Potent antitumor activity of Oct4 and hypoxia dual-regulated oncolytic adenovirus against bladder cancer

Advancing Lung Cancer Treatment with Combined c-Met Promoter-Driven Oncolytic Adenovirus and Rapamycin

Lung cancer remains a formidable health challenge due to its high mortality and morbidity rates. Non-small cell lung cancer (NSCLC) constitutes approximately 85% of all lung cancer cases, with small cell lung cancer (SCLC) accounting for the remainder. Both NSCLC and SCLC cells express receptor tyrosine kinases, which may be overexpressed or mutated in lung cancer, leading to increased activation. The c-Met receptor tyrosine kinase, crucial for cell transformation and tumor growth, invasion, and metastasis, became the focus of our study. We used an E1B55KD-deleted, replication-selective oncolytic adenovirus (Ad.What), driven by the c-Met promoter, targeting lung cancer cells with c-Met overexpression, thus sparing normal cells. Previous studies have shown the enhanced antitumor efficacy of oncolytic adenoviruses when combined with chemotherapeutic agents. We explored combining rapamycin, a selective mTOR inhibitor with promising clinical trial outcomes for various cancers, with Ad.What. This combination increased infectivity by augmenting the expression of coxsackievirus and adenovirus receptors and αV integrin on cancer cells and induced autophagy. Our findings suggest that combining a c-Met promoter-driven oncolytic adenovirus with rapamycin could be an effective lung cancer treatment strategy, offering a targeted approach to exploit lung cancer cells' vulnerabilities, potentially marking a significant advancement in managing this deadly disease.

Syngeneic mesenchymal stem cells loaded with telomerase-dependent oncolytic adenoviruses enhance anti-metastatic efficacy

Oncolytic adenoviruses have emerged as a promising therapeutic approach for cancer therapy. However, systemic delivery of the viruses to metastatic tumors remains a major challenge. Mesenchymal stem cells (MSCs) possess tumor tropism property and can be used as cellular vehicles for delivering oncolytic adenoviruses to tumor sites. Since telomerase activity is found in ~90% of human carcinomas, but undetected in normal adult cells, the human telomerase reverse transcriptase gene (TERT) promoter can be exploited for regulating the replication of oncolytic adenoviruses. Here, we evaluated the antitumor effects of syngeneic murine MSCs loaded with the luciferase-expressing, telomerase-dependent oncolytic adenovirus Ad.GS2 (MSC-Ad.GS2) and Ad.GS2 alone on metastatic MBT-2 bladder tumors. MSCs supported a low degree of Ad.GS2 replication, which could be augmented by coculture with MBT-2 cells or tumor-conditioned medium (TCM), suggesting that viral replication is increased when MSC-Ad.GS2 migrates to tumor sites. MBT-2 cells and TCM enhanced viral replication in Ad.GS2-infected MSCs. SDF-1 is a stem cell homing factor. Our results suggest that the SDF-1/STAT3/TERT signaling axis in MSCs in response to the tumor microenvironment may contribute to the enhanced replication of Ad.GS2 carried by MSCs. Notably, we demonstrate the potent therapeutic efficacy of systemically delivered MSC-Ad.GS2 in pleural disseminated tumor and experimental metastasis models using intrapleural and tail vein injection of MBT-2 cells, respectively. Treatment with MSC-Ad.GS2 significantly reduced tumor growth and prolonged the survival of mice bearing metastatic bladder tumors. Since telomerase is expressed in a broad spectrum of cancers, this therapeutic strategy may be broadly applicable.

Oct4 and Hypoxia Dual-Regulated Oncolytic Adenovirus Armed with shRNA-Targeting Dendritic Cell Immunoreceptor Exerts Potent Antitumor Activity against Bladder Cancer

