Synergistic suppression effect on tumor growth of hepatocellular carcinoma by combining oncolytic adenovirus carrying XAF1 with cisplatin

Synergistic antitumor immune response mediated by paclitaxel-conjugated nanohybrid oncolytic adenovirus with dendritic cell therapy

Dendritic cell (DC)-based vaccines have emerged as a promising strategy in cancer immunotherapy due to low toxicity. However, the therapeutic efficacy of DC as a monotherapy is insufficient due to highly immunosuppressive tumor environment. To address these limitations of DC as immunotherapeutic agent, we have developed a polymeric nanocomplex incorporating (1) oncolytic adenovirus (oAd) co-expressing interleukin (IL)-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) and (2) arginine-grafted bioreducible polymer with PEGylated paclitaxel (APP) to restore antitumor immune surveillance function in tumor milieu and potentiate immunostimulatory attributes of DC vaccine. Nanohybrid complex (oAd/APP) in combination with DC (oAd/APP+DC) induced superior expression level of antitumor cytokines (IL-12, GM-CSF, and interferon gamma) than either oAd/APP or DC monotherapy in tumor tissues, thus resulting in superior intratumoral infiltration of both endogenous and exogenous DCs. Furthermore, oAd/APP+DC treatment led superior migration of DC to secondary lymphoid organs, such as draining lymph nodes and spleen, in comparison with either monotherapy. Superior migration profile of DCs in oAd/APP+DC treatment group resulted in more prolific activation of tumor-specific T cells in these lymphoid organs and greater intratumoral infiltration of T cells. Additionally, oAd/APP+DC treatment led to lower subset of tumor infiltrating lymphocytes and splenocytes being immunosuppressive regulatory T cells than any other treatment groups. Collectively, oAd/APP+DC led to superior induction of antitumor immune response and amelioration of immunosuppressive tumor microenvironment to elicit potent tumor growth inhibition than either monotherapy.

Recent advances in oncolytic virus therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly refractory cancer and the fourth leading cause of cancer-related mortality worldwide. Despite the development of a detailed treatment strategy for HCC, the survival rate remains unsatisfactory. Oncolytic virus has been extensively researched as a new cancer therapeutic agent in the treatment of HCC. Researchers have designed a variety of recombinant viruses based on natural oncolytic diseases, which can increase the targeting of oncolytic viruses to HCC and their survival in tumors, as well as kill tumor cells and inhibit the growth of HCC through a variety of mechanisms. The overall efficacy of oncolytic virus therapy is known to be influenced by anti-tumor immunity, toxic killing effect and inhibition of tumor angiogenesis, etc. Therefore, a comprehensive review of the multiple oncolytic mechanisms of oncolytic viruses in HCC has been conducted. So far, a large number of relevant clinical trials are under way or have been completed, and some encouraging results have been obtained. Studies have shown that oncolytic virus combined with other HCC therapies may be a feasible method, including local therapy, chemotherapy, molecular targeted therapy and immunotherapy. In addition, different delivery routes for oncolytic viruses have been studied so far. These studies make oncolytic virus a new and attractive drug for the treatment of HCC.

Molecular identification and functional analysis of X-linked inhibitor of apoptosis -associated factor-1 (XAF1) in grass carp, Ctenopharyngodon idella

X-linked inhibitor of apoptosis protein (XIAP) -associated factor 1 (XAF1) is an interferon-stimulated gene which exhibits pro-apoptosis effect. In this study, XAF1 was characterized from grass carp Ctenopharyngodon idella and its expression pattern and function were analyzed. The open reading frame (orf) of XAF1 is 789 nucleotides (nt) encoding 262 amino acids. SMART online search results showed that a C2H2-type and six C2HC-type zinc-fingers were found in XAF1, however, the XAF1 of grass carp showed high sequence identity to zebrafish (71%), low sequence identity to tetrapods (21-22%). Rt-qPCR results showed that XAF1 was constitutively expressed in all tested organs/tissues with highest expression in blood. An inductive expression of XAF1 at mRNA level was observed in peripheral blood leucocytes (PBLs) and C. idellus kidney cells (CIKs) after treatment with C. idellus recombinant interferon-γ (rIFNg). Overexpressing XAF1 in CIKs exhibited resistance against grass carp reovirus (GCRV) and more sensitivity to cisplatin. These results implied a functional homologue of XAF1 in evolution, however the mechanism may require further investigation.

Clinical application and detection techniques of liquid biopsy in gastric cancer

Gastric cancer (GC) is one of the most common tumors worldwide and the leading cause of tumor-related mortality. Endoscopy and serological tumor marker testing are currently the main methods of GC screening, and treatment relies on surgical resection or chemotherapy. However, traditional examination and treatment methods are more harmful to patients and less sensitive and accurate. A minimally invasive method to respond to GC early screening, prognosis monitoring, treatment efficacy, and drug resistance situations is urgently needed. As a result, liquid biopsy techniques have received much attention in the clinical application of GC. The non-invasive liquid biopsy technique requires fewer samples, is reproducible, and can guide individualized patient treatment by monitoring patients' molecular-level changes in real-time. In this review, we introduced the clinical applications of circulating tumor cells, circulating free DNA, circulating tumor DNA, non-coding RNAs, exosomes, and proteins, which are the primary markers in liquid biopsy technology in GC. We also discuss the current limitations and future trends of liquid biopsy technology as applied to early clinical biopsy technology.

