Aptamer-assisted tumor localization of bacteria for enhanced biotherapy

Despite bacterial-mediated biotherapies have been widely explored for treating different types of cancer, their implementation has been restricted by low treatment efficacy, due largely to the absence of tumor-specific accumulation following administration. Here, the conjugation of aptamers to bacterial surface is described by a simple and cytocompatible amidation procedure, which can significantly promote the localization of bacteria in tumor site after systemic administration. The surface density of aptamers can be easily adjusted by varying feed ratio and the conjugation is able to increase the stability of anchored aptamers. Optimal bacteria conjugated with an average of 2.8 × 105 aptamers per cell present the highest specificity to tumor cells in vitro, separately generating near 2- and 4-times higher accumulation in tumor tissue at 12 and 60 hours compared to unmodified bacteria. In both 4T1 and H22 tumor-bearing mouse models, aptamer-conjugated attenuated Salmonella show enhanced antitumor efficacy, along with highly activated immune responses inside the tumor. This work demonstrates how bacterial behaviors can be tuned by surface conjugation and supports the potential of aptamer-conjugated bacteria for both targeted intratumoral localization and enhanced tumor biotherapy.

Recombinant Mycobacterium smegmatis delivering a fusion protein of human macrophage migration inhibitory factor (MIF) and IL-7 exerts an anticancer effect by inducing an immune response against MIF in a tumor-bearing mouse model

BackgroundMacrophage migration inhibitory factor (MIF) is a pleotropic inflammatory cytokine that is overexpressed in a number of cancer types including most types of human cancer. Inhibition of MIF signaling can restore anticancer immune responses in tumor microenvironments. In this study, we aimed to develop a therapeutic vaccine capable of inhibiting tumor development by inducing anti-MIF immune responses.MethodsWe introduced a recombinant Mycobacterium smegmatis (rSmeg-hMIF-hIL-7) vaccine that could deliver a fusion protein of human macrophage migration inhibitory factor (MIF) and interleukin 7, which could act as a target antigen and as an adjuvant of cancer vaccine, respectively. We checked the anticancer potential of the vaccine in a tumor-bearing mouse model.ResultsWe found that rSmeg-hMIF-hIL-7 showed enhanced oncolytic activity compared with PBS, BCG or Smeg in MC38-bearing mice, and there was an increase in the humoral and cell-mediated immune responses against MIF. rSmeg-hMIF-hIL-7 can also induce a neutralizing effect regarding MIF tautomerase activity in the serum of vaccinated mice. We also found downregulation of MIF, CD74, and CD44, which are related to the MIF signaling pathway and PI3K/Akt and MMP2/9 signaling, which are regulated by MIF in the tumor tissue of rSmeg-hMIF-hIL-7-vaccinated mice, suggesting a significant role of the anti-MIF immune response to rSmeg-hMIF-hIL-7 in its anticancer effect. In addition, rSmeg-hMIF-hIL-7 treatment led to enhanced activation of CD4+ and CD8+ T cells in the tumor regions of vaccinated mice, also contributing to the anticancer effect. This trend was also found in LLC-bearing and PanO2-bearing mouse models. In addition, rSmeg-hMIF-hIL-7 treatment exerted an enhanced anticancer effect with one of the immune checkpoint inhibitors, the anti-PD-L1 antibody, in a tumor-bearing mouse model.ConclusionsIn conclusion, our data showed that rSmeg-hMIF-hIL-7 exerts a strong antitumor immune response in mice, possibly by inhibiting the MIF-dependent promotion of tumorigenesis by the anti-MIF immune response and via enhanced cytotoxic T cell recruitment into tumor microenvironments. We also found that it also exerted an enhanced anticancer effect with immune checkpoint inhibitors. These results suggest that rSmeg-hMIF-hIL-7 is a potential adjuvant for cancer immunotherapy. This is the first report to prove anticancer potential of immunotherapeutic vaccine targeting immune response against MIF.

Aptamer-assisted tumor localization of bacteria for enhanced biotherapy

Despite bacterial-mediated biotherapies have been widely explored for treating different types of cancer, their implementation has been restricted by severe side effects and low treatment efficacies, due largely to the absence of tumor-specific accumulation following administration. Here, the conjugation of aptamers to bacterial surface is described by a simple and cytocompatible amidation procedure, which can significantly promote the localization of bacteria in tumor site after systemic administration. The surface density of aptamers can be easily adjusted by varying feed ratio and the conjugation is able to increase the stability of anchored aptamers. Optimal bacteria conjugated with an average of 2.8 × 105 aptamers per cell present the highest specificity to tumor cells in vitro, separately generating near 2- and 5-times higher accumulation in tumor tissue at 12 and 60 hours compared to unmodified bacteria. In both 4T1 and H22 tumor-bearing mouse models, aptamer-conjugated attenuated Salmonella show strikingly enhanced antitumor efficacy, along with highly activated immune responses inside the tumor. This work demonstrates how bacterial behaviors can be tuned by surface conjugation and supports the potential of aptamer-conjugated bacteria for both targeted intratumoral localization and enhanced tumor biotherapy.

