Mesenchymal stem cells (MSCs) represent a promising tool for cell therapy, particularly for their antitumor effects. This cell population can be isolated from multiple tissue sources and also display an innate ability to home to areas of inflammation, such as tumors. Upon entry into the tumor microenvironment niche, MSCs promote or inhibit tumor progression by various mechanisms, largely through the release of soluble factors. These factors can be immunomodulatory by activating or inhibiting both the adaptive and innate immune responses. The mechanisms by which MSCs modulate the immune response are not well understood. Because of this, the relationship between MSCs and immune cells within the tumor microenvironment niche continues to be an active area of research in order to help explain the apparent contradictory findings currently available in the literature. The ongoing research aims to enhance the potential of MSCs in future therapeutic applications.

Mesenchymal stromal cells (MSCs) are a multipotent cell population of clinical interest because of their ability to migrate to injury and tumor sites, where they may participate in tissue repair and modulation of immune response. Although the processes regulating MSC function are incompletely understood, it has been shown that stimulation of Toll-like receptors (TLRs) can alter MSC activity. More specifically, it has been reported that human bone marrow-derived MSCs can be "polarized" by TLR priming into contrasting immunomodulatory functions, with opposite (supportive or suppressive) roles in tumor progression and inflammation. Adipose-derived MSCs (ASCs) represent a promising alternative MSC subpopulation for therapeutic development because of their relative ease of isolation and higher abundance compared with their bone marrow-derived counterparts; however, the polarization of ASCs remains unreported. In this study, we evaluated the phenotypic and functional consequences of short-term, low-level stimulation of ASCs with TLR3 and TLR4 agonists. In these assays, we identified transient gene expression changes resembling the reported pro-inflammatory and anti-inflammatory MSC phenotypes. Furthermore, these priming strategies led to changes in the functional properties of ASCs, affecting their ability to migrate and modulate immune-mediated responses to prostate cancer cells in vitro. TLR3 stimulation significantly decreased ASC migration, and TLR4 stimulation increased ASC immune-mediated killing potential against prostate cancer cells.

Some cytokines can reengineer anti-tumor immunity to modify the tumor micro-environment. Interleukin-27 (IL-27) can partially reduce tumor growth in several animal models, including prostate cancer. We hypothesized that addition of IL-18, which can induce the proliferation of several immune effector cells through inducing IFNγ could synergize with IL-27 to enhance tumor growth control. We describe our findings on the effects of IL-27 gene delivery on prostate cancer cells and how sequential therapy with IL-18 enhanced the efficacy of IL-27. The combination of IL-27 followed by IL-18 (27→18) successfully reduced cancer cell viability, with significant effects in cell culture and in an immunocompetent mouse model. We also examined a novel chimeric cytokine, comprising an IL-27 targeted at the C-terminus with a short peptide, LSLITRL (27pepL). This novel cytokine targets a receptor upregulated in tumor cells (IL-6Rα) via the pepL ligand. Interestingly, when we compared the 27→18 combination with the single 27pepL therapy, we observed a similar efficacy for both. This efficacy was further enhanced when 27pepL was sequenced with IL-18 (27pepL→18). The observed reduction in tumor growth and significantly enriched canonical pathways and upstream regulators, as well as specific immune effector signatures (as determined by bioinformatics analyses in the tumor microenvironment) supported the therapeutic design, whereby IL-27 or 27pepL can be more effective when delivered with IL-18. This cytokine sequencing approach allows flexible incorporation of both gene delivery and recombinant cytokines as tools to augment IL-27’s bioactivity and reengineer efficacy against prostate tumors and may prove applicable in other therapeutic settings.

An emerging approach in treating skeletal malignancies utilizes osteoimmunology to investigate new multifunctional immune-stimulatory agents that can simultaneously combat tumor growth and promote bone repair. We have hypothesized that cytokine Interleukin-27 (IL-27) is an excellent candidate biologic to help rebalance the prostate tumor cells and bone cell environment. In this work, we examined the proof of principle for a short, secreted luciferase (Nanoluc or Nluc) fusion with IL-27 to produce a novel cytokine-based biologic (Nluc-27), whereby we examined its efficacy in vitro in reducing prostate tumor growth and rebalancing bone cell proliferation and differentiation. This work demonstrates the targeting and anti-tumor efficacy of the Nluc-27 fusion cytokine in cancer and bone cell models. The fusion cytokine is detectable in conditioned media, and bioactive in different cell systems. This novel Nluc-27 cytokine will allow flexible incorporation of other targeting domains and may serve as flexible tool to augment IL-27′s bioactivity and reengineer its efficacy against prostate tumor or bone cells, and may prove applicable to several other cell types for targeted gene therapy applications.

Persistent infection with HPV causes nearly 5% of all cancers worldwide, including cervical and oropharyngeal cancers. Compared to HPV-negative (HPV−) head and neck squamous cell carcinomas (HNSCCs), HPV-positive (HPV+) HNSCCs exhibit a significantly improved treatment response; however, established treatment regimens were largely developed for HPV− disease. Effectively de-escalating therapy and optimizing treatment protocols to minimize toxicity for both HPV+ and HPV− tumors has been variably successful, in part due to the heterogeneity of cellular subpopulations. Single-cell RNA sequencing (scRNAseq) has primarily been used to define immune cell populations rather than the cell type of origin, epithelial cells. To address this, we analyzed published scRNAseq data of HPV+ and HPV− HNSCCs to distinguish epithelial tumor cell populations as a function of HPV status. We identified the transcriptome signatures, ontologies, and candidate biomarkers of newly identified epithelial subpopulations with attention to those that are shared or enriched in HPV+ or HPV− HNSCCs. We hypothesize that distinct epithelial cell populations and reprogramming in HPV− versus HPV+ HNSCC represent important components of the pro-tumor environment. These are described here as a foundation for the identification of new epithelial-cell-specific biomarkers, effectors, and candidate targets for optimizing the treatment of HNSCC.

The tumor microenvironment (TME) influences prostate cancer (PCa) progression through stromal and immune interactions. Adipose‐derived mesenchymal stromal cells (ASCs) modulate immune tone, while inorganic arsenic (iAs), a widespread toxicant, is linked to immune suppression and carcinogenesis. Their combined impact on PCa immunity has remained unclear. Using a Ras‐driven murine PCa model (TC2Ras, which mimics aggressive, immune‐interactive PCa through constitutive Ras signaling), we assessed ASC and chronic iAs exposure effects on tumor growth, immune infiltration, and transcriptomic remodeling via flow cytometry, RNA‐seq, and qPCR. ASC‐conditioned media increased TC2Ras viability by up to 82%, an effect reversed by iAs (300–1000 ppb). In vivo, ASC co‐implantation significantly elevated tumor weight in ASC + iAs tumors. ASC promoted approximately twofold macrophage and CD4 ⁺ T‐cell infiltration, while iAs suppressed macrophages and MDSCs. We performed RNA‐seq and qPCR, confirming that a sustained IFNγ‐IRF1 activation (approximately eightfold) in ASC tumors occurred alongside an iAs‐driven downregulation of adaptive immunity, as well as an upregulation of immune checkpoint genes (Pdcd1, Lag3). These findings demonstrate that ASC–iAs crosstalk remodels the TME toward immune tolerance and chronic IFNγ signaling, potentially facilitating tumor progression and revealing novel mechanisms by which environmental toxicants may influence cancer immunity through stromal cell interactions.