Inflammatory environment created by fibroblast aggregates induces growth arrest and phenotypic shift of human myeloma cells

Abstract

Multiple myeloma (MM) is characterized by accumulation of clonal plasma cells (PCs) predominantly in the bone marrow but tumor cells appear in the circulation in significant numbers as the disease progress. The occurrence of circulating multiple myeloma cells raises question concerning interactions between these cells and stroma of peripheral organs specifically under certain pathophysiological conditions, e.g., inflammation. Therefore, in the present study we exposed three human multiple myeloma cell lines to sterile inflammation produced in a culture dish by clusters of cell-cell contact-activated dermal fibroblasts. We now observed that myeloma cells responded differently to this particular type of stromal cell activation, nemosis. Two cell lines U-266 and LP-1 were minimally affected by the proinflammatory signalling, while the third cell line RPMI 8226 responded with growth arrest and altered expression of three phenotypic markers CD38, CD45, and CD138, indicating dedifferentiation shift of these cells to less mature PC-like phenotype. In a preliminary study we identified a subclone of cells having similar phenotype in 14 out of 23 analysed specimens of MM patients. This set of data indicates that the observed phenomenon might be clinically relevant. Our results emphasize the potential role of activated stromal fibroblasts and subsequent inflammation in altering phenotype of PCs and directing myeloma progression towards dormancy. Given the significant implication of dormant myeloma cells that might serve as a major cellular basis for the relapse, understanding their unique biology and precise elucidation of the underlying molecular mechanisms for the maintenance of quiescence is important. Therefore, we consider this study as a particular contribution to development of experimental model for in vitro studies of cancer dormancy.

Fibroblast spheroids as a model to study sustained fibroblast quiescence and their crosstalk with tumor cells

“…In addition to senescence, fibroblast spheroids caused differentiation of RT3 tumors, as measured by CK7 expression. This is in accordance with previous finding that conditioned medium from the fibroblast spheroids can cause differentiation and growth arrest of leukemia and myeloma cells [12,26]. Interestingly, restoration of senescence in liver tumors results in CK7-mediated differentiation [22], and furthermore, CK7-mediated cell differentiation was found to be adjacent to senescent hepatocytes [27], suggesting a close interplay between CK7 and senescence.…”

Expression of factors involved in dental pulp physiopathological processes by nemotic human pulpal fibroblasts

“…These studies highlight intricate relationships between the different cell types within the same tissue but also the significance of soluble factors in these cell interactions (Peura et al 2012). Indeed, activated nemotic fibroblasts are able to encourage leucocyte chemotaxis, to induce angiogenic responses of endothelial cells and to arrest the growth of tumour cells through the release of cytokines, chemokines and other growth factors , Szabova et al 2015.…”

DNA Methylation Mediates EMT Gene Expression in Human Pancreatic Ductal Adenocarcinoma Cell Lines

“…Four PDAC cell lines, BxPC-3, MIA PaCa-2, and PANC-1, derived from the primary adenocarcinoma, and SU86.86 cells derived from liver metastasis, were used to assess EMTrelated changes in gene expression and DNA methylation. Inflammatory conditions were modeled by indirect cell co-cultivation through a conditioned media (CM) containing a wide range of cytokines and inflammatory molecules produced by activated fibroblasts [32]. Cells were cultured in a monolayer for two and six days in either DMEM under normoxic conditions (Control), CM in normoxia (CM), DMEM in hypoxia (1% O 2 , HY), or CM in hypoxia (CM + HY) (for details, see Material and Methods).…”

“…The pancreatic cells were indirectly co-cultured with contact-activated stromal fibroblasts to establish an experimental fibro-inflammatory in vitro model [74]. As previously described, activated fibroblasts were characterized by the production of inflammationassociated cytokines and growth factors, e.g., IL-1, IL-6, IL-8, IL-11, LIF, GM-CSF, and COX-2 related-prostaglandins [32]. All PDAC cell lines were cultivated with or without a conditioned medium (CM) for 2 and 6 days in normoxic or hypoxic conditions.…”