tRNA-derived fragments in gastric cancer: Biomarkers and functions

tRNA‐derived fragments (tRFs), non‐coding RNAs that regulate protein expression after transcription, have recently been identified as potential biomarkers. We identified differentially expressed tRFs in gastric cancer (GC) and the biological properties of tRFs in predicting the malignancy status of GCs as possible biomarkers. Until 15 February 2022, two independent reviewers did a thorough search in electronic databases of Scopus, EMBASE and PubMed. The QUADAS scale was used for quality assessment of the included studies. Ten articles investigating the clinical significance of tRFs, including 928 patients, were analysed. In 10 GC studies, seven tRFs were considerably upregulated and five tRFs were significantly downregulated when compared to controls. Risk of bias was rated low for index test, and flow as well as timing domains in relation to the review question. The applicability of the index test, flow and timing and patient selection for 10 studies was deemed low. In this study, we review the advances in the study of tRFs in GC and describe their functions in gene expression regulation, such as suppression of translation, cell differentiation, proliferation and the related signal transduction pathways associated with them. Our findings may offer researchers new ideas for cancer treatment as well as potential biomarkers for further research in GC.

An oncolytic adenovirus delivering TSLC1 inhibits Wnt signaling pathway and tumor growth in SMMC-7721 xenograft mice model

Tumor suppressor in lung cancer-1 (TSLC1) was first identified as a tumor suppressor for lung cancer, and frequently downregulated in various types of cancers including hepatocellular carcinoma (HCC). The Wnt pathway plays a critical role in tumorigenesis, migration, and invasion in HCC. However, the function of TSLC1 in modulating Wnt signaling in HCC is unclear. In this study, we evaluated the effect of TSLC1-armed oncolytic adenovirus (S24-TSLC1) on the Wnt/β-catenin pathway, cell viability, invasion and migration abilities of HCC in vitro and the growth of SMMC-7721-xenografted tumor in mice model. We detected the expression of TSLC1 in tumor samples and HCC cell lines. The results showed that TSLC1 expression was low in HCC, but high in pericarcinomatous tissue and normal cells, which implied that TSLC1 is a tumor suppressor of liver cancer. S24-TSLC1 exhibited an antitumor effect on HCC cell growth in vitro, but did little damage to normal liver cells. Overexpression of TSLC1 downregulated the transcriptional activity of TCF4/β-catenin and inhibited the mRNA or protein expression of Wnt target genes cyclinD1 and c-myc. S24-TSLC1 also inhibited the invasion and migration of HCC cells. Animal experiments further confirmed that S24-TSLC1 significantly inhibited tumor growth of the SMMC-7721-xenografted tumor. In conclusion, TSLC1 could downregulate the Wnt signal pathway and suppress HCC cell growth, migration and invasion, suggesting that S24-TSLC1 may be a potent antitumor agent for future clinical trials in liver cancer treatment.

Oncolytic viruses as a promising therapeutic strategy for hematological malignancies

The incidence of hematological malignancies such as multiple myeloma, leukemia, and lymphoma has increased over time. Although bone marrow transplantation, immunotherapy and chemotherapy have led to significant improvements in efficacy, poor prognosis in elderly patients, recurrence and high mortality among hematological malignancies remain major challenges, and innovative therapeutic strategies should be explored. Besides directly lyse tumor cells, oncolytic viruses can activate immune responses or be engineered to express therapeutic factors to increase antitumor efficacy, and have gradually been recognized as an appealing approach for fighting cancers. An increasing number of studies have applied oncolytic viruses in hematological malignancies and made progress. In particular, strategies combining immunotherapy and oncolytic virotherapy are emerging. Various phase I clinical trials of oncolytic reovirus with lenalidomide or programmed death 1(PD-1) immune checkpoint inhibitors in multiple myeloma are ongoing. Moreover, preclinical studies of combinations with chimeric antigen receptor T (CAR-T) cells are underway. Thus, oncolytic virotherapy is expected to be a promising approach to cure hematological malignancies. This review summarizes progress in oncolytic virus research in hematological malignancies. After briefly reviewing the development and oncolytic mechanism of oncolytic viruses, we focus on delivery methods of oncolytic viruses, especially systemic delivery that is suitable for hematological tumors. We then discuss the main types of oncolytic viruses applied for hematological malignancies and related clinical trials. In addition, we present several ways to improve the antitumor efficacy of oncolytic viruses. Finally, we discuss current challenges and provide suggestions for future studies.

Clinical diagnostic values of transfer RNA-derived fragment tRF-19-3L7L73JD and its effects on the growth of gastric cancer cells

Background and aim: Medicine has made great progress, but gastric cancer is still one of the most common malignant tumors worldwide. tRNA-derived fragments (tRFs), a type of small non-coding RNA, have been found to play important roles in cancers. Due to an abundance of modifications, tRFs have the potential to serve as cancer biomarkers. However, the relationship between tRFs and gastric cancer is still largely unclear. We have identified a new tRF, tRF-19-3L7L73JD, found to be expressed at a lower level in gastric cancer patients than healthy controls. Our study aims to explore the diagnostic value of tRF-19-3L7L73JD screening in gastric cancer and to investigate its effects on the growth of gastric cancer cells.

Methods: Using quantitative reverse transcription-polymerase chain reaction, we identified tRF-3L7L73JD as differentially expressed in plasma from gastric cancer patients compared to healthy controls. We measured tRF-3L7L73JD levels in plasma from 40 gastric cancer patients and healthy controls. Furthermore, we tested another cohort containing 89 gastric cancer patients and 98 healthy controls to validate our findings. Next, we analyzed the relationship between levels of tRF-19-3L7L73JD in plasma and clinicopathological data of gastric cancer patients, and then evaluated the effects of tRF-19-3L7L73JD on gastric cancer cell growth. Cell proliferation was measured by the Cell Counting Kit‐8 and clone formation experiments after transfer with tRF-19-3L7L73JD mimics. The changes in cell migration ability were explored through the scratch and Transwell experiments. Finally, we explored changes in apoptosis and cell cycle by flow cytometry.

