Oncolytic Virus-Driven Biotherapies from Bench to Bedside.

With advances in cancer biology and an ever-deepening understanding of molecular virology, oncolytic virus (OV)-driven therapies have developed rapidly and become a promising alternative to traditional cancer therapies. In recent years, satisfactory results for oncolytic virus therapy (OVT) are achieved at both the cellular and organismal levels, and efforts are being increasingly directed toward clinical trials. Unfortunately, OVT remains ineffective in these trials, especially when performed using only a single OV reagent. In contrast, integrated approaches, such as using immunotherapy, chemotherapy, or radiotherapy, alongside OVT have demonstrated considerable efficacy. The challenges of OVT in clinical efficacy include the restricted scope of intratumoral injections and poor targeting of intravenous administration. Further optimization of OVT delivery is needed before OVs become a viable therapy for tumor treatment. In this review, the development process and antitumor mechanisms of OVs are introduced. The advances in OVT delivery routes to provide perspectives and directions for the improvement of OVT delivery are highlighted. This review also discusses the advantages and limitations of OVT monotherapy and combination therapy through the lens of recent clinical trials and aims to chart a course toward safer and more effective OVT strategies.

Boarding Oncolytic Viruses onto Tumor-Homing Bacterium-Vessels for Augmented Cancer Immunotherapy.

Oncolytic viruses (OVs) have been widely used as anticancer therapeutics because of their systemic immune responses during viral replication. However, the low enrichment of OVs within tumors and limited immune activation have hindered their clinical application. Herein, we proposed the concept of bacteria-assisted targeting of OVs to tumors, with liposome-cloaked oncolytic adenoviruses (OAs) conjugated onto tumor-homing Escherichia coli BL21 (designated as E. coli-lipo-OAs) for enhanced cancer immunotherapy. Notably, the enrichment of OAs transported by self-propelled bacterial microbe vehicles in E. coli-lipo-OAs in a nonsmall cell lung tumor can be potentiated by more than 170-fold compared with that of intravenously injected bare OAs. In vivo studies further revealed that E. coli-lipo-OAs administered intravenously significantly enhanced antitumor immunity through bacterial-viral-augmented immune responses. Our findings suggest that the self-driving microbe vehicle as a systemic delivery system for OVs can be a potent platform for developing future anticancer biotherapeutics at the clinical level.

Old drug new tricks: Chlorhexidine acts as a potential allosteric inhibitor toward PAK1.

This paper describes the identification of chlorhexidine, an agent commonly used in clinical as a novel potential allosteric inhibitor of PAK1. In cellular assays, chlorhexidine showed a good inhibitory profile, and its inhibitory profile was even better than IPA-3, a well-known allosteric inhibitor. In pharmacology experiments, chlorhexidine successfully inhibited the relief of PAK1 dimer and inhibited the activation of PAK1. Our findings offer an insight for the new drug development of PAK1 inhibitor. We also provide a possible explanation for the phenomenon that the application of the chlorhexidine in peritoneal lavage inhibited the development of tumor.

HSF1, in association with MORC2, downregulates ArgBP2 via the PRC2 family in gastric cancer cells.

Arg Kinase-binding protein 2 (ArgBP2) is considered to be a scaffold protein that coordinates multiple signaling pathways converging on cell adhesion and actin cytoskeletal organization. It also plays an important role in blocking cancer metastasis as a potential tumor suppressor. However, its regulation mechanisms in tumor migration, especially in gastric cancer, are not fully understood. Here, we identified an ArgBP2 enhancer and showed that heat shock factor 1 (HSF1) directly interacted with microrchidia CW-type zinc finger 2 (MORC2) and bound to the enhancer of ArgBP2. HSF1 was found to promote proliferation, migration and invasion of gastric cancer cells. HSF1 or/and MORC2 increased recruitment of the polycomb repressive complex 2 (PRC2), particularly enhancer of zeste homolog 2 (EZH2), to the ArgBP2 enhancer and catalyzed tri-methylation of lysine 27 on histone H3 (H3K27me3), leading to transcriptional repression of ArgBP2. In addition, HSF1 and MORC2-induced migration and invasion in gastric cancer cells was dependent on ArgBP2 or EZH2. Clinical data exhibited a negative correlation of ArgBP2 with MORC2, HSF1, and EZH2. Our results thus contribute to the knowledge of the regulatory mechanism of HSF1 in down-regulating ArgBP2, providing new insight into the HSF1&MORC2-PRC2-ArgBP2 signaling pathway and a better understanding of their functions in gastric cancer cells.