Effects of orlistat combined with enzalutamide and castration through inhibition of fatty acid synthase in a PC3 tumor-bearing mouse model

Androgen deprivation therapy (ADT) is one of the typical treatments used for patients with prostate cancer (PCa). ADT, however, may fail when PCa develops castration-resistance. Fatty acid synthase (FASN), a critical enzyme involved in fatty acid synthesis, is found to be upregulated in PCa. Since enzalutamide and ADT are frequently used for the treatment of PCa, this study aimed to unravel the underlying mechanism of combination of orlistat, a FASN inhibitor, and enzalutamide using PC3 cell line; and orlistat and castration in PC3 tumor-bearing animal model. Cytotoxicity was determined by AlamarBlue assay. Drug effects on the cell cycle and protein expressions were assayed by the flow cytometry and Western blot. Electromobility shift assay was used to evaluate the NF-κB activity. The tumor growth delay, expressions of the signaling–related proteins, and histopathology post treatments of orlistat and castration were evaluated in PC3 tumor-bearing mouse model. The results showed that orlistat arrested the PC3 cells at the G1 phase of the cell cycle and enhanced the cytotoxic effects of enzalutamide synergistically. Pretreatment with orlistat combined with castration inhibited the tumor growth significantly compared with those of castration and orlistat treatments alone in PC3 tumor-bearing mice. Combination treatment reduced both fatty acid synthase and NF-κB activities and their downstream effector proteins. The present study demonstrated the synergistic effects of orlistat combined with enzalutamide in vitro and castration in vivo on human prostate cancer.

Personal Neoantigens From Patients With NSCLC Induce Efficient Antitumor Responses

ObjectiveTo develop a neoantigen-targeted personalized cancer treatment for non-small cell lung cancer (NSCLC), neoantigens were obtained from collected human lung cancer samples, and the utility of neoantigen and neoantigen-reactive T cells (NRTs) was assessed.MethodsTumor specimens from three patients with NSCLC were obtained and analyzed by whole-exome sequencing, and neoantigens were predicted accordingly. Dendritic cells and T lymphocytes were isolated, NRTs were elicited and IFN-γ ELISPOT tests were conducted. HLA-A2.1/Kb transgenic mice were immunized with peptides from HLA-A*02:01+patient with high immunogenicity, and NRTs were subjected to IFN-γ, IL-2 and TNF-α ELISPOT as well as time-resolved fluorescence assay for cytotoxicity assays to verify the immunogenicity in vitro. The HLA-A*02:01+lung cancer cell line was transfected with minigene and inoculated into the flanks of C57BL/6nu/nu mice and the NRTs induced by the immunogenic polypeptides from autologous HLA-A2.1/Kb transgenic mice were adoptively transfused to verify their immunogenicity in vivo.ResultsMultiple putative mutation-associated neoantigens with strong affinity for HLA were selected from each patient. Immunogenic neoantigen were identified in all three NSCLC patients, the potency of ACAD8-T105I, BCAR1-G23V and PLCG1-M425L as effective neoantigen to active T cells in suppressing tumor growth was further proven both in vitro and in vivo using HLA-A2.1/Kb transgenic mice and tumor-bearing mouse models.ConclusionNeoantigens with strong immunogenicity can be screened from NSCLC patients through the whole-exome sequencing of patient specimens and machine-learning-based neoantigen predictions. NRTs shown efficient antitumor responses in transgenic mice and tumor-bearing mouse models. Our results indicate that the development of neoantigen-based personalized immunotherapies in NSCLC is possible.PrecisNeoantigens with strong immunogenicity were screened from NSCLC patients. This research provides evidence suggesting that neoantigen-based therapy might serve as feasible treatment for NSCLC.

Granulocytes Acquire Antiapoptosis Activity and Promote Tumor Growth during Tumor Progress

Granulocytes play important roles in cancer, and their apoptotic status is often changed by the influence of tumor environment. However, the changes and the function on granulocyte apoptosis in cancer are unclear. In this study, we used tumor-bearing mouse model and tumor patients to analyzed the apoptosis of granulocytes in different tissues by flow analysis and TUNEL fluorescence staining, and found that the percentage of apoptosis cells in granulocytes was significantly decreased in late-stage tumor-bearing mouse and patients. The in vitro co-culture experiment showed that these antiapoptotic granulocytes could significantly inhibit T cell proliferation, and RNA-seq proved that there was obvious difference on the transcriptome between these cells and control cells, particularly immune-related genes. What is important, adoptive transfer of these antiapoptotic granulocytes promoted tumor progress in mouse model. Conclusively, we found that granulocytes in late-stage tumor could delay the process of apoptosis, inhibit T cell proliferation, and acquire pro-tumor activity, which provides a new therapeutic target for tumor immunity.

The novel ZEB1-upregulated protein PRTG induced by Helicobacter pylori infection promotes gastric carcinogenesis through the cGMP/PKG signaling pathway

Helicobacter pylori (H. pylori) is listed as a class I carcinogen in human gastric cancer; however, the underlying mechanisms are poorly understood. In this study, we identified Protogenin (PRTG) was upregulated in both gastric cancer tissues and H. pylori-infected tissues by analyzing dysregulated genes in TCGA and GEO databases. Importantly, upregulated PRTG predicted poor prognosis of gastric cancer patients and integrative analysis revealed that PRTG served as an oncogenic protein in gastric cancer and was required for H. pylori-mediated tumorigenic activities in in vitro cellular and in vivo tumor-bearing mouse models. Mechanistically, H. pylori infection enhanced PRTG expression by promoting transcriptional factor ZEB1 stabilization and recruitment to the PRTG promoter, and which then activated the sub-following cGMP/PKG signaling pathway in bioinformatic and cellular studies. Cellular studies further confirmed that PRTG depended on activating cGMP/PKG axis to promote proliferation, metastasis, and chemoresistance of gastric cancer cells. The PKG inhibitor KT5823 played synergistic anti-tumor effects with cisplatin and paclitaxel to gastric cancer cells in in vitro cellular and in vivo tumor-bearing mouse models. Taken together, our findings suggested that H. pylori infection depends on ZEB1 to induce PRTG upregulation, and which leading to the development and progression of gastric cancer through activating cGMP/PKG signaling pathway. Blocking PRTG/cGMP/PKG axis, therefore, presents a promising novel therapeutic strategy for gastric cancer.