Loss of Forkhead Box O3 Facilitates Inflammatory Colon Cancer: Transcriptome Profiling of the Immune Landscape and Novel Targets

Abstract

Background & AimsDiminished forkhead box O3 (FOXO3) function drives inflammation and cancer growth; however, mechanisms fostering these pathobiologies are unclear. Here, we aimed to identify in colon loss of FOXO3-dependent cellular and molecular changes that facilitate inflammation-mediated tumor growth.MethodsFOXO3 knockout (KO) and wild-type (WT) mice were used in the AOM/DSS model of inflammation-mediated colon cancer. Bioinformatics were used for profiling of mRNA sequencing data from human and mouse colon and tumors; specific targets were validated in human colon cancer cells (shFOXO3).ResultsIn mice, FOXO3 deficiency led to significantly elevated colonic tumor burden (incidence and size) compared with WT (P < .05). In FOXO3 KO colon, activated molecular pathways overlapped with those associated with mouse and human colonic inflammation and cancer, especially human colonic tumors with inflammatory microsatellite instability (false discovery rate < 0.05). FOXO3 KO colon, similar to tumors, had increased neutrophils, macrophages, B cells, T cells, and decreased natural killer cells (false discovery rate < 0.05). Moreover, in KO colon differentially expressed transcripts were linked to activation of inflammatory nuclear factor kappa B, tumorigenic cMyc, and bacterial Toll-like receptor signaling. Among differentially expressed transcripts, we validated altered expression of integrin subunit alpha 2 (ITGA2), ADAM metallopeptidase with thrombospondin type 1 motif 12, and ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 5 in mouse WT and FOXO3 KO colon and tumors (P < .05). Similarly, their altered expression was found in human inflammatory bowel disease and colon cancer tissues and linked to poor patient survival. Ultimately, in human colon cancer cells, FOXO3 knockdown (shFOXO3) led to significantly increased ITGA2, and silencing ITGA2 (siRNA) alone diminished cell growth.ConclusionsWe identified the loss of FOXO3-mediated immune landscape, pathways, and transcripts that could serve as biomarkers and new targets for inflammatory colon cancer treatment.

S1P Lyase Regulates Intestinal Stem Cell Quiescence via Ki-67 and FOXO3

“…Emerging evidence indicates that FOXO3 acts as a tumor suppressor in cancer: FOXO3 is commonly inactivated in cancer cell lines either by cytoplasmic sequestration of FOXO3 protein or by mutation of the FOXO3 gene [ 29 ]. Its inactivation is, furthermore, associated with the initiation and progression of cancer: FOXO3 knockout mice show increased Ki-67 staining in colon crypts [ 30 ] due to increased cell cycle activity, respectively. In experimental studies, overexpression of FOXO3 inhibits the proliferation, tumorigenic potential, and invasiveness of cancer cells, while silencing of FOXO3 results in marked attenuation of protection against tumorigenesis [ 29 ].…”

Metformin Attenuates ROS via FOXO3 Activation in Immune Cells

“…Single-nucleotide polymorphisms (SNPs) for FOXO3 have been found to be associated with longevity (2,3) and favorable outcomes in inflammatory disease (4). A role of FOXO3 in dampening immune reactions was discussed in several studies (5,6). We showed that Foxo3 plays an important role in acute viral infection as its activation attenuated natural killer (NK) cell responses in a viral myocarditis model (7).…”

FOXO3 is a latent tumor suppressor for FOXO3-positive and cytoplasmic-type gastric cancer cells

“…Consistently, simultaneous disruption of Foxo1 , Foxo3 , and Foxo4 in mice resulted in the development of thymic lymphoma and hemangiomas, supporting a possible tumor-suppressor role of FOXOs [ 14 ]. Furthermore, Foxo3 deficiency accelerated tumor development in a colitis-associated colon cancer mouse model [ 15 ].…”