Inhibitory effect of Camellia sinensis, Ilex paraguariensis and Ardisia compressa tea extracts on the proliferation of human head and neck squamous carcinoma cells

Abstract

In vitro cell proliferation, cell cycle arrest and induction of apoptosis were investigated, using three human head and neck squamous cell carcinoma (HNSCC) cell lines (OSCC-3, SCC-61, and SQ-20B). Aqueous extracts of Camellia sinensis, Ilex paraguariensis, and Ardisia compressa were tested and (-) epigallocatechin-3-gallate (EGCG) was used for comparison. For EGCG the IC₅₀ values were between 80 and 166 μM and for the extracts among 75 and 505 μM eq. (+) catechin, with C. sinensis demonstrating dominant cytotoxicity. There was not a correlation between antioxidant capacity and cytotoxicity. Flow cytometry analysis revealed similarities in response for EGCG and C. sinensis. The A. compressa extract altered DNA distribution (P < 0.05) and was the most effective in induction of apoptosis via caspases (P < 0.05). Not all HNSCC cells tested responded to the same preventive agents. The fact that A. compressa inhibits HNSCC cell proliferation makes this aqueous extract a potential source of chemopreventive agents.

Keywords: Ardisia compressa; Camellia sinensis; Chemoprevention; Head and neck squamous carcinoma cells; Ilex paraguariensis; Polyphenols.

Fig. 1

Effect of AT on OSCC-3 cell histomorphology. (A) Control, 24 h; (B) treated with 112.7 μM eq. (+) catechin AT, 24 h; (C) control, 48 h; (D) treated with 112.7 μM eq. (+) catechin AT, 48 h (original magnification, ×32).

Fig. 2

Cell cycle distribution (%) of SCC-61, HaCaT, SQ-20B and OSCC-3 exposed to etoposide, EGCG, GT, MT or AT for 48 h; see Section 2 for details. Values are means ± SD from three independent experiments performed in triplicate. Bars with different letters are statistically different from the control (PBS) (P < 0.05) for each cell cycle stage, □ G0/G1; S; ■ G2/M, within treatments. IC₅₀ concentrations were used and these differed depending on extract and cell line tested (see Table 1).

Fig. 3

Induction of apoptosis (%) by extracts in HaCaT, immortalized human keratinocytes, and HNSCC cells. Rapidly proliferating HaCaT and three HNSCC cells; SCC-61, SQ-20B and OSCC-3, were exposed to IC₅₀ concentrations of EGCG and etoposide, GT and MT (AT: IC₂₀ for SCC-61 and OSCC-3). Values are means ± SD from three independent experiments performed in triplicate. *Statistically different from PBS (P < 0.05) for either alive or apoptotic cells. □ alive cells, ■ apoptotic cells.

Fig. 4

(A) Caspase activation by Ardisia compressa extract in HNSCC cell lines. Cell were treated with AT for 48 h. (B) Effect of AT on cell death. Cells were treated with AT for 48 h, data are shown as percent of the total number of tumorogenic cells (SCC-61, OSCC-3, SQ-20B). (C) Control (cells without treatment). Values are means ± SD from three independent experiments performed in triplicate.