TỐI ƯU HÓA QUY TRÌNH GIẢI TRÌNH TỰ VÙNG PROMOTOR GEN MMP-9 (rs3918242) TRÊN MẪU MÔ VÙI NẾN CỦA BỆNH NHÂN CARCINÔM DẠ DÀY LOẠI TẾ BÀO KÉM KẾT DÍNH

Abstract

Introduction: Poorly cohesive carcinoma (PCC) of the stomach carries a poor prognosis and is associated with the expression of matrix metalloproteinase-9 (MMP-9), in which single-nucleotide polymorphism (SNP) rs3918242 located in the promoter region of the MMP-9 gene has been reported to correlate with the risk of disease progression. However, analyzing this SNP in formalin-fixed paraffin-embedded block (FFPE) samples remains challenging due to DNA degradation caused by fixation and long-term storage. This study aims to optimize the Sanger sequencing workflow for the MMP-9 promoter region derived from FFPE specimens of patients with poorly cohesive gastric carcinoma by touchdown PCR (TD-PCR). Subject and Method: An experimental descriptive study was conducted to compare the performance of conventional PCR and touchdown PCR on 21 FFPE specimens diagnosed as poorly cohesive gastric carcinoma at the Department of Pathology, University Medical Center Ho Chi Minh City, from January 2022 to September 2023. Results: The study included 21 FFPE tissue samples from patients diagnosed with poorly cohesive gastric carcinoma, with the majority of patients aged ≥50 years (76%), with an equal male-to-female ratio (52% and 48%), and tumors typically localized in the antrum (38%), lesser curvature, and body of the stomach (33% and 24%). FFPE samples were primarily obtained from lesions with macroscopic ulceration (67%) and tumors at the deeply invasive stage (pT4, accounting for 52%). The TD-PCR technique has superior amplification efficiency compared to conventional PCR. At all the investigated pairing temperatures (56°C, 58°C, 60°C, and 62°C), TD-PCR successfully amplified 100% of the samples (21/21), whereas conventional PCR only amplified 4 to 12 samples (33.33%). Sanger sequencing of TD-PCR products yielded clear signals and well-defined electropherogram peaks, with genotyping results comparable to those obtained using conventional PCR amplification. Conclusion: TD-PCR is an effective technique to amplify promoter sequences in the MMP-9 rs3918242 gene region from FFPE tissue samples of patients with poorly cohesive gastric carcinoma.