Interferon gamma (IFNg) is a pleiotropic cytokine that can potentially reprogram the tumor microenvironment; however, the antitumor immunomodulatory properties of IFNg still need to be validated due to variable therapeutic outcomes in preclinical and clinical studies. We developed a replication-deficient Semliki Forest virus vector expressing IFNg (SFV/IFNg) and evaluated its immunomodulatory antitumor potential in vitro in a model of 3D spheroids and in vivo in an immunocompetent 4T1 mouse breast cancer model. We demonstrated that SFV-derived, IFN-g-stimulated bone marrow macrophages can be used to acquire the tumoricidal M1 phenotype in 3D nonattached conditions. Coculturing SFV/IFNg-infected 4T1 spheroids with BMDMs inhibited spheroid growth. In the orthotopic 4T1 mouse model, intratumoral administration of SFV/IFNg virus particles alone or in combination with the Pam3CSK4 TLR2/1 ligand led to significant inhibition of tumor growth compared to the administration of the control SFV/Luc virus particles. Analysis of the composition of intratumoral lymphoid cells isolated from tumors after SFV/IFNg treatment revealed increased CD4+ and CD8+ and decreased T-reg (CD4+/CD25+/FoxP3+) cell populations. Furthermore, a significant decrease in the populations of cells bearing myeloid cell markers CD11b, CD38, and CD206 was observed. In conclusion, the SFV/IFNg vector induces a therapeutic antitumor T-cell response and inhibits myeloid cell infiltration in treated tumors.

Chitinase‐like proteins (CLP) are chitin‐binding proteins that lack chitin hydrolyzing activity, but possess cytokine‐like and growth factor‐like properties, and play crucial role in intercellular crosstalk. Both human and mice express two members of CLP family: YKL‐40 and stabilin‐1 interacting chitinase‐like protein (SI‐CLP). Despite numerous reports indicating the role of YKL‐40 in the support of angiogenesis, tumor cell proliferation, invasion and metastasis, the role of its structurally related protein SI‐CLP in cancer was not reported. Using gain‐of‐function approach, we demonstrate in the current study that the expression of recombinant SI‐CLP in mouse TS/A mammary adenocarcinoma cells results in significant and persistent inhibition of in vivo tumor growth. Using quantitative immunohistochemistry, we show that on the cellular level this phenomenon is associated with reduced infiltration of tumor‐associated macrophages (TAMs), CD4+ and FoxP3+ cells in SI‐CLP expressing tumors. Gene expression analysis in TAM isolated from SI‐CLP‐expressing and control tumors demonstrated that SI‐CLP does not affect macrophage phenotype. However, SI‐CLP significantly inhibited migration of murine bone‐marrow derived macrophages and human primary monocytes toward monocyte‐recruiting chemokine CCL2 produced in the tumor microenvironment (TME). Mechanistically, SI‐CLP did not affect CCL2/CCR2 interaction, but suppressed cytoskeletal rearrangements in response to CCL2. Altogether, our data indicate that SI‐CLP functions as a tumor growth inhibitor in mouse breast cancer by altering cellular composition of TME and blocking cytokine‐induced TAM recruitment. Taking into consideration weak to absent expression of SI‐CLP in human breast cancer, it can be considered as a therapeutic protein to block TAM‐mediated support of breast tumor growth.

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A battery of tests for detection human papillomavirus DNA, mRNA corresponding to viral oncogenes, and viral oncoprotein E7 in cancer bladder urothelium was piloted in 35 samples of bladder cancer. DNA of human papillomavirus type 16 (causes cervical cancer) was found in 16 (46%) samples; E6/E7 oncogene transcript and E7 oncoprotein of human papillomavirus type 16 were detected in 10 and 7 human papillomavirus DNA-positive samples, respectively. These findings attest to association of bladder cancer with human papillomavirus in Russia.

Chronic HCV infection and associated liver cancer impose a heavy burden on the healthcare system. Direct acting antivirals eliminate HCV, unless it is drug resistant, and partially reverse liver disease, but they cannot cure HCV-related cancer. A possible remedy could be a multi-component immunotherapeutic vaccine targeting both HCV-infected and malignant cells, but also those not infected with HCV. To meet this need we developed a two-component DNA vaccine based on the highly conserved core protein of HCV to target HCV-infected cells, and a renowned tumor-associated antigen telomerase reverse transcriptase (TERT) based on the rat TERT, to target malignant cells. Their synthetic genes were expression-optimized, and HCV core was truncated after aa 152 (Core152opt) to delete the domain interfering with immunogenicity. Core152opt and TERT DNA were highly immunogenic in BALB/c mice, inducing IFN-γ/IL-2/TNF-α response of CD4+ and CD8+ T cells. Additionally, DNA-immunization with TERT enhanced cellular immune response against luciferase encoded by a co-delivered plasmid (Luc DNA). However, DNA-immunization with Core152opt and TERT mix resulted in abrogation of immune response against both components. A loss of bioluminescence signal after co-delivery of TERT and Luc DNA into mice indicated that TERT affects the in vivo expression of luciferase directed by the immediate early cytomegalovirus and interferon-β promoters. Panel of mutant TERT variants was created and tested for their expression effects. TERT with deleted N-terminal nucleoli localization signal and mutations abrogating telomerase activity still suppressed the IFN-β driven Luc expression, while the inactivated reverse transcriptase domain of TERT and its analogue, enzymatically active HIV-1 reverse transcriptase, exerted only weak suppressive effects, implying that suppression relied on the presence of the full-length/nearly full-length TERT, but not its enzymatic activity. The effect(s) could be due to interference of the ectopically expressed xenogeneic rat TERT with biogenesis of mRNA, ribosomes and protein translation in murine cells, affecting the expression of immunogens. HCV core can aggravate this effect, leading to early apoptosis of co-expressing cells, preventing the induction of immune response.