Results: tRF-19-3L7L73JD showed lower expression in the tested gastric cancer patients. In the validation cohort tRF-19-3L7L73JD was also expressed at low levels in the pre-operative plasma group compared with healthy plasma and post-operative plasma groups. Additionally, a comparison of gastric cancer cell lines with normal gastric epithelial cell lines produced the same result. We found that tRF-19-3L7L73JD expression in patients was related to tumor size. The area under the curve (AUC) was 0.6230, with sensitivity and specificity of 0.4045 and 0.7959, respectively. Cellular function studies revealed that tRF-19-3L7L73JD inhibited cell proliferation and migration, induced apoptosis, and arrested cells at G₀/G₁ phases, suggesting it may suppress the development of gastric cancer.

Conclusion: The results suggest that tRF-19-3L7L73JD may be useful as a biomarker of gastric cancer.

Oncolytic Adenovirus CD55-Smad4 Suppresses Cell Proliferation, Metastasis, and Tumor Stemness in Colorectal Cancer by Regulating Wnt/β-Catenin Signaling Pathway

During the past few decades, colorectal cancer (CRC) incidence and mortality have significantly increased, and CRC has become the leading cause of cancer-related death worldwide. Thus, exploring novel effective therapies for CRC is imperative. In this study, we investigated the effect of oncolytic adenovirus CD55-Smad4 on CRC cell growth. Cell viability assay, animal experiments, flow cytometric analysis, cell migration, and invasion assays, and Western blotting were used to detect the proliferation, apoptosis, migration, and invasion of CRC cells. The oncolytic adenovirus CD55-Smad4 was successfully constructed and effectively suppressed CRC cell proliferation in vivo and in vitro. Notably, CD55-Smad4 activated the caspase signaling pathway, inducing the apoptosis of CRC cells. Additionally, the generated oncolytic adenovirus significantly suppressed migration and invasion of CRC cells by overexpressing Smad4 and inhibiting Wnt/β-catenin/epithelial-mesenchymal transition (EMT) signaling pathway. Moreover, CRC cells treated with CD55-Smad4 formed less and smaller spheroid colonies in serum-free culture than cells in control groups, suggesting that CD55-Smad4 suppressed the stemness of CRC cells by inhibiting the Wnt/β-catenin pathway. Together, the results of this study provide valuable information for the development of a novel strategy for cancer-targeting gene-virotherapy and provide a deeper understanding of the critical significance of Smad4 in gene therapy of CRC.

Doxorubicin hydrochloride enhanced antitumour effect of CEA-regulated oncolytic virotherapy in live cancer cells and a mouse model

Oncolytic adenovirus (OA) has attracted increasing attention due to their specific proliferation in tumour cells and resulting in lysis of tumour cells. To further improve the antitumour effect of OA, in this study, we combined CD55-TRAIL-IETD-MnSOD (CD55-TMn), a CEA-controlled OA constructed previously, and chemotherapy to investigate their synergistic effect and possible mechanisms. MTT assay was performed to detect antitumour effects. Hoechst 33 342 and flow cytometric analysis were used to examine cell apoptosis. Western blotting was performed to examine cell pyroptosis and apoptosis mechanism. Animal experiment was used to detect antitumour effect of doxorubicin hydrochloride (Dox) combined with CD55-TMn in vivo. We firstly found that Dox promotes gene expression mediated by CEA-regulated OA and virus progeny replication by activating phosphorylation of Smad3, and Dox can enhance antitumour effect of CEA-regulated CD55-TMn by promoting cell apotopsis and cell pyroptosis. Thus, our results provide an experimental and theoretical basis on tumour therapy by combination treatment of the oncolytic virotherapy and chemotherapy and it is expected to become a novel strategy for liver cancer therapy.

Synergistic Suppression Effect on Tumor Growth of Colorectal Cancer by Combining Radiotherapy With a TRAIL-Armed Oncolytic Adenovirus

The combination of gene therapy and radiation is a promising new treatment for cancer. This study aimed to clarify the synergistic effect of targeted oncolytic adenovirus (radiotherapy-tumor necrosis factor-related apoptosis-inducing ligand) and radiotherapy on colorectal cancer cells and elucidate the mechanisms of the underlying antitumor activity. Viability, cell cycle status, and apoptosis of treated colorectal cancer cells were determined via MTT and flow cytometric assays. The molecular mechanism underlying apoptotic pathway activation was elucidated through Western blot analysis of caspase-8, caspase-3, and PARP proteins. Combination treatment with radiotherapy-tumor necrosis factor-related apoptosis-inducing ligand and radiotherapy displayed significantly greater antitumor activity than either of the monotherapies. The primary mechanism behind the antitumor activity in the SW480 and Lovo colorectal cancer cell lines was apoptosis induction through the caspase pathway and G1 phase arrest. In an SW480 xenograft model of colorectal cancer, the combination therapy achieved a significantly greater reduction in tumor volume than the monotherapies. Overall, in this study, we demonstrate that the oncolytic radiotherapy-tumor necrosis factor-related apoptosis-inducing ligand construct can sensitize human colorectal cancer cells to radiation-induced apoptosis both in vitro and in vivo. Therefore, our findings point toward a novel synergistic approach to colorectal cancer treatment.

