Signature of VDR miRNAs and epigenetic modulation of vitamin D signaling in melanoma cell lines.

Abstract

BACKGROUND:

Melanoma cells express the nuclear vitamin D receptor (VDR), indicating that malignant melanoma represents a promising target for treatment with 1,25-dihydroxyvitamin D3 (1,25(OH)(2)D(3)) or its analogs. We previously showed that some melanoma cell lines are resistant to the antiproliferative effects of 1,25(OH)(2)D(3) and that 1,25(OH)(2)D(3)-sensitivity can, at least in part, be restored by co-treatment with the histone deacetylase inhibitor (HDACI) Trichostatin A (TSA) or with the DNA methyltransferase inhibitor (DNMTI), 5-azacytidine (5-Aza). This study aimed at gaining further insights into the molecular mechanisms that underlie the epigenetic modulation of 1,25(OH)(2)D(3)-sensitivity in melanoma cells.

MATERIALS AND METHODS:

The expression of VDR mRNA, protein and two candidates of VDR microRNAs (miR-125b, miR-27b) were compared in 1,25(OH)(2)D(3)-responsive (MeWo, SK-Mel28) and -resistant (SK-Mel5, IGR) melanoma cell lines and in normal human melanocytes (NHM) using real time PCR and western blot analysis. Additionally, the effect of 1,25(OH)(2)D(3), epigenetic modulating drugs (TSA, 5-Aza) and miR-125b antisense on the expression of VDR messenger RNA (mRNA)/protein, miR-125b and miR-27b was investigated.

RESULTS:

Treatment with 1,25(OH)(2)D(3) and/or epigenetic drugs (5-Aza, TSA) modulated the VDR mRNA expression in the 1,25(OH)(2)D(3)-responsive and - resistant melanoma cell lines and in the NHM. Treatment with 5-Aza, but not with TSA, reduced the expression of miR-125b in the 1,25(OH)(2)D(3)-responsive and -resistant melanoma cell lines and in the NHM. Treatment with 1,25(OH)(2)D(3) and/or epigenetic drugs (5-Aza, TSA) reduced the miR-27b expression in three out of four melanoma cell lines. Moreover, no difference was observed in VDR protein expression in the 1,25(OH)(2)D(3)-responsive as compared to the 1,25(OH)(2)D(3)-resistant melanoma cell lines. Transfection with miR-125b antisense did not affect the VDR mRNA/protein expression in the IGR cells.

CONCLUSION:

Responsiveness to 1,25(OH)(2)D(3) corresponds to the expression level of VDR mRNA which in turn might be regulated by VDR microRNAs or epigenetic modulating drugs.

• Authors: Salma Essa, Sandra Reichrath, Ulrich Mahlknecht, Mathias Montenarh, Thomas Vogt, Jörg Reichrath
• Journal: Anticancer research (Anticancer Res) Vol. 32 Issue 1 Pg. 383-9 (Jan 2012) ISSN: 1791-7530 [Electronic] Greece
• PMID: 22213330 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antimetabolites, Antineoplastic
• MIRN125 microRNA, human
• MIRN27 microRNA, human
• MicroRNAs
• RNA, Messenger
• Receptors, Calcitriol
• dihydroxy-vitamin D3
• Vitamin D
• Azacitidine

Topics

• Antimetabolites, Antineoplastic (pharmacology)
• Apoptosis (drug effects)
• Azacitidine (pharmacology)
• Blotting, Western
• Cell Proliferation (drug effects)
• Cells, Cultured
• Epigenomics
• Humans
• Melanocytes (cytology, drug effects, metabolism)
• Melanoma (drug therapy, genetics, metabolism)
• MicroRNAs (genetics)
• RNA, Messenger (genetics)
• Real-Time Polymerase Chain Reaction
• Receptors, Calcitriol (genetics, metabolism)
• Skin Neoplasms (drug therapy, genetics, metabolism)
• Vitamin D (analogs & derivatives, pharmacology)