miR-31 promotes oncogenesis in intrahepatic cholangiocarcinoma cells via the direct suppression of RASA1

Abstract

MicroRNAs (miRNAs) are involved in the pathogenesis of intrahepatic cholangiocarcinoma (ICC). However, the role of microRNA-31 (miR-31) in ICC has yet to be elucidated. In this study, we demonstrated that the expression of miR-31 was significantly upregulated in ICC tissues and the human ICC cell line HCCC-9810, when compared with that in normal adjacent tissues. Bioinformatic analysis and a dual-luciferase reporter assay revealed RAS p21 GTPase activating protein 1 (RASA1) to be a direct target of miR-31 in HCCC-9810 cells. Further investigation showed that the protein expression level of RASA1 was significantly decreased in ICC tissues, suggesting an inverse correlation between miR-31 and RASA1 expression during the tumorigenesis of ICC. Moreover, the forced downregulation of miR-31 by its inhibitor in HCCC-9810 cells significantly inhibited cell proliferation and promoted cell apoptosis. However, when the cells were cotransfected with miR-31 inhibitor and RASA1-specific small interfering RNA (siRNA), these changes were attenuated. Further analysis of the molecular mechanism showed that the activity of the RAS-mitogen-activated protein kinase (MAPK) signaling pathway was significantly decreased in miR-31-downregulated HCCC-8910 cells, while cotransfection with miR-31 inhibitor and RASA1-specific siRNA attenuated this effect. These results indicate that the downregulation of RASA1 by miR-31 promoted cellular proliferation and inhibited cellular apoptosis, partially by upregulating the activity of the RAS-MAPK signaling pathway in ICC. In conclusion, the present study revealed important regulatory functions of miR-31 and RASA1 in ICC, indicating that miR-31 and RASA1 may become promising diagnostic and/or therapeutic targets for ICC.

Transcriptional Regulation of miR-31 by Oncogenic KRAS Mediates Metastatic Phenotypes by Repressing RASA1

“…Of these 18 targets, RASA1 (p120RasGAP) was of particular interest because it functions as a negative regulator of RAS pathway activation and modulates invasion-behavior through interaction with p190RhoGAP (24, 25). Moreover, RASA1 was demonstrated to be a miR-31 target in colorectal and liver cancers (26, 27). The RASA1 3′ UTR contains one predicted miR-31 binding site which is highly conserved in vertebrates (Figure 5A).…”

“…Multiple miRNA profiling studies have documented the upregulation of miR-31 in pancreatic cancer cell lines and tumors (17, 26, 29, 30). We have found that miR-31 is moderately to highly expressed in 16 of 23 pancreatic and colorectal cancer cell lines.…”

MicroRNA-31 initiates lung tumorigenesis and promotes mutant KRAS-driven lung cancer

“…RASA1 inhibits RAS-induced transformation by functioning as a negative regulator of RAS by promoting the inactive GDP-bound form of RAS (29). It was previously reported that miR-31 targets RASA1 in intrahepatic cholangiocarcinoma and colorectal cancer (39,40), but whether miR-31 targeted it in the lung was unknown. The SPRED and SPRY genes FBS and penicillin/streptomycin.…”

MicroRNAs in liver tissue engineering — New promises for failing organs

“…Most of these microRNAs play a role in cell-cycle control and proliferation. For example, Hu et al found upregulated miR-31 expression in cholangiocarcinoma cells causing altered RAS/MAPK signaling [82]. Other investigators reported on a role for miR-138 in regulating cholangiocarcinoma proliferation, cell-cycle control, and migration, possibly by direct regulation of RhoC [83].…”