Overexpression of Adenovirus E1A Reverses Transforming Growth Factor-β-induced Epithelial-mesenchymal Transition in Human Esophageal Cancer Cells

The epithelial-mesenchymal transition (EMT), a normal biological process by which epithelial cells acquire a mesenchymal phenotype, is associated with migration, metastasis, and chemoresistance in cancer cells, and with poor prognosis in patients with esophageal cancer. However, therapeutic strategies to inhibit EMT in tumor environments remain elusive. Here, we show the therapeutic potential of telomerase-specific replication- competent oncolytic adenovirus OBP-301 in human esophageal cancer TE4 and TE6 cells with an EMT phenotype. Transforming growth factor-β (TGF-β) administration induced the EMT phenotype with spindleshaped morphology, upregulation of mesenchymal markers and EMT transcription factors, migration, and chemoresistance in TE4 and TE6 cells. OBP-301 significantly inhibited the EMT phenotype via E1 accumulation. EMT cancer cells were susceptible to OBP-301 via massive autophagy induction. OBP-301 suppressed tumor growth and lymph node metastasis of TE4 cells co-inoculated with TGF-β-secreting fibroblasts. Our results suggest that OBP-301 inhibits the TGF-β-induced EMT phenotype in human esophageal cancer cells. OBP-301-mediated E1A overexpression is a promising antitumor strategy to inhibit EMT-mediated esophageal cancer progression

Biological Ablation of Sentinel Lymph Node Metastasis in Submucosally Invaded Early Gastrointestinal Cancer

Currently, early gastrointestinal cancers are treated endoscopically, as long as there are no lymph node metastases. However, once a gastrointestinal cancer invades the submucosal layer, the lymph node metastatic rate rises to higher than 10%. Therefore, surgery is still the gold standard to remove regional lymph nodes containing possible metastases. Here, to avoid prophylactic surgery, we propose a less-invasive biological ablation of lymph node metastasis in submucosally invaded gastrointestinal cancer patients. We have established an orthotopic early rectal cancer xenograft model with spontaneous lymph node metastasis by implantation of green fluorescent protein (GFP)-labeled human colon cancer cells into the submucosal layer of the murine rectum. A solution containing telomerase-specific oncolytic adenovirus was injected into the peritumoral submucosal space, followed by excision of the primary rectal tumors mimicking the endoscopic submucosal dissection (ESD) technique. Seven days after treatment, GFP signals had completely disappeared indicating that sentinel lymph node metastasis was selectively eradicated. Moreover, biologically treated mice were confirmed to be relapse-free even 4 weeks after treatment. These results indicate that virus-mediated biological ablation selectively targets lymph node metastasis and provides a potential alternative to surgery for submucosal invasive gastrointestinal cancer patients

Radiosensitization by telomerase-dependent oncolytic adenovirus

DNA修復機能阻害は放射線感受性を増強させるため，DNA修復に関与する因子の阻害剤は放射線増感剤となり得る．我々の開発したテロメラーゼ依存的腫瘍融解アデノウイルス製剤OBP-301（テロメライシン）は，アデノウイルスE1B55kDaタンパクを介して細胞のDNA修復に重要な役割を果たすMRN複合体（Mre11，Rad50，NBS1）を分解する機能を有する．このMRN複合体の分解によりATM（ataxia-telangiectasia mutated）の活性化が抑制され結果的にDNA修復機構が阻害される．我々はOBP-301と放射線との併用が強力な相乗効果を生み出すことをマウスの皮下腫瘍モデルおよび食道癌同所性モデルにおいて証明した．これらの結果はOBP-301が将来有望な放射線増感剤となり得ることだけでなく，E1B55kDaタンパクを産生する腫瘍融解アデノウイルス製剤と放射線との併用が悪性腫瘍に対する有力な治療戦略となり得ることを示す

Fluorescence virus-guided capturing system of human colorectal circulating tumour cells for non-invasive companion diagnostics

Background Molecular-based companion diagnostic tests are being used with increasing frequency to predict their clinical response to various drugs, particularly for molecularly targeted drugs. However, invasive procedures are typically required to obtain tissues for this analysis. Circulating tumour cells (CTCs) are novel biomarkers that can be used for the prediction of disease progression and are also important surrogate sources of cancer cells. Because current CTC detection strategies mainly depend on epithelial cell-surface markers, the presence of heterogeneous populations of CTCs with epithelial and/or mesenchymal characteristics may pose obstacles to the detection of CTCs. Methods We developed a new approach to capture live CTCs among millions of peripheral blood leukocytes using a green fluorescent protein (GFP)-expressing attenuated adenovirus, in which the telomerase promoter regulates viral replication (OBP-401, TelomeScan). Results Our biological capturing system can image epithelial and mesenchymal tumour cells with telomerase activities as GFP-positive cells. After sorting, direct sequencing or mutation-specific PCR can precisely detect different mutations in KRAS, BRAF and KIT genes in epithelial, mesenchymal or epithelial–mesenchymal transition-induced CTCs, and in clinical blood samples from patients with colorectal cancer. Conclusions This fluorescence virus-guided viable CTC capturing method provides a non-invasive alternative to tissue biopsy or surgical resection of primary tumours for companion diagnostics

