Concordant DNA methylation in synchronous colorectal carcinomas

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Epigenetic alterations are implicated in colorectal carcinogenesis.
• Understanding the field defect is crucial for cancer risk assessment and prevention.
• Investigating genetic and epigenetic markers in multiple colorectal neoplasias (M-CRN) and solitary colorectal cancers (S-CRC) can elucidate tumor development patterns.

Purpose of the Study:

• To test the hypothesis that epigenetic changes mediate the field defect in colorectal carcinogenesis.
• To evaluate methylation status of eight genes and mutations in BRAF and KRAS in M-CRNs and S-CRCs.
• To assess concordance of molecular markers and histological features between synchronous colorectal tumors.

Main Methods:

• Analysis of methylation status for MINT1, MINT2, MINT31, MLH1, p16, p14, MGMT, and ESR1 genes.
• Detection of BRAF and KRAS mutations.
• Comparison of molecular and histological data between 57 M-CRNs and 69 S-CRCs.
• Assessment of methylation and mutation concordance in paired tumors from the same anatomical site.

Main Results:

• No significant difference in overall methylation between M-CRNs and S-CRCs, except for higher p14 and MGMT methylation in M-CRNs.
• Significant concordance in methylation for MINT1, p16, MLH1, and MGMT between tumors from the same site.
• BRAF mutations showed concordance in proximal pairs but discordance in different site pairs; KRAS mutations showed no concordance.
• Histological cribriform glandular configuration was concordant in 80% of paired cancers from similar locations.

Conclusions:

• Synchronous colorectal tumors from the same site exhibit high concordance in gene methylation, BRAF mutations, and histological features.
• These findings support the concept of a patient-specific predisposition to distinct colorectal cancer subtypes.
• Results have implications for refining screening and secondary prevention strategies for colon cancer.