Green tea induces annexin-I expression in human lung adenocarcinoma A549 cells: involvement of annexin-I in actin remodeling

Abstract

Green tea polyphenols exhibit multiple antitumor activities in various in vitro and in vivo tumor models, and the mechanisms of action are not clear. Previously, we found that green tea extract (GTE) regulates actin remodeling in different cell culture systems. Actin remodeling plays an important role in cancer cell morphology, cell adhesion, motility, and invasion. Using proteomic approaches, we found GTE-induced expression of annexin-I, a multifunctional actin binding protein, in these cell lines. In this study, we aimed to further define the functional role of GTE-induced annexin-I expression in actin remodeling, cell adhesion, and motility in lung adenocarcinoma A549 cells. We found that GTE stimulates the expression of annexin-I in a dose-dependent fashion. The GTE-induced annexin-I expression appears to be at the transcription level, and the increased annexin-I expression mediates actin polymerization, resulting in enhanced cell adhesion and decreased motility. Annexin-I specific interference resulted in loss of GTE-induced actin polymerization and cell adhesion, but not motility. In fact, annexin-I specific interference itself inhibited motility even without GTE. Together, annexin-I plays an important role in GTE-induced actin remodeling, and it may serve as a potential molecular target associated with the anticancer activities of green tea.

Green tea inhibits cycolooxygenase-2 in non-small cell lung cancer cells through the induction of Annexin-1

“…The purity of the catechins in the GTE was 84% [14]. The GTE is a mixture of many catechin compounds, consisted of epigallocatechin gallate (EGCG, 43.0% by weight), epicatechin-3-gallate (ECG, 13.7%), epicatechin (EC, 6.0%), gallocatechin gallate (GCG, 5.6%), epigallocatechin (EGC, 4.0%).…”

“…Immunofluorescence analysis was performed as previously described [14]. Cells cultured directly on 1 cm diameter cover glass were fixed with 3.7% paraformaldehyde for 0.5 h were incubated with 1:3000 mouse monoclonal anti-annexin-I (BD) for 1 h, 1:500 Cy3-conjugated AffiniPure Goat Anti-Mouse IgG (HþL) (Jackson ImmunoResearch Lab, West Grove, PA, USA) for 0.5 h. Images were generated using a Nikon TE300 microscope equipped with an Imaging Microimager II digital camera.…”

“…Three small interfering RNA (siRNA)-coding oligos against human ANX1 mRNA were purchased from (Qiagen Inc., Valencia, CA, USA) as previously described [14]. The siRNA transfection of cells was performed using the transfection reagent (Qiagen) according to the manufacturer’s instructions.…”

“…However, the antineoplastic mechanism of green tea in lung cancer is not fully understood. We recently identified a functional protein target ANX1 induced by GTE in human urothelial MC-T11 cells and A549 cells using proteomic approach [13,14]. We found that GTE-induced ANX1 up-regulation in A549 cells is dose-dependent and occurs at the transcriptional level.…”

Anticancer Natural Compounds as Epigenetic Modulators of Gene Expression

“…EGCG was found to inhibit DNMT activity and reactivate methylation-silenced RARβ gene in human colon and prostate cancer cells [267]. EGCG was shown to demethylate the promoter DNA regions of genes encoding Annexin A1 ( ANXA1 ) and Wnt Inhibitory Factor 1 ( WIF1 ) in lung cancer cells [280-282]. Exposure of human epidermoid carcinoma A431 cells to EGCG treatment decreased global DNA methylation levels, as well as the levels of 5-methylcytosine, DNMT activity, and DNMT1, DNMT3A and DNMT3B proteins [283].…”