Hassan S.S.El-Khazragy N.Elshimy A.A.Aboelhussein M.M.Saleh S.A.Fadel S.Atia H.A.Matbouly S.Tamer N.Clinical Pathology DepartmentNational Cancer InstituteCairo UniversityCairoEgypt; Clinical Pathology/Hematology and Biomedical Research DepartmentsFaculty of MedicineAin Shams UniversityCairoEgypt; Biomedical Research DepartmentGlobal Research LabsCairoEgypt; Medical Microbiology and Immunology DepartmentFaculty of MedicineCairo University and New Giza UniversityCairoEgypt; Medical Biochemistry and Molecular Biology DepartmentFaculty of MedicineAin- Shams UniversityCairoEgypt; Internal Medicine DepartmentFaculty of MedicineAin- Shams UniversityCairoEgypt; Pediatric Oncology DepartmentNational Cancer InstituteCairo UniversityGizaEgypt; Clinical Pathology DepartmentFaculty of MedicineNew Giza UniversityGizaEgypt; Department of PediatricsFaculty of MedicineAin Shams UniversityCairoEgypt; Faculty of BiotechnologyOctober University for Modern Sciences and Arts (MSA)GizaEgypt2020-01-092020-01-0920197302312https://doi.org/10.1002/jcb.29512PubMedID31696995https://t.ly/GgxqEScopusHepatitis C virus (HCV) infection is a major public health problem, having a high prevalence in Egypt. Leukemia and lymphoma have been associated with HCV infection. MicroRNA-155 (miR-155) has been reported to play a regulatory role in cancer, inflammation, and immune response to infection. The expression level of miR-155 in HCV viremic patients is controversial; although high miR-155 levels were demonstrated in HCV genotypes 1,2, and 3, low levels of miR-155 were detected in Egyptian patients with HCV genotype 4. Several studies have investigated the correlation between the levels of miRNA-155 and the replication of HCV, others have evaluated miRNA-155 as a prognostic biomarker in different types of cancer. No studies have investigated the impact of miRNA-155 knockdown on HCV pediatric patients associated with childhood acute lymphoblastic leukemia (ALL). We knocked-out the miR_155a in cultured polymorphonuclear cells (PBMCs) obtained from 60 children with ALL; 30 were associated with HCV-4 infection and 30 were HCV negative. The miR_155a, HCV viral load, and cell proliferation werre assessed in treated and untreated cells using TaqMan assay quantitative polymerase chain reaction. We found that miRNA-155 was significantly upregulated by seven folds in the HCV-4 associated ALL group; while being linked to high HCV viral load and leukemic burden, miR_155a knock-out can improve the disease outcome. We conclude that miR-155 is a critical miRNA that is considered a therapeutic target in pediatric HCV leukemic patients. 2019 Wiley Periodicals, Inc.EnglishHCV associated leukemia/lymphomain vitro knock-downmiR-155pediatricprognosisArticlehttps://doi.org/10.1002/jcb.29512PubMedID31696995