Immunotherapy has emerged as a promising modality for cancer treatment. Dendritic cell immunoreceptor (DCIR), a C-type lectin receptor, is expressed mainly by dendritic cells (DCs) and mediates inhibitory intracellular signaling. Inhibition of DCIR activation may enhance antitumor activity. DCIR is encoded by CLEC4A in humans and by Clec4a2 in mice. Gene gun-mediated delivery of short hairpin RNA (shRNA) targeting Clec4a2 into mice bearing bladder tumors reduces DCIR expression in DCs, inhibiting tumor growth and inducing CD8+ T cell immune responses. Various oncolytic adenoviruses have been developed in clinical trials. Previously, we have developed Ad.LCY, an oncolytic adenovirus regulated by Oct4 and hypoxia, and demonstrated its antitumor efficacy. Here, we generated a Clec4a2 shRNA-expressing oncolytic adenovirus derived from Ad.LCY, designated Ad.shDCIR, aimed at inducing more robust antitumor immune responses. Our results show that treatment with Ad.shDCIR reduced Clec4a expression in DCs in cell culture. Furthermore, Ad.shDCIR exerted cytolytic effects solely on MBT-2 bladder cancer cells but not on normal NIH 3T3 mouse fibroblasts, confirming the tumor selectivity of Ad.shDCIR. Compared to Ad.LCY, Ad.shDCIR induced higher cytotoxic T lymphocyte (CTL) activity in MBT-2 tumor-bearing immunocompetent mice. In addition, Ad.shDCIR and Ad.LCY exhibited similar antitumor effects on inhibiting tumor growth. Notably, Ad.shDCIR was superior to Ad.LCY in prolonging the survival of tumor-bearing mice. In conclusion, Ad.shDCIR may be further explored as a combination therapy of virotherapy and immunotherapy for bladder cancer and likely other types of cancer.

Hypoxia-induced cancer cell reprogramming: a review on how cancer stem cells arise

Cancer stem cells are a subset of cells within the tumor that possess the ability to self-renew as well as differentiate into different cancer cell lineages. The exact mechanisms by which cancer stem cells arise is still not completely understood. However, current research suggests that cancer stem cells may originate from normal stem cells that have undergone genetic mutations or epigenetic changes. A more recent discovery is the dedifferentiation of cancer cells to stem-like cells. These stem-like cells have been found to express and even upregulate induced pluripotent stem cell markers known as Yamanaka factors. Here we discuss developments in how cancer stem cells arise and consider how environmental factors, such as hypoxia, plays a key role in promoting the progression of cancer stem cells and metastasis. Understanding the mechanisms that give rise to these cells could have important implications for the development of new strategies in cancer treatments and therapies.

Oncolytic Viruses for the Treatment of Bladder Cancer: Advances, Challenges, and Prospects

Bladder cancer is one of the most prevalent cancers. Despite recent advancements in bladder cancer therapy, new strategies are still required for improving patient outcomes, particularly for those who experienced Bacille Calmette-Guerin failure and those with locally advanced or metastatic bladder cancer. Oncolytic viruses are either naturally occurring or purposefully engineered viruses that have the ability to selectively infect and lyse tumor cells while avoiding harming healthy cells. In light of this, oncolytic viruses serve as a novel and promising immunotherapeutic strategy for bladder cancer. A wide diversity of viruses, including adenoviruses, herpes simplex virus, coxsackievirus, Newcastle disease virus, vesicular stomatitis virus, alphavirus, and vaccinia virus, have been studied in many preclinical and clinical studies for their potential as oncolytic agents for bladder cancer. This review aims to provide an overview of the advances in oncolytic viruses for the treatment of bladder cancer and highlights the challenges and research directions for the future.

Oncolytic Adenovirus: Prospects for Cancer Immunotherapy

Immunotherapy has moved to the forefront of modern oncologic treatment in the past few decades. Various forms of immunotherapy currently are emerging, including oncolytic viruses. In this therapy, viruses are engineered to selectively propagate in tumor cells and reduce toxicity for non-neoplastic tissues. Adenovirus is one of the most frequently employed oncolytic viruses because of its capacity in tumor cell lysis and immune response stimulation. Upregulation of immunostimulatory signals induced by oncolytic adenoviruses (OAds) might significantly remove local immune suppression and amplify antitumor immune responses. Existing genetic engineering technology allows us to design OAds with increasingly better tumor tropism, selectivity, and antitumor efficacy. Several promising strategies to modify the genome of OAds have been applied: capsid modifications, small deletions in the pivotal viral genes, insertion of tumor-specific promoters, and addition of immunostimulatory transgenes. OAds armed with tumor-associated antigen (TAA) transgenes as cancer vaccines provide additional therapeutic strategies to trigger tumor-specific immunity. Furthermore, the combination of OAds and immune checkpoint inhibitors (ICIs) increases clinical benefit as evidence shown in completed and ongoing clinical trials, especially in the combination of OAds with antiprogrammed death 1/programed death ligand 1 (PD-1/PD-L1) therapy. Despite remarkable antitumor potency, oncolytic adenovirus immunotherapy is confronted with tough challenges such as antiviral immune response and obstruction of tumor microenvironment (TME). In this review, we focus on genomic modification strategies of oncolytic adenoviruses and applications of OAds in cancer immunotherapy.

