, and a murine flank tumor model showed significantly enhanced regression of shEcadWRO tumors in response to oncolytic HSV-1 as compared with control tumors. A separate model of EMT induction through transforming growth factor-β stimulation confirmed enhanced HSV-1 susceptibility in Panc1 cells. These results demonstrate that the process of EMT leads to increased herpesviral susceptibility through enhanced cell surface nectin-1 expression, suggesting that cancers exhibiting EMT may be naturally sensitive targets for herpesviral therapy.

The expression of the Nectin complex in human breast cancer and the role of Nectin-3 in the control of tight junctions during metastasis

Introduction

Nectins are a family of integral protein molecules involved in the formation of functioning Adherens and Tight Junctions (TJ). Aberrant expression is associated with cancer progression but little is known how this effects changes in cell behaviour. This study aimed to ascertain the distribution of Nectins-1 to -4 in human breast cancer and the effect on junctional integrity of Nectin-3 modulation in human endothelial and breast cancer cells.

Methods

A human breast tissue cohort was processed for Q-PCR and immunohistochemistry for analysis of Nectin-1/-2/-3/-4. Nectin-3 over-expression was induced in the human breast cancer cell line MDA-MB-231 and the human endothelial cell line HECV. Functional testing was carried out to ascertain changes in cell behaviour.

Results

Q-PCR revealed a distinct reduction in node positive tumours and in patients with poor outcome. There was increased expression of Nectin-1/-2 in patients with metastatic disease, Nectin-3/-4 was reduced. IHC revealed that Nectin-3 expression showed clear changes in distribution between normal and cancerous cells. Nectin-3 over-expression in MDA-MB-231 cells showed reduced invasion and migration even when treated with HGF. Changes in barrier function resulted in MDAN3 cells showing less change in resistance after 2h treatment with HGF (p<0.001). Nectin-3 transformed endothelial cells were significantly more adhesive, irrespective of treatment with HGF (p<0.05) and had reduced growth. Barrier function revealed that transformed HECV cells had significantly tighter junctions that wildtype cells when treated with HGF (p<0.0001). HGF-induced changes in permeability were also reduced. Overexpression of Nectin-3 produced endothelial cells with significantly reduced ability to form tubules (p<0.0001). Immunoprecipitation studies discovered hitherto novel associations for Nectin-3. Moreover, HGF appeared to exert an effect on Nectin-3 via tyrosine and threonine phosphorylation.

Conclusions

Nectin-3 may be a key component in the formation of cell junctions and be a putative suppressor molecule to the invasion of breast cancer cells.

Utility of a histone deacetylase inhibitor (PXD101) for thyroid cancer treatment

Background

We evaluated the therapeutic effects of the histone deacetylase inhibitor PXD101 alone and in combination with conventional chemotherapy in treating thyroid cancer.

Methodology/Principal Findings

We studied eight cell lines from four types of thyroid cancer (papillary, follicular, anaplastic and medullary). The cytotoxicity of PXD101 alone and in combination with three conventional chemotherapeutic agents (doxorubicin, paclitaxel and docetaxel) was measured using LDH assay. Western blot assessed expression of acetylation of histone H3, histone H4 and tubulin, proteins associated with apoptosis, RAS/RAF/ERK and PI3K/AKT/mTOR signaling pathways, DNA damage and repair. Apoptosis and intracellular reactive oxygen species (ROS) were measured by flow cytometry. Mice bearing flank anaplastic thyroid cancers (ATC) were daily treated with intraperitoneal injection of PXD101 for 5 days per week. PXD101 effectively inhibited thyroid cancer cell proliferation in a dose-dependent manner. PXD101 induced ROS accumulation and inhibited RAS/RAF/ERK and PI3K/mTOR pathways in sensitive cells. Double-stranded DNA damage and apoptosis were induced by PXD101 in both sensitive and resistant cell lines. PXD101 retarded growth of 8505C ATC xenograft tumors with promising safety. Combination therapy of PXD101with doxorubicin and paclitaxel demonstrated synergistic effects against four ATC lines invitro.

Conclusions

PXD101 represses thyroid cancer proliferation and has synergistic effects in combination with doxorubicin and paclitaxel in treating ATC. These findings support clinical trials using PXD101 for patients with this dismal disease.