GRIK3: A novel oncogenic protein related to tumor TNM stage, lymph node metastasis, and poor prognosis of GC.

Glutamate receptor, ionotropic, kainate 3 (GRIK3), as a member of the glutamate kainate receptor family, mainly participated in neuroactive ligand receptor interaction pathway. Other members of GRIK family were previously reported to regulate cellular migration, transformation, and proliferation in tumor. However, the mechanism of GRIK3 in tumor is still unclear. Therefore, the purpose of our study was to reveal the expression and clinical significance of GRIK3 in gastric cancer (GC). First, we performed the expression analysis and survival analysis of GRIK3 using The Cancer Genome Atlas (TCGA) database, and the results showed that the GRIK3 expressed differentially between gastric cancer tissues and the adjacent normal tissues and that higher expression of GRIK3 was associated with poor survival outcomes. And the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that GRIK3 mainly took part in cancer-related process. Subsequently, the validated immunohistochemistry showed that GRIK3 expressed higher in the GC tissues than in the matched normal tissues and the patients with overexpressed GRIK3 had worse survival outcomes. The univariate and multivariate analyses suggested that the expression of GRIK3 was an independent prognostic factor to predict GC prognosis. Furthermore, additional experiment showed that the lymph node metastasis tissues had higher GRIK3 expression than their matched primary GC tissues. These findings suggested that elevated GRIK3 expression could serve as an independent prognostic biomarker and a novel potential treatment target for patients with GC.

Microchidia protein 2, MORC2, downregulates the cytoskeleton adapter protein, ArgBP2, via histone methylation in gastric cancer cells.

ArgBP2 is an adapter protein that plays an important role in actin-dependent processes such as cell adhesion and migration. However, its function and regulation mechanisms in gastric cancer have not yet been investigated. Here, we showed the low expression of ArgBP2 mRNA level in gastric tumor samples and its repressive function in the proliferation, migration, and invasion of gastric cancer cells. Then, we cloned and identified ArgBP2 promoter and verified that MORC2 bound to the promoter. Moreover, we demonstrated that MORC2 enhanced the recruitment of EZH2, which promoted the tri-methylation of H3K27, leading to the transcriptional repression of ArgBP2. Our results might thus contribute to understanding the molecular mechanisms of ArgBP2 regulation and suggesting ArgBP2 as a potential therapeutic target for gastric cancer.

Erratum: A Novel Pak1/ATF2/miR-132 Signaling Axis Is Involved in the Hematogenous Metastasis of Gastric Cancer Cells.

[This corrects the article DOI: 10.1016/j.omtn.2017.07.005.].

Erythrocyte-Leveraged Oncolytic Virotherapy (ELeOVt): Oncolytic Virus Assembly on Erythrocyte Surface to Combat Pulmonary Metastasis and Alleviate Side Effects.

Despite being a new promising tool for cancer therapy, intravenous delivery of oncolytic viruses (OVs) is greatly limited by poor tumor targeting, rapid clearance in the blood, severe organ toxicity, and cytokine release syndrome. Herein, a simple and efficient strategy of erythrocyte-leveraged oncolytic virotherapy (ELeOVt) is reported, which for the first time assembled OVs on the surface of erythrocytes with up to near 100% efficiency and allowed targeted delivery of OVs to the lung after intravenous injection to achieve excellent treatment of pulmonary metastases while greatly improving the biocompatibility of OVs as a drug. Polyethyleneimine (PEI) as a bridge to assemble OVs on erythrocytes also played an important role in promoting the transfection of OVs. It is found that ELeOVt approach significantly prolonged the circulation time of OVs and increased the OVs distribution in the lung by more than tenfold, thereby significantly improving the treatment of lung metastases while reducing organ and systemic toxicity. Taken together, these findings suggest that the ELeOVt provides a biocompatible, efficient, and widely available approach to empower OVs to combat lung metastasis.