Recombinant viruses with other anti-cancer therapeutics: a step towards advancement of oncolytic virotherapy

Cancer as a disease is a multifaceted foe which sometimes succumbs to the prescribed treatment and sometimes develops resistance against various therapies. Conventional cancer therapies suffer from many limitations, the least of which is their specificity and systemic side effects. In a majority of cases, acquired mutations render the cancer cells resistant to therapy and lower the prognostic outcome. In the constant effort to devise a therapeutic moiety which can comprehensively eliminate cancer cells, oncolytic viruses provide an attractive avenue as they selectively infect and lyse cancer cells sparing normal cells from their effects. Viruses can be engineered for their host specificity and toxicity as a promising anti-cancer tool. As it is essential to devise a strategy to address all targets involved in cancer development and progression, the idea of using oncolytic viruses with enhanced anti-cancer activity through arming with foreign genes gained merit and is showing promising advent in clinical studies. The use of oncolytic viruses as an agent of combination therapy for cancer treatment also gained much attention in the recent past. This review focuses on the emerging role of oncolytic viruses as vital components of anti-cancer regimen presenting a new dimension in an ever-changing cancer therapy scenario.

Curcumin reversed chronic tobacco smoke exposure induced urocystic EMT and acquisition of cancer stem cells properties via Wnt/β-catenin

Tobacco smoke (TS) is the most important single risk factor for bladder cancer. Epithelial–mesenchymal transition (EMT) is a transdifferentiation process, involved in the initiation of TS-related cancer. Cancer stem cells (CSCs) have an essential role in the progression of many tumors including TS-related cancer. However, the molecular mechanisms of TS exposure induced urocystic EMT and acquisition of CSCs properties remains undefined. Wnt/β-catenin pathway is critical for EMT and the maintenance of CSCs. The aim of our present study was to investigate the role of Wnt/β-catenin pathway in chronic TS exposure induced urocystic EMT, stemness acquisition and the preventive effect of curcumin. Long time TS exposure induced EMT changes and the levels of CSCs’ markers were significant upregulated. Furthermore, we demonstrated that Wnt/β-catenin pathway modulated TS-triggered EMT and stemness, as evidenced by the findings that TS elevated Wnt/β-catenin activation, and that TS-mediated EMT and stemness were attenuated by Wnt/β-catenin inhibition. Treatment of curcumin reversed TS-elicited activation of Wnt/β-catenin, EMT and CSCs properties. Collectively, these data indicated the regulatory role of Wnt/β-catenin in TS-triggered urocystic EMT, acquisition of CSCs properties and the chemopreventive effect of curcumin.

Chemotherapeutics-induced Oct4 expression contributes to drug resistance and tumor recurrence in bladder cancer

Cancer cells initially characterized as sensitive to chemotherapy may acquire resistance to chemotherapy and lead to tumor recurrence through the expansion of drug-resistant population. Acquisition of drug resistance to conventional chemotherapy is a major obstacle in the treatment of recurrent cancer. Here we investigated whether anticancer drugs induced Oct4 expression, thereby contributing to acquired drug resistance and tumor recurrence in bladder cancer. We identified a positive correlation of Oct4 expression with tumor recurrence in 122 clinical specimens of superficial high-grade (stages T1-2) bladder transitional cell carcinoma (TCC). Increased Oct4 levels in bladder tumors were associated with short recurrence-free intervals in the patients. Chemotherapy induced Oct4 expression in bladder cancer cells. Notably, treatment with cisplatin increased CD44-positive bladder cancer cells expressing Oct4, representing cancer stem-like cell subpopulation. Forced expression of Oct4 reduced, whereas knockdown of Oct4 enhanced, drug sensitivity in bladder cancer cells. Furthermore, tumor cells overexpressing Oct4 responded poorly to cisplatin in vivo. In regard to clinical relevance, inhibition of Oct4 by all-trans retinoic acid (ATRA) synergistically increased sensitivity to cisplatin in bladder cancer cells. Furthermore, the combination of cisplatin and ATRA was superior to cisplatin alone in suppressing tumor growth. Therefore, our results provide evidence that Oct4 increases drug resistance and implicate that inhibition of Oct4 may be a therapeutic strategy to circumvent drug resistance.