Expression of HSV-1 receptors in EBV-associated lymphoproliferative disease determines susceptibility to oncolytic HSV

Epstein-Barr virus (EBV)-associated B cell lymphoproliferative disease (LPD) after hematopoietic stem cell or solid organ transplantation remains a life-threatening complication. Expression of the virus-encoded gene product, EBER, has been shown to prevent apoptosis via blockade of PKR activation. Because PKR is a major cellular defense against Herpes simplex virus, and oncolytic HSV-1 (oHSV) mutants have shown promising anti-tumor efficacy in preclinical models, we sought to determine whether EBV-LPD cells are susceptible to infection by oHSVs. We tested three primary EBV-infected lymphocyte cell cultures from neuroblastoma (NB) patients as models of naturally acquired EBV-LPD. NB12 was most susceptible, NB122R was intermediate, and NB88R2 was essentially resistant. Despite EBER expression, PKR was activated by oHSV infection. Susceptibility to oHSV correlated with the expression of the HSV receptor, nectin-1. The resistance of NB88R2 was reversed by exogenous nectin-1 expression, whereas down-regulation of nectin-1 on NB12 decreased viral entry. Xenografts derived from the EBV-LPDs exhibited only mild (NB12) or no (NB88R2) response to oHSV injection, compared with a neuroblastoma cell line that showed a significant response. We conclude that EBV-LPDs are relatively resistant to oHSV virotherapy, in some cases due to low virus receptor expression but also due to intact anti-viral PKR signaling.

Utility of a PI3K/mTOR inhibitor (NVP-BEZ235) for thyroid cancer therapy

BACKGROUND

We assessed the utility of the dual PI3K/mTOR inhibitor NVP-BEZ235 (BEZ235) as single agent therapy and in combination with conventional chemotherapy for thyroid cancer.

METHODOLOGY/PRINCIPAL FINDINGS

Eight cell lines from four types of thyroid cancer (papillary, follicular, anaplastic, medullary) were studied. The cytotoxicity of BEZ235 and five conventional chemotherapeutic agents alone and in combination was measured using LDH assay. Quantitative western blot assessed expression of proteins associated with cell cycle, apoptosis and signaling pathways. Cell cycle distribution and apoptosis were measured by flow cytometry. Murine flank anaplastic thyroid cancers (ATC) were treated with oral BEZ235 daily. We found that BEZ235 effectively inhibited cell proliferation of all cancer lines, with ATC exhibiting the greatest sensitivity. BEZ235 consistently inactivated signaling downstream of mTORC1. BEZ235 generally induced cell cycle arrest at G0/G1 phase, and also caused apoptosis in the most sensitive cell lines. Baseline levels of p-S6 ribosomal protein (Ser235/236) and p27 correlated with BEZ235 sensitivity. Growth of 8505C ATC xenograft tumors was inhibited with BEZ235, without any observed toxicity. Combination therapy of BEZ235 and paclitaxel consistently demonstrated synergistic effects against ATC in vitro.

CONCLUSIONS

BEZ235 as a single therapeutic agent inhibits thyroid cancer proliferation and has synergistic effects in combination with paclitaxel in treating ATC. These findings encourage future clinical trials using BEZ235 for patients with this fatal disease.

Preclinical efficacy of the oncolytic measles virus expressing the sodium iodide symporter in iodine non-avid anaplastic thyroid cancer: a novel therapeutic agent allowing noninvasive imaging and radioiodine therapy

Anaplastic thyroid cancer is an extremely aggressive disease resistant to radioiodine treatment because of loss of sodium iodide symporter (NIS) expression. To enhance prognosis of this fatal cancer, we validated the preclinical efficacy of measles virus (MV)-NIS, the vaccine strain of the oncolytic MV (MV-Edm), modified to include the NIS gene. Western blotting analysis confirmed that a panel of eight anaplastic thyroid cancer (ATC)-derived cell lines do not express NIS protein, but do express CD46, the MV receptor. In vitro cell death assays and in vivo xenograft studies demonstrate the oncolytic efficacy of MV-NIS in BHT-101 and KTC-3, ATC-derived cell lines. Radioactive iodine uptake along with single-photon emission computed tomography (SPECT)-computed tomography imaging of KTC-3 xenografts after (99)Tc(m) administration confirmed NIS expression in vitro and in vivo, respectively, after virus treatment. Adjuvant administration of RAI, to MV-NIS-treated KTC-3 tumors showed a trend for increased tumor cell killing. As current treatment for ATC is only palliative, and MV-NIS is currently Food and Drug Administration approved for human clinical trials in myeloma, our data indicate that targeting ATC with MV-NIS could prove to be a novel therapeutic strategy for effective treatment of iodine-resistant ATC and will expedite its testing in clinical trials for this aggressive disease.

