Abstract 317: Berberine-mediated reprogramming of the inflammatory environment in anaplastic thyroid cancer (2021)

Abstract Anaplastic thyroid cancer's (ATC) undifferentiated, inflammatory nature makes it one of the most aggressive cancers, with a five-year survival rate of only 4% when metastatic. ATC is a rare cancer that is refractory to conventional therapeutic modalities. Without high expression of targetable genetic lesions, small molecule inhibitors alone have been insufficient in trials. Treatment of ATC could benefit from a holistic approach that reprograms the inflammatory tumor microenvironment (TME). Berberine (BBR), a natural plant-derived alkaloid used extensively in Traditional Chinese Medicine, is a compound shown to exhibit anti-microbial, anti-inflammatory, and anti-cancer properties. Our work aims to exploit the anti-inflammatory activity of BBR in ATC. As the inflammatory status of ATC defines its intractable nature, remodeling its secretome, including its cytokine and chemokine profile and its exosomal cargo, in the TME fundamentally targets ATC's progressive determinant - inflammation. Exosomes, membrane-bound extracellular vesicles, are secreted by cells in the TME, including activated tumor-associated macrophages and ATC cells. Exosomal cargo primarily consists of miRNAs. We observed distinct miRNA expression from ATC-secreted exosomes when compared to papillary thyroid cancer (PTC)-secreted exosomes. Comparative analysis revealed ten miRNAs specifically downregulated in exosomes secreted from anaplastic-like 8505C compared to papillary BCPAP, including: hsa-miR-26b-5p, hsa-miR-125b-5p, hsamiR-138-5p, hsa-miR-148a-5p, hsamiR-152-5p, hsa-miR-191-5p, hsa-miR-9-5p, hsa-miR-21-5p, hsa-miR-134-5p, and hsa-miR-379-5p. The first six miRNAs listed are tumor suppressors, and as such, their downregulation may be contributory to the metastatic propensity and aggressiveness of ATC and its refractory nature towards conventional treatments. In activated macrophage-derived exosomes, miR-21-5p and miR-138-5p were also upregulated. ATC-secreted exosomes activate macrophages, subsequently priming the TME to be pro-tumorigenic and pro-inflammatory. This reciprocal interaction between inflammatory macrophages and ATC cells mediated by exosomal miRNAs defines its metastatic and inflammatory phenotype. We also observed that BBR significantly downregulates phosphorylation of MEK, ERK, and ribosomal protein S6 in proliferating ATC cells with as low as 10 μM BBR treatment. These are important downstream regulators of the pro-proliferative, pro-survival, and metabolic MAPK and PI3K-PTEN-AKT signaling pathways. Overall, the ability for BBR to alleviate the pro-inflammatory phenotype of ATC and remodel its immune environment, while simultaneously depressing overactive signaling in these cell survival pathways, may mark it as an important agent to make ATC amenable to combination therapy with small molecule inhibitors (MEKi) or other immunotherapeutics. Citation Format: Tara Jarboe, Nicole DeSouza, Sarnath Singh, Augustine Moscatello, Jan Geliebter, Raj K. Tiwari, Xiu-Min Li. Berberine-mediated reprogramming of the inflammatory environment in anaplastic thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 317.