Differential Promoter Methylation of MMP-9 and E-Cadherin Genes in CLL: Evidence for a Pathogenic Role of MMP-9 Hypomethylation

Background/Objectives: Chronic lymphocytic leukemia (CLL) is characterized by genetic and epigenetic alterations. This study aimed to assess the methylation status of E-Cadherin and MMP-9 gene promoters and to explore their relationships with disease pathogenesis and hematological parameters in CLL patients. Methods: A case–control study was conducted with 70 newly diagnosed CLL patients and 70 age- and sex-matched healthy controls. Promoter methylation of E-Cadherin and MMP-9 genes was evaluated using methylation-specific PCR (MSP) and methylation-sensitive restriction enzyme PCR (MSRE-PCR), respectively. Results: The median patient age was 62 years, and 68.5% were males. Binet stage A was the most common stage (57.3%). E-Cadherin promoter methylation was detected in 75.7% of CLL patients and 77.1% of controls (p = 0.91), showing no significant association with disease occurrence; however, it showed a significant correlation with higher lymphocyte counts (p = 0.01). In contrast, MMP-9 promoter methylation was significantly less frequent in CLL cases (70.0%) than in controls (100%, p = 0.001). Unmethylated MMP-9 correlated significantly with female gender (p = 0.02), lower hemoglobin (p = 0.031), reduced platelet counts (p = 0.001), and higher lymphocyte counts (p = 0.035). Conclusions: MMP-9 promoter hypomethylation may play a pathogenic role in CLL and is associated with female gender and cytopenia, whereas E-Cadherin methylation appears to be non-specific. MMP-9 methylation status could therefore serve as a potential biomarker for CLL biology and prognosis.