Abstract P1-04-02: Multicellular spheroids to dissect the interplay between human immune system and cancer

Abstract The interaction between various components in the tumor environment plays a pivotal role in tumor development, migration and metastasis. While the 2-dimensional (2D) in vitro culture methods fail to assimilate the complexity of tumor microenvironment, the 3D multicellular tumor spheroids support co-culture conditions and allow a more physiologically relevant environment. We are working to establish such 3D model to investigate the molecular mechanisms regulating the interactions between human cancer cells such as melanoma or breast cancer, myeloid cells and T cells. Spheroids were developed using hanging drop technique with multiple cancer cell lines, dermal fibroblasts and immune cells. Preliminary experiments were carried out to determine the optimum conditions for spheroid formation. Spheroid formation occurred within 72 hours and their integrity was maintained throughout the experiments. Immunofluorescence analysis of spheroid cryosections showed a homogeneous distribution of fibroblasts in spheroids. Addition of purified blood CD14+ blood monocytes to the mixture of cancer cells and dermal fibroblasts enabled monocyte integration into spheroids. Adding melanoma specific CD8+ T cells to tumor spheroids formed by melanoma cell line (Me275), dermal fibroblasts and monocytes resulted in homogeneous infiltration and increased number of cell death. Addition of PBMCs to the mix of breast cancer cells and fibroblasts enabled the discrimination of spheroids into two groups, tumor spheroids with immune cells at the margin preferentially located at tumor margin and tumor spheroids with infiltrating immune cells. These preliminary observations resemble those from our in vivo models of humanized mice, where different tumor xenografts show different level of immune cell infiltration. Thus, our 3D model might allow the classification of tumor cells based on immune cell infiltration and could potentially be used to assess the distribution of immune infiltrates and the interaction of cancer cells with immune compartments. Citation Format: Elaheh Ahmadzadeh, Jan Martinek, Florentina Marches, Gabby Aucello, Chun I Yu, Karolina Palucka. Multicellular spheroids to dissect the interplay between human immune system and cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-04-02.