Oncolytic Adenovirus-A Nova for Gene-Targeted Oncolytic Viral Therapy in HCC

Hepatocellular carcinoma (HCC) is one of the most frequent cancers worldwide, particularly in China. Despite the development of HCC treatment strategies, the survival rate remains unpleasant. Gene-targeted oncolytic viral therapy (GTOVT) is an emerging treatment modality-a kind of cancer-targeted therapy-which creates viral vectors armed with anti-cancer genes. The adenovirus is a promising agent for GAOVT due to its many advantages. In spite of the oncolytic adenovirus itself, the host immune response is the determining factor for the anti-cancer efficacy. In this review, we have summarized recent developments in oncolytic adenovirus engineering and the development of novel therapeutic genes utilized in HCC treatment. Furthermore, the diversified roles the immune response plays in oncolytic adenovirus therapy and recent attempts to modulate immune responses to enhance the anti-cancer efficacy of oncolytic adenovirus have been discussed.

The combination of lonafarnib and sorafenib induces cyclin D1 degradation via ATG3-mediated autophagic flux in hepatocellular carcinoma cells

Combination treatment is a promising strategy to improve prognosis of hepatocellular carcinoma (HCC). Sorafenib is a traditional first-line agent approved for the treatment of advanced HCC, though with limited efficacy. Previously, we reported that lonafarnib, an orally bioavailable non-peptide inhibitor targeting farnesyltransferase, synergizes with sorafenib against the growth of HCC cells. In the present study, we aim to clarify the underlying mechanism of this combination strategy. Initially, using in vitro HCC cell model, we confirmed that synergistic treatment of lonafarnib and sorafenib suppressed cell viability and colony formation, and induced cell death. We then found conversion of LC3-I to LC3-II via combination the treatment and observed formation of autophagosomes by electron microscopy. Knockdown of ATG3 inhibited the autophagic flux induced by the combination treatment. Furthermore, we demonstrated that drug-eliciting autophagy selectively promoted the degradation of cyclin D1 in a lysosome-dependent manner and subsequently inhibited DNA synthesis through downregulating the phosphorylation of Rb protein. In conclusion, our results provide a deeper insight into the mechanism for the combination treatment of lonafarnib and sorafenib in HCC therapy.

Oncolytic viro-chemotherapy exhibits antitumor effect in laryngeal squamous cell carcinoma cells and mouse xenografts

Background: Oncolytic virus can specifically replicate in and then lyse tumor cells, but seldom in normal cells. Further studies have shown the significant therapeutic effect of oncolytic virotherapy combining with other strategies, such as chemo-, radio-, and immunotherapy et al. In this study, we investigated the combinational effect of oncolytic virus ZD55-TRAIL and chemotherapy drug doxorubicin (DOX) on human laryngeal squamous cell carcinoma (LSCC).

Methods: The effect of ZD55-TRAIL combined with DOX on cell growth was assessed in LSCC Hep2 cells and normal cells by MTT assay. Hochest 33342 staining was performed to observe cell morphological changes. Western blot was used to detect the expression of apoptotic activation proteins. The in vivo antitumor efficacy of combination treatment was estimated in laryngeal cancer xenograft models.

Results: The combination of ZD55-TRAIL and DOX exhibited enhanced inhibitory effects on laryngocarcinoma cell growth, and had few side effects to normal cells in vitro. Chemotherapy drug increased the inducement of tumor cell apoptosis mediated by oncolytic virus. In vivo experiment confirmed that the combination treatment significantly inhibited Hep2 laryngocarcinoma xenografts growth in mice.

Conclusion: The oncolytic viro-chemotherapy is a potent therapeutic approach for in vitro cytotoxicity evaluation of Hep2 cells and xenograft growth in vivo.

Role of autophagy in tumorigenesis, metastasis, targeted therapy and drug resistance of hepatocellular carcinoma

Autophagy is a “self-degradative” process and is involved in the maintenance of cellular homeostasis and the control of cellular components by facilitating the clearance or turnover of long-lived or misfolded proteins, protein aggregates, and damaged organelles. Autophagy plays a dual role in cancer, including in tumor progression and tumor promotion, suggesting that autophagy acts as a double-edged sword in cancer cells. Liver cancer is one of the greatest leading causes of cancer death worldwide due to its high recurrence rate and poor prognosis. Especially in China, liver cancer has become one of the most common cancers due to the high infection rate of hepatitis virus. In primary liver cancer, hepatocellular carcinoma (HCC) is the most common type. Considering the perniciousness and complexity of HCC, it is essential to elucidate the function of autophagy in HCC. In this review, we summarize the physiological function of autophagy in cancer, analyze the role of autophagy in tumorigenesis and metastasis, discuss the therapeutic strategies targeting autophagy and the mechanisms of drug-resistance in HCC, and provide potential methods to circumvent resistance and combined anticancer strategies for HCC patients.

Synergistic antitumor effect of the combination of a dual cancer-specific oncolytic adenovirus and cisplatin on lung cancer cells

The effect of the combination of a recombinant adenovirus (ATV) expressing a specific apoptin protein and cisplatin on human lung cancer cells (A549 cells) was determined. The inhibitory effects of ATV and cisplatin, ATV alone, or cisplatin alone on the migration and invasion of A549 cells were evaluated in vitro using cell proliferation, wound healing, Transwell migration and Matrigel invasion assays. The tumor inhibition effect on A549 cells in vivo was assessed by observing the tumor growth and survival rate of nude mice with subcutaneous tumor xenografts grown from implanted A549 cells after treatment with ATV, cisplatin, or ATV combined with cisplatin. The proliferation (P<0.01), migration (P<0.01), and invasion (P<0.01) on A549 cells was suppressed significantly by ATV, cisplatin, and ATV and cisplatin, in a dose- and time-dependent manner. The inhibition of tumor growth in transplanted nude mice in the ATV combined with cisplatin group was significantly higher than that displayed in the other groups, and the survival rate of the combined treatment group was significantly higher than that of the group treated with cisplatin alone. The results indicated that the combined application of ATV and cisplatin could reduce toxicity and showed a synergistic effect in reducing tumor growth and increasing survival. Thus, there is a potential research value in treating tumors using the combination of ATV and cisplatin, which provides a foundation for future preclinical studies on this antitumor treatment.

