Ex Vivo Model of Neuroblastoma Plasticity

SIMPLE SUMMARY: The complexity of tumor cell plasticity is still poorly understood. In particular, cellular changes during the metastatic process are difficult to monitor. This is a descriptive study of cell lines derived from primary tumors of xenografted LAN-1 cells and the corresponding three generations of bone metastases. Our results of ex vivo analysis of the cell lines depict the ability of tumor cells to adapt and survive in different microenvironments undergoing significant cellular alterations. The cell lines show strong phenotypical and biochemical changes and even an altered response to immune cells and chemotherapy. In conclusion, this mouse model allows to analyze the complex changes in tumor cell populations during metastasis and can be adapted to cell lines from different tumor origins. ABSTRACT: Tumor plasticity is essential for adaptation to changing environmental conditions, in particular during the process of metastasis. In this study, we compared morphological and biochemical differences between LAN-1 neuroblastoma (NB) cells recovered from a subcutaneous xenograft primary tumor (PT) and the corresponding three generations of bone metastasis (BM I–III). Moreover, growth behavior, as well as the response to chemotherapy and immune cells were assessed. For this purpose, F-actin was stained, mRNA and protein expression assessed, and lactate secretion analyzed. Further, we measured adhesion to collagen I, the growth rate of spheroids in the presence and absence of vincristine, and the production of IL-6 by peripheral blood mononuclear cells (PBMCs) co-incubated with PT or BM I–III. Analysis of PT and the three BM generations revealed that their growth rate decreased from PT to BM III, and accordingly, PT cells reacted most sensitively to vincristine. In addition, morphology, adaption to hypoxic conditions, as well as transcriptomes showed strong differences between the cell lines. Moreover, BM I and BM II cells exhibited a significantly different ability to stimulate human immune cells compared to PT and BM III cells. Interestingly, the differences in immune cell stimulation corresponded to the expression level of the cancer-testis antigen MAGE-A3. In conclusion, our ex vivo model allows to analyze the adaption of tumor populations to different microenvironments and clearly demonstrates the strong alteration of tumor cell populations during this process.