Mutational burden, MHC-I expression and immune infiltration as limiting factors for in situ vaccination by TNFα and IL-12 gene electrotransfer

Signaling controversy and future therapeutical perspectives of targeting sphingolipid network in cancer immune editing and resistance to tumor necrosis factor-α immunotherapy

Anticancer immune surveillance and immunotherapies trigger activation of cytotoxic cytokine signaling, including tumor necrosis factor-α (TNF-α) and TNF-related apoptosis-inducing ligand (TRAIL) pathways. The pro-inflammatory cytokine TNF-α may be secreted by stromal cells, tumor-associated macrophages, and by cancer cells, indicating a prominent role in the tumor microenvironment (TME). However, tumors manage to adapt, escape immune surveillance, and ultimately develop resistance to the cytotoxic effects of TNF-α. The mechanisms by which cancer cells evade host immunity is a central topic of current cancer research. Resistance to TNF-α is mediated by diverse molecular mechanisms, such as mutation or downregulation of TNF/TRAIL receptors, as well as activation of anti-apoptotic enzymes and transcription factors. TNF-α signaling is also mediated by sphingosine kinases (SphK1 and SphK2), which are responsible for synthesis of the growth-stimulating phospholipid, sphingosine-1-phosphate (S1P). Multiple studies have demonstrated the crucial role of S1P and its transmembrane receptors (S1PR) in both the regulation of inflammatory responses and progression of cancer. Considering that the SphK/S1P/S1PR axis mediates cancer resistance, this sphingolipid signaling pathway is of mechanistic significance when considering immunotherapy-resistant malignancies. However, the exact mechanism by which sphingolipids contribute to the evasion of immune surveillance and abrogation of TNF-α-induced apoptosis remains largely unclear. This study reviews mechanisms of TNF-α-resistance in cancer cells, with emphasis on the pro-survival and immunomodulatory effects of sphingolipids. Inhibition of SphK/S1P-linked pro-survival branch may facilitate reactivation of the pro-apoptotic TNF superfamily effects, although the role of SphK/S1P inhibitors in the regulation of the TME and lymphocyte trafficking should be thoroughly assessed in future studies.

Drug-induced altered self-presentation increases tumor immunogenicity

Anti-human immunodeficiency virus (HIV) drug abacavir (ABC) binds to the specific allele of human leukocyte antigen (HLA-B*57:01) and activates CD8+ T cells by presenting altered abnormal peptides. Here, we examined the effect of ABC-induced altered self-presentation by HLA-B*57:01 on immunogenicity of cancer cells and CD8+ T-cell-dependent anti-tumor immunity. We established human-mouse chimeric HLA-B*57:01-expressing tumor cell lines (B16F10 and 3LL) and tested the anti-tumor effect of ABC in vivo. ABC treatment inhibited the growth of HLA-B*57:01-expressing tumors by a CD8+ T-cell-dependent mechanism. ABC treatment induced CXCR3-dependent infiltration of CD8+ T cells into HLA-B*57:01-expressing tumors, and activated those tumor-infiltrating CD8+ T cells to proliferate and secrete IFN-γ. The activation of CD8+ T cells using drug-induced altered self-presentation may be a new strategy to increase tumor immunogenicity and improve the efficacy of immunotherapy.

What We Learned about the Feasibility of Gene Electrotransfer for Vaccination on a Model of COVID-19 Vaccine

DNA vaccination is one of the emerging approaches for a wide range of applications, including prophylactic vaccination against infectious diseases and therapeutic vaccination against cancer. The aim of this study was to evaluate the feasibility of our previously optimized protocols for gene electrotransfer (GET)-mediated delivery of plasmid DNA into skin and muscle tissues on a model of COVID-19 vaccine. Plasmids encoding the SARS-CoV-2 proteins spike (S) and nucleocapsid (N) were used as the antigen source, and a plasmid encoding interleukin 12 (IL-12) was used as an adjuvant. Vaccination was performed in the skin or muscle tissue of C57BL/6J mice on days 0 and 14 (boost). Two weeks after the boost, blood, spleen, and transfected tissues were collected to determine the expression of S, N, IL-12, serum interferon-γ, the induction of antigen-specific IgG antibodies, and cytotoxic T-cells. In accordance with prior in vitro experiments that indicated problems with proper expression of the S protein, vaccination with S did not induce S-specific antibodies, whereas significant induction of N-specific antibodies was detected after vaccination with N. Intramuscular vaccination outperformed skin vaccination and resulted in significant induction of humoral and cell-mediated immunity. Moreover, both boost and adjuvant were found to be redundant for the induction of an immune response. Overall, the study confirmed the feasibility of the GET for DNA vaccination and provided valuable insights into this approach.

