Abstract
Background: Circulating tumor cells are important precursor of colorectal cancer metastasis, which attributes to the main cause of cancer-related death. The ability to adopt epithelial-mesenchymal transition (EMT) process facilitates CTCs generation, thereby overcoming metastatic bottlenecks and realizing distant metastasis. However, the potential molecular mechanism of CRC EMT remains largely unknown.Methods: RT-qPCR, immunohistochemical staining, and western blot were used to detect the expression of mRNA and protein in CRC. Loss- and gain-of-function approaches were performed to investigate the effect of SNHG16 on CRC cell phenotypes. Function assays, including wounding healing, transwell assay, and clone formation were used to assess the effect of SNHG16 on tumor biological behavior. Then, RNA immunoprecipitation, Chromatin Immunoprecipitation, Co-Immunoprecipitation, GST-pull down, biotin-labeled miR-195-5p pull down, and dual-luciferase assay were performed to uncover the underlying mechanism for molecular interaction. Finally, CRC nude mice xenograft model experiment was performed to evaluate the influence of SNHG16 on tumor progression in vivo Results: Compared with normal tissue and cell line, SNHG16 was significantly upregulated in CRC. Clinical investigation revealed that SNHG16 high expression was correlated with advanced TNM stage, distant metastasis, and poor prognosis of cancer patients. According to Loss- and gain-of-function experiment, SNHG16 could promote CRC proliferation, migration, invasion, EMT, mesenchymal-type CTCs (MCTCs) generation, and liver metastasis through YAP1 in vitro and in vivo. Mechanistic research indicates that, SNHG16 could act as miRNA sponge to sequester miR-195-5p on Ago2, thereby protecting YAP1 from repression and facilitating CRC liver metastasis and tumor progression. Moreover, YAP1 could combine with TEA Domain Transcription Factor 1 (TEAD1) to form a YAP1/TEAD1 complex, which could in turn bind to the promoter of SNHG16 and regulate its transcription. In addition, both of YAP1 and TEAD1 are indispensable during this process. Finally, we demonstrated that YAP1 significantly promoted the tumor progression, and SNHG16 could rescue the effect of YAP1 on tumor progressionConclusion: Herein, we clarified a hitherto unexplored positive feedback loop between SNHG16 and YAP1/TEAD1. These findings provided new sights in CRC liver metastasis, and it may act as a potential candidate in the treatment of CRC.
KCNQ1OT1/miR-217/ZEB1 feedback loop facilitates cell migration and epithelial-mesenchymal transition in colorectal cancer