Novel genetic and epigenetic alterations in ... - Ous-research.no

Novel genetic and epigenetic alterations in ... - Ous-research.no Novel genetic and epigenetic alterations in ... - Ous-research.no

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embedded carcinomas was analyzed in two different PCRs: the mononucleotide markers(BAT25 and BAT26) and the dinucleotide markers (D2S123, D5S346 and D17S250) wereanalyzed separately using the same PCR conditions with the exception of number of cycles(mononucleotide markers – 30 cycles; dinucleotide markers – 35 cycles). Samples whichshowed instability at more than 20% of the markers were denoted MSI-H, the ones withonly one instable marker were denoted MSI-L, while samples with no instable markers weredenoted MSS.Mutation screeningMutation analysis of the above selected target genes was performed by fragment analysis ofthe microsatellite-containing regions of each gene. With the exception of PTEN and EP300,which both had repeats of interest in two separate exons, only one fragment was investigatedper gene, yielding a total of 43 fragments, ranging from 61-236 bp in size. The fragmentswere amplified in multiplex PCRs averaging in five genes per reaction using the same PCRconditions as the pentaplex MSI-markers (see Supplementary table for primer and PCRdetails). When possible, the primer sequences were those that had been used in previousstudies – by now some gene fragments have canonical primer sequences – the remainderwere designed for this study using the Primer3 program. † Default settings were used exceptfor adjusting melting temperatures upon occasion. All primer pairs were assessed for† http://frodo.wi.mit.edu/cgi-bin/primer36

specificity, i.e. that they only amplify unique sequences of the human genome, by in silicoPCR, ‡ and for hairpin and/or primer-dimer formation at NetPrimer. §The fragments were labeled with the G5 dye set from Applied Biosystems; PET – red, NED– yellow, VIC – green, and 6-FAM – blue. The size standard used was GS500 LIZ (orange).All fragments were analyzed on a 3730 DNA Analyzer (Applied Biosystems, Foster City,CA, USA) using default Microsatellite Analysis settings in the GeneMapper3.7 software.Electropherograms were visually examined for insertions/deletions by three independentauthors, TA, ECR and MAM, against corresponding fragments from DNA from fourdifferent disease-free individuals. All assays were duplicated in tandem runs using differentPCR machines to ensure the robustness of the results.Mutation verification by sequencingIn order to determine the false discovery rate of the fragment analysis results, 18 of thegenes (ACVR2A, AIM2, ASTE1, AXIN2, BLM, EPHB2, GRK4, MBD4, PTHLH, RAD50,RBBP8, RCC2, SEMG1, SLC23A2, SYCP1, TAF1B, WISP3 and ZMYND8) weresequenced. Genomic DNA from a total of 107 samples was re-amplified with new primersincluding M13-tails, and directly sequenced in both directions on a 3730 Genetic Analyzer(Applied Biosystems). An initial PCR was performed using HotStar HiFidelity Polymerase(QIAGEN) following manufacture’s instructions in a 25μl reaction before enzymatic clean-‡ http://genome.ucsc.edu/cgi-bin/hgpcr§ http://www.premierbiosoft.com/netprimer7

specificity, i.e. that they only amplify unique sequences of the human ge<strong>no</strong>me, by <strong>in</strong> silicoPCR, ‡ <strong>and</strong> for hairp<strong>in</strong> <strong>and</strong>/or primer-dimer formation at NetPrimer. §The fragments were labeled with the G5 dye set from Applied Biosystems; PET – red, NED– yellow, VIC – green, <strong>and</strong> 6-FAM – blue. The size st<strong>and</strong>ard used was GS500 LIZ (orange).All fragments were analyzed on a 3730 DNA Analyzer (Applied Biosystems, Foster City,CA, USA) us<strong>in</strong>g default Microsatellite Analysis sett<strong>in</strong>gs <strong>in</strong> the GeneMapper3.7 software.Electropherograms were visually exam<strong>in</strong>ed for <strong>in</strong>sertions/deletions by three <strong>in</strong>dependentauthors, TA, ECR <strong>and</strong> MAM, aga<strong>in</strong>st correspond<strong>in</strong>g fragments from DNA from fourdifferent disease-free <strong>in</strong>dividuals. All assays were duplicated <strong>in</strong> t<strong>and</strong>em runs us<strong>in</strong>g differentPCR mach<strong>in</strong>es to ensure the robustness of the results.Mutation verification by sequenc<strong>in</strong>gIn order to determ<strong>in</strong>e the false discovery rate of the fragment analysis results, 18 of thegenes (ACVR2A, AIM2, ASTE1, AXIN2, BLM, EPHB2, GRK4, MBD4, PTHLH, RAD50,RBBP8, RCC2, SEMG1, SLC23A2, SYCP1, TAF1B, WISP3 <strong>and</strong> ZMYND8) weresequenced. Ge<strong>no</strong>mic DNA from a total of 107 samples was re-amplified with new primers<strong>in</strong>clud<strong>in</strong>g M13-tails, <strong>and</strong> directly sequenced <strong>in</strong> both directions on a 3730 Genetic Analyzer(Applied Biosystems). An <strong>in</strong>itial PCR was performed us<strong>in</strong>g HotStar HiFidelity Polymerase(QIAGEN) follow<strong>in</strong>g manufacture’s <strong>in</strong>structions <strong>in</strong> a 25μl reaction before enzymatic clean-‡ http://ge<strong>no</strong>me.ucsc.edu/cgi-b<strong>in</strong>/hgpcr§ http://www.premierbiosoft.com/netprimer7

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