Preferential MGMT hypermethylation in SDH-deficient wild-type GIST

Olivier T Giger, Rogier Ten Hoopen, David Shorthouse, Shukri Abdullahi, Venkata Ramesh Bulusu, Saili Jadhav, Eamonn R Maher, Ruth T Casey

Research output: Contribution to journalArticlepeer-review


AIMS: Wild-type gastrointestinal stromal tumours (wtGIST) are frequently caused by inherited pathogenic variants, or somatic alterations in the succinate dehydrogenase subunit genes (SDHx). Succinate dehydrogenase is a key enzyme in the citric acid cycle. SDH deficiency caused by SDHx inactivation leads to an accumulation of succinate, which inhibits DNA and histone demethylase enzymes, resulting in global hypermethylation. Epigenetic silencing of the DNA repair gene MGMT has proven utility as a positive predictor of the therapeutic efficacy of the alklyating drug temozolomide (TMZ) in tumours such as glioblastoma multiforme. The aim of this study was to examine MGMT promoter methylation status in a large cohort of GIST.

METHODS: MGMT methylation analysis was performed on 65 tumour samples including 47 wtGIST (33 SDH-deficient wtGIST and 11 SDH preserved wtGIST) and 21 tyrosine kinase (TK) mutant GIST.

RESULTS: MGMT promoter methylation was detected in 8 cases of SDH-deficient (dSDH) GIST but in none of the 14 SDH preserved wild-type GIST or 21 TK mutant GIST samples analysed. Mean MGMT methylation was significantly higher (p 0.0449) and MGMT expression significantly lower (p<0.0001) in dSDH wtGIST compared with TK mutant or SDH preserved GIST. No correlation was identified between SDHx subunit gene mutations or SDHC epimutation status and mean MGMT methylation levels.

CONCLUSION: MGMT promoter hypermethylation occurs exclusively in a subset of dSDH wtGIST. Data from this study support testing of tumour MGMT promoter methylation in patients with dSDH wtGIST to identify those patients who may benefit from most from TMZ therapy.

Original languageEnglish
Pages (from-to)34-39
Number of pages6
JournalJournal of Clinical Pathology
Issue number1
Early online date5 Oct 2022
Publication statusPublished - 14 Dec 2023

Bibliographical note

© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.
This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See:


  • Humans
  • Succinate Dehydrogenase
  • Gastrointestinal Stromal Tumors/genetics
  • DNA Methylation
  • Epigenesis, Genetic
  • Mutation
  • Protein-Tyrosine Kinases/genetics
  • DNA Repair Enzymes/genetics
  • DNA Modification Methylases/genetics
  • Tumor Suppressor Proteins/genetics


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