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    Abstract:
    Abstract Osteosarcoma is a rare disease diagnosed as malignant bone tumor. It is generally refractory to chemotherapy, which contributes to its poor prognosis. The reversal of chemoresistance is a major clinical challenge to improve the prognostic outcome of osteosarcoma patients. We developed a tumor-specific replication-competent oncolytic adenovirus, OBP-301 (telomelysin) and assessed its synergistic effects with chemotherapeutic agents (cisplatin and doxorubicin) using human osteosarcoma cell lines and a xenograft tumor model. The molecular mechanism underlying the chemosensitizing effect of OBP-301 was evaluated in aspects of apoptosis induction. OBP-301 inhibits anti-apoptotic myeloid cell leukemia 1 (MCL1) expression, which in turn leads to chemosensitization in human osteosarcoma cells. The siRNA-mediated knockdown of MCL1 expression sensitized human osteosarcoma cells to common chemotherapeutic agents. We also found that upregulation of microRNA-29 targeting MCL1 via virally induced transcriptional factor E2F-1 activation was critical for the enhancement of chemotherapy-induced apoptosis in osteosarcoma cells. Telomerase-specific oncolytic adenovirus synergistically suppressed the viability of human osteosarcoma cells in combination with chemotherapeutic agents. The combination treatment also significantly inhibited tumor growth, as compared to monotherapy, in an osteosarcoma xenograft tumor model. Our data suggest that replicative virus-mediated tumor-specific MCL1 ablation may be a promising strategy to attenuate chemoresistance in osteosarcoma patients.
    Keywords:
    MCL1
    Oncolytic adenovirus
    Immunotherapy with tumor-infiltrating lymphocytes (TIL) or oncolytic adenoviruses, have shown promising results in cancer treatment, when used as separate therapies. When used in combination, the antitumor effect is synergistically potentiated due oncolytic adenovirus infection and its immune stimulating effects on T cells. Indeed, studies in hamsters have shown a 100% complete response rate when animals were treated with oncolytic adenovirus coding for TNFa and IL-2 (Ad5/3-E2F-D24-hTNFa-IRES-hIL2; TILT-123) and TIL therapy. In humans, one caveat with oncolytic virus therapy is that intratumoral injection has been traditionally preferred over systemic administration, for achieving sufficient virus concentrations in tumors, especially when neutralizing antibodies emerge. We have previously shown that 5/3 chimeric oncolytic adenovirus can bind to human lymphocytes for avoidance of neutralization. In this study, we hypothesized that incubation of oncolytic adenovirus (TILT-123) with TILs prior to systemic injection would allow delivery of virus to tumors. This approach would deliver both components in one self-amplifying product. TILs would help deliver TILT-123, whose replication will recruit more TILs and increase their cytotoxicity. In vitro, TILT-123 was seen binding efficiently to lymphocytes, supporting the idea of dual administration. We show in vivo in different models that virus could be delivered to tumors with TILs as carriers.
    Oncolytic adenovirus
    Systemic administration
    Adenovirus infection
    Citations (25)
    Oncolytic adenovirus therapy is believed to be a promising way to treat cancer patients. To be able to target tumor cells with an oncolytic adenovirus, expression of the adenovirus receptor on the tumor cell is essential. Different adenovirus types bind to different receptors on the cell, of which the expression can vary between tumor types. Pre-existing neutralizing immunity to human adenovirus species C type 5 (HAdV-C5) has hampered its therapeutic efficacy in clinical trials, hence several adenoviral vectors from different species are currently being developed as a means to evade pre-existing immunity. Therefore, knowledge on the expression of appropriate adenovirus receptors on tumor cells is important. This could aid in determining which tumor types would benefit most from treatment with a certain oncolytic adenovirus type. This review provides an overview of the known receptors for human adenoviruses and how their expression on tumor cells might be differentially regulated compared to healthy tissue, before and after standardized anticancer treatments. Mechanisms behind the up- or downregulation of adenovirus receptor expression are discussed, which could be used to find new targets for combination therapy to enhance the efficacy of oncolytic adenovirus therapy. Additionally, the utility of the adenovirus receptors in oncolytic virotherapy is examined, including their role in viral spread, which might even surpass their function as primary entry receptors. Finally, future directions are offered regarding the selection of adenovirus types to be used in oncolytic adenovirus therapy in the fight against cancer.
