ABSTRACT
Oesophageal cancer (EC) represents a significant cause of cancer worldwide. Yes-associated protein (YAP) is reported to correlate with the initiation of multiple cancers including EC, but the underlying mechanism remains elusive. The current study aimed to investigate the molecular mechanism of YAP-TEAD in the occurrence and progression of EC. EC tissues and cells were obtained, followed by determination of the expression of YAP, c-Jun, pc-Jun and IRS2. The effect of YAP-TEAD on the biological EC cell processes was explored through gain- and loss-of-function approaches. The interaction between YAP and TEAD was detected by co-immunoprecipitation. The binding of TEAD to the c-Jun promoter was determined using chromatin immunoprecipitation. Tumour formation in the nude mice was detected in order to ascertain the effect of YAP and IRS2 in vivo. We found elevated YAP in the EC tissues and cells. YAP silencing led to a decrease in EC cell proliferation, invasion and sphere formation. YAP-TEAD complex bound to the promotor of c-Jun, and c-Jun led to an increase in the expression of IRS2 through the JNK/c-Jun pathway. Additionally, pc-Jun and phosphorylated JNK were localized in the nuclear in addition to displaying enhanced expression in the EC tissues. IRS2 overexpression negated the inhibition of cell proliferation, invasion and sphere formation triggering YAP silencing. YAP up-regulated IRS2 and aggravated EC in vivo. Taken together, YAP-TEAD activates the JNK/c-Jun pathway to up-regulate IRS2, ultimately promoting EC progression. Therefore, YAP-TEAD inhibition could be a promising therapeutic approach for EC treatment.
Subject(s)
Cell Cycle Proteins/metabolism , Esophageal Neoplasms/genetics , Esophageal Neoplasms/metabolism , Gene Expression Regulation, Neoplastic , Insulin Receptor Substrate Proteins/genetics , Transcription Factors/metabolism , Animals , Cell Cycle Proteins/genetics , Cell Line, Tumor , Disease Models, Animal , Esophageal Neoplasms/pathology , Gene Silencing , Humans , Immunohistochemistry , Insulin Receptor Substrate Proteins/metabolism , MAP Kinase Signaling System , Male , Mice , Models, Biological , Protein Binding , Signal Transduction , Transcription Factors/geneticsABSTRACT
Colorectal cancer (CRC) is one of the most common human malignancies. An increasing body of evidence has revealed the important roles long noncoding RNA (lncRNA) plays in the growth dynamics of CRC cells. In this study, we aimed to define the role of LINC00337 in the malignant phenotypes, especially angiogenesis, of CRC and clarify the underlying molecular basis. Bioinformatic analyses identified promoter region methylation of CNN1 in CRC, which was further validated by BSP and MSP assays. Loss- and gain- of function approaches were used to determine the roles of CNN1 and LINC00337 in vitro and in vivo. MTT-based method, Transwell migration/invasion assays, and tube formation assay were adopted to evaluate the cancer cell proliferation, migration/invasion, and proangiogenetic potency respectively in vitro. The tumor growth, microvascular density (MVD) and markers of proliferation (Ki67) and angiogenesis (VEGF) were quantified in nude mice xenografted with CRC cells. It was found that CNN1 downregulation and LINC00337 overexpression occurred in CRC tissues and cells. Besides, the CNN1 promoter region was hypermethylated in CRC. CNN1 overexpression or LINC00337 knockdown restricted CRC cell proliferation, migration/invasion, and proangiogenetic potency in vitro, which was substantiated by the in vivo experiments evidenced by facilitated tumor growth and MVD as well as elevated Ki67 and VEGF. Furthermore, our mechanistic evidence revealed that LINC00337 recruited DNMT1 to the promoter region of CNN1 and restricted the transcription of CNN1. Taken together, this study indicates that LINC00337 facilitates the tumorigenesis and angiogenesis in CRC via recruiting DNMT1 to inhibit the expression of CNN1.