Circular RNA 0068669 as a new biomarker for hepatocellular carcinoma metastasis

BACKGROUND

Circular RNAs (circRNAs) play important roles in disease occurrence. However, the roles of circRNAs in the diagnosis of hepatocellular carcinoma (HCC) are largely unknown. The aim of this study is to investigate the clinical diagnostic values of hsa_circ_0068669 (Alias: hsa_circ_103561), one of the representative HCC-associated circRNAs.

METHODS

Hsa_circ_0068669 expression levels in HCC tissues, HCC cell lines, and chronic hepatitis tissues were detected by real-time quantitative reverse transcription-polymerase chain reaction. Its expression levels between HCC tissues and adjacent non-tumorous tissues were analyzed using paired t test. Independent t test and one-way analysis of variance (ANOVA) were performed to analyze the relationships between hsa_circ_0068669 expression levels and clinicopathological factors of patients with HCC. A receiver operating characteristic (ROC) curve was established to estimate the value of hsa_circ_0068669 as a biomarker in HCC.

RESULTS

Hsa_circ_0068669 expression was significantly downregulated in HCC tissues and HCC cell lines compared with paired non-tumorous tissues and normal hepatic cell line, respectively. Moreover, hsa_circ_0068669 expression in HCC tissues was decreased comparing with chronic hepatitis tissues. Furthermore, hsa_circ_0068669 expression was correlated with microvascular invasion and TNM stages.

CONCLUSIONS

Our findings indicate that hsa_circ_0068669 might be served as a novel potential biomarker for HCC metastasis.

Oncolytic virotherapy in upper gastrointestinal tract cancers

Upper gastrointestinal tract malignancies are among the most challenging cancers with regard to response to treatment and prognosis. Cancers of the esophagus, stomach, pancreas, liver, and biliary tree have dismal 5-year survival, and very modest improvements in this rate have been made in recent times. Oncolytic viruses are being developed to address these malignancies, with a focus on high safety profiles and low off-target toxicities. Each viral platform has evolved to enhance oncolytic potency and the clinical response to either single-agent viral therapy or combined viral treatment with radiotherapy and chemotherapy. A panel of genomic alterations, chimeric proteins, and pseudotyped capsids are the breakthroughs for vector success. This article revisits developments for each viral platform to each tumor type, in an attempt to achieve maximum tumor selectivity. From the bench to clinical trials, the scope of this review is to highlight the beginnings of translational oncolytic virotherapy research in upper gastrointestinal tract malignancies and provide a bioengineering perspective of the most promising platforms.

Oncolytic Adenoviruses in Gastrointestinal Cancers

Gastrointestinal malignancies are challenging cancers with considerable economic and societal impacts on health care systems worldwide. While advances in surgical approaches have provided benefits to a proportion of patients, only modest improvements have been attained in the treatment of patients with advanced disease, resulting in limited improvement in survival rates in these patients. Oncolytic adenoviruses are being developed to address gastrointestinal malignancies. Each platform has evolved to maximize tumor-cell killing potency while minimizing toxicities. Tumor-specific bioengineered adenoviruses using chimeric promoters, prodrug convertase enzymes, lethal genes, tumor suppressor genes, and pseudo-typed capsids can provide the innovations for eventual success of oncolytic virotherapy. This article will review the developments in adenoviral platforms in the context of specific gastrointestinal cancers. From the bench to the implementation of clinical trials, this review aims to highlight advances in the field from its early days to the current state of affairs as it pertains to the application of adenoviral oncolytic therapy to gastrointestinal cancers.

Synergistic antitumor activity of triple-regulated oncolytic adenovirus with VSTM1 and daunorubicin in leukemic cells

V-set and transmembrane domain-containing 1 (VSTM1), which is downregulated in bone marrow cells from leukemia patients, may provide a diagnostic and treatment target. Here, a triple-regulated oncolytic adenovirus was constructed to carry a VSTM1 gene expression cassette, SG611-VSTM1, and contained the E1a gene with a 24-nucleotide deletion within the CR2 region under control of the human telomerase reverse transcriptase promoter, E1b gene directed by the hypoxia response element, and VSTM1 gene controlled by the cytomegalovirus promoter. Real-time quantitative PCR and Western blot analyses showed that SG611-VSTM1 expressed VSTM1 highly efficiently in the human leukemic cell line K562 compared with SG611. In Cell Counting Kit-8 and flow cytometric assays, SG611-VSTM1 exhibited more potent anti-proliferative and pro-apoptotic effects in leukemic cells compared with SG611 and exerted synergistic cytotoxicity with low-dose daunorubicin (DNR) in vitro. In xenograft models, SG611-VSTM1 intratumorally injected at a dose of 1 × 10(9) plaque forming units combined with intraperitoneally injected low-dose DNR displayed significantly stronger antitumor effects than either treatment alone. Histopathologic examination revealed that SG611-VSTM1 induced apoptosis of leukemic cells. These results implicate an important role for VSTM1 in the pathogenesis of leukemia, and SG611-VSTM1 may be a promising agent for enhancing chemosensitivity in leukemia therapy.

