title: Promoter hypermethylation of tetraspanin members contributes to their silencing in myeloma cell lines.
abstract: Multiple myeloma (MM) cell interactions with their microenvironment modulate acquired drug resistance and disease progression. Indeed, reported aberrant gene methylation underscores the possible role of epigenetic events in MM's molecular profile. Membranal tetraspanins are often inversely correlated with cancer prognosis and metastasis, however mutations were unidentified hitherto. Their promoter characteristics and frequent down-regulation conform to transcriptional silencing by chromatin remodeling. We delineated the baseline expression of select tetraspanins in MM cell lines (RPMI 8226, U266, ARP1, ARK, CAG and EBV transformed ARH77) and fresh bone marrow samples (n = 9) for the first time and determined reduced expression of CD9, CD81 and absence of CD82. Thus, we aimed to assess their promoter methylation status. Indeed, we established CD9, CD81 and CD82 promoter methylation in MM cell lines employing methyl-specific-PCR of bisulfite modified G-DNA and PCR of G-DNA digested with methylation-sensitive restriction enzyme (Hin6I). Re-transcription of assayed genes in the cell lines following de-methylation [5-aza-2'-deoxycytidine (5-aza-dC)] confirmed the mechanistic significance of methylation to their regulation. Combined de-methylation and de-acetylation [Trichostatin A (TsA)] induced synergistic elevation of CD82 mRNA. We conclude that chromatin remodeling contributes to tetraspanin silencing in MM.
authors.affiliation: Oncogenetic Laboratory, Sapir Medical Center, Meir Hospital, Kfar Sava 44281, Israel. Druckerl@clalit.org.il
authors.forename: Liat
authors.initials: L
authors.lastname: Drucker
authors.forename: Tali
authors.initials: T
authors.lastname: Tohami
authors.forename: Shelly
authors.initials: S
authors.lastname: Tartakover-Matalon
authors.forename: Victoria
authors.initials: V
authors.lastname: Zismanov
authors.forename: Hava
authors.initials: H
authors.lastname: Shapiro
authors.forename: Judith
authors.initials: J
authors.lastname: Radnay
authors.forename: Michael
authors.initials: M
authors.lastname: Lishner
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly; D019175:DNA Methylation; D015536:Down-Regulation; D020868:Gene Silencing; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D009101:Multiple Myeloma / Q000235:genetics* / Q000473:pathology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic
chemical_list: D015703:Antigens, CD; D008562:Membrane Glycoproteins