Calcipotriol affects keratinocyte proliferation by decreasing expression of early growth response-1 and polo-like kinase-2.
OBJECTIVE
Calcipotriol is a potent drug for topical treatment of psoriasis because it manages to inhibit keratinocyte proliferation. In the present study we investigated the effects of calcipotriol on gene expression in human keratinocytes in terms of mechanism of how calcipotriol decreases proliferation.


METHODS
Cell proliferation was analyzed by MTT assay. The differential display approach together with qPCR was used to assess the gene expression after treatment. In addition, Western immunoblotting revealed differences on the protein level. Finally, transfection of the KCs with specific small interfering RNA determined the genes necessary to inhibit proliferation.


RESULTS
KCs proliferation was decreased in a concentration-dependent manner. Moreover, calcipotriol dowregulated the expression of two proliferation factors: early growth response-1 (EGR1) and polo-like kinase-2 (PLK2). The protein levels of EGR1 and PLK2 were also decreased. Specific siRNA against EGR1 and PLK2 in KCs resulted in marked reduction of EGR1 and PLK2 expression. In both cases, the reduction resolved in the decreased proliferation of KCs.


CONCLUSIONS
This study provides a new insight into how calcipotriol affects proliferation of keratinocytes by decreasing the expression of EGR1 and PLK2. Furthermore, the results offer groundwork for developing novel compounds for the treatment of hyperproliferative skin disorders like psoriasis.
Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Askerceva 7, 1000, Ljubljana, Slovenia. jernej.kristl@ffa.uni-lj.si
Jernej
J
Kristl
Petra
P
Slanc
Metka
M
Krasna
Ales
A
Berlec
Matjaz
M
Jeras
Borut
B
Strukelj
D015153:Blotting, Western; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D003879:Dermatologic Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D014162:Transfection; D000097869:Polo-Like Kinase 1
D002117:Calcitriol; D018797:Cell Cycle Proteins; D003879:Dermatologic Agents; D051766:Early Growth Response Protein 1; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000097869:Polo-Like Kinase 1; C497325:EGR1 protein, human; C055085:calcipotriene