Differences in the Effects of EGCG on Chromosomal Stability and Cell Growth between Normal and Colon Cancer Cells

Abstract

The tea catechin epigallocatechin-3-gallate (EGCG) proved to be the most potent physiologically active tea compound in vitro. It possesses antioxidant as well as pro-oxidant properties. EGCG has the effect of inducing apoptosis of tumor cells and inhibiting cell proliferation. Whether this effect is associated with the antioxidant or pro-oxidative effects of EGCG affecting the genome stability of normal and cancer cells has not been confirmed. Here, we selected Human normal colon epithelial cells NCM460 and colon adenocarcinoma cells COLO205 to investigate the effects of EGCG (0−40 μg/mL) on the genome stability and cell growth status. Chromosomal instability (CIN), nuclear division index (NDI), and apoptosis was measured by cytokinesis-block micronucleus assay (CBMN), and the expression of core genes in mismatch repair (hMLMLH1 and hMSH2) was examined by RT-qPCR. We found that EGCG significantly reduced CIN and apoptosis rate of NCM460 at all concentrations (5−40 μg/mL) and treatment time, EGCG at 5 μg/mL promoted cell division; EGCG could significantly induce chromosome instability in COLO205 cells and trigger apoptosis and inhibition of cell division. These results suggest that EGCG exhibits different genetic and cytological effects in normal and colon cancer cells.

Keywords: apoptosis; chromosomal instability (CIN); epigallocatechin-3-gallate (EGCG); human colon cell.

Figure 1

Viability of COLO205 cells in media containing 0, 5, 10, 20, 40, 80 μg/mL EGCG 24 h.

Figure 2

(A) The effect of EGCG on the frequency of BNC containing chromosomal instability (CIN) biomarkers (MN and/or NPB and/or NBUD); (B) The average effect of 96-h exposure to EGCG at doses of 0, 5, 10, 20, 40 μg/mL on CIN frequency in the NCM460 cell line.

Figure 3

(A) The effect of EGCG dose on the frequency of BNC containing chromosomal instability (CIN) biomarkers (MN and /or NPB and/or NBUD); (B) The average effect of 96-h exposure to EGCG at doses of 0, 5, 10, 20, 40 μg/mL on CIN frequency in the COLO205 cell line.

Figure 4

The combined average of the effect of EGCG on NDI in NCM460 (A) and COLO205 (B). Note: Significant differences between EGCG-treated groups and controls at each treatment interval are indicated by * p < 0.05, ** p < 0.01 and *** p < 0.001.

Figure 5

The effects of EGCG dose on apoptotic cells (%) of NCM460 (A) and COLO205 (B) cells. Significant differences between EGCG-treated groups and controls at each treatment interval are indicated by * p < 0.05, ** p < 0.01, and *** p < 0.001.

Figure 6

The effect of EGCG on the expression of hMLH1 (A) and hMSH2 (B) in the NCM460 cell line. Bars sharing different letters are significantly different. Significant differences between EGCG-treated groups and controls at each treatment interval are indicated by * p < 0.05, ** p < 0.01, and *** p < 0.001.

Figure 7

The effect of EGCG on the expression of hMLH1 (A) and hMSH2 (B). Bar sharing different letters were significant differences from each other. Significant differences between EGCG-treated groups and controls at each treatment interval are indicated by * p < 0.05, ** p < 0.01, and *** p < 0.001.