Ginger Root Bioactive Compounds Specifically Inhibits Growth of Colon Cancer Cells in Culture

Abstract

Objective: Colon cancer is affluent among many people, and having cancer greatly impacts the lives of many. Ginger is a common food, particularly in Asian cuisine. However, the health benefits of ginger as a whole food and 6-gingerol, its bioactive compound in prevention of colon cancer have not been fully addressed. This experiment investigated effects of ginger juice and 6-gingerol on colon cancer cell growth and death.

Methods: Fresh ginger roots were homogenized for juice preparation. Total phenolic contents of ginger juice were measured using Folin-C assay. Colon cancer SW480 cells and normal colon epithelial cells CCD-18Co were treated with ginger juice and/or 6-gingerol. Cell metabolic activity was assessed by MTT assay. Cell apoptosis and cell cycle arrest were accessed by immunoblotting. Data were analyzed by 2-way ANOVA with a Tukey post-hoc test and statistical significance was set at P < .05.

Results: The results showed that ginger juice selectively inhibited SW480 cell growth at 25 µL/mL for 40 hours. High doses of ginger juice (at 50 and 100 µL/mL for 40 hours) inhibited the growth of both cell types. This was independent of caspase-3 activation. Six-gingerol specifically inhibited SW480 cell growth starting at 0.5 µmoL/L (P < .01). More than 1 µmoL/L 6-gingerol did not give more power to inhibit SW480 cell growth. The results also showed that CCD-18Co cell growth rates were not changed after 6-gingerol treatments (up to 10 µmoL/L, P > .1). Immunoblotting results revealed that the elevation of Myt1 levels and decreases in CDK1, p21 Wafl/Cip1 and pSer642-Wee1 only occurred in SW480 but not CCD-18Co cells when treated with 1 and/or 2.5 µmoL/L 6-gingerol for 40 hours.

Conclusion: 6-gingerol can specifically inhibit SW480 cancer cells without killing normal CCd-18Co cells, through cell cycle arrest. Ginger juice can selectively inhibit colon cancer cell growth in a narrow window at ~25 µL/mL.

Keywords: 6-Gingerol; apoptosis; cell cycle arrest; colorectal cancer; epithelial cell; phenol.

Figure 1.

Ginger juice selectively inhibited SW480 cell growth at 25 µL/mL Colon cancer SW480 and normal colon epithelial CCD-18Co cells were treated with ginger juice for 40 hours. Cell metabolic activity was measured by MTT assay, data was normalized to the group of SW480 “0” (A). Whole cell lysates were subject to immunoblotting to detect caspase-3 activation as shown in cleaved caspase-3 (B). Representative immunoblotting images are shown. Data are from 4 independent replicates. Values with different letters are statistically different. N = 4. P < .05.

Figure 2.

6-gingerol specifically inhibited SW480 cell growth Colon cancer SW480 and normal colon epithelial CCD-18Co cells were treated with various doses of 6-gingerol for 40 hours. Cell metabolic activity was measured by MTT assay, data was normalized to the group of SW480 “0” (A). Whole cell lysates were subject to immunoblotting to detect caspase-3 activation as shown in cleaved caspase-3 (B). Representative immunoblotting images are shown. Data are from 4 independent replicates. Values with different letters are statistically different. N = 4. P < .05.

Figure 3.

6-gingerol regulates protein levels in cell cycle arrest and cell death Colon cancer SW480 and normal colon epithelial CCD-18Co cells were treated with various doses of 6-gingerol for 40 hours. Whole cell lysates were subject to immunoblotting. Representative immunoblotting images are shown (A). ImageJ was used to quantify immunoblotting images (B). Data are from 4 independent replicates. Values with different letters are statistically different. N = 4. P < .05.

Figure 4.

6-gingerol regulates levels of proteins involved in G2/M cell cycle arrest Colon cancer SW480 and normal colon epithelial CCD-18Co cells were treated with various doses of 6-gingerol for 40 hours. Whole cell lysates were subject to immunoblotting. Representative immunoblotting images are shown (A). ImageJ was used to quantify immunoblotting images (B). Data are from 4 independent replicates. Values with different letters are statistically different. Abbreviations: CDK1, cyclin dependent kinase 1. N = 4, P < .05.