title: In vitro comparison of the vitamin D endocrine system in 1,25(OH)2D3-responsive and -resistant melanoma cells.
abstract: We studied effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], its analog seocalcitol (EB 1089), and 25-hydroxyvitamin D3 [25(OH)D3], on the growth of seven melanoma cell lines. While three cell lines (MeWo, SK-Mel-28, SM) responded to antiproliferative effects of active vitamin D analogs, the others (SK-Mel-5, SK-Mel-25, IGR, MeUuso) were resistant. A strong induction (7000-fold) of 1,25-dihydroxyvitamin D-24-hydroxylase (24OHase, CYP24) mRNA was detected in responsive cell lines along with 1,25(OH)2D3-treatment, indicating functional integrity of vitamin D receptor (VDR)-mediated transcription. In contrast, induction of 24OHase was much lower in resistant melanoma cells (70-fold). VDR mRNA was induced up to 3-fold both in responsive and resistant cell lines along with 1,25(OH)2D3-treatment. RNA for vitamin D-activating enzymes vitamin D-25-hydroxylase (25OHase, CYP27A1) and 25-hydroxyvitamin D-lalpha-hydroxylase (lalphaOHase, CYP27B1) was detected in all melanoma cell lines analyzed, additionally we show splicing variants of lalphaOHase in SK-Mel-28 cells. Expression of 250Hase and laOHase was marginally modulated along with treatment. Proliferation of melanoma cells was not inhibited by treatment with 25(OH)D3, indicating no significant stimulation of endogeneous production of antiproliferative acting 1,25(OH)2D3. In conclusion, we characterize the vitamin D endocrine system in melanoma cells and demonstrate that the majority of melanoma cell lines analyzed is resistant to antiproliferative effects of 1,25(OH)2D3. It can be speculated that these alterations are of importance for pathogenesis and growth of metastasizing malignant melanoma. Additionally, our findings indicate that only a minority of cases with metastasizing melanoma may represent a promising target for palliative treatment with new vitamin D analogs that exert little calcemic side effects or for pharmacological modulation of 1,25(OH)2D3-synthesis/metabolism.
authors.affiliation: Department of Dermatology , The Saarland University Hospital, Homburg Germany. hajrei@uniklinik.saarland.de
authors.forename: Jörg
authors.initials: J
authors.lastname: Reichrath
authors.forename: Martin
authors.initials: M
authors.lastname: Rech
authors.forename: Maryam
authors.initials: M
authors.lastname: Moeini
authors.forename: Eckart
authors.initials: E
authors.lastname: Meese
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Tilgen
authors.forename: Markus
authors.initials: M
authors.lastname: Seifert
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D017398:Alternative Splicing; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002117:Calcitriol / Q000031:analogs & derivatives / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D053493:Cholestanetriol 26-Monooxygenase / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D004703:Endocrine System / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008545:Melanoma / Q000378:metabolism*; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism*; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D014807:Vitamin D / Q000378:metabolism*; D065668:Vitamin D3 24-Hydroxylase
chemical_list: D000970:Antineoplastic Agents; D018167:Receptors, Calcitriol; D014807:Vitamin D; D013250:Steroid Hydroxylases; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D002117:Calcitriol; C078903:seocalcitol