PurposeWe previously reported that forkhead transcription factors of the O class 1 (FOXO1) expression in gastric cancer (GC) was associated with angiogenesis-related molecules. However, there is little experimental evidence for the direct role of FOXO1 in GC. In the present study, we investigated the effect of FOXO1 on the tumorigenesis and angiogenesis in GC and its relationship with SIRT1.Materials and MethodsStable GC cell lines (SNU-638 and SNU-601) infected with a lentivirus containing FOXO1 shRNA were established for animal studies as well as cell culture experiments. We used xenograft tumors in nude mice to evaluate the effect of FOXO1 silencing on tumor growth and angiogenesis. In addition, we examined the association between FOXO1 and SIRT1 by immunohistochemical tissue array analysis of 471 human GC specimens and Western blot analysis of xenografted tumor tissues.ResultsIn cell culture, FOXO1 silencing enhanced hypoxia inducible factor-1α (HIF-1α) expression and GC cell growth under hypoxic conditions, but not under normoxic conditions. The xenograft study showed that FOXO1 downregulation enhanced tumor growth, microvessel areas, HIF-1α activation and vascular endothelial growth factor (VEGF) expression. In addition, inactivated FOXO1 expression was associated with SIRT1 expression in human GC tissues and xenograft tumor tissues.ConclusionOur results indicate that FOXO1 inhibits GC growth and angiogenesis under hypoxic conditions via inactivation of the HIF-1α–VEGF pathway, possibly in association with SIRT1. Thus, development of treatment modalities aiming at this pathway might be useful for treating GC.
FOXO1, a forkhead box O (FOXO) transcription factor, and nuclear factor-κB (NF-κB) are prognostically significant transcription factors in gastric cancer. As their relationship has been inconsistent depending on the cell type, we aimed to investigate whether FOXO1 is associated with NF-κB p65 (RelA) in gastric cancer. Immunohistochemistry was performed on tissue array slides containing 298 gastric carcinoma specimens. We found that the cytoplasmic expression of pFOXO1, the inactive form of FOXO1, was positively correlated with nuclear RelA expression (p = 0.024). In addition, the expressions of pFOXO1 and RelA were positively related with cyclin D1 expression (p = 0.014 and p = 0.001, respectively) and Ki-67 labeling index (p = 0.025 and p = 0.017, respectively). However, they did not show association with the expressions of cyclin E, p53 and pRb. Cell culture experiments showed that FOXO1 overexpression by transfection of FOXO1 AAA mutant gene suppressed NF-κB activation in SNU-484 gastric cancer cells. These results suggest that FOXO1 and NF-κB are negatively associated and that FOXO1 is a negative upstream regulator of NF-κB in gastric cancer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.