Seok-Jun Kim1, Hyeok-Gu Kang2, Kyungeun Kim3,4, Hoyoung Kim5, Fredrik Zetterberg6, Young Soo Park7, Hyun-Soo Cho5, Stephen M Hewitt3, Joon-Yong Chung3, Ulf J Nilsson8, Hakon Leffler9, Kyung-Hee Chun10. 1. Department of Biomedical Science, BK21 FOUR Educational Research Group for Age-Associated Disorder Control Technology, College of Natural Science, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju, 61452, Republic of Korea. 2. Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea. 3. Experimental Pathology Laboratory, Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA. 4. Department of Pathology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea. 5. Department of Systems Biology and Division of Life Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea. 6. Galecto Biotech AB, Sahlgrenska Science Park, Medicinaregatan 8 A, 413 46, Gothenburg, Sweden. 7. Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea. 8. Centre for Analysis and Synthesis, Department of Chemistry, Lund University, POB 124, 22100, Lund, Sweden. 9. Department of Laboratory Medicine, Section MIG-Microbiology, Immunology, Glycobiology, Lund University, Lund, Sweden. 10. Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea. khchun@yuhs.ac.
Abstract
BACKGROUND: Aberrant activation of the WNT/β-catenin and STAT3 signaling pathways plays a critical role in cancer progression. However, direct targeting of these pathways as an anti-cancer therapeutic approach needs to be reconsidered due to its serious side effects. Here, we demonstrate that overexpression of WNT induces STAT3 activation in a galectin-3-dependent manner. METHODS: We investigated how galectin-3 mediates the crosstalk between WNT/β-catenin and STAT3 signaling and whether inhibition of galectin-3 can reduce gastric cancer. The molecular mechanisms were analyzed by biochemical assays using cultured gastric cancer cells, patient tissues, and genetically engineered mice. Moreover, we confirm of therapeutic effects of GB1107, a cell-penetrating galectin-3 specific inhibitor, using orthotopic gastric cancer-bearing mice RESULTS: Increased levels of galectin-3 and STAT3 phosphorylation were detected in the stomach tissues of WNT1-overexpressing mouse models. Also, high expression levels and co-localization of β-catenin, pSTAT3, and galectin-3 in patients with advanced gastric cancer were correlated with a poorer prognosis. Galectin-3 depletion significantly decreased STAT3 Tyr705 phosphorylation, which regulates its nuclear localization and transcriptional activation. A peptide of galectin-3 (Y45-Q48) directly bound to the STAT3 SH2 domain and enhanced its phosphorylation. GB1107, a specific membrane-penetrating inhibitor of galectin-3, significantly reduced the activation of both STAT3 and β-catenin and inhibited tumor growth in orthotopic gastric cancer-bearing mice. CONCLUSIONS: We propose that galectin-3 mediates the crosstalk between the WNT and STAT3 signaling pathways. Therefore GB1107, a galectin-3-specific inhibitor, maybe a potent agent with anti-gastric cancer activity. Further studies are needed for its clinical application in gastric cancer therapy.
BACKGROUND: Aberrant activation of the WNT/β-catenin and STAT3 signaling pathways plays a critical role in cancer progression. However, direct targeting of these pathways as an anti-cancer therapeutic approach needs to be reconsidered due to its serious side effects. Here, we demonstrate that overexpression of WNT induces STAT3 activation in a galectin-3-dependent manner. METHODS: We investigated how galectin-3 mediates the crosstalk between WNT/β-catenin and STAT3 signaling and whether inhibition of galectin-3 can reduce gastric cancer. The molecular mechanisms were analyzed by biochemical assays using cultured gastric cancer cells, patient tissues, and genetically engineered mice. Moreover, we confirm of therapeutic effects of GB1107, a cell-penetrating galectin-3 specific inhibitor, using orthotopic gastric cancer-bearing mice RESULTS: Increased levels of galectin-3 and STAT3 phosphorylation were detected in the stomach tissues of WNT1-overexpressing mouse models. Also, high expression levels and co-localization of β-catenin, pSTAT3, and galectin-3 in patients with advanced gastric cancer were correlated with a poorer prognosis. Galectin-3 depletion significantly decreased STAT3 Tyr705 phosphorylation, which regulates its nuclear localization and transcriptional activation. A peptide of galectin-3 (Y45-Q48) directly bound to the STAT3 SH2 domain and enhanced its phosphorylation. GB1107, a specific membrane-penetrating inhibitor of galectin-3, significantly reduced the activation of both STAT3 and β-catenin and inhibited tumor growth in orthotopic gastric cancer-bearing mice. CONCLUSIONS: We propose that galectin-3 mediates the crosstalk between the WNT and STAT3 signaling pathways. Therefore GB1107, a galectin-3-specific inhibitor, maybe a potent agent with anti-gastric cancer activity. Further studies are needed for its clinical application in gastric cancer therapy.