c-Myc affects hedgehog pathway via KCNQ1OT1/RAC1: A new mechanism for regulating HSC proliferation and epithelial-mesenchymal transition

Background: This study aimed to probe into the potential mechanism of KCNQ1OT1 in liver fibrosis. Methods: The pathological changes in liver tissues were observed by Masson and hematoxylin-eosin (HE) staining. The proliferation or cell cycle of hepatic stellate cells (HSCs) was analyzed by MTT or flow cytometry. The expressions of epithelial markers E-cadherin, interstitial markers Snail and Vimentin, and hedgehog signaling pathway-related molecules Hhip, Shh, and Gli2 were detected by Western blot. The interaction or binding of c-Myc with the KCNQ1OT1 promoter was analyzed by dual-luciferase reporter gene or Chromatin immunoprecipitation (ChIP)-qPCR, and the interaction between KCNQ1OT1 and RAC1 was assessed by RNA immunoprecipitation and RNA pull-down. Moreover, the stability of RAC1 protein was detected by cycloheximide-chase and ubiquitination. Results: c-Myc and KCNQ1OT1 were up-regulated in liver fibrosis tissues and cells. After the interference with c-Myc in primary-1-Day HSCs, the down-regulated KCNQ1OT1 restrained HSC proliferation and EMT by down-regulating RAC1 expression and restraining the hedgehog pathway. Conclusion: Our results indicated that the interference with c-Myc down-regulated RAC1 expression and restrained the hedgehog pathway by down-regulating KCNQ1OT1, thus restraining HSC proliferation and EMT in liver fibrosis. (C) 2020 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Automated summary

In liver fibrosis, the up-regulation of c-Myc and KCNQ1OT1 was observed. Inhibiting c-Myc led to a decrease in KCNQ1OT1 expression, thereby blocking HSC proliferation and EMT, ultimately suppressing the progression of liver fibrosis.