Hypoxia Moderates γ(1)34.5-Deleted Herpes Simplex Virus Oncolytic Activity in Human Glioma Xenoline Primary Cultures

Hypoxia plays a critical role in the tumor microenvironment of high-grade gliomas by promoting the glioma stem cell (GSC)-like phenotype, which displays resistance to standard therapies. We tested three glioblastoma multiforme xenograft lines (xenolines) against γ(1)34.5-deleted recombinant oncolytic herpes simplex virus (oHSV) C101 under 1% (hypoxia) and 20.8% (normoxia) oxygen tension for effects on oHSV infectivity, replication, and cytotoxicity in all tumor cells and CD133(+) GSCs. Expression levels of CD133, a putative GSC marker, and CD111 (nectin-1), an adhesion molecule that is the most efficient method for HSV entry, increased significantly under hypoxia in all three xenolines. Despite increased CD111 expression under hypoxic conditions, oHSV infectivity, cytotoxicity and viral recovery were not improved or were diminished in all three xenolines under hypoxia. In contrast, wild-type HSV-1 equally infected xenoline cells in normoxia and hypoxia, suggesting that the 34.5 mutation plays a role in the decreased C101 infectivity in hypoxia. Importantly, CD133(+) cells were not more resistant to oHSV than CD133(-) tumor cells regardless of oxygen tension. Furthermore, CD133 expression decreased as viral dose increased in two of the xenolines suggesting that up-regulation of CD133 in hypoxia was not the cause of reduced viral efficacy. Our findings that oHSV infectivity and cytotoxicity were diminished under hypoxia in several GBM xenolines likely have important implications for clinical applications of oHSV therapies, especially considering the vital role of hypoxia in the microenvironment of GBM tumors.

Molecular network pathways and functional analysis of tumor signatures associated with development of resistance to viral gene therapy

Replication-competent attenuated herpes simplex viruses have proven effective in killing many cancer cell lines. However, determinants of resistance to oncolytic therapy are mostly unknown. We developed viral therapy-resistant cells and examined changes in gene-expression pattern compared with therapy-sensitive parental cells. Colon cancer cell line HT29 and hepatoma cell line PLC5 were exposed to increasing concentrations of virus G207. Therapy-resistant cells were isolated and grown in vitro. Tumorigenicity was confirmed by ability of cell lines to form tumors in mice. Human Genome U133A complementary DNA microarray chips were used to determine gene-expression patterns, which were analyzed in the context of molecular network interactions, pathways and gene ontology. In parental cell lines, 90-100% of cells were killed by day 7 at 1.0 multiplicity of infection. In resistant cell lines, cytotoxicity assay confirmed 200- to 400-fold resistance. Microarray analysis confirmed changes in gene expressions associated with resistance: cell surface proteins affecting viral attachment and entry, cellular proteins affecting nucleotide pools and proteins altering apoptotic pathways. These changes would decrease viral infection and replication. Our study identifies gene-expression signatures associated with resistance to oncolytic viral therapy. These data provide potential targets to overcome resistance, and suggest that molecular assays may be useful in selecting patients for trial with this novel treatment.

Engineered herpes simplex viruses efficiently infect and kill CD133+ human glioma xenograft cells that express CD111

Oncolytic herpes simplex viruses (HSV) hold promise for therapy of glioblastoma multiforme (GBM) resistant to traditional therapies. We examined the ability of genetically engineered HSV to infect and kill cells that express CD133, a putative marker of glioma progenitor cells (GPC), to determine if GPC have an inherent therapeutic resistance to HSV. Expression of CD133 and CD111 (nectin-1), the major entry molecule for HSV, was variable in six human glioma xenografts, at initial disaggregation and after tissue culture. Importantly, both CD133+ and CD133- populations of glioma cells expressed CD111 in similar relative proportions in five xenografts, and CD133+ and CD133- glioma cell subpopulations were equally sensitive to killing in vitro by graded dilutions of wild-type HSV-1(F) or several different gamma(1)34.5-deleted viruses. GPC did not display an inherent resistance to HSV. While CD111 expression was an important factor for determining sensitivity of glioma cells to HSV oncolysis, it was not the only factor. Our findings support the notion that HSV will not be able to effectively enter, infect, and kill cells in tumors that have low CD111 expression (<20%). However, virotherapy with HSV may be very effective against CD111+ GPC resistant to traditional therapies.

Herpes simplex virus oncolytic therapy for pediatric malignancies

Despite improving survival rates for children with cancer, a subset of patients exist with disease resistant to traditional therapies such as surgery, chemotherapy, and radiation. These patients require newer, targeted treatments used alone or in combination with more traditional approaches. Oncolytic herpes simplex virus (HSV) is one of these newer therapies that offer promise for several difficult to treat pediatric malignancies. The potential benefit of HSV therapy in pediatric solid tumors including brain tumors, neuroblastomas, and sarcomas is reviewed along with the many challenges that need to be addressed prior to moving oncolytic HSV therapy from the laboratory to the beside in the pediatric population.

Bevacizumab increases viral distribution in human anaplastic thyroid carcinoma xenografts and enhances the effects of E1A-defective adenovirus dl922-947

PURPOSE

Anaplastic thyroid carcinoma is a prime target for innovative therapy because it represents one of the most lethal human neoplasms and is refractory to conventional treatments such as chemotherapy and radiotherapy. We have evaluated a novel therapeutic approach based on the oncolytic replication-selective adenovirus dl922-947.

