Abstract A24: Cancer cells reduce macrophage CXCR3/CXCL10 axis expression through canonical NF-κB signaling


 Tumor-associated macrophage (TAM) infiltration of tumors via chemokine axis are linked with tumor progression and metastasis. There are forty-seven known chemokines and nineteen known chemokine receptors in humans. Many of these chemokines have a dual functionality in cell survival and growth. Notably, CXCL10 and its receptor CXCR3 are associated with both angiogenesis and angiostasis, among other functions, both pro and anti-tumor. This duality is coupled with the uncertainty of which signaling pathways are responsible for CXCL10 expression and supression during tumor progression. Recent literature states that nuclear factor-kappaB (NF-κB) signaling is required for driving the expression of CXCL10 during traditional macrophage activation; however, little is known about the chemokine’s suppression. To determine the role of NF-κB on CXCR3/CXCL10 modulation in macrophages within the context of cancer, we performed three co-culture experiments to examine the gene expression level changes within bone marrow-derived macrophages (BMDMs) from an NF-κB (p65) deficient mouse model (p65fl/fl/LysMCre) and compared them to control BMDMs (LysMCre). The first co-culture included a murine glioblastoma multiforme (GBM) cell line (GL261), while the other two included different murine triple-negative breast cancer (TNBC) cell lines (AT-3, 4T1). BMDMs, from either LysMCre or p65fl/fl/LysMCre mice, were seeded into 6-well plates, let rest for 24 hours, and then cancer cells were seeded onto the transwell insert. Cells shared the growth medium for 24 hours before collection and subsequent RNA isolation, cDNA synthesis, and qPCR analysis. Here, we identified that BMDM CXCL10 gene expression is drastically reduced when co-cultured with the three different cancer cell lines. Furthermore, we found that conditional deletion of canonical NF-κB signaling (p65) in BMDMs significantly recovered their CXCL10 expression when co-cultured with GL261 glioma cells and AT-3 breast cancer cells. Co-culture with 4T1 breast cancer cells also showed a recovering CXCL10 gene expression in the NF-κB (p65) deficient BMDMs. Additionally, the chemokine’s receptor, CXCR3, gene expression was signficantly reduced in all three co-culture conditions. However, in comparison, there was no significant difference in CXCR3 gene expression in the NF-κB (p65) deficient BMDMs in the same co-cultures. Thus, canonical NF-κB signaling is implicated in maintenance of CXCL10 expression in BMDMs, but not obviously involved in the alteration of their CXCR3 expression.
 Citation Format: Ahmet K Korkaya, Jennifer W Bradford. Cancer cells reduce macrophage CXCR3/CXCL10 axis expression through canonical NF-κB signaling [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr A24.