Phosphatidylinositol 3-kinase mediates the ability of retinol to decrease colorectal cancer cell invasion

Area of Science:

• Oncology
• Molecular Biology
• Nutritional Science

Background:

• Retinol (vitamin A) has been shown to reduce colorectal cancer cell invasion and phosphatidylinositol 3-kinase (PI3K) activity via a retinoic acid receptor-independent pathway.
• The relationship between retinol's effects on invasion and PI3K activity requires further elucidation.

Purpose of the Study:

• To investigate the link between retinol's inhibition of PI3K activity and its anti-metastatic effects in colorectal cancer.
• To determine if constitutively active PI3K in colorectal cancer cells abrogates the anti-metastatic effects of retinol.

Main Methods:

• Utilized parental HCT-116 cells (wild-type and constitutively active PI3K alleles) and mutant HCT-116 cell lines (homozygous for constitutively active PI3K).
• Assessed the impact of retinol treatment on cell invasion, matrix metalloproteinase-9 (MMP-9) activity, and tissue inhibitor of matrix metalloproteinase-I (TIMP-I) levels in vitro.
• Evaluated the effect of vitamin A supplementation on colorectal cancer metastasis in athymic mice injected with parental or mutant HCT-116 cells.

Main Results:

• Retinol (10 μM) reduced invasion and decreased MMP-9 activity while increasing TIMP-I levels in parental HCT-116 cells.
• These effects were not observed in mutant HCT-116 cell lines with constitutively active PI3K.
• Vitamin A supplementation tended to reduce metastasis in mice injected with parental cells but had no effect in mice injected with mutant cells.

Conclusions:

• The ability of retinol to inhibit PI3K activity is crucial for its anti-metastatic effect in colorectal cancer.
• Targeting PI3K signaling represents a potential therapeutic strategy for managing colorectal cancer metastasis.