Carboplatin enhances lymphocyte-endothelial interactions to promote CD8+ T cell trafficking into the ovarian tumor microenvironment.

OBJECTIVES: Standard chemotherapy agents, including carboplatin, have known immunogenic properties. We sought to determine how carboplatin may influence lymphocyte trafficking to tumor sites. METHODS: Murine models of ovarian cancer were utilized to examine lymphocyte trafficking with common clinically used agents including carboplatin, anti-PD-1 antibody, or anti-VEGFR-2 antibody. Adhesion interactions of lymphocytes with tumor vasculature were measured using intravital microscopy, lymphocyte homing with immunohistochemistry, and treatment groups followed for overall survival. RESULTS: Carboplatin chemotherapy profoundly alters the tumor microenvironment to promote lymphocyte adhesive interactions with tumor vasculature and resultant improvement in lymphocyte trafficking. The measured results seen with carboplatin in the tumor microenvironment were superior to anti-PD-1 treatment or anti-VEGFR-2 which may have contributed to increased overall survival in carboplatin treated groups. CONCLUSIONS: These novel findings suggest a role for chemotherapeutic agents to broadly influence anti-tumor immune responses beyond the induction of immunogenic tumor cell death.

Monocyte Chemoattractant Protein-Induced Protein 1 Overexpression Modulates Transcriptome, Including MicroRNA, in Human Neuroblastoma Cells.

The recently discovered MCPIP1 (monocyte chemoattractant protein-induced protein 1), a multidomain protein encoded by the MCPIP1 (ZC3H12A) gene, has been described as a new differentiation factor, a ribonuclease, and a deubiquitination-supporting factor. However, its role in cancer is poorly recognized. Our recent analysis of microarrays data showed a lack of expression of the MCPIP1 transcript in primary neuroblastoma, the most common extracranial solid tumor in children. Additionally, enforced expression of the MCPIP1 gene in BE(2)-C cells caused a significant decrease in neuroblastoma proliferation and viability. Aim of the present study was to further investigate the role of MCPIP1 in neuroblastoma, using expression DNA microarrays and microRNA microarrays. Transient transfections of BE(2)-C cells were used for overexpression of either wild type of MCPIP1 (MCPIP1-wt) or its RN-ase defective mutant (MCPIP1-ΔPIN). We have analyzed changes of transcriptome and next, we have used qRT-PCR to verify mRNA levels of selected genes responding to MCPIP1 overexpression. Additionally, protein levels were determined for some of the selected genes. The choline transporter, CTL1, encoded by the SLC44A1 gene, was significantly repressed at the specific mRNA and protein levels and most importantly this translated into a decreased choline transport in MCPIP1-overexpressing cells. Then, we have found microRNA-3613-3p as the mostly altered in the pools of cells overexpressing the wild type MCPIP1. Next, we analyzed the predicted targets of the miR-3613-3p and validated them using qRT-PCR and western blot. These results indicate that the expression of miR-3613-3p might be regulated by MCPIP1 by cleavage of its precursor form.

Consequences of the perivascular niche remodeling for tumoricidal T-cell trafficking into metastasis of ovarian cancer.

The treatment-induced activation level within the perivascular tumor microenvironment (TME) that supports T-cell trafficking and optimal T-cell differentiation is unknown. We investigated the mechanisms by which inflammatory responses generated by tumor-specific T cells delivered to ovarian tumor-bearing mice alone or after oncolytic vaccinia virus-driven immunogenic cancer cell death affect antitumor efficacy. Analyses of the perivascular TME by spatially resolved omics technologies revealed reduced immunosuppression and increased tumoricidal T-cell trafficking and function after moderate inflammatory responses driven by a CXCR4 antagonist-armed oncolytic virus. Neither weak nor high inflammation created a permissive TME for T-cell trafficking. Notably, treatment-mediated differences in T-cell effector programs acquired within the perivascular TME contrasted with comparable antigenic priming in the tumor-draining lymph nodes regardless of the activation mode of antigen-presenting cells. These findings provide new insights into combinatorial treatment strategies that enable tumor-specific T cells to overcome multiple barriers for enhanced trafficking and control of tumor growth.

Reprogramming the tumor microenvironment leverages CD8+ T cell responses to a shared tumor/self antigen in ovarian cancer.