Adverse events of PD-(L)1 inhibitors plus anti-VEGF(R) agents compared with PD-(L)1 inhibitors alone for cancer patients: a systematic review and meta-analysis.

Background: Anti-PD-(L)1 antibody monotherapy or in combination with VEGF(R) blockade has been applied widely for cancer treatment. Whether combination therapy increases irAEs still remains controversial. Methods: A systematic review and meta-analysis comparing PD-(L)1 and VEGF(R) blockade combination therapy with PD-(L)1 inhibitors alone was performed. Phase II or III randomized clinical trials reporting irAEs or trAEs were included. The protocol was registered with PROSPERO, CRD42021287603. Results: Overall, 77 articles were included in the meta-analysis. A total of 31 studies involving 8,638 participants were pooled and an incidence for PD-(L)1 inhibitor monotherapy with any grade and grade ≥3 irAEs of 0.25 (0.20, 0.32) and 0.06 (0.05, 0.07), respectively, were reported. Two studies with 863 participants pooled for PD-(L)1 and VEGF(R) blockade showed that an incidence of any grade and grade ≥3 irAEs were 0.47 (0.30, 0.65) and 0.11 (0.08, 0.16), respectively. Regarding pairwise comparisons for irAEs, only one study was included, indicating no significant difference between the two regimens in terms of colitis, hyperthyroidism, and hypothyroidism for any grade and grade ≥3, while there was a trend of higher incidence for any grade hyperthyroidism under the combination therapy. The incidence of reactive cutaneous capillary endothelial proliferation (RCCEP) was as high as 0.80 under camrelizumab monotherapy. Conclusion: Total incidences of any grade and grade ≥3 irAEs were higher in the combination treatment group. Direct comparisons indicated no significant difference between the two regimens for any grade and grade ≥3 specific irAEs. RCCEP and thyroid disorders need to be paid attention to clinically. Moreover, trials with direct comparisons are needed and the safety profiles of the two regimens should be further explored. Exploration of the mechanism of action and regulatory management of adverse events should be enhanced. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=287603, identifier CRD42021287603.

Progress in oncolytic viruses modified with nanomaterials for intravenous application.

In oncolytic virus (OV) therapy, a critical component of tumor immunotherapy, viruses selectively infect, replicate within, and eventually destroy tumor cells. Simultaneously, this therapy activates immune responses and mobilizes immune cells, thereby eliminating residual or distant cancer cells. However, because of OVs' high immunogenicity and immune clearance during circulation, their clinical applications are currently limited to intratumoral injections, and their use is severely restricted. In recent years, numerous studies have used nanomaterials to modify OVs to decrease virulence and increase safety for intravenous injection. The most commonly used nanomaterials for modifying OVs are liposomes, polymers, and albumin, because of their biosafety, practicability, and effectiveness. The aim of this review is to summarize progress in the use of these nanomaterials in preclinical experiments to modify OVs and to discuss the challenges encountered from basic research to clinical application.

Drug conjugate-based anticancer therapy - Current status and perspectives.

Drug conjugates are conjugates comprising a tumor-homing carrier tethered to a cytotoxic agent via a linker that are designed to deliver an ultra-toxic payload directly to the target cancer cells. This strategy has been successfully used to increase the therapeutic efficacy of cytotoxic agents and reduce their toxic side effects. Drug conjugates are being developed worldwide, with the potential to revolutionize current cancer treatment strategies. Antibody-drug conjugates (ADCs) have developed rapidly, and 14 of them have received market approval since the first approval event by the Food and Drug Administration in 2000. However, there are some limitations in the use of antibodies as carriers. Other classes of drug conjugates are emerging, such as targeted drugs conjugated with peptides (peptide-drug conjugates, PDCs) and polymers (polymer-drug conjugates, PolyDCs) with the remaining constructs similar to those of ADCs. These novel drug conjugates are gaining attention because they overcome the limitations of ADCs. This review summarizes the current state and advancements in knowledge regarding the design, constructs, and clinical efficacy of different drug conjugates.