Combination of oncolytic adenovirus and luteolin exerts synergistic antitumor effects in colorectal cancer cells and a mouse model

In recent years, oncolytic viruses have attracted increasing interest due to their potent antitumor effects. Luteolin, a natural product, has additionally been observed to exhibit various pharmacological antitumor activities. Previously, a novel dual-targeting oncolytic adenovirus, complement decay-accelerating factor (CD55)-tumor necrosis factor ligand superfamily member 10 (TRAIL), was constructed, which exhibited significant growth inhibitory effects in various types of tumor cell. The present study investigated whether the combination of luteolin and CD55-TRAIL was able to exert a synergistic antitumor effect in colorectal carcinoma (CRC) cells. The cytotoxicity and tumor cell apoptosis mediated by combination treatment in CRC cells were detected via an MTT assay, Hoechst staining and western blotting, respectively. Tumor growth in vivo was examined in a CRC mouse xenograft model following various treatments. The results demonstrated that the addition of luteolin enhanced oncolytic adenovirus-mediated enhanced green fluorescent protein, early region 1A and TRAIL expression. The combination of CD55-TRAIL with luteolin synergistically inhibited tumor growth and promoted CRC cellular apoptosis in vitro and in vivo. Additionally, the combination of CD55-TRAIL with luteolin significantly decreased cytotoxicity in lung/bronchial normal epithelial cells, compared with single treatment. Therefore, the combination of CD55-TRAIL with luteolin may be a novel efficient therapeutic strategy for CRC in the future.

Role of X‑linked inhibitor of apoptosis‑associated factor‑1 in vasculogenic mimicry in ovarian cancer

X-linked inhibitor of apoptosis‑associated factor 1 (XAF1) was identified as a novel X-linked inhibitor of apoptosis (XIAP) binding partner that may reverse the anti‑apoptotic effect of XIAP. Previous studies have revealed that XAF1 serves an important role in cancer angiogenesis. Vasculogenic mimicry (VM) describes the formation of fluid‑conducting channels by highly invasive and genetically dysregulated tumor cells. VM is critical for tumor blood supply and is associated with aggressive actions and metastasis. The aim of present study was to investigate the potential association between XAF1 expression with VM of ovarian cancer, and evaluate the role of XAF1 in tumor cell migration and invasion of SKOV3 cells. VM structure and XAF1 expression were detected in 94 tissue samples of advanced epithelial ovarian cancer (EOC). Invasion and migration of the SKOV3 human ovarian carcinoma cell line were identified by Transwell assay. It was revealed that the presence of VM was associated with high grade advanced ovarian cancer. Reduced XAF1 expression was significantly associated with presence of VM. Overexpression of XAF1 significantly reduced invasion and migration of SKOV3 cells, and inhibited vascular endothelial growth factor protein expression. Furthermore, vasculature was suppressed by overexpression of XAF1 in vivo in xenograft models. In conclusion, XAF1 expression was associated with VM in ovarian cancer, suggesting a potential role of XAF1 in the formation of VM in EOC. These findings may facilitate the development of novel therapeutic agents for the treatment of ovarian cancer.

Upregulation of Coxsackie Adenovirus Receptor Sensitizes Cisplatin-Resistant Lung Cancer Cells to CRAd-Induced Inhibition

Objective. Conditionally replicating adenoviruses (CRAds) have been proven potent oncolytic viruses in previous studies. They selectively replicate in the tumor cells because of incorporated survivin promoter and ultimately lead to their killing with minimal side effects on normal tissue. Chemotherapy with cisplatin is commonly employed for treating tumors, but its cytotoxic effects and development of resistance remained major concerns to be dealt with. The aim of this study was to explore the anticancer potential of survivin regulated CRAd alone or in combination with cisplatin in the A549 lung cancer cell line and cisplatin-resistant lung cancer cell line, A549-DDPR.

Methods. CRAd was genetically engineered in our laboratory by removing its E1B region and adding survivin promoter to control its replication. A549, H292, and H661 lung cancer cell lines were procured from the CAS-China. The anti-tumor effectiveness of combined treatment (cisplatin plus CRAd) was evaluated in vitro through MTS assays and in vivo through mouse model experimentation. RT- PCR was used to assess MDR gene and mRNA expression of coxsackie adenoviral receptor (CAR).

Results. Results of in vitro studies established that A549 lung cancer cells were highly sensitive to cisplatin showing dose-dependent inhibition. The resistant cells of A549-DDPR exhibited very less sensitivity to cisplatin but were infected with CRAd more efficiently as compared to A549. A549-DDPR cells exhibited higher expression of MDR gene and CAR in the RT-PCR analysis. The nearly similar rise in the CAR expression was seen when lung cancer cell lines received cisplatin in combined treatment (cisplatin plus CRAd). Combined anti-cancer therapy (cisplatin plus oncolytic virus) proved more efficient than monotherapy in the killing of cancer cells. Results of in vivo experiments recapitulated nearly similar tumor inhibition activities.

Conclusion. This study highlighted the significant role of survivin in gene therapy as it has the potential to render CRAd more tumor specific. It also establishes that higher CAR expression plays a vital role in the success of adenovirus-based therapies. Furthermore, a careful combination of chemotherapy drugs and oncolytic viruses can culminate in significant therapeutic achievements against cancer.

