Poly I:C-priming of adipose-derived mesenchymal stromal cells promotes a pro-tumorigenic phenotype in an immunocompetent mouse model of prostate cancer.

Introduction: Mesenchymal stromal cells (MSC) are envisioned as a potential cellular vehicle for targeted cancer therapies due to their tumor tropism and immune permissiveness. An obstacle in their use is the duality in their interactions within tumors, rendering them pro-tumorigenic or anti-tumorigenic, in a context dependent manner. MSC preconditioning, or priming, has been proposed as a strategy for directing the effector properties of MSC at tumor sites. Methods: We primed human MSC derived from adipose tissues (ASC), a clinically advantageous MSC source, utilizing toll-like receptor agonists. Subsequently, we explored the consequences in tumor progression and transcriptome upon the interaction of tumor cells with primed or unprimed ASC in an in vivo model of prostate cancer, the second most common cancer and second leading cause of cancer related death in men in the USA. Results and discussion: In the studied model, poly I:C-primed ASC were found to significantly accelerate tumor growth progression. And while unprimed and LPS-primed ASC did not exert a significant effect on tumor growth at the macroscopic level, gene expression analyses suggested that all treatments promoted distinct modulatory effects in the tumor microenvironment, including altered modulation of angiogenesis, and immune response processes. However, the effects resulting from the collective interaction across these processes must be sufficiently skewed in a pro-tumorigenic or anti-tumorigenic direction for evidence of tumor progression modulation to be detectable at the macroscopic level. Our study highlights potential MSC-tumor microenvironment interactions that may be leveraged and should be considered in the development of cancer therapeutics utilizing MSC.

Evaluation of human adipose-derived mesenchymal stromal cell Toll-like receptor priming and effects on interaction with prostate cancer cells.

BACKGROUND AIMS: 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. METHODS: In this study, we evaluated the phenotypic and functional consequences of short-term, low-level stimulation of ASCs with TLR3 and TLR4 agonists. RESULTS: 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. CONCLUSIONS: TLR3 stimulation significantly decreased ASC migration, and TLR4 stimulation increased ASC immune-mediated killing potential against prostate cancer cells.

Reengineering Tumor Microenvironment with Sequential Interleukin Delivery.

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.

Copper transporter 1 affinity as a delivery strategy to improve the cytotoxic profile of rationally designed copper(II) complexes for cancer treatment.

Cisplatin is widely used to treat different types of cancer, but its severe side effects are the major disadvantage of this treatment. Therefore, other metals are currently the subject of research in the rational development of anticancer drugs, such as copper, that has been demonstrated to be promising in this scenario. Here, we evaluated the effects of two novel copper complexes against breast cancer cell lines, and also examined the influence of overexpressing copper transporter 1 (CTR1) on the cytotoxicity of these complexes. Complex (1) [Cu(sdmx-)2(phen)] showed low IC50 values, induced intense cell morphological changes and arrested the cell cycle at the sub-G1 phase in cancer cells. Complex (1) was tested in transfected cells overexpressing the CTR1 receptor in order to compare its steric effects with a less bulky ligand and more labile complex (2) [CuCl2(impy)]. A significant reduction of IC50 value was observed in CTR1 overexpressing cells for complex (2) (32 µM to 20 µM) as compared to (1) (2.78 µM to 3.41 µM), evidencing a possible uptake through copper reduction (Cu+2 â†’ Cu+1) mediated by CTR1. Thus, considering that CTR1 is a mediator of metallodrugs uptake, the development of strategies that use rational drug design is important in order to improve the therapeutic efficacy through greater specificity and consecutive reduction of side effects. Here we show the example for the case of copper(II) complexes.

The Immunomodulatory Effects of Mesenchymal Stem Cell Polarization within the Tumor Microenvironment Niche.

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.