Engineered bacterial outer membrane vesicles encapsulating oncolytic adenoviruses enhance the efficacy of cancer virotherapy by augmenting tumor cell autophagy.

Oncolytic adenovirus (Ad) infection promotes intracellular autophagy in tumors. This could kill cancer cells and contribute to Ads-mediated anticancer immunity. However, the low intratumoral content of intravenously delivered Ads could be insufficient to efficiently activate tumor over-autophagy. Herein, we report bacterial outer membrane vesicles (OMVs)-encapsulating Ads as microbial nanocomposites that are engineered for autophagy-cascade-augmented immunotherapy. Biomineral shells cover the surface antigens of OMVs to slow their clearance during in vivo circulation, enhancing intratumoral accumulation. After entering tumor cells, there is excessive H2O2 accumulation through the catalytic effect of overexpressed pyranose oxidase (P2O) from microbial nanocomposite. This increases oxidative stress levels and triggers tumor autophagy. The autophagy-induced autophagosomes further promote Ads replication in infected tumor cells, leading to Ads-overactivated autophagy. Moreover, OMVs are powerful immunostimulants for remolding the immunosuppressive tumor microenvironment, facilitating antitumor immune response in preclinical cancer models in female mice. Therefore, the present autophagy-cascade-boosted immunotherapeutic method can expand OVs-based immunotherapy.

Virus-Protein Corona Replacement Strategy to Improve the Antitumor Efficacy of Intravenously Injected Oncolytic Adenovirus.

Intravenous administration of oncolytic adenoviruses (OVs) is a hopeful tumor therapeutic modality. However, the sharp clearance of OVs by the immune system dampens its effectiveness. Many studies have attempted to extend the circulation of intravenously administered OVs, almost all by preventing OVs from binding to neutralizing antibodies and complements in the blood, but the results have not been satisfactory. In contrast to previous conclusions, we found that the key to improving the circulation of OVs is to prevent the formation of the virus-protein corona rather than simply preventing the binding of neutralizing antibodies or complements to OVs. After identifying the key protein components of the virus-protein corona, we proposed a virus-protein corona replacement strategy, where an artificial virus-protein corona was formed on OVs to completely prevent the interaction of OVs with key virus-protein corona components in the plasma. It was found that this strategy dramatically prolonged the circulation time of OVs by over 30 fold and increased the distribution of OVs in tumors by over 10-fold, resulting in superior antitumor efficacy in primary and metastatic tumor models. Our finding provides a perspective on intravenous delivery of OVs, shifting the focus of future studies from preventing OV binding with neutralization antibodies and complements to preventing OVs from interacting with key virus-protein corona components in the plasma.

Self-assembled short peptides: Recent advances and strategies for potential pharmaceutical applications.

Self-assembled short peptides have intrigued scientists due to the convenience of synthesis, good biocompatibility, low toxicity, inherent biodegradability and fast response to change in the physiological environment. Therefore, it is necessary to present a comprehensive summary of the recent advances in the last decade regarding the construction, route of administration and application of self-assembled short peptides based on the knowledge on their unique and specific ability of self-assembly. Herein, we firstly explored the molecular mechanisms of self-assembly of short peptides, such as non-modified amino acids, as well as Fmoc-modified, N-functionalized, and C-functionalized peptides. Next, cell penetration, fusion, and peptide targeting in peptide-based drug delivery were characterized. Then, the common administration routes and the potential pharmaceutical applications (drug delivery, antibacterial activity, stabilizers, imaging agents, and applications in bioengineering) of peptide drugs were respectively summarized. Last but not least, some general conclusions and future perspectives in the relevant fields were briefly listed. Although with certain challenges, great opportunities are offered by self-assembled short peptides to the fascinating area of drug development.

