EXPLORING EXPRESSION PROFILES AND SIGNALING PATHWAYS OF INFILTRATING MACROPHAGES IN THE TUMOR MICROENVIRONMENT OF ANAPLASTIC THYROID CANCER

BRUGO, MARIA BELEN; QUIROZ, JM; HERRERA, MELISA ROCÍO; BAIGORRI, ELIANA; VOLPINI, XIMENA; FOZZATTI, LAURA; MOTRAN, CLAUDIA CRISTINA

San Luis

Congreso; LXXI REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2023

Sociedad Argentina de Inmunología

Immune cells are recruited into the tumor microenvironment (TME) during tumorprogression. Anaplastic Thyroid Cancer (ATC), is heavily infiltrated by tumorassociatedmacrophages (TAMs), making them attractive targets for therapy. Wehave previously reported that treatment of THP-1 cells (a human monocyte-like cellline) with conditioned media derived from ATC cells induces their activation towardsa pro-tumoral phenotype, accompanied by an increase in the immune checkpointmarker TIM3. The Wnt/β-catenin pathway plays a crucial role in the pathogenesisof various cancers, and numerous therapeutic strategies have been developed toinhibit this pathway. However, the role of the Wnt/β-catenin pathway in TAMsphenotype in ATC remains unexplored.To first characterize gene expression programs of ATC-associated TAMs, weanalyzed single-cell RNA sequencing data from ATC and adjacent normal thyroidhuman biopsies reported by Lina Lu et al (GSE193581). The tumor immunelandscape showed an enrichment of monocytes and macrophages compared tonormal tissue (27% vs. 5% and 20% vs. 1.3%, respectively). ATC-infiltratingmacrophages exhibited upregulated expression of pro-angiogenic genes (Vegfa,Tgfbi, and Hif1a) and M2-associated genes (Cd163, Cd68, and Col1a2), unlikemacrophages from adjacent tissue. ATC-infiltrating monocytes displayed geneexpression patterns associated with inflammatory responses, angiogenesis, andTNF/IL6 production. Interestingly, the expression of β-catenin (Ctnnb1) and Tim-3(Havcr2) was higher in macrophages, monocytes, and dendritic cellscompared toNK, T, or B cells. While TAMs from ATC and normal tissue showed comparableexpression levels of these genes, a significant positive correlation between Ctnnb1and Havcr2 expression emerged in the ATC context, absent in normal-adjacentTAMs. A similar correlation was observed between Havcr2 expression and Vegfa,a key pro-angiogenic mediator. To validated the sc-RNAseq results, THP-1 cellswere treated with conditioned media derived from 8505C cells (human ATC cell line)or control medium for different times. PCR analysis revealed upregulation of β-catenin and associated pathway genes (C-myc and Axin2). Notably, β-catenin(Ctnnb1) expression increased at 30 minutes, followed by Axin2 and C-myc at onehour, persisting at 6 and 24 hours. Our study reveals the complex immune cell andsignaling pathway dynamics in the anaplastic TME, highlighting the importance ofthe Wnt/b-catenin pathway.