EXPERIMENTAL DESIGN

The antitumor efficacies of the E1ADeltaCR2 (dl922-947) and DeltaE1B55K (dl1520) mutants were compared in human thyroid anaplastic carcinoma cells in culture and in xenografts in vivo. To enhance the effects of dl922-947, anaplastic thyroid carcinoma tumor xenografts were treated with dl922-947 in combination with bevacizumab.

RESULTS

We showed that the efficacy of dl922-947 exceeded that of dl1520 in all tested anaplastic thyroid carcinoma cells in vitro and in vivo. Furthermore, bevacizumab in combination with dl922-947 significantly reduced tumor growth compared with single treatments alone. Bevacizumab treatment significantly improved viral distribution in neoplastic tissues.

CONCLUSIONS

Our data showed that dl922-947 had a higher oncolytic activity compared with dl1520 in anaplastic thyroid carcinoma cell lines and might represent a better option for virotherapy of anaplastic thyroid carcinoma. Moreover, bevacizumab increased the oncolytic effects of dl922-947 by enhancing viral distribution in tumors. The results described herein encourage the use of the dl922-947 virus in combination with bevacizumab.

Synergy of a herpes oncolytic virus and paclitaxel for anaplastic thyroid cancer

PURPOSE

Novel therapeutic regimens are needed to improve the dismal outcomes of patients with anaplastic thyroid cancer (ATC). Oncolytic herpes simplex virus have shown promising activity against human ATC. We studied the application of oncolytic herpes simplex virus (G207 and NV1023) in combination with currently used chemotherapeutic drugs (paclitaxel and doxorubicin) for the treatment of ATC.

EXPERIMENTAL DESIGN AND RESULTS

All four agents showed dose-response cytotoxicity in vitro for the human ATC cell lines KAT4 and DRO90-1. G207, combined with paclitaxel, showed synergistic cytotoxicity. Chou-Talalay combination indices ranged from 0.56 to 0.66 for KAT4, and 0.68 to 0.74 for DRO90-1 at higher affected fractions. Paclitaxel did not enhance G207 viral entry and early gene expression or G207 viral replication. Paclitaxel combined with G207 compared with single-agent treatment or controls showed significantly increased microtubule acetylation, mitotic arrest, aberrant chromatid separation, inhibition of metaphase to anaphase progression, and apoptosis. A single i.t. injection of G207 combined with biweekly i.p. paclitaxel injections in athymic nude mice bearing KAT4 flank tumors showed significantly reduced mean tumor volume (74 +/- 38 mm(3)) compared with G207 alone (388 +/- 109 mm(3)), paclitaxel alone (439 +/- 137 mm(3)), and control (520 +/- 160 mm(3)) groups at 16 days. There was no morbidity in vivo attributable to therapy.

CONCLUSIONS

Mechanisms of paclitaxel antitumoral activity, including microtubule acetylation, mitotic block, and apoptosis, were enhanced by G207, which also has direct oncolytic effects. Combination of G207 and paclitaxel therapy is synergistic in treating ATC and holds promise for patients with this fatal disease.

Herpes oncolytic therapy of salivary gland carcinomas

Oncolytic herpes simplex viruses (HSV) have demonstrated potent antitumoral effects against a variety of human malignancies in preclinical studies and are in early clinical trials. We explored the activity of an attenuated, replication-competent, oncolytic HSV (NV1023) for the treatment of human salivary gland carcinomas. NV1023 was able to successfully enter into 4 mucoepidermoid carcinoma (H292, H3118, HTB-41, UT-MUC-1) and 2 adenocarcinoma (HSY, HSG) cell lines, as measured by lacZ assays after exposure to 5 viral particles per cell (MOI 5). Viral plaque assays showed variation of viral replication within these cell lines, ranging from a 268-fold increase (H292) to a 3-fold increase (HSG) in viral titer. At MOI 5, all cell lines showed >95% cytotoxicity from NV1023 by Day 7, except for HSY (73%). At MOI 0.1, H3118 and UT-MUC-1 remained highly sensitive to NV1023, both showing >95% cytotoxicity by Day 7. The mucoepidermoid carcinomas were more sensitive to NV1023 at low viral concentrations compared with the adenocarcinomas. Flank tumors of H3118, HTB-41 and HSY in nude mice showed significant tumor volume reductions after a single intratumoral injection of NV1023 (2 x 10(7) plaque-forming units). These data suggest that oncolytic herpes viruses have significant efficacy entering, replicating within, and lysing human salivary gland carcinomas. These promising biologic agents should be further investigated as novel therapy for patients with salivary carcinomas failing conventional treatment.