    Oncolytic adenovirus
    Virotherapy
    Receptor expression
    Adenovirus infection
    Citations (35)
    Abstract Virotherapy using oncolytic adenovirus is an effective anticancer strategy. However, the tumor selectivity of oncolytic adenoviruses is not enough high. To develop oncolytic adenovirus with a low risk of off-tumor toxicity, we constructed a photoactivatable oncolytic adenovirus (paOAd). In response to blue light irradiation, the expression of adenoviral E1 genes, which are necessary for adenoviral replication, is induced and replication of this adenovirus occurs. In vitro, efficient lysis of various human cancer cell lines was observed by paOAd infection followed by blue light irradiation. Importantly, there was no off-tumor toxicity unless the cells were irradiated by blue light. In vivo, tumor growth in a subcutaneous tumor model and a mouse model of liver cancer was significantly inhibited by paOAd infection followed by blue light irradiation. In addition, paOAd also showed a therapeutic effect on cancer stem cells. These results suggest that paOAd is useful as a safe and therapeutically effective cancer therapy.
    Oncolytic adenovirus
    Virotherapy
    Citations (14)
    Due to the anatomical structure of the rectum, the treatment of rectal cancer remains challenging. Ad-E2F, an oncolytic adenovirus containing the E2F-1 promoter, can selectively replicate within and kill cancer cells derived from solid tumors. Thus, this virus provides a novel approach for the treatment of rectal cancer. Given the poor efficacy and possible adverse reactions that arise from the use of oncolytic virus alone and the results of our analysis of the efficacy of Ad-E2F in the treatment of rectal cancer, we investigated the use of oncolytic adenovirus in combination with adoptive immunotherapy using cytokine-induced killer (CIK) cells as a therapeutic treatment for rectal cancer. Our results illustrated that E2F-1 gene expression is higher in rectal cancer tissue than in normal tissue. Furthermore, the designed oncolytic adenovirus Ad-E2F is capable of selectively killing colorectal cell lines but has no significant effect on CIK cells. The results of in vitro and in vivo experiments demonstrated that combined therapy with Ad-E2F and CIK cells produce stronger antitumor effects than the administration of Ad-E2F or CIK cells alone. For low rectal cancers that are suitable for intratumoral injection, local injections of oncolytic viruses in combination with CIK cell-based adoptive immunotherapy may be suitable as a novel comprehensive therapeutic approach.
    Oncolytic adenovirus
    E2F
    Cytokine-induced killer cell
    Citations (24)
    As an innovative class of promising cancer therapeutic,oncolytic adenovirus has been commonly used recently due to its ability to infect and lyse cancer cells specifically,while ideally leaving normal cells unharmed. A potential advantage of oncolytic adenoviral vectors over conventional antitumor agents is that viral replication in the tumor will amplify the input virus dose,leading to spread of the virus throughout the tumor. To observe the inhibiting effect of oncolytic adenovirus on the lung cancer cell growth in combination with hyperthermia and to determine whether it can improve the expression levels of therapeutic gene delivered by replication-deficient adenovirus,an oncolytic adenovirus named Ad-HSP70p-E1A was constructed by employing the human HSP70 gene promoter to drive the expression of adenovirus E1A gene. The experimental results show that in vitro,Ad-HSP70p-E1A can replicate in lung carcinoma A549 cell line and destroy those cancer cells to some extent. While combined with hyperthermia,the number of replicative virions released from lung carcinoma increased about 2~10 times and the oncolytic effect on lung carcinoma A549 cell line increased 5 times at least. In addition,when combined with oncolytic adenovirus Ad-HSP70p-E1A,replication-deficient adenoviruses such as AdGFP,Ad-CMV-hGMCSF and Ad-CMV-mIL12 at the moi of 10 are expected to lead to the expression level of therapeutic gene at higher levels. The green fluorescence protein increased 76.64 times,while cytokines GMCSF and IL12 increased 5 times and 7 times respectively.
    Oncolytic adenovirus
    Virotherapy