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Updated: May 12, 2026
A Fluorescence-based Assay for Characterization and Quantification of Lipid Droplet Formation in Human Intestinal Organoids
Published on: October 13, 2019
FOXO3 growth inhibition of colonic cells is dependent on intraepithelial lipid droplet density
Wentao Qi1, Philip S Fitchev2, Mona L Cornwell2
1Department of Medicine, Division of Gastroenterology, Northshore University HealthSystem Research Institute, Evanston, Illinois 60201.
Abstract:
Forkhead transcription factor FOXO3 plays a critical role in suppressing tumor growth, in part, by increasing the cell cycle inhibitor p27kip1, and Foxo3 deficiency in mice results in marked colonic epithelial proliferation. Here, we show in Foxo3-deficient colonic epithelial cells a striking increase in intracytoplasmic lipid droplets (LDs), a dynamic organelle recently observed in human tumor tissue. Although the regulation and function of LDs in non-adipocytes is unclear, we hypothesize that the anti-proliferative effect of FOXO3 was dependent on lowering LD density, thus decreasing fuel energy in both normal and colon cancer cells. In mouse colonic tumors, we found an increased expression of LD coat protein PLIN2 compared with normal colonic epithelial cells. Stimulation of LD density in human colon cancer cells led to a PI3K-dependent loss of FOXO3 and a decrease in the negative regulator of lipid metabolism in Sirtuin6 (SIRT6). Foxo3 deficiency also led to a decrease in SIRT6, revealing the existence of LD and FOXO3 feedback regulation in colonic cells. In parallel, LD-dependent loss of FOXO3 led to its dissociation from the promoter and decreased expression of the cell cycle inhibitor p27kip1. Stimulation of LD density promoted proliferation in colon cancer cells, whereas silencing PLIN2 or overexpression of FOXO3 inhibited proliferation. Taken together, FOXO3 and LDs might serve as new targets for therapeutic intervention of colon cancer.
Insights
Forkhead box O3 (FOXO3) suppresses colon cancer by reducing lipid droplets (LDs). Loss of FOXO3 increases LDs, promoting cancer cell proliferation, suggesting FOXO3 and LDs as therapeutic targets.
Area of Science:
- Cell Biology
- Molecular Biology
- Oncology
Background:
- Forkhead transcription factor FOXO3 is crucial for suppressing tumor growth by regulating p27kip1.
- FOXO3 deficiency in mice leads to significant colonic epithelial proliferation.
- Intracytoplasmic lipid droplets (LDs) are increasingly observed in human tumor tissues.
Purpose of the Study:
- To investigate the role of FOXO3 in regulating lipid droplet density in colonic cells.
- To determine the relationship between LD density, FOXO3, and colon cancer cell proliferation.
- To explore FOXO3 and LDs as potential therapeutic targets for colon cancer.
Main Methods:
- Analysis of LDs and PLIN2 expression in Foxo3-deficient and normal colonic epithelial cells and mouse colonic tumors.
- Stimulation of LD density in human colon cancer cells and assessment of FOXO3 and SIRT6 levels.
- Investigating the effect of LD density manipulation on FOXO3 promoter binding and p27kip1 expression.
- Evaluating the impact of PLIN2 silencing or FOXO3 overexpression on colon cancer cell proliferation.
Main Results:
- Foxo3-deficient colonic cells exhibit a striking increase in intracytoplasmic LDs.
- Increased LD density in human colon cancer cells leads to PI3K-dependent loss of FOXO3 and decreased SIRT6.
- LD-dependent loss of FOXO3 results in decreased p27kip1 expression and promotes colon cancer cell proliferation.
- Silencing PLIN2 or overexpressing FOXO3 inhibits colon cancer cell proliferation.
Conclusions:
- FOXO3 regulates LD density, and this interplay is critical in colon cancer.
- Increased LD density promotes colon cancer cell proliferation by inhibiting FOXO3.
- FOXO3 and LDs represent promising novel therapeutic targets for colon cancer intervention.
