Apoptosis inducing effects of Kuding tea polyphenols in human buccal squamous cell carcinoma cell line BcaCD885

Abstract

Tea polyphenols are functional substances present in tea. Kuding tea as a traditional drink also contains these compounds. After 25, 50 and 100 μg/mL of Kuding tea polyphenol treatment for 48 h, cell proliferation of human buccal squamous cell carcinoma cell line BcaCD885 was inhibited, and the 100 μg/mL of Kuding tea polyphenol showed the highest inhibitory rate at 72.3%. Compared to the lower concentration, the 100 μg/mL of Kuding tea polyphenols significantly (p < 0.05) induced apoptosis as determined by flow cytometry analysis, the content of sub-G1 cancer cells was 32.7%. By RT-PCR and western blot assays, Kuding tea polyphenol significantly induced apoptosis in BcaCD885 cancer cells (p < 0.05) by upregulating caspase-3, caspase-8, caspase-9, Fas/FasL, Bax, p53, p21, E2F1, p73 and downregulating Bcl-2, Bcl-xL, HIAP-1, and HIAP-2 mRNA and protein expressions. Kuding tea polyphenols thus present apoptosis inducing effects in vitro.

Figure 1

Time-dependent growth inhibition by Kuding tea polyphenol in human buccal squamous cell carcinoma cell line BcaCD885. Cells were plated at an initial density of 1 × 10⁵ cells per plate in six well plates and incubated for 24 h.

Figure 2

Apoptosis induced by Kuding tea polyphenol. The DNA content of sub-G1 human buccal squamous cell carcinoma cell line BcaCD885 was evaluated using a flow cytometer. Apoptosis was monitored by staining with annexin-V FITC. a–d, mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.

Figure 3

Effects of Kuding tea polyphenol on the mRNA expression of procapase-3, -8, -9 and protein expression of capase-3, -8 , -9 in human buccal squamous cell carcinoma cell line BcaCD885. Fold-ratio: gene expression/GAPDH (β-actin) × control numerical value (control fold ratio: 1). a–d, mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.

Figure 4

Effects of Kuding tea polyphenol on the mRNA and protein expression of Fas/FasL in human buccal squamous cell carcinoma cell line BcaCD885. a–d, mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.

Figure 5

Effects of Kuding tea polyphenol on the mRNA and protein expression of Bax, Bcl-2 and Bcl-xL in human buccal squamous cell carcinoma cell line BcaCD885. Fold-ratio: gene expression/GAPDH (β-actin) × control numerical value (control fold ratio: 1). a–d, mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.

Figure 6

Effects of Kuding tea polyphenol on the mRNA and protein expression of HIAP-1 and HIAP-2 in human buccal squamous cell carcinoma cell line BcaCD885. Fold-ratio: gene expression/GAPDH (β-actin) × control numerical value (control fold ratio: 1). a–d, mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.

Figure 7

Effects of Kuding tea polyphenol on the mRNA and protein expression of p53 and p21 in human buccal squamous cell carcinoma cell line BcaCD885. Fold-ratio: gene expression/GAPDH (β-actin) × control numerical value (control fold ratio: 1). a–d, mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.

Figure 8

Effects of Kuding tea polyphenol on the mRNA and protein expression of E2F1 and p73 in human buccal squamous cell carcinoma cell line BcaCD885. Fold-ratio: gene expression/GAPDH (β-actin) × control numerical value (control fold ratio: 1). a–d, Mean values with different letters over the bars are significantly different (p < 0.05) according to Duncan’s multiple range test.