Da Hyun Jung1, Yoo Jin Bae2, Jie-Hyun Kim3, You Keun Shin2, Hei-Cheul Jeung2. 1. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea. 2. Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea. 3. Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea, otilia94@yuhs.ac.
Abstract
INTRODUCTION: Human epidermal growth factor 2 (HER2) gene overexpression in breast carcinoma cell lines has been shown to drive mammary carcinogenesis and tumor growth and invasion through its effects on mammary stem cells. OBJECTIVE: Therefore, we investigated the mechanism by which HER2 regulates cancer stem cell (CSC) activity in gastric cancer cells. METHODS: HER2 was transfected into MKN28 gastric cancer cells, and its role in regulating CSC activity was determined by characterizing the HER2-overexpressing cells. RESULTS: The sphere formation assay revealed that the sphere sizes and frequency of sphere formation were significantly greater for the HER2-overexpressing cells than for the MKN28 control cells. The CSC markers Oct-4 and BMI1 were more highly expressed in the HER2-overexpressing cells, as were the EMT markers. This was accompanied by a significant enhancement in cellular invasion of the Matrigel and migration. The E-cadherin level was significantly downregulated, and the mesenchymal marker Snail upregulated, in the HER2-transfected cells. HER2 overexpression activated the well-characterized CSC-associated Wnt/β-catenin signaling pathway, as shown by the luciferase assay. After treatment of these cells with the Wnt signal inhibitor PRI-724, the BMI1 and Oct-4 levels were decreased for 24 h and Snail was also downregulated. Immunofluorescence staining revealed the significant restoration of E-cadherin levels in the HER2-transfected cells after PRI-724 treatment. CONCLUSIONS: These results established a role for HER2 in regulating gastric CSC activity, with Wnt/β-catenin signaling being mediated via a HER2-dependent pathway. In summary, HER2-overexpressing gastric cancer cells exhibited increased stemness and invasiveness and were regulated by Wnt/β-catenin signaling.
INTRODUCTION:Human epidermal growth factor 2 (HER2) gene overexpression in breast carcinoma cell lines has been shown to drive mammary carcinogenesis and tumor growth and invasion through its effects on mammary stem cells. OBJECTIVE: Therefore, we investigated the mechanism by which HER2 regulates cancer stem cell (CSC) activity in gastric cancer cells. METHODS:HER2 was transfected into MKN28gastric cancer cells, and its role in regulating CSC activity was determined by characterizing the HER2-overexpressing cells. RESULTS: The sphere formation assay revealed that the sphere sizes and frequency of sphere formation were significantly greater for the HER2-overexpressing cells than for the MKN28 control cells. The CSC markers Oct-4 and BMI1 were more highly expressed in the HER2-overexpressing cells, as were the EMT markers. This was accompanied by a significant enhancement in cellular invasion of the Matrigel and migration. The E-cadherin level was significantly downregulated, and the mesenchymal marker Snail upregulated, in the HER2-transfected cells. HER2 overexpression activated the well-characterized CSC-associated Wnt/β-catenin signaling pathway, as shown by the luciferase assay. After treatment of these cells with the Wnt signal inhibitor PRI-724, the BMI1 and Oct-4 levels were decreased for 24 h and Snail was also downregulated. Immunofluorescence staining revealed the significant restoration of E-cadherin levels in the HER2-transfected cells after PRI-724 treatment. CONCLUSIONS: These results established a role for HER2 in regulating gastric CSC activity, with Wnt/β-catenin signaling being mediated via a HER2-dependent pathway. In summary, HER2-overexpressing gastric cancer cells exhibited increased stemness and invasiveness and were regulated by Wnt/β-catenin signaling.
Authors: Jacek Baj; Izabela Korona-Głowniak; Alicja Forma; Amr Maani; Elżbieta Sitarz; Mansur Rahnama-Hezavah; Elżbieta Radzikowska; Piero Portincasa Journal: Cells Date: 2020-04-23 Impact factor: 6.600