Microsatellite instability and altered expressions of MLH1 and MSH2 in gastric cancer

Nor Hasyimah Haron, Ezanee Azlina Mohamad Hanif, Mohd Rizal Abdul Manaf, Jasmi Ali Yaakub, Roslan Harun, Ramelah Mohamed, Isa Mohamed Rose

Research output: Contribution to journalArticle

Abstract

Introduction: Microsatellite instability (MSI) is a hallmark of defective DNA mismatch repair (MMR) of genes especially MLH1 and MSH2. It is frequently involved in the carcinogenesis of various tumours including gastric cancer (GC). However, MSI in GCs have not been reported in Malaysia before. Objective: This study was conducted to determine the microsatellite instability (MSI) status in gastric cancer by microsatellite analysis, sequencing, its association with MLH1 and MSH2 protein expression and H.pylori infection by immunohistochemistry. Method: A total of 60 gastric cancer cases were retrieved. DNA was extracted from paired normal and tumour tissues while MLH1 and MSH2 protein expression as well as H. pylori status were determined by IHC staining. For microsatellite analysis, polymerase chain reaction (PCR) was performed for paired tissue samples using a panel of five microsatellite markers. MSI-positive results were subjected for DNA sequencing to assess mutations in the MLH1 and MSH2 genes. Results: Microsatellite analysis identified ten MSI positive cases (16.7%), out of which only six cases (10.3%) showed absence of MLH1 (n=3) or MSH2 (n=3) protein expression by IHC. The most frequent microsatellite marker in MSI positive cases was BAT26 (90%). Nine of ten MSI positive cases were intestinal type with one diffuse and all were located distally. H. pylori infection was detected in 13 of 60 cases (21.7%) including in three MSI positive cases. All these results however were not statistically significant. Our sequencing data displayed novel mutations. However these data were not statistically correlated with expression levels of MLH1 and MSH2 proteins by IHC. This may be due to small sample size to detect small or moderately sized effects. Conclusion: The frequency of MSI in this study was comparable with published results. Determination of affected MMR genes by more than two antibodies may increase the sensitivity of IHC to that of MSI analysis.

Original languageEnglish
Pages (from-to)509-517
Number of pages9
JournalAsian Pacific Journal of Cancer Prevention
Volume20
Issue number2
DOIs
Publication statusPublished - 1 Feb 2019

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Microsatellite Instability
Stomach Neoplasms
Microsatellite Repeats
Pylorus
DNA Mismatch Repair
Genes
Mutation
Malaysia
Infection
DNA Sequence Analysis
Sample Size
Neoplasms
Carcinogenesis
Immunohistochemistry
Staining and Labeling
Polymerase Chain Reaction

Keywords

  • Gastric cancer
  • Immunohistochemistry
  • Microsatellite analysis
  • Microsatellite instability

ASJC Scopus subject areas

  • Epidemiology
  • Oncology
  • Public Health, Environmental and Occupational Health
  • Cancer Research

Cite this

Microsatellite instability and altered expressions of MLH1 and MSH2 in gastric cancer. / Haron, Nor Hasyimah; Hanif, Ezanee Azlina Mohamad; Abdul Manaf, Mohd Rizal; Yaakub, Jasmi Ali; Harun, Roslan; Mohamed, Ramelah; Rose, Isa Mohamed.

In: Asian Pacific Journal of Cancer Prevention, Vol. 20, No. 2, 01.02.2019, p. 509-517.

Research output: Contribution to journalArticle

Haron, Nor Hasyimah ; Hanif, Ezanee Azlina Mohamad ; Abdul Manaf, Mohd Rizal ; Yaakub, Jasmi Ali ; Harun, Roslan ; Mohamed, Ramelah ; Rose, Isa Mohamed. / Microsatellite instability and altered expressions of MLH1 and MSH2 in gastric cancer. In: Asian Pacific Journal of Cancer Prevention. 2019 ; Vol. 20, No. 2. pp. 509-517.
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AU - Abdul Manaf, Mohd Rizal

AU - Yaakub, Jasmi Ali

AU - Harun, Roslan

AU - Mohamed, Ramelah

AU - Rose, Isa Mohamed

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AB - Introduction: Microsatellite instability (MSI) is a hallmark of defective DNA mismatch repair (MMR) of genes especially MLH1 and MSH2. It is frequently involved in the carcinogenesis of various tumours including gastric cancer (GC). However, MSI in GCs have not been reported in Malaysia before. Objective: This study was conducted to determine the microsatellite instability (MSI) status in gastric cancer by microsatellite analysis, sequencing, its association with MLH1 and MSH2 protein expression and H.pylori infection by immunohistochemistry. Method: A total of 60 gastric cancer cases were retrieved. DNA was extracted from paired normal and tumour tissues while MLH1 and MSH2 protein expression as well as H. pylori status were determined by IHC staining. For microsatellite analysis, polymerase chain reaction (PCR) was performed for paired tissue samples using a panel of five microsatellite markers. MSI-positive results were subjected for DNA sequencing to assess mutations in the MLH1 and MSH2 genes. Results: Microsatellite analysis identified ten MSI positive cases (16.7%), out of which only six cases (10.3%) showed absence of MLH1 (n=3) or MSH2 (n=3) protein expression by IHC. The most frequent microsatellite marker in MSI positive cases was BAT26 (90%). Nine of ten MSI positive cases were intestinal type with one diffuse and all were located distally. H. pylori infection was detected in 13 of 60 cases (21.7%) including in three MSI positive cases. All these results however were not statistically significant. Our sequencing data displayed novel mutations. However these data were not statistically correlated with expression levels of MLH1 and MSH2 proteins by IHC. This may be due to small sample size to detect small or moderately sized effects. Conclusion: The frequency of MSI in this study was comparable with published results. Determination of affected MMR genes by more than two antibodies may increase the sensitivity of IHC to that of MSI analysis.

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