Crosstalks between Raf-kinase inhibitor protein and cancer stem cell transcription factors (Oct4, KLF4, Sox2, Nanog)

Raf-kinase inhibitor protein has been reported to inhibit both the Raf/mitogen extracellular signal-regulated kinase/extracellular signal-regulated kinase and nuclear factor kappa-light-chain of activated B cells pathways. It has also been reported in cancers that Raf-kinase inhibitor protein behaves as a metastatic suppressor as well as a chemo-immunosensitizing factor to drug/immune-mediated apoptosis. The majority of cancers exhibit low or no levels of Raf-kinase inhibitor protein. Hence, the activities of Raf-kinase inhibitor protein contrast, in part, to those mediated by several cancer stem cell transcription factors for their roles in resistance and metastasis. In this review, the existence of crosstalks in the signaling pathways between Raf-kinase inhibitor protein and several cancer stem cell transcription factors (Oct4, KLF4, Sox2 and Nanog) was assembled. Oct4 is induced by Lin28, and Raf-kinase inhibitor protein inhibits the microRNA binding protein Lin28. The expression of Raf-kinase inhibitor protein inversely correlates with the expression of Oct4. KLF4 does not interact directly with Raf-kinase inhibitor protein, but rather interacts indirectly via Raf-kinase inhibitor protein's regulation of the Oct4/Sox2/KLF4 complex through the mitogen-activated protein kinase pathway. The mechanism by which Raf-kinase inhibitor protein inhibits Sox2 is via the inhibition of the mitogen-activated protein kinase pathway by Raf-kinase inhibitor protein. Thus, Raf-kinase inhibitor protein's relationship with Sox2 is via its regulation of Oct4. Inhibition of extracellular signal-regulated kinase by Raf-kinase inhibitor protein results in the upregulation of Nanog. The inhibition of Oct4 by Raf-kinase inhibitor protein results in the failure of the heterodimer formation of Oct4 and Sox2 that is necessary to bind to the Nanog promoter for the transcription of Nanog. The findings revealed that there exists a direct correlation between the expression of Raf-kinase inhibitor protein and the expression of each of the above transcription factors. Based on these analyses, we suggest that the expression level of Raf-kinase inhibitor protein may be involved in the regulation of the cancer stem cell phenotype.

Adenovirus-mediated downregulation of the ubiquitin ligase RNF8 sensitizes bladder cancer to radiotherapy

The ubiquitin ligase RNF8 promotes the DNA damage response (DDR). We observed that the expression of RNF8 was increased in bladder cancer cells and that this change in RNF8 expression could be reversed by adenovirus-mediated shRNA treatment. Moreover, we found that RNF8 knockdown sensitized bladder cancer cells to radiotherapy, as demonstrated by reduced cell survival. Additionally, the absence of RNF8 induced a high rate of apoptosis and impaired double-strand break repair signaling after radiotherapy. Furthermore, experiments on nude mice showed that combining shRNF8 treatment with radiotherapy suppressed implanted bladder tumor growth and enhanced apoptotic cell death in vivo. Altogether, our results indicated that RNF8 might be a novel target for bladder cancer treatment.

Virus-host interactions under hypoxia

Oxygen tension can exert a significant effect on viral propagation in vitro and possibly in vivo. In general, hypoxia restricts the replication of viruses that naturally infect tissues exposed to ambient oxygen and induces the growth of viruses that naturally target tissues exposed to low oxygen. Some viruses can reprogram cell bioenergetics towards lowering cellular respiration and therefore oxygen consumption in order to support their replication. Aim of this review is to summarize findings on the interplay between viral infection and oxygen levels, highlighting the implicated oxygen tension-sensitive elements and metabolic determinants and concluding with possible therapeutic approaches targeting these mediators.

