Abstract
BackgroundOur previous studies revealed that Jagged 2 (JAG2) is involved in the regulation of migration and invasion of colon cancer cells without affecting cell proliferation. This study further explored the specific mechanism by which JAG2 promotes migration and invasion of colorectal cancer cells.MethodsJAG2 mRNA expression in different clinical stages of colorectal cancer and normal intestinal tissues was detected by quantitative PCR (QPCR). QPCR and Western Blot were used to analyze the differential expression of JAG2 mRNA and protein between normal human colon tissue cells and various colorectal cancer cells. Co-expression status of JAG2 and epithelial–mesenchymal transition (EMT) markers in colon cancer tissues and cells was analyzed. The difference between TGF-β-induced EMT model and the JAG2 overexpression model were compared in promoting migration and invasion of HT29 cells. HT29 cells were treated with EMT pathway inhibitors (LY2157299 and Slug siRNA) to identify a cross-talk between the JAG2 effect and the Notch pathway. Co-expressed genes of JAG2 in colorectal cancer cells were identified using siRNA and transcriptome microarray technology. The mutual regulation of JAG2 and the co-expressed gene PRAF2 and the regulation of the paracrine effect of exosomes were analyzed.ResultsJAG2 was abnormally expressed in colorectal cancer tissues and directly related to clinical stages. Similar to the findings in tissues, the expression of both JAG2 mRNA and protein was significantly increased in the colorectal cancer cell lines compared with that of normal colorectal cell line CCD18-Co. It was shown in our cell model that JAG2 was involved in the regulation of migration and invasion independent of the canonical Notch signaling pathway. More interestingly, JAG2 also promoted the migration and invasion of colon cancer cells in a non-EMT pathway. Further analysis revealed the co-expression of JAG2 with PRAF2 in colorectal cancer cells. JAG2-rich exosomes were released from colorectal cancer cells in a PRAF2-dependent way, while these exosomes regulated the metastasis of colorectal cancer cells in a paracrine manner.ConclusionsThis is the evidence supporting the biological function of JAG2 through non-canonical Notch and non-EMT-dependent pathways and also the first demonstration of the functions of PRAF2 in colorectal cancer cells. These findings also provide theoretical basis for the development of small molecules or biological agents for therapeutic intervention targeting JAG2/PRAF2.
Highlights
Our previous studies revealed that Jagged 2 (JAG2) is involved in the regulation of migration and invasion of colon cancer cells without affecting cell proliferation
The relative expression of JAG2 mRNA in colorectal cancer tissues was determined by quantitative PCR and the results showed that the overall expression of JAG2 in colorectal cancer tissues was increased compared with that of adjacent tissues and the relative content of JAG2 mRNA increased with the clinical stages (N0, N1, and N2) (Fig. 1a), indicating that JAG2 was abnormally expressed in colorectal cancer tissues and directly related to clinical stages of the disease
Migration and invasion assay of HT29 cells following transfection with pCMV-control or pCMV-JAG2 vectors. c No significant changes of epithelial–mesenchymal transition (EMT) markers were detected with the altered JAG2 expression in human colorectal cancer cells
Summary
Our previous studies revealed that Jagged 2 (JAG2) is involved in the regulation of migration and invasion of colon cancer cells without affecting cell proliferation. Cancer invasion and metastasis is one of the leading causes of tumor-related death worldwide and many signaling pathways, including the Hedgehog, Wnt, and Notch, are involved in this process [1]. Mammals possess four homologous notch receptors, referred to as NOTCH1, NOTCH2, NOTCH3, and NOTCH4 [6] These receptors are expressed as heterodimers on the cell membrane and composed of an extracellular region, a single transmembrane-pass, and an intracellular region [7]. The RAM domain is the main binding site for C promoter binding factor-1/Recombination signal binding protein-Jkappa, CBF1/RBPJк); the ANK mediates the interaction between Notch and other proteins and plays an important role in the Notch signaling pathway as an enhancer for the activation of the Notch signal; and the PEST motif is involved in the degradation of the Notch receptors. Notch ligands, including Delta and Serrate in Drosophila and Jagged (JAG1), Jagged (JAG2), Delta, Delta, and Delta in human, are single-pass transmembrane proteins and expressed on adjacent cells [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
