MLH1 Methylation Status and Microsatellite Instability in Patients with Colorectal Cancer

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Colorectal cancer (CRC) is a significant health concern.
• MLH1 gene methylation is implicated in CRC pathogenesis.
• Microsatellite instability (MSI) is a hallmark of certain cancers.

Purpose of the Study:

• To compare MLH1 CpG island methylation with MSI presence in CRC patients.
• To investigate the frequency of MSI in Mexican CRC patients.
• To determine if specific MLH1 methylation regions correlate with MSI status.

Main Methods:

• Analysis of 138 CRC tumor samples.
• DNA extraction and bisulfite conversion.
• MLH1 methylation assessment via methylation-specific PCR (MS-PCR).
• MSI evaluation using multiplex PCR and capillary electrophoresis.
• Statistical analysis using R studio and SPSS.

Main Results:

• 7.2% of samples exhibited MSI (5.8% MSI-High, 1.4% MSI-Low).
• MLH1 methylation showed a significant association with MSI-High (p < 0.01).
• No correlation was found between specific MLH1 methylation regions and MSI status.
• Region A was frequently methylated.

Conclusions:

• MLH1 methylation is significantly associated with MSI-High in CRC.
• Specific MLH1 methylation regions do not correlate with MSI status.
• This study reports the first description of MSI frequency in Mexican patients irrespective of age.