Regulatory effects of lycopene on the key signaling receptors in human cutaneous squamous cell carcinoma cell line COLO16

Abstract

Objective To evaluate the regulatory effects of lycopene on the key signaling receptors in human cutaneous squamous cell carcinoma cell line COLO16. Methods Cultured COLO16 cells were divided into 6 groups to be treated with lycopene at different concentrations of 0, 5, 10, 15, 20, and 25 μmol/L, respectively, for 24 hours (control group and 5, 10, 15, 20, 25 μmol/L lycopene groups) , followed by estimation of the cell viability by lactate dehydrogenase (LDH) assay. Lycopene at a safe concentration was selected based on the LDH assay, and used for the determination of expression of signaling receptors, and Western blot analysis was performed to measure the expression of key signaling receptor proteins, including epidermal growth factor receptor (EGFR) , glucocorticoid receptor (GR) , retinoic acid receptor-alpha (RAR-α) , retinoid X receptor-alpha (RXR-α) , androgen receptor (AR) and progesterone receptor (PR) . Statistical analysis was carried out by one-way analysis of variance (ANOVA), Tukey multiple comparison teat and Brown-Forsythe test with the SPSS software. Results After 24-hour treatment with lycopene at different concentrations, there were significant differences in the rate of cell death among these groups (F= 13.116, P 0.05) compared with those without lycopene treatment. Conclusion Lycopene can decrease the viability of COLO16 cells, inhibit the activation of EGFR protein, and up-regulate the expression of GR, and these effects may be specific for tumor cells. Key words: Carcinoma, squamous cell; Cell line, tumor; Receptor, epidermal growth factor; Receptors, glucocorticoid; COLO16 cells; Lycopene