Abstract: Bi Suyun, Li Li, Xu Song, Zhang Mengli, Gu Heng, Zhou Zhihai, Chen Xu Department of Dermatology and Venereology, Tianjin Medical University General Hospital, Tianjin 300070, China （Bi SY, Zhou ZH）; Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing 210042, China （Li L, Xu S, Zhang ML, Gu H, Chen X） Corresponding authors: Chen Xu, Email: doctor_chx@126.com; Zhou Zhihai, Email: zhouzh65@sohu.com 【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 of signaling receptors, and Western blot analysis was performed to measure the 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）, and the rate of cell death in the 25 μmol/L lycopene group significantly differed from that in the control group （P < 0.05）. Therefor, lycopene at concentrations of 5, 10 and 20 μmol/L were selected to treat COLO16 and HaCaT cells as well as human epidermal keratinocyte （HEK） for 24 hours in the following experiment. The treatment with lycopene significantly decreased the phosphorylation level of EGFR （P < 0.05）, but significantly increased the of GR protein （P < 0.05）, and showed no significant effects on the protein of RAR-α, RXR-α, AR, and PR in COLO16 cells. After 24-hour treatment with lycopene at concentrations of 5, 10 and 20 μmol/L, there were no significant changes in the phosphorylation level of EGFR protein or the of GR protein in HaCaT cells and HEK （all 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 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