Chemovirotherapy of Pancreatic Adenocarcinoma by Combining Oncolytic Vaccinia Virus GLV-1h68 with nab-Paclitaxel Plus Gemcitabine

Oncolytic viruses have proven their therapeutic potential against a variety of different tumor entities both in vitro and in vivo. Their ability to selectively infect and lyse tumor cells, while sparing healthy tissues, makes them favorable agents for tumor-specific treatment approaches. Particularly, the addition of virotherapeutics to already established chemotherapy protocols (so-called chemovirotherapy) is of major interest. Here we investigated the in vitro cytotoxic effect of the oncolytic vaccinia virus GLV-1h68 combined with dual chemotherapy with nab-paclitaxel plus gemcitabine in four human pancreatic adenocarcinoma cell lines (AsPc-1, BxPc-3, MIA-PaCa-2, and Panc-1). This chemovirotherapeutic protocol resulted in enhanced tumor cell killing in two tumor cell lines compared to the respective monotherapies. We were thereby able to show that the combination of oncolytic vaccinia virus GLV-1h68 with nab-paclitaxel and gemcitabine has great potential in the chemovirotherapeutic treatment of advanced pancreatic adenocarcinoma. However, the key to a successful combinatorial chemovirotherapeutic treatment seems to be a profound viral replication, as tumor cell lines that were non-responsive to the combination therapy exhibited a reduced viral replication in the presence of the chemotherapeutics. This finding is of special significance when aiming to achieve a virus-mediated induction of a profound and long-lasting antitumor immunity.

A supramolecular nanoparticle system based on β-cyclodextrin-conjugated poly-l-lysine and hyaluronic acid for co-delivery of gene and chemotherapy agent targeting hepatocellular carcinoma

A novel supramolecular nanoparticle system with core-shell structure was designed based on β-cyclodextrin-conjugated poly-l-lysine (PLCD) and hyaluronic acid for co-delivery of gene and chemotherapy agent targeting hepatocellular carcinoma (HCC). PLCD was synthesized by the conjugation of monoaldehyde activated β-cyclodextrin with poly-l-lysine via Shiff's base reaction. Doxorubicin, as a model therapeutic drug, was included into the hydrophobic cavity of β-cyclodextrin in PLCD through host-guest interaction. OligoRNA, as a model gene, was further condensed into the inclusion complexes by electrostatic interaction to form oligoRNA and doxorubicin co-loaded supramolecular nanoparticle system. Hyaluronic acid, which is often over-expressed by HCC cells, was coated on the surface of the above nanoparticles to construct HCC-targeted nanoparticle system. These nanoparticles had regular spherical shape with classic "core-shell" structure, and their size and zeta potential were 195.8nm and -22.7mV, respectively. The nanoparticles could effectively deliver doxorubicin and oligoRNA into HCC cells via CD44 receptor-mediated endocytosis and significantly inhibit the cell proliferation. In the nude mice bearing MHCC-97H tumor, the nanoparticles could be efficiently accumulated in the tumor, suggesting their strong hepatoma-targeting capability. These findings demonstrated that this novel supramolecular nanoparticle system had a promising potential for combining gene therapy and chemotherapy to treat HCC.

Synergistic suppression effect on tumor growth of ovarian cancer by combining cisplatin with a manganese superoxide dismutase-armed oncolytic adenovirus

Gene therapy on the basis of oncolytic adenovirus is a novel approach for human cancer therapeutics. We aim to investigate whether it will synergistically reinforce their antiovarian cancer activities when the combined use of ZD55-manganese superoxide dismutase (MnSOD) and cisplatin was performed. The experiments in vitro showed that ZD55-MnSOD enhances cisplatin-induced apoptosis and causes remarkable ovarian cancer cell death. Apoptosis induction by treatment with ZD55-MnSOD and/or cisplatin was detected in SKOV-3 by apoptotic cell staining, flow cytometry, and western blot analysis. In addition, the cytotoxicity caused by ZD55-MnSOD to normal cells was examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay and western blot analysis. Animal experiment further confirmed that combination of ZD55-MnSOD and cisplatin achieved significant inhibition of SKOV-3 ovarian tumor xenografted growth. In summary, we have demonstrated that ZD55-MnSOD can sensitize human ovarian cancer cells to cisplatin-induced cell death and apoptosis in vitro and in vivo. These findings indicate that the combined treatment with ZD55-MnSOD and cisplatin could represent a rational approach for antiovarian cancer therapy.

Nutlin-3 treatment spares cisplatin-induced inhibition of bone healing while maintaining osteosarcoma toxicity

The majority of Osteosarcoma (OS) patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. These protocols include distraction osteogenesis (DO), which is characterized by direct new bone formation. Cisplatin (CDP) is extensively used for OS chemotherapy and recent studies, using a mouse DO model, have demonstrated that CDP has profound negative effects on bone repair. Recent oncological therapeutic strategies are based on the use of standard cytotoxic drugs plus an assortment of biologic agents. Here we demonstrate that the previously reported CDP-associated inhibition of bone repair can be modulated by the administration of a small molecule p53 inducer (nutlin-3). The effects of nutlin-3 on CDP osteotoxicity were studied using both pre- and post-operative treatment models. In both cases the addition of nutlin-3, bracketing CDP exposure, demonstrated robust and significant bone sparing activity (p < 0.01-0.001). In addition the combination of nutlin-3 and CDP induced equivalent OS tumor killing in a xenograft model. Collectively, these results demonstrate that the induction of p53 peri-operatively protects bone healing from the toxic effects of CDP, while maintaining OS toxicity. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1716-1724, 2016.