Tumor Radiosensitization by Gene Electrotransfer-Mediated Double Targeting of Tumor Vasculature

Targeting the tumor vasculature through specific endothelial cell markers involved in different signaling pathways represents a promising tool for tumor radiosensitization. Two prominent targets are endoglin (CD105), a transforming growth factor β co-receptor, and the melanoma cell adhesion molecule (CD1046), present also on many tumors. In our recent in vitro study, we constructed and evaluated a plasmid for simultaneous silencing of these two targets. In the current study, our aim was to explore the therapeutic potential of gene electrotransfer-mediated delivery of this new plasmid in vivo, and to elucidate the effects of combined therapy with tumor irradiation. The antitumor effect was evaluated by determination of tumor growth delay and proportion of tumor free mice in the syngeneic murine mammary adenocarcinoma tumor model TS/A. Histological analysis of tumors (vascularization, proliferation, hypoxia, necrosis, apoptosis and infiltration of immune cells) was performed to evaluate the therapeutic mechanisms. Additionally, potential activation of the immune response was evaluated by determining the induction of DNA sensor STING and selected pro-inflammatory cytokines using qRT-PCR. The results point to a significant radiosensitization and a good therapeutic potential of this gene therapy approach in an otherwise radioresistant and immunologically cold TS/A tumor model, making it a promising novel treatment modality for a wide range of tumors.

Tumor cell-based vaccine contributes to local tumor irradiation by eliciting a tumor model-dependent systemic immune response

Multimodal treatment approaches, such as radio-immunotherapy, necessitate regimen optimization and the investigation of the interactions of different modalities. The aim of this study was two-fold. Firstly, to select the most effective combination of irradiation and the previously developed tumor cell-based vaccine and then to provide insight into the immune response to the selected combinatorial treatment. The study was performed in immunologically different murine tumor models: B16F10 melanoma and CT26 colorectal carcinoma. The most effective combinatorial treatment was selected by comparing three different IR regimens and three different vaccination regimens. We determined the local immune response by investigating immune cell infiltration at the vaccination site and in tumors. Lastly, we determined the systemic immune response by investigating the amount of tumor-specific effector lymphocytes in draining lymph nodes. The selected most effective combinatorial treatment was 5× 5 Gy in combination with concomitant single-dose vaccination (B16F10) or with concomitant multi-dose vaccination (CT26). The combinatorial treatment successfully elicited a local immune response at the vaccination site and in tumors in both tumor models. It also resulted in the highest amount of tumor-specific effector lymphocytes in draining lymph nodes in the B16F10, but not in the CT26 tumor-bearing mice. However, the amount of tumor-specific effector lymphocytes was intrinsically higher in the CT26 than in the B16F10 tumor model. Upon the selection of the most effective combinatorial treatment, we demonstrated that the vaccine elicits an immune response and contributes to the antitumor efficacy of tumor irradiation. However, this interaction is multi-faceted and appears to be dependent on the tumor immunogenicity.

SERPINH1 is a Potential Prognostic Biomarker and Correlated With Immune Infiltration: A Pan-Cancer Analysis

Background: Serpin peptidase inhibitor clade H, member 1 (SERPINH1) is a gene encoding a member of the serpin superfamily of serine proteinase inhibitors. The upregulated of SERPINH1 was associated with poor prognosis in breast cancer, stomach adenocarcinoma, and esophageal carcinoma. However, the role of SERPINH1 in pan-cancer is largely unexplored.

Methods: SERPINH1 expression and the correlation with prognosis in human pan-cancer were analyzed by the Cancer Genome Atlas and the Genotype-Tissue Expression dataset. Pearson correlation analysis was applied to evaluate the role of SERPINH1 expression in tumor mutation burden (TMB), microsatellite instability (MSI), mismatch repair (MMR), DNA methyltransferase, and common immunoregulators. Spearman’s correlation test was used to analysis SERPINH1 expression in tumor immune infiltration and infiltrating immune cells via the Tumor Immune Evaluation Resource database. Furtherly, immunohistochemistry staining of SERPINH1 was acquired from the Human Protein Atlas database for validation.

Results: SERPINH1 was abnormally expressed in fourteen cancers. The high expression of SERPINH1 significantly reduced the overall survival (OS), disease-specific survival, and progression free interval in eleven cancers. Moreover, SERPINH1 expression was correlated with MMR, MSI, TMB, and DNA methylation in multiple types of cancer. Also, SERPINH1 expression showed strong association with immunoregulators and immune checkpoint markers in testicular germ cell tumors, brain lower grade glioma (LGG), pheochromocytoma and paraganglioma. In addition, SERPINH1 expression was related to immune cell infiltration in multiple cancers, particularly in breast invasive carcinoma, LGG, and liver hepatocellular carcinoma. The result of immunohistochemistry verification shown that SERPINH1 staining was higher in tumor samples than in normal tissue in colon adenocarcinoma, head and neck squamous cell carcinoma, kidney renal papillary cell carcinoma and cervical squamous cell carcinoma, which was consistent with the result of OS.

Conclusion: Overall, these results indicate that SERPINH1 may serve as an important prognostic biomarker and correlate with tumor immunity in human pan-cancer.