Abstract 100: IL-1β pathway promotes cell proliferation and 5-FU resistance in African American colon cancer cell lines

Field: Biochemistry, Genetics and Molecular Biology (Life Sciences)

Abstract Introduction: Colorectal Cancer (CRC) is the third most common cancer and third cause of cancer-related death in the US. When taking race and ethnicity into consideration, African Americans (AA) present with the highest incidence and mortality rates for CRC. Studies have found that AA patients, when compared to Caucasian American (CA) patients, have a lower response to the standard of care chemotherapeutic agent 5-Fluorouracil (5-FU) as well as lower frequency of MSI tumors, making them also less likely to respond to conventional immunotherapies. Our recent findings have shown that tumors from AA patients present higher expression of genes involved in pro-inflammatory processes as well as lower expression of genes promoting anti-tumoral activities. One of the genes that was found upregulated in AA tumors is IL1B, which encodes for the pro-inflammatory cytokine Interleukin-1β (IL-1β). Therefore, we investigated the role of the IL-1β pathway in novel AA colon cancer cell lines. Here, we evaluated changes in cell proliferation, apoptosis, 5-FU response, and activation of inflammatory pathways. Methods: Our approach includes analysis of gene expression in both AA and CA colon cancer cell lines by using RNA sequencing to evaluate pro-inflammatory genes differentially expressed among the cell lines. Furthermore, we used an MTS assay to detect viable cells following treatment with IL-1β, alone or in combination with different concentrations of 5-FU, as well as analyzing changes in apoptosis via Flow Cytometry. To better understand the mechanisms of IL-1β-induced effects, we used IL-1 Receptor Antagonist (IL-1Ra) to block the IL-1β pathway and evaluated changes in cell viability and 5-FU response via MTS assay, as well as activation of NF-kB pathway, via detection of phospho-IкB-α protein using Western Blot analysis. Results: Results from MTS assays indicated that cell proliferation in response to IL-1β differs between the AA and the CA colon cancer cell lines, with the AA colon cancer cells being more sensitive to lower concentrations of the cytokine when compared to CA cell lines. Further, we saw an increased expression of phospho-IкB-α following treatment with IL-1β. This expression was reduced when the cells were treated in combination with IL-1β and the IL-1Ra. The IL-1Ra also appears to reduce the pro-proliferative effects induced by IL-1β. Importantly, our results show that 5-FU sensitivity is drastically reduced in the presence of IL-1β for both AA and CA colon cancer cell lines, suggesting that IL-1β may play a role in defining resistance to the chemotherapeutic drug. Conclusions: Taken together, our results demonstrated a differential response to IL-1β for the AA colon cancer cell lines, suggesting a probable role played by the cytokine in driving inflammation-related cancer progression and reveals a possible new target to exploit in immunotherapy for this population. Citation Format: Marzia Spagnardi, Jenny Paredes, Jone Garai, Jovanny Zabaleta, Jennie Williams, Laura Martello-Rooney. IL-1β pathway promotes cell proliferation and 5-FU resistance in African American colon cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 100.