Non-Toxicological Role of Aryl Hydrocarbon Receptor in Obesity-Associated Multiple Myeloma Cell Growth and Survival

• Published in: Cancers 2023-11, Vol.15 (21), p.5255
• Main Authors: Diedrich, Jonathan D, Cole, Craig E, Pianko, Matthew J, Colacino, Justin A, Bernard, Jamie J
• Format: Article
• Language: English
• Subjects: Adipocytes; Biotechnology industry; Bone marrow; Cancer; Cell culture; Cell growth; Cell survival; Collagen; Comparative analysis; CYP1B1 gene; Cytochrome P450; Cytokines; Gene expression; Genes; Genetic transcription; Growth; Health aspects; Hematology; Hydrocarbons; Ligands; Lipids; Localization; Metabolism; Monoclonal gammopathy; Multiple myeloma; Obesity; Occupational health and safety; Paternity; Proteins; Risk factors; Tumors
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers15215255

Obesity is not only a risk factor for multiple myeloma (MM) incidence, but it is also associated with an increased risk of progression from myeloma precursors-monoclonal gammopathy of undetermined significance-and smoldering myeloma. Adipocytes in the bone marrow (BMAs) microenvironment have been shown to facilitate MM cell growth via secreted factors, but the nature of these secreted factors and their mechanism of action have not been fully elucidated. The elevated expression of aryl hydrocarbon receptor (AhR) is associated with a variety of different cancers, including MM; however, the role of AhR activity in obesity-associated MM cell growth and survival has not been explored. Indeed, this is of particular interest as it has been recently shown that bone marrow adipocytes are a source of endogenous AhR ligands. Using multiple in vitro models of tumor-adipocyte crosstalk to mimic the bone microenvironment, we identified a novel, non-toxicological role of the adipocyte-secreted factors in the suppression of AhR activity in MM cells. A panel of six MM cell lines were cultured in the presence of bone marrow adipocytes in (1) a direct co-culture, (2) a transwell co-culture, or (3) an adipocyte-conditioned media to interrogate the effects of the secreted factors on MM cell AhR activity. Nuclear localization and the transcriptional activity of the AhR, as measured by and gene induction, were suppressed by exposure to BMA-derived factors. Additionally, decreased AhR target gene expression was associated with worse clinical outcomes. The knockdown of AhR resulted in reduced expression and increased cellular growth. This tumor-suppressing role of and was supported by patient data which demonstrated an association between reduced target gene expression and worse overall survival. These data demonstrated a novel mechanism by which bone marrow adipocytes promote MM progression.