FN1 mRNA 3'-UTR supersedes traditional fibronectin 1 in facilitating the invasion and metastasis of gastric cancer through the FN1 3'-UTR-let-7i-5p-THBS1 axis.

Background: Current clinical treatments for gastric cancer (GC), particularly advanced GC, lack infallible therapeutic targets. The 3'-untranslated region (3'-UTR) has attracted increasing attention as a drug target. Methods: In vitro and in vivo experiments were conducted to determine the function of FN1 3'-UTR and FN1 protein in invasion and metastasis. RNA pull-down assay and high-throughput sequencing were used to screen the factors regulated by FN1 3'-UTR and construct the regulatory network. Western blotting and polymerase chain reaction were used to examine the correlation of intermolecular expression levels. RNA-binding protein immunoprecipitation was used to verify the correlation between FN1 3'-UTR and target mRNAs. Results: The FN1 3'-UTR may have stronger prognostic implications than the FN1 protein in GC patients. Upregulation of FN1 3'-UTR significantly promoted the invasive and metastatic abilities of GC cells to a greater extent than FN1 protein in vitro and in vivo. A novel regulatory network was constructed based on the FN1 3'-UTR-let-7i-5p-THBS1 axis, wherein FN1 3'-UTR displayed stronger oncogenic effects than the FN1 protein. Conclusions: FN1 3'-UTR may be a better therapeutic target for constructing targeted drugs in GC than the FN1 protein.

Inhibition of Tumor Metastasis by Liquid-Nitrogen-Shocked Tumor Cells with Oncolytic Viruses Infection.

Despite the superior tumor lytic efficacy of oncolytic viruses (OVs), their systemic delivery still faces the challenges of limited circulating periods, poor tumor tropism, and spontaneous antiviral immune responses. Herein, a virus-concealed tumor-targeting strategy enabling OVs' delivery toward lung metastasis via systemic administration is described. The OVs can actively infect, be internalized, and cloak into tumor cells. Then the tumor cells are subsequently treated with liquid-nitrogen-shocking to eliminate the pathogenicity. Such a Trojan Horse-like vehicle avoids virus neutralization and clearance in the bloodstream and facilitates tumor-targeted delivery for more than 110-fold virus enrichment in the tumor metastasis. In addition, this strategy can serve as a tumor vaccine and initiate endogenous adaptive antitumor effects through increasing the memory T cells and modulating the tumor immune microenvironment, including reducing the M2 macrophage, downregulating Treg cells, and priming T cells.

Gastric cancer cell supernatant causes apoptosis and fibrosis in the peritoneal tissues and results in an environment favorable to peritoneal metastases, in vitro and in vivo.

BACKGROUND: In this study, we examined effects of soluble factors released by gastric cancer cells on peritoneal mesothelial cells in vitro and in vivo. METHODS: HMrSV5, a human peritoneal mesothelial cell line, was incubated with supernatants from gastric cancer cells. Morphological changes of HMrSV5 cells were observed. Apoptosis of HMrSV5 cells was observed under a transmission electron microscope and quantitatively determined by MTT assay and flow cytometry. Expressions of apoptosis-related proteins (caspase-3, caspase-8, Bax, bcl-2) were immunochemically evaluated. RESULTS: Conspicuous morphological changes indicating apoptosis were observed in HMrSV5 cells 24 h after treatment with the supernatants of gastric cancer cells. In vivo, peritoneal tissues treated with gastric cancer cell supernatant were substantially thickened and contained extensive fibrosis. CONCLUSIONS: These findings demonstrate that supernatants of gastric cancer cells can induce apoptosis and fibrosis in HMrSV5 human peritoneal mesothelial cells through supernatants in the early peritoneal metastasis, in a time-dependent manner, and indicate that soluble factors in the peritoneal cavity affect the morphology and function of mesothelial cells so that the resulting environment can become favorable to peritoneal metastases.

