title: Marked increase of CYP24A1 mRNA level in hepatocellular carcinoma cell lines following vitamin D administration.
abstract: OBJECTIVE
  1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) inhibits cell growth and induces apoptosis in numerous types of tumors. We aimed to examine the mRNA and protein expression of 1,25(OH)(2)D(3)-inactivating CYP24A1 and mRNA expression of the activating CYP27B1 enzymes, as well as that of vitamin D receptor (VDR), in hepatocellular carcinoma (HCC) cell cultures in response to 1,25(OH)(2)D(3) administration.
  
  
  METHODS
  Increasing amounts of 1,25(OH)(2)D(3) (0.256-10 nM) were added to cultures of HepG2, Huh-Neo, Hep3B, Huh5-15 human HCC cell lines and cells then incubated for various time periods (30 min-28 h). The mRNA expression was analyzed by real time reverse transcription-polymerase chain reaction (RT-PCR). CYP24A1 protein in HepG2 cells was detected by immuncytochemistry.
  
  
  RESULTS
  CYP24A1 mRNA expression significantly (p<0.0001) increased in response to 1,25(OH)(2)D(3) administration in two cell lines: in HepG2 cells, the CYP24A1 mRNA level exhibited 5,300-fold elevation, reaching a maximum value at 8 h; in Huh-Neo cells, the increase was 152-fold that of the baseline value, with the maximum being reached at 14 h. There was no significant change in Hep3B and Huh5-15 cell lines, nor was there any change in CYP27B1 and VDR gene expression in any cell cultures. Immuncytochemistry in HepG2 cells proved that gene activation was followed by CYP24A1 protein synthesis.
  
  
  CONCLUSIONS
  Our novel data indicate that administration of 1,25(OH)(2)D(3) results in a marked increase of CYP24A1 mRNA expression in some, but not all, human HCC lines in vitro. These differences could be dependent upon the origin of the tumor cells.
authors.affiliation: First Department of Internal Medicine, Semmelweis University, Korányi Sándor Street 2/A, H-1083 Budapest, Hungary. horvath.evelyn@gmail.com
authors.forename: Evelin
authors.initials: E
authors.lastname: Horvath
authors.forename: Péter
authors.initials: P
authors.lastname: Lakatos
authors.forename: Bernadett
authors.initials: B
authors.lastname: Balla
authors.forename: János Pál
authors.initials: JP
authors.lastname: Kósa
authors.forename: Bálint
authors.initials: B
authors.lastname: Tóbiás
authors.forename: Hasan
authors.initials: H
authors.lastname: Jozilan
authors.forename: Katalin
authors.initials: K
authors.lastname: Borka
authors.forename: Henrik Csaba
authors.initials: HC
authors.lastname: Horváth
authors.forename: Ilona
authors.initials: I
authors.lastname: Kovalszky
authors.forename: Ferenc
authors.initials: F
authors.lastname: Szalay
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013250:Steroid Hydroxylases / Q000096:biosynthesis* / Q000235:genetics; D014807:Vitamin D / Q000494:pharmacology*; D065668:Vitamin D3 24-Hydroxylase
chemical_list: D012333:RNA, Messenger; D014807:Vitamin D; D013250:Steroid Hydroxylases; C585549:CYP24A1 protein, human; D065668:Vitamin D3 24-Hydroxylase