Abstract 2788: The interplay between tumor-cell derived FoxO1 and macrophage in the tumor microenvironment of esophageal squamous cell carcinoma

Abstract

Abstract Introduction: Esophageal squamous cell cancer (ESCC) is the predominant histologic type in China with high incidence and mortality. FOXO1 is considered as a tumor suppressor in several cancers, but its role in tumor immunology still remain elusive. A better understanding of how FOXO1 mediates the secretion of downstream chemokines, such as CCL20, and thus its ability in regulating macrophage function would be of crucial for further investigation. Materials and Methods: Quantitative PCR and immunohistochemistry were used to study the expression of FoxO1 in clinical ESCC samples. The survival analysis was performed based on the result of tissue microarray and corresponding clinicopathological information. Stable foxo1-transfected cell lines were constructed in human ESCC cell lines, and ELISA, western blotting and Quantitative PCR were conducted to evaluate the expression of foxo1 and its downstream molecule CCL20. The subsets of macrophages were identified through Flow cytometry and qPCR. Results: The expression of FOXO1 was significantly upregulated in tumorous tissue when comparing to adjacent normal tissue and predicted a poor prognosis in ESCC patients. Besides, the analysis of TCGA database indicated that the markers of M2 macrophage were upregulated in foxo1-high expressing tumor tissues when compared with foxo1-low expressing tumor tissues. In vitro, we have successfully differentiated monocytic cell line THP-1 into macrophage M0, M1 and M2. The M1 and M2 markers (CD80, CD163 and CD68) were measured by flow cytometry, while their major cytokines (IL6, TNF-α, CCL17, CCL18, IL1β and IL10) were detected by qPCR. The ELISA, western blot and qPCR results showed that the expression of CCL20 was upregulated in foxo1-high expressing tumor cells when compared to negative control. The migration assay showed that ESCC cells transfected with foxo1 could recruit more M2 macrophages when compared with foxo1-low expression ESCC cells and the effect was diminished upon blockade with anti-CCL20 neutralizing antibody in tumor cells. Besides, we found out that M2 macrophage could promote the migration and EMT of tumor cells by using M2 conditioned medium. Conclusions: FoxO1 displays an important role in M2 macrophage migration through the modulation of CCL20. This increased CCL20 reported in ESCC may become specific molecular/cellular processes operative in the TME of ESCC patients. Note: This abstract was not presented at the meeting. Citation Format: Ying Wang, Xinyuan Guan, Woon Ngar Kam. The interplay between tumor-cell derived FoxO1 and macrophage in the tumor microenvironment of esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2788.