A Genetically Engineered Oncolytic Adenovirus Decoys and Lethally Traps Quiescent Cancer Stem-like Cells in S/G(2)/M Phases

Purpose: Because chemoradiotherapy selectively targets proliferating cancer cells, quiescent cancer stem-like cells are resistant. Mobilization of the cell cycle in quiescent leukemia stem cells sensitizes them to cell death signals. However, it is unclear that mobilization of the cell cycle can eliminate quiescent cancer stem-like cells in solid cancers. Thus, we explored the use of a genetically-engineered telomerase-specific oncolytic adenovirus, OBP-301, to mobilize the cell cycle and kill quiescent cancer stem-like cells. Experimental Design: We established CD133(+) cancer stem-like cells from human gastric cancer MKN45 and MKN7 cells. We investigated the efficacy of OBP-301 against quiescent cancer stem-like cells. We visualized the treatment dynamics of OBP-301 killing of quiescent cancer stem-like cells in dormant tumor spheres and xenografts using a fluorescent ubiquitination cell-cycle indicator (FUCCI). Results: CD133(+) gastric cancer cells had stemness properties. OBP-301 efficiently killed CD133(+) cancer stem-like cells resistant to chemoradiotherapy. OBP-301 induced cell-cycle mobilization from G(0)-G(1) to S/G(2)/M phases and subsequent cell death in quiescent CD133(+) cancer stem-like cells by mobilizing cell-cycle-related proteins. FUCCI enabled visualization of quiescent CD133(+) cancer stem-like cells and proliferating CD133(-) non-cancer stem-like cells. Three-dimensional visualization of the cell-cycle behavior in tumor spheres showed that CD133(+) cancer stem-like cells maintained stemness by remaining in G(0)-G(1) phase. We showed that OBP-301 mobilized quiescent cancer stem-like cells in tumor spheres and xenografts into S/G(2)/M phases where they lost viability and cancer stem-like cell properties and became chemosensitive. Conclusion: Oncolytic adenoviralinfection is an effective mechanism of cancer cell killing in solid cancer and can be a new therapeutic paradigm to eliminate quiescent cancer stem-like cells

Dual Programmed Cell Death Pathways Induced by p53 Transactivation Overcome Resistance to Oncolytic Adenovirus in Human Osteosarcoma Cells

Tumor suppressor p53 is a multifunctional transcription factor that regulates diverse cell fates, including apoptosis and autophagy in tumor biology. p53 overexpression enhances the antitumor activity of oncolytic adenoviruses; however, the molecular mechanism of this occurrence remains unclear. We previously developed a tumor-specific replication-competent oncolytic adenovirus, OBP-301, that kills human osteosarcoma cells, but some human osteosarcoma cells were OBP-301-resistant. In this study, we investigated the antitumor activity of a p53-expressing oncolytic adenovirus, OBP-702, and the molecular mechanism of the p53-mediated cell death pathway in OBP-301-resistant human osteosarcoma cells. The cytopathic activity of OBP-702 was examined in OBP-301-sensitive (U2OS and HOS) and OBP-301-resistant (SaOS-2 and MNNG/HOS) human osteosarcoma cells. The molecular mechanism in the OBP-702-mediated induction of two cell death pathways, apoptosis and autophagy, was investigated in OBP-301-resistant osteosarcoma cells. The antitumor effect of OBP-702 was further assessed using an orthotopic OBP-301-resistant MNNG/HOS osteosarcoma xenograft tumor model. OBP-702 suppressed the viability of OBP-301-sensitive and -resistant osteosarcoma cells more efficiently than OBP-301 or a replication-deficient p53-expressing adenovirus (Ad-p53). OBP-702 induced more profound apoptosis and autophagy when compared with OBP-301 or Ad-p53. E1A-mediated miR-93/106b upregulation induced p21 suppression, leading to p53-mediated apoptosis and autophagy in OBP-702-infected cells. p53 overexpression enhanced adenovirus-mediated autophagy through activation of damage-regulated autophagy modulator (DRAM). Moreover, OBP-702 suppressed tumor growth in an orthotopic OBP-301-resistant MNNG/HOS xenograft tumor model. These results suggest that OBP-702-mediated p53 transactivation is a promising antitumor strategy to induce dual apoptotic and autophagic cell death pathways via regulation of miRNA and DRAM in human osteosarcoma cells. Mol Cancer Ther; 12(3); 314-25