Tumor antigen-driven responses to weakly immunogenic self-antigens and neoantigens directly affect treatment efficacy following immunotherapy. Using orthotopically grown SV40 T antigen+ ovarian carcinoma in antigen-naive wild-type or TgMISIIR-TAg-Low transgenic mice expressing SV40 T antigen as a self-antigen, we investigated the impact of CXCR4-antagonist-armed oncolytic virotherapy on tumor progression and antitumor immunity. Immunostaining and single-cell RNA sequencing analyses of the peritoneal tumor microenvironment of untreated tumors in syngeneic wild-type mice revealed the presence of SV40 T antigen-specific CD8+ T cells, a balanced M1/M2 transcriptomic signature of tumor-associated macrophages, and immunostimulatory cancer-associated fibroblasts. This contrasted with polarized M2 tumor-associated macrophages, immunosuppressive cancer-associated fibroblasts, and poor immune activation in TgMISIIR-TAg-Low mice. Intraperitoneal delivery of CXCR4-antagonist-armed oncolytic vaccinia virus led to nearly complete depletion of cancer-associated fibroblasts, M1 polarization of macrophages, and generation of SV40 T antigen-specific CD8+ T cells in transgenic mice. Cell depletion studies revealed that the therapeutic effect of armed oncolytic virotherapy was dependent primarily on CD8+ cells. These results demonstrate that targeting the interaction between immunosuppressive cancer-associated fibroblasts and macrophages in the tolerogenic tumor microenvironment by CXCR4-A-armed oncolytic virotherapy induces tumor/self-specific CD8+ T cell responses and consequently increases therapeutic efficacy in an immunocompetent ovarian cancer model.

Induction of cell death in ovarian cancer cells by doxorubicin and oncolytic vaccinia virus is associated with CREB3L1 activation.

We have demonstrated that oncolytic vaccinia virus synergizes with doxorubicin (DOX) in inducing immunogenic cell death in platinum-resistant ovarian cancer cells and increases survival in syngeneic and xenograft tumor models. However, the mechanisms underlying the virus- and doxorubicin-mediated cancer cell death remain unknown. In this study, we investigated the effect of the oncolytic virus and doxorubicin used alone or in combination on activation of the cytoplasmic transcription factor CREB3L1 (cyclic AMP [cAMP] response element-binding protein 3-like 1) in ovarian cancer cell lines and clinical specimens. We demonstrated that doxorubicin-mediated cell death in ovarian cancer cell lines was associated with nuclear translocation of CREB3L1 and that the effect was augmented by infection with oncolytic vaccinia virus or treatment with recombinant interferon (IFN)-ß used as a viral surrogate. This combination treatment was also effective in mediating nuclear translocation of CREB3L1 in cancer cells isolated from ovarian tumor biopsies at different stages of disease progression. The measurement of CREB3L1 expression in clinical specimens of ovarian cancer revealed lack of correlation with the stage of disease progression, suggesting that understanding the mechanisms of nuclear accumulation of CREB3L1 after doxorubicin treatment alone or in combination with oncolytic virotherapy may lead to the development of more effective treatment strategies against ovarian cancer.

Recruitment of Intratumoral CD103+ Dendritic Cells by a CXCR4 Antagonist-Armed Virotherapy Enhances Antitumor Immunity.

Intratumoral dendritic cells play an important role in stimulating cytotoxic T cells and driving antitumor immunity. Using a metastatic ovarian tumor model in syngeneic mice, we explored whether therapy with a CXCR4 antagonist-armed oncolytic vaccinia virus activates endogenous CD103+ dendritic cell responses associated with the induction of adaptive immunity against viral and tumor antigens. The overall goal of this study was to determine whether expansion of CD103+ dendritic cells by the virally delivered CXCR4 antagonist augments overall survival and in situ boosting with a tumor antigen peptide-based vaccine. We found that locoregional delivery of the CXCR4-A-armed virus reduced the tumor load and the immunosuppressive network in the tumor microenvironment, leading to infiltration of CD103+ dendritic cells that were capable of phagocytic clearance of cellular material from virally infected cancer cells. Further expansion of tumor-resident CD103+ DCs by injecting the FMS-related tyrosine kinase 3 ligand, the formative cytokine for CD103+ DCs, provided a platform for a booster immunization with the Wilms tumor antigen 1 peptide-based vaccine delivered intraperitoneally with polyriboinosinic:polyribocytidylic acid as an adjuvant. The vaccine-induced antitumor responses inhibited tumor growth and increased overall survival, indicating that expansion of intratumoral CD103+ dendritic cells by CXCR4-A-armed oncovirotherapy treatment can potentiate in situ cancer vaccine boosting.