A combination hepatoma-targeted therapy based on nanotechnology: pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH

Combination targeted therapy is a promising cancer therapeutic strategy. Here, using PEI-Mn0.5Zn0.5Fe2O4 nanoparticles (PEI-MZF-NPs) as magnetic media for MFH (magnetic fluid hyperthermia) and gene transfer vector for gene-therapy, a combined therapy, pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH, for hepatoma is developed. AntiAFPMcAb (Monoclonal antibody AFP) is exploited for targeting. The plasmids pHRE-Egr1-HSV-TK are achieved by incorporation of pEgr1-HSV-TK and pHRE-Egr1-EGFP. Restriction enzyme digestion and PCR confirm the recombinant plasmids pHRE-Egr1-HSV-TK are successfully constructed. After exposure to the magnetic field, PEI-MZF-NPs/pHRE-Egr1-EGFP fluid is warmed rapidly and then the temperature is maintained at 43 °C or so, which is quite appropriate for cancer treatment. The gene expression reaches the peak when treated with 200 μCi (131)I for 24 hours, indicating that the dose of 200 μCi might be the optimal dose for irradiation and 24 h irradiation later is the best time to initiate MFH. The in vitro and in vivo experiments demonstrate that pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH can greatly suppress hepatic tumor cell proliferation and induce cell apoptosis and necrosis and effectively inhibit the tumor growth, much better than any monotherapy does alone. Furthermore, the combination therapy has few or no adverse effects. It might be applicable as a strategy to treat hepatic cancer.

Etoposide enhances antitumor efficacy of MDR1-driven oncolytic adenovirus through autoupregulation of the MDR1 promoter activity

Conditionally replicating adenoviruses (CRAds), or oncolytic adenoviruses, such as E1B55K-deleted adenovirus, are attractive anticancer agents. However, the therapeutic efficacy of E1B55K-deleted adenovirus for refractory solid tumors has been limited. Environmental stress conditions may induce nuclear accumulation of YB-1, which occurs in multidrug-resistant and adenovirus-infected cancer cells. Overexpression and nuclear localization of YB-1 are associated with poor prognosis and tumor recurrence in various cancers. Nuclear YB-1 transactivates the multidrug resistance 1 (MDR1) genes through the Y-box. Here, we developed a novel E1B55K-deleted adenovirus driven by the MDR1 promoter, designed Ad5GS3. We tested the feasibility of using YB-1 to transcriptionally regulate Ad5GS3 replication in cancer cells and thereby to enhance antitumor efficacy. We evaluated synergistic antitumor effects of oncolytic virotherapy in combination with chemotherapy. Our results show that adenovirus E1A induced E2F-1 activity to augment YB-1 expression, which shut down host protein synthesis in cancer cells during adenovirus replication. In cancer cells infected with Ad5WS1, an E1B55K-deleted adenovirus driven by the E1 promoter, E1A enhanced YB-1 expression, and then further phosphorylated Akt, which, in turn, triggered nuclear translocation of YB-1. Ad5GS3 in combination with chemotherapeutic agents facilitated nuclear localization of YB-1 and, in turn, upregulated the MDR1 promoter activity and enhanced Ad5GS3 replication in cancer cells. Thus, E1A, YB-1, and the MDR1 promoter form a positive feedback loop to promote Ad5GS3 replication in cancer cells, and this regulation can be further augmented when chemotherapeutic agents are added. In the in vivo study, Ad5GS3 in combination with etoposide synergistically suppressed tumor growth and prolonged survival in NOD/SCID mice bearing human lung tumor xenografts. More importantly, Ad5GS3 exerted potent oncolytic activity against clinical advanced lung adenocarcinoma, which was associated with elevated levels of nuclear YB-1 and cytoplasmic MDR1 expression in the advanced tumors. Therefore, Ad5GS3 may have therapeutic potential for cancer treatment, especially in combination with chemotherapy. Because YB-1 is expressed in a broad spectrum of cancers, this oncolytic adenovirus may be broadly applicable.