Toll-like receptor-4 is a target for suppression of proliferation and chemoresistance in HepG2 hepatoblastoma cells.
Toll-like receptor-4 (TLR4) is known to influence growth and migration of hepatocellular tumors; however, its role in hepatoblastoma remains poorly understood. This study investigated the regulatory role of TLR4 in proliferation and chemoresistance of HepG2 hepatoblastoma cells. Treatment with lipopolysaccharide (LPS), a TLR4 agonist, was found to significantly upregulate TLR4 expression in HepG2 cells, but not in malignant Huh-7 and Sk-Hep1 hepatocellular carcinoma cells. Additionally, IL-6 enhanced LPS-induced TLR4 upregulation. LPS-stimulated TLR4 activation increased proliferation, nitric oxide synthase (NOS) expression, and NO production in HepG2 cells. Chemotherapeutic agents, cisplatin and doxorubicin, effectively inhibited TLR4 expression in HepG2 cells. Characterization of LPS-induced signaling activation and blockade with kinase inhibitors revealed the involvement of Akt and MAPK pathways in LPS-enhanced NO release from, and proliferation of HepG2 cells. Mechanistically, gene modifications as a result of TLR4 transfection and siRNA-mediated knockdown further demonstrated a crucial role for TLR4 in the regulation of NOS expression, cell proliferation, and chemoresistance in HepG2 cells. These findings suggest that targeting TLR4 expression and its cognate signaling may modulate proliferation and chemosensitivity in hepatoblastoma cells and serve as a potential therapeutic target.
Division of Hematology/Oncology, Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan.
Chih-Cheng
CC
Hsiao
Department of Medical Research, E-Da Hospital, Kaohsiung 82445, Taiwan.
Po-Han
PH
Chen
Division of Cardiology, Department of Internal Medicine, Kaohsiung Chang-Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan.
Cheng-I
CI
Cheng
Department of Surgery, E-Da Hospital, Kaohsiung 82445, Taiwan.
Ming-Shian
MS
Tsai
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, E-Da Hospital, Kaohsiung 82445, Taiwan.
Chih-Yang
CY
Chang
Department of Medical Research, E-Da Hospital, Kaohsiung 82445, Taiwan.
Shang-Chieh
SC
Lu
Department of Medical Research, E-Da Hospital, Kaohsiung 82445, Taiwan.
Ming-Chu
MC
Hsieh
Department of Surgery, E-Da Hospital, Kaohsiung 82445, Taiwan.
Yu-Chun
YC
Lin
Department of Surgery, E-Da Hospital, Kaohsiung 82445, Taiwan. Electronic address: pohuang1115@ntu.edu.tw.
Po-Huang
PH
Lee
Department of Medical Research, E-Da Hospital, Kaohsiung 82445, Taiwan. Electronic address: danyhkao@gmail.com.
Ying-Hsien
YH
Kao
D049109:Cell Proliferation / Q000187:drug effects*; D002945:Cisplatin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D055785:Gene Knockdown Techniques; D056945:Hep G2 Cells; D018197:Hepatoblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D008070:Lipopolysaccharides; D047428:Protein Kinase Inhibitors; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D009569:Nitric Oxide; D004317:Doxorubicin; D019001:Nitric Oxide Synthase; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D002945:Cisplatin
Lipopolysaccharide; Nitric oxide production; Nitric oxide synthase; Signal transduction; Small interfering RNA