Carrier cell-mediated cell lysis of squamous cell carcinoma by squamous cell carcinoma antigen 1 promoter-driven oncolytic adenovirus

The squamous cell carcinoma antigen (SCCA) serves as a serological marker for squamous cell carcinomas. Molecular cloning of the SCCA genomic region has revealed the presence of two tandemly arrayed genes, SCCA1 and SCCA2. We examined the promoter activity of the 5'-flanking proximal region of the SCCA1 gene. Deletion analysis of SCCA1 promoter identified a 175-bp core promoter region and an enhancer region at -525 to -475 bp upstream of the transcription start site. The transcriptional activity of the SCCA1 promoter was up-regulated in squamous cell carcinoma cells, compared with normal keratinocyte, normal non-keratinocyte and adenocarcinoma cells. Five tandem repeats of enhancer increased SCCA1 promoter activity by 4-fold. Oncolytic adenovirus driven by the SCCA1 promoter with 5 tandem repeats of enhancer specifically killed squamous cell carcinoma cells in vitro and in vivo. A549 carrier cells infected with the oncolytic adenovirus induced complete regression of tumor by overcoming immunogenicity and adenovirus-mGM-CSF augmented the antitumor effect of carrier cells. These findings suggest that SCCA1 promoter is a potential target of gene therapy for squamous cell carcinoma

Current state of therapeutic development for rare cancers in Japan, and proposals for improvement

This article discusses current obstacles to the rapid development of safe and effective treatments for rare cancers, and considers measures required to overcome these challenges. In order to develop novel clinical options for rare cancers, which tend to remain left out of novel therapeutic development because of their paucity, efficient recruitment of eligible patients, who tend to be widely dispersed across the country and treated at different centers, is necessary. For this purpose, it is important to establish rare cancer registries that are linked with clinical studies, to organize a central pathological diagnosis system and biobanks for rare cancers, and to consolidate patients with rare cancers to facilities that can conduct clinical studies meeting international standards. Establishing an all‐Japan cooperative network is essential. Clinical studies of rare cancers have considerable limitations in study design and sample size as a result of paucity of eligible patients and, as a result, the level of confirmation of the efficacy and safety shown by the studies is relatively low. Therefore, measures to alleviate these weaknesses inherent to external conditions need to be explored. It is also important to reform the current research environment in order to develop world‐leading treatment for rare cancers, including promotion of basic research, collaboration between industry and academia, and improvement of the infrastructure for clinical studies. Collaboration among a wide range of stakeholders is required to promote the clinical development of treatment for rare cancers under a nationwide consensus

Intra-Aortic Clusters Undergo Endothelial to Hematopoietic Phenotypic Transition during Early Embryogenesis

Intra-aortic clusters (IACs) attach to floor of large arteries and are considered to have recently acquired hematopoietic stem cell (HSC)-potential in vertebrate early mid-gestation embryos. The formation and function of IACs is poorly understood. To address this issue, IACs were characterized by immunohistochemistry and flow cytometry in mouse embryos. Immunohistochemical analysis revealed that IACs simultaneously express the surface antigens CD31, CD34 and c-Kit. As embryos developed from 9.5 to 10.5 dpc, IACs up-regulate the hematopoietic markers CD41 and CD45 while down-regulating the endothelial surface antigen VE-cadherin/CD144, suggesting that IACs lose endothelial phenotype after 9.5 dpc. Analysis of the hematopoietic potential of IACs revealed a significant change in macrophage CFC activity from 9.5 to 10.5 dpc. To further characterize IACs, we isolated IACs based on CD45 expression. Correspondingly, the expression of hematopoietic transcription factors in the CD45(neg) fraction of IACs was significantly up-regulated. These results suggest that the transition from endothelial to hematopoietic phenotype of IACs occurs after 9.5 dpc

Roles of p53 in various biological aspects of hematopoietic stem cells

Hematopoietic stem cells (HSCs) have the capacity to self-renew as well as to differentiate into all blood cell types, and they can reconstitute hematopoiesis in recipients with bone marrow ablation. In addition, transplantation therapy using HSCs is widely performed for the treatment of various incurable diseases such as hematopoietic malignancies and congenital immunodeficiency disorders. For the safe and successful transplantation of HSCs, their genetic and epigenetic integrities need to be maintained properly. Therefore, understanding the molecular mechanisms that respond to various cellular stresses in HSCs is important. The tumor suppressor protein, p53, has been shown to play critical roles in maintenance of "cell integrity" under stress conditions by controlling its target genes that regulate cell cycle arrest, apoptosis, senescence, DNA repair, or changes in metabolism. In this paper, we summarize recent reports that describe various biological functions of HSCs and discuss the roles of p53 associated with them

Roles of p53 in Various Biological Aspects of Hematopoietic Stem Cells

Hematopoietic stem cells (HSCs) have the capacity to self-renew as well as to differentiate into all blood cell types, and they can reconstitute hematopoiesis in recipients with bone marrow ablation. In addition, transplantation therapy using HSCs is widely performed for the treatment of various incurable diseases such as hematopoietic malignancies and congenital immunodeficiency disorders. For the safe and successful transplantation of HSCs, their genetic and epigenetic integrities need to be maintained properly. Therefore, understanding the molecular mechanisms that respond to various cellular stresses in HSCs is important. The tumor suppressor protein, p53, has been shown to play critical roles in maintenance of “cell integrity” under stress conditions by controlling its target genes that regulate cell cycle arrest, apoptosis, senescence, DNA repair, or changes in metabolism. In this paper, we summarize recent reports that describe various biological functions of HSCs and discuss the roles of p53 associated with them

Biosafety studies of carrier cells infected with a replication-competent adenovirus introduced by IAI.3B promoter

The use of carrier cells infected with oncolytic viruses in cancer gene therapy is an attractive method because it can overcome viral immunogenicity and induce tumor immunity and significant antitumor activity. To enable human clinical trials of this treatment, acute and chronic toxicity tests must first be performed to ensure safety. IAI.3B promoter, oncolytic adenovirus AdE3-IAI.3B introduced by IAI.3B promoter, and A549 carrier cells infected with AdE3-IAI.3B were highly active in cancer cells but not in normal cells. Freeze-thawing increased the antitumor effect of A549 carrier cells by promoting the translocation of oncolytic adenovirus particles from the nucleus to the cytoplasm following the rupture of the nuclear membranes. No deaths or abnormal blood test data resulted from acute toxicity tests conducted in nude mice after a single dose. In chronic toxicity tests in rabbits, there were no serious side effects after eight doses of 1.25 × 107 cells/kg or less for 4 weeks; a significant immune response is known to elicit increased numbers of antiadenovirus antibodies and enlarge the spleen. From these results, it could be concluded that cancer gene therapy of recurrent solid tumors using carrier cells can be safely trialed in humans