Study Of The Inhibitory Effect Of EGCG On The Growth Of Salivary Adenoid Cystic Carcinoma Cells And EGFR/Erk Signal Transduction Pathway

Background and Objective:Adenoid cystic carcinoma (ACC) is one of the most common tumor in salivary. Although it grows slowly, it’s strongly invasive. ACC often grows along nerves and blood vessels. It tends to recurrence and metastasis. Nowadays we mainly treat ACC with surgery and radiotherapy. However these treatments are not ideal with poor prognosis. Though the curative effect of conventional chemotherapy should be affirmed, but its side effects and the fact that it causes the drug resistance of tumor cells are still hard problems in clinic. So to find or develop a non-toxic drugs which can inhibit tumor cell growth become a research focus of stomatology.Tea polyphenols has a good anti-tumor activity, though its mechanism remains unclear. Tea polyphenols are collectively polyphenols in tea, EGCG ((-)-Epigallocatechin-3-gallate) is the most of it. EGCG of tea polyphenols can inhibit the growth of oral cancer, lung cancer, stomach cancer, colorectal cancer and other cancer cells. Now it has been found it inhibits tumor formation, growth and metastasis through a variety of ways. The inhibitory effect of EGCG and its mechanism on different types of tumor cells is not consistent. So far, the inhibitory effect of EGCG and its mechanism on adenoid cystic carcinoma have not been recorded. This paper is to study the effect and the mechanism of EGCG on proliferation and apoptosis of SACC-83, and to provide cytological experimental foundation for further animal experiments and clinical application of EGCG.Research Method:The subject of this study is SACC-83, one of the adenoid cystic carcinoma cells. This study is aimed to find out effect and mechanism of EGCG (0-80μM) on the growth of SACC-83. Cell morphology is observed by inverted microscope, cell proliferation activity is detected by MTS method, cell apoptosis is detected by flow cytometry. Furthermore, we use Western Blot method to measure the expression level of EGFR/Erk signaling pathways and anti-apoptotic proteins Bcl-2after treated with EGCG on SACC-83cells, to explore the impact of EGCG on the growth of SACC-83cells, and to preliminarily investigate the mechanism of EGCG on cell growth.Results:1. By observe the cellular morphology under an inverted microscope we found that SACC-83cells appeared gradual apoptosis with EGCG concentration increased after being treated with EGCG (0-80μM) for48h. The cells shrinked, the connection with surrounding cells disappeared, suspension cells increased and cytoplasmic vacuoles were apparent.2. By MTS assay, EGCG (0-80μM) was found to have the effect of inhibiting the proliferation of SACC-83cells. When the concentration of EGCG reached to40μM, the cell proliferation rate was below the control group (P<0.05) after48,72h. Cell proliferation rate was significantly different (P<0.05) from the control group after being treated with EGCG of80μM for24,48,72h. After48,72h, the cell proliferation rate of 80μM group was significantly lower than40μM group, and the cell proliferation rate of40μM group was significantly lower than20μM group (P<0.05). EGCG concentration in the range of40-80μM can inhibit the growth of SACC-83cells, and there is a dose effect.3. By flow cytometry analysis, being treated with EGCG (0-80μM) for24,48,72h, apoptosis rate of SACC-83cells in20μM,40μM and80μM concentrations groups significantly increased in comparison with the control group, and the apoptosis rate of20μM group was significantly higher than that of10μM group (P<0.05). At these three time points, we did not find the differences in apoptosis rate among20μM,40μM and80μM groups (P>0.05). EGCG at concentrations of20-80μM can promote the apoptotic of SACC-83cells.4. By Western blot assay, after being treated with EGCG (0-80μM) for48h on SACC-83cells, with the increasing concentration, the expression of EGFR, p-Erk, Bcl-2protein decreased, and the expression of Erk was stable. EGCG has the effect of inhibiting the expression of Bcl-2, EGFR protein, and the phosphorylation of Erk protein on SACC-83cells.Conclusions:1. EGCG has the effect of inhibiting the growth of SACC-83cells. EGFR/Erk signaling pathway participates in the process, and has positive correlation with the concentration of EGCG2. EGCG has the effect of promoting the apoptosis of SACC-83cells. Anti-apoptotic protein Bcl-2participates in the process, and has positive correlation with the concentration of EGCG.