Emerging systemic delivery strategies of oncolytic viruses: A key step toward cancer immunotherapy.

Oncolytic virotherapy (OVT) is a novel type of immunotherapy that induces anti-tumor responses through selective self-replication within cancer cells and oncolytic virus (OV)-mediated immunostimulation. Notably, talimogene laherparepvec (T-Vec) developed by the Amgen company in 2015, is the first FDA-approved OV product to be administered via intratumoral injection and has been the most successful OVT treatment. However, the systemic administration of OVs still faces huge challenges, including in vivo pre-existing neutralizing antibodies and poor targeting delivery efficacy. Recently, state-of-the-art progress has been made in the development of systemic delivery of OVs, which demonstrates a promising step toward broadening the scope of cancer immunotherapy and improving the clinical efficacy of OV delivery. Herein, this review describes the general characteristics of OVs, focusing on the action mechanisms of OVs as well as the advantages and disadvantages of OVT. The emerging multiple systemic administration approaches of OVs are summarized in the past five years. In addition, the combination treatments between OVT and traditional therapies (chemotherapy, thermotherapy, immunotherapy, and radiotherapy, etc.) are highlighted. Last but not least, the future prospects and challenges of OVT are also discussed, with the aim of facilitating medical researchers to extensively apply the OVT in the cancer therapy.

Downregulation of connective tissue growth factor inhibits the growth and invasion of gastric cancer cells and attenuates peritoneal dissemination.

BACKGROUND: Connective tissue growth factor (CTGF) has been shown to be implicated in tumor development and progression. However, the role of CTGF in gastric cancer remains largely unknown. RESULTS: In this study, we showed that CTGF was highly expressed in gastric cancer tissues compared with matched normal gastric tissues. The CTGF expression in tumor tissue was associated with histologic grade, lymph node metastasis and peritoneal dissemination (P < 0.05). Patients with positive CTGF expression had significantly lower cumulative postoperative 5 year survival rate than those with negative CTGF expression (22.9% versus 48.1%, P < 0.001). We demonstrated that knockdown of CTGF expression significantly inhibited cell growth of gastric cancer cells and decreased cyclin D1 expression. Moreover, knockdown of CTGF expression also markedly reduced the migration and invasion of gastric cancer cells and decreased the expression of matrix metalloproteinase (MMP)-2 and MMP-9. Animal studies revealed that nude mice injected with the CTGF knockdown stable cell lines featured a smaller number of peritoneal seeding nodules than the control cell lines. CONCLUSIONS: These data suggest that CTGF plays an important role in cell growth and invasion in human gastric cancer and it appears to be a potential prognostic marker for patients with gastric cancer.

Clinicopathologic characteristics and prognosis of signet ring cell carcinoma of the stomach: results from a Chinese mono-institutional study.

BACKGROUND: Signet ring cell carcinoma (SRC) of the stomach is a histological type based on microscopic characteristics, and its clinicopathologic characteristics and prognosis are still controversial. METHODS: A retrospective analysis was under taken for 2,315 patients with gastric cancer who had undergone gastrectomy from 1980 to 2004. Among them, 211 patients had SRC and were compared with 2,104 patients with non-signet ring cell carcinoma (NSRC). RESULTS: Significant differences were noted in age, gender, and depth of tumor invasion between patients with SRC and NSRC of early gastric carcinoma. There were statistically significant differences in age, gender, macroscopic appearance, tumor size, depth of tumor invasion, peritoneal dissemination, and curability between patients with SRC and NSRC of advanced gastric carcinoma. In early gastric carcinoma, patients with SRC had a significantly better survival rate than those with NSRC, and the signet ring cell histology was an independent predictive factor. In advanced gastric carcinoma, there was no significant difference of survival rate between SRC and NSRC, and the signet ring cell histology was not an independent predictive factor. CONCLUSIONS: SRC is a distinct type of gastric carcinoma in terms of clinicopathologic characteristics and prognosis.