Development of an In Vitro Assay to Assess Pharmacological Compounds and Reversion of Tumor-Derived Immunosuppression of Dendritic Cells

ABSTRACT

Background

Cancer immunotherapies have achieved much success and have become the forefront treatment of cancers previously associated with poor prognosis. However, a major challenge in cancer immunotherapies remains the heterogeneity of the immunoregulatory capacities of cancers, and not all patients of a given cancer responds to current therapeutic strategies. To address this issue and to facilitate the development of new pharmacological compounds, we here describe an in vitro model of dendritic cell suppression by cancer cells.

Methods

We treated monocyte-derived dendritic cells with conditioned medium from cancer cell lines and assessed their maturation using ELISA and flow cytometry. In addition, we assessed their ability to induce T cell activation and differentiation.

Results

We found that both the phenotypic and functional maturation of dendritic cells was suppressed by the conditioned medium. The expression of IL-12p70, TNF-α, CD80, CD83, and CD86 was significantly reduced by conditioned medium from the 786-O and HeLa cell lines, and CD4⁺ T cells had a weaker T_H1 phenotype with significantly decreased expression of IFN-γ and T-bet following co-culturing. Furthermore, we use our model to characterize the differential immunoregulatory capacities of primary cancers by using conditioned medium of cultured primary cancer cells.

Conclusion

This model can be used to screen pharmacological compounds seeking to alleviate the immunosuppression of the tumor microenvironment and can furthermore be used to investigate the immunoregulatory capacities of primary cancer cells, which could be a helpful prognostic tool following tumor resection.

KEYWORDS:

• Drug screening
• in vitro assay
• dendritic cells
• immunosuppression
• tolerance

Acknowledgments

We would like to thank our laboratory technicians Trine Møller and Dorthe Pedersen for their valuable technical assistance, and Morten Hansen from CCIT-DK for his contribution to this work by kindly providing us with conditioned medium from primary melanoma and renal cell carcinoma.

Declaration of interests

This research was carried out at Bioneer A/S, a company in which Jesper Larsen, Mikkel Møller Andersen, and Monika Gad are current or former employees. Bioneer A/S provides DC based screening services for customers. Furthermore, Anders Elm Pedersen was during the project an employee at Merck Denmark and is currently employed by Almirall, but the present work is not related to these employments.

Data availability statement

The data that support the findings of this study are available from the corresponding author, Mikkel Møller Andersen, upon reasonable request.

Additional information

Funding

This work was supported by the Danish Ministry of Higher Education and Science [grant number 9044-00004B] as a part of the performance contract “Immunmodulering i lægemiddeludvikling og stamcelleterapi” (Immunomodulation in pharmacological development and stem cell therapy) that Bioneer A/S undertook as an Approved Technological Service (GTS; Godkendt Teknologisk Service) company in Denmark.