MGMT methylation assessment in glioblastoma: MS-MLPA versus human methylation 450K beadchip array and immunohistochemistry.
OBJECTIVE
The MGMT gene encodes a DNA repair enzyme that counteracts with chemotherapy efficiency, specifically with alkylating agents such as temozolomide (TMZ). It is well established that MGMT methylation should be screened as a predictive marker for TMZ in glioblastoma, and we thus aimed to determine a reliable and practical diagnostic method of MGMT methylation detection.


METHODS
55 glioblastomas were investigated for MGMT methylation status using methylation-specific multiplexed ligation probe amplification (MS-MLPA), illumina human methylation 450K BeadChip array (HM450 K) analysis, and compared to MGMT protein expression by immunohistochemistry (IHC) staining. The methylation status of promoter, intron and all MGMT CpG targeted sites were separately correlated to patient's survival.


RESULTS
In addition to MS-MLPA and 450 K concordance, our results showed significantly higher overall survival (OS) of patients receiving TMZ and presenting MGMT methylated promoter (mean OS = 21.5 months, p = 0.046). Including all glioblastoma cases and regardless of chemotherapy, MS-MLPA showed significant survival difference between MGMT methylated and unmethylated cases (mean OS = 13, p = 0.021).


CONCLUSIONS
We concluded that in glioblastoma, MGMT promoter methylation predicts TMZ sensitivity. This current comparative analysis leads to consider that MS-MLPA is a valuable as HM450 K array for MGMT methylation status screening.
Laboratory of Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Street Ibn Eljazzar, 4000, Sousse, Tunisia. tsaoussen@yahoo.fr.
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Trabelsi
Department of Imagery, Sahloul University Hospital, Sousse, Tunisia.
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Mama
Department of Neurosurgery, Sahloul University Hospital, Sousse, Tunisia.
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Ladib
Department of Neurosurgery, Sahloul University Hospital, Sousse, Tunisia.
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Karmeni
Laboratory of Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Street Ibn Eljazzar, 4000, Sousse, Tunisia.
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Haddaji Mastouri
Laboratory of Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Street Ibn Eljazzar, 4000, Sousse, Tunisia.
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Chourabi
Department of Cytopathology, Farhat Hached University Hospital, Sousse, Tunisia.
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Mokni
Department of Imagery, Sahloul University Hospital, Sousse, Tunisia.
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Tlili
Department of Neurosurgery, Sahloul University Hospital, Sousse, Tunisia.
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Krifa
Department of Cytopathology, Farhat Hached University Hospital, Sousse, Tunisia.
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Yacoubi
Laboratory of Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Street Ibn Eljazzar, 4000, Sousse, Tunisia.
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Saad
Laboratory of Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Street Ibn Eljazzar, 4000, Sousse, Tunisia.
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H'mida Ben Brahim
D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics*; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics* / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D015996:Survival Rate; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
D014408:Biomarkers, Tumor; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes
HM450 K beadchip array; MGMT; MS-MLPA; Methylation