MiR-92b-3p Represses Invasion And Metastasis Of Esophageal Cancer By Targeting ITGA6 And RAB23

Cell motility plays critical roles in invasion-metastasis cascade of malignant cells. Investigations in this field have shown that tumor cells in the process of local invasion and distant metastasis would face constantly changing microenvironment. Because stromal cells and extracellular matrix intensively crosstalk with tumor cells locating in distinct microenvironment, tumor cells would adopt different motility modes to achieve the goal of colonizing in new organs. Among various migration manners, a large body of evidence strongly demonstrates that chemotaxis is essential in invasion and metastasis of multiple types of cancers. In this study, taking into account the complexity and plasticity of motility of tumor cells in vivo, we established an in vitro model based on transwell assay to study mechanisms underlying the chemotaxis of esophageal squamous cell carcinoma (ESCC).Since the first microRNA lin-4 was discovered from C. elegans in 1993, the last twenty years have witnessed the emergence of this super-family of small non-coding RNA as consequential post-transcription regulators under almost all physiological and pathological conditions in plants and animals. Undoubtedly, it has been widely realized that microRNAs promote or repress invasion and metastasis of malignant cells with different tissue origins. However, heterogeneity of tumor genetic backgrounds, complicated interactions between tumor cells and microenvironment, and intricate regulation network of microRNAs hinder our extensive understanding of how microRNAs modulate the journey of cancer cells from primary sites to metastatic organs. We therefore focus on which microRNAs participate in chemotaxis of ESCC cells and clarify how these RNAs do their jobs.We established two groups of cell sub-lines, namely 30-M-U/D-4 and 180-M-U/D-4 respectively, with distinct motility capacity (D indicates stronger motility capacity whereas U means weaker) based on in vitro transwell assay. Being screened by microRNA chip (LC SCIENCE, USA),30-M-U/D-4 and 180-M-U/D-4 cells manifested multiple differentially expressed microRNAs. Among these candidate RNAs, qRT-PCR and functional experiments in vitro and in vivo showed that miR-92b-3p dramatically inhibited migration and invasion of 30-M-D-4 and KYSE-450 cells, but this small RNA did not exert detectable influence on proliferation and apoptosis of the treated cells. Repression of miR-92b-3p, on the other hand, significantly promoted migration and invasion of KYSE-510 cells in vitro. Combined use of seven algorithms to evaluate the potential targets of miR-92b-3p presented several candidates involved into cellular motility. Further experimental evidence demonstrated that ITGA6 and RAB23 were bona fide targets of miR-92b-3p, thereby indicating that these two proteins were implicated into invasion and metastasis of ESCC. We then compared the expressions of miR-92b-3p, ITGA6, RAB23, ITGB1, and ITGB4 in 28 ESCC tumor specimens with counterparts from the adjacent normal tissues. Except ITGA6 and ITGB4, no significant differences in expressions of the other three were found in the following statistical evaluation (p 0.05).Our investigation for the first time identified that miR-92b-3p hampered migration and further impeded invasion-metastasis cascade of ESCC cells and probed its regulation mechanisms. All results together would deepen our comprehensions of microRNAs in ESCC local invasion and distant metastasis, and offer a promise of miR-92b-3p in clinical practice.