👤 Doaa M Hefni

DNA methylation plays a pivotal role in the pathogenesis of Acute Lymphocytic Leukemia (ALL), a hematological malignancy marked by abnormal cellular behavior and immune dysregulation. This study aimed to investigate how alterations in DNA methylation affect lysosmal function in pediatric ALL. A total of 50 blood samples were collected from children diagnosed with ALL and analyzed for biochemical markers associated with the disease. Expression levels of key DNA methylation regulators, including DNA methyltransferase 1 (DNMT1) and DNMT3, were evaluated and compared with those from healthy controls. In addition, pro-inflammatory cytokines, interleukin-6 (IL-6), interleukin-27 (IL-27), and tumor necrosis factor-alpha (TNF-α), were monitored over a six-day period prior to treatment initiation. The study also assessed the expression of lysosome-associated membrane proteins, LAMP1 and LAMP2, which are essential for lysosomal function and the degradation of autophagosomes. To determine the DNA methylation status of the promoter regions of these genes, genomic DNA underwent sodium bisulfite treatment and digestion with methylation-sensitive and methylation-dependent restriction enzymes, followed by amplification with gene-specific primers. Our results revealed a significant upregulation of DNMT1 and DNMT3 in ALL samples, along with a marked downregulation of TET1 gene expression, which is responsible for DNA demethylation. This suggests that disrupted DNA methylation dynamics may contribute to the pathogenesis of the disease. Furthermore, methylation levels within the CpG islands of the LAMP1 and LAMP2 promoter regions were substantially elevated, showing more than a seven-fold increase in ALL samples compared to healthy control blood samples. In ALL samples, the expression levels of LAMP1 and LAMP2 were significantly reduced, may due to promoter region hypermethylation, which contributes to lysosomal dysfunction. In parallel, the expression of autophagy-related genes such as ATG5 and LC3B, markers of autophagy initiation and maturation, respectively, was markedly increased, suggesting an accumulation of autophagosomes that depend on functional lysosomes for complete degradation. Additionally, elevated levels of pro-inflammatory cytokines IL-6, IL-27, and TNF-α were consistently observed in ALL patients, indicating heightened immune activation that may drive disease progression. Collectively, these findings underscore the pivotal role of DNA methylation in disrupting lysosomal function, leading to autophagosome accumulation and impaired recycling of cytoplasmic components. Show less

The molecular mechanisms whereby angiopoietin-like 4 (ANGPTL4), a pluripotent protein implicated in cancer development, contributes to head and neck squamous cell carcinoma (HNSCC) growth and dissemination are unclear. We investigated ANGPTL4 expression in human normal oral keratinocytes (NOKs), dysplastic oral keratinocytes (DOKs), oral leukoplakia cells (LEUK1), and HNSCC cell lines, as well as in tissue biopsies from patients with oral dysplasia, and primary and metastatic HNSCC. We further examined the contribution of ANGPTL4 cancer progression in an HNSCC orthotopic floor-of mouth tumor model and the signaling pathways linking ANGPTL4 to cancer cell migration. ANGPTL4 expression was upregulated in premalignant DOKs and HNSCC cell lines compared to NOKs and was increased in tissue biopsies from patients with oral dysplasia, as well as in primary and metastatic HNSCC. We also observed that downregulation of ANGPTL4 expression inhibited primary and metastatic cancer growth in an HNSCC orthotopic tumor model. Interestingly, ANGPTL4 binding to the neuropilin1 (NRP1) receptor led to phosphorylation of the focal adhesion protein, paxillin (PXN), and tumor cell migration; this was dependent on the tyrosine kinase ABL1. Treatment with the ABL1 inhibitor, dasatinib and small interfering RNA silencing of NRP1 or ABL1 expression blocked PXN phosphorylation and tumor cell migration. Our findings suggest an early, sustained, and angiogenesis-independent autocrine role for ANGPTL4 in HNSCC progression and expose ANGPTL4/NRP1/ABL1/PXN as an early molecular marker and vulnerable target for the prevention of HNSCC growth and metastasis. Show less