Enhanced antitumor effect of combining TRAIL and MnSOD mediated by CEA-controlled oncolytic adenovirus in lung cancer

Lung cancer, especially adenocarcinoma, is one of the leading causes of death in the world. Carcinoembryonic antigen (CEA), a superb non-small-cell lung cancer marker candidate, showed a beneficial effect in cancer therapy with oncolytic adenovirus in recent studies. Cancer-targeting dual gene-virotherapy delivers two therapeutic genes, linked by a connexon, in the replication-deficient vector instead of one gene so that they can work in common. In this study, we constructed a tumor-specific oncolytic adenovirus, CD55-TRAIL-IETD-MnSOD. The virus has the fusion protein complementary DNAs for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and for manganese superoxide dismutase (MnSOD) complementary DNA linked through a 4-amino acid caspase-8 cleavage site (IETD), and uses a CEA promoter to control virus E1A express. This is the first work to use a CEA promoter-regulated oncolytic adenovirus carrying two therapeutic genes for cancer research. Its targeting and anticancer capacity was evaluated by in vitro and in vivo experiments. The results indicated that CD55-TRAIL-IETD-MnSOD caused more cell apoptosis than CD55-TRAIL or CD55-MnSOD alone, or their combination in vitro, with low cytotoxicity of normal cells. In the A549 tumor xenograft model in nude mice, data showed that CD55-TRAIL-IETD-MnSOD could effectively suppress tumor growth than single gene groups, with no histological damage in liver, spleen or kidney tissues. Thus, the CEA-regulated dual-gene oncolytic virus CD55-TRAIL-IETD-MnSOD may be a novel potential therapy for lung cancer.

Targeting adeno-associated virus and adenoviral gene therapy for hepatocellular carcinoma

Human hepatocellular carcinoma (HCC) heavily endangers human heath worldwide. HCC is one of most frequent cancers in China because patients with liver disease, such as chronic hepatitis, have the highest cancer susceptibility. Traditional therapeutic approaches have limited efficacy in advanced liver cancer, and novel strategies are urgently needed to improve the limited treatment options for HCC. This review summarizes the basic knowledge, current advances, and future challenges and prospects of adeno-associated virus (AAV) and adenoviruses as vectors for gene therapy of HCC. This paper also reviews the clinical trials of gene therapy using adenovirus vectors, immunotherapy, toxicity and immunological barriers for AAV and adenoviruses, and proposes several alternative strategies to overcome the therapeutic barriers to using AAV and adenoviruses as vectors.

Cancer immunotherapy via combining oncolytic virotherapy with chemotherapy: recent advances

Oncolytic viruses are multifunctional anticancer agents with huge clinical potential, and have recently passed the randomized Phase III clinical trial hurdle. Both wild-type and engineered viruses have been selected for targeting of specific cancers, to elicit cytotoxicity, and also to generate antitumor immunity. Single-agent oncolytic virotherapy treatments have resulted in modest effects in the clinic. There is increasing interest in their combination with cytotoxic agents, radiotherapy and immune-checkpoint inhibitors. Similarly to oncolytic viruses, the benefits of chemotherapeutic agents may be that they induce systemic antitumor immunity through the induction of immunogenic cell death of cancer cells. Combining these two treatment modalities has to date resulted in significant potential in vitro and in vivo synergies through various mechanisms without any apparent additional toxicities. Chemotherapy has been and will continue to be integral to the management of advanced cancers. This review therefore focuses on the potential for a number of common cytotoxic agents to be combined with clinically relevant oncolytic viruses. In many cases, this combined approach has already advanced to the clinical trial arena.

Stimulation of the hypoxia pathway modulates chemotherapy resistance in Hodgkin's lymphoma cells

Hodgkin's lymphoma (HL) is a malignant disease of the lymphatic system. The therapy has been improved during the last decades but there are still patients who cannot be cured, and the therapy is associated with several adverse late effects. Therefore, we asked which genes might be involved in the chemotherapy resistance of HL cells. We observed that HL cells became more resistant against cisplatin after treatment with cobalt chloride. Therefore, we analyzed which genes were differentially expressed between cells incubated in medium with or without cobalt chloride. We found several genes which were up- or downregulated in the presence of cobalt chloride and might be involved in the modulation of chemotherapy resistance. Cobalt chloride is a hypoxia-mimetic agent. Therefore, we tested chemo-resistance and gene expression of HL cells under hypoxic conditions and confirmed the results from the cobalt chloride experiments. Taken together, activation of the hypoxia pathway led to altered gene expression and drug resistance of HL cells. Differentially expressed genes might be interesting targets for the development of future treatment strategies against drug-resistant HL.

A novel Golgi protein (GOLPH2)-regulated oncolytic adenovirus exhibits potent antitumor efficacy in hepatocellular carcinoma

Golgi apparatus is the organelle mainly functioning as protein processing and secretion. GOLPH2 is a resident Golgi glycoprotein, usually called GP73. Recent data displayed that GOLPH2 is a superb hepatocellular carcinoma (HCC) marker candidate, and even its specificity is better than liver cancer marker AFP. Oncolytic adenoviruses are broadly used for targeting cancer therapy due to their selective tumor-killing effect. However, it was reported that traditionally oncolytic adenovirus lack the HCC specificity. In this study, a novel dual-regulated oncolytic adenovirus GD55 targeting HCC was first constructed based on our cancer targeted gene-viral therapeutic strategy. To verify the targeting and effectiveness of GOLPH2-regulated oncolytic adenovirus GD55 in HCC, the anticancer capacity was investigated in HCC cell lines and animal model. The results proved that the novel GOLPH2-regulated GD55 conferred higher adenovirus replication and infectivity for liver cancer cells than oncolytic adenovirus ZD55. The GOLPH2-regulated GD55 exerted a significant grow-suppressing effect on HCC cells in vitro but little damage to normal liver cells. In animal experiment, antitumor effect of GD55 was more effective in HCC xenograft of nude mice than that of ZD55. Thus GOLPH2-regulated GD55 may be a promising oncolytic virus agent for future liver cancer treatment.