Calcipotriol inhibits autocrine phosphorylation of EGF receptor in a calcium-dependent manner, a possible mechanism for its inhibition of cell proliferation and stimulation of cell differentiation.
We report in this study that proliferation inhibition of SCC13 cells by calcipotriol was possibly mediated by its inhibitory effect on autocrine activation of EGF receptor. Based on MTT assay, PCNA staining, DAPI staining, and involucrin immunocytochemical staining, we showed that calcipotriol inhibited cell growth and stimulated differentiation but did not induce apoptosis. Western blot analysis of concanavalin-A-bound fraction demonstrated that calcipotriol specifically dephosphorylated 170- and 66-kDa polypeptides from 8 h posttreatment and complete dephosphorylation was observed at 12 h posttreatment. The 170- and 66-kDa polypeptides were confirmed as EGF receptor and Shc, respectively. Calcipotriol-mediated EGF receptor dephosphorylation required the presence of extracellular calcium. Similar kinetics of the dephosphorylation was also observed in HaCaT cells cultured in medium of high calcium concentration. By BrdU labeling, we also showed calcium dependency of calcipotriol for the inhibition of cell proliferation. Therefore, EGF receptor deactivation by calcipotriol might be a mechanism of action for the inhibition of cell proliferation and the stimulation of differentiation in SCC13 cell and HaCaT cells.
Lee
E
E
National Research Laboratory of Tissue Engineering, Korea Cancer Center Hospital, KAERI, 215-4, Gongneung-Dong, Nowon-Gu, Seoul, 139-706, Korea.
Jeon
S H
SH
Yi
J Y
JY
Jin
Y J
YJ
Son
Y S
YS
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D019898:Autocrine Communication / Q000187:drug effects*; D015153:Blotting, Western; D001973:Bromodeoxyuridine; D002117:Calcitriol / Q000031:analogs & derivatives / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D066246:ErbB Receptors / Q000378:metabolism*; D005456:Fluorescent Dyes; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000187:drug effects; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013778:Tetrazolium Salts; D013844:Thiazoles
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000970:Antineoplastic Agents; D005456:Fluorescent Dyes; D018809:Proliferating Cell Nuclear Antigen; D011498:Protein Precursors; D011506:Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013778:Tetrazolium Salts; D013844:Thiazoles; C055085:calcipotriene; C032253:involucrin; D066246:ErbB Receptors; C022616:thiazolyl blue; D002117:Calcitriol; D001973:Bromodeoxyuridine; D002118:Calcium