ABSTRACT
Gallbladder carcinoma (GBC) is one of the most common fatal biliary tract tumors in the world. Its 3-year survival rate is 30% and the recurrence rate remains very high. miR-365 was downregulated in numerous tumors and worked as tumor suppressor gene. However, the role of miR-365 in GBC was unclear. In this study, our results found that the expression of miR-365 in GBC tissues was reduced rather than that in non-cancerous tissues. miR-365 overexpression inhibited the proliferation, metastasis and expansion of GBC CSCs. Mechanically, bioinformatic and luciferase reporter analysis identified Ras-related C3 botulinum toxin substrate 1 (RAC1) as a direct target of miR-365. Overexpression of miR-365 in GBC cells reduced the RAC1 mRNA and protein expression. The special RAC1 inhibitor EHop-106 abolished the discrepancy of growth, metastasis and self-renewal ability between miR-365-overexpression GBC cells and their control cells, which further demonstrated that RAC1 was involved in miR-365-disrupted GBC cells growth, metastasis and self-renewal. More importantly, reduced expression of miR-365 was a predictor of poor prognosis of GBC patients. In conclusion, miR-365 inhibited GBC cell growth, metastasis and self-renewal capacity by directly targeting RAC1, and may therefore prove to be a novel prognosis biomarker for GBC patients.
Subject(s)
Disease Progression , Gallbladder Neoplasms/diagnosis , Gallbladder Neoplasms/metabolism , MicroRNAs/biosynthesis , Cell Line, Tumor , Cell Proliferation/physiology , Gallbladder Neoplasms/genetics , Gallbladder Neoplasms/prevention & control , Humans , MicroRNAs/genetics , PrognosisABSTRACT
Liver cancer stem cells (CSCs) were involved in tumorigenesis, progression, recurrence, and drug resistance of hepatocellular carcinoma (HCC). miR-365 was downregulated in hepatocellular carcinoma and inhibited HCC cell proliferation and invasion. However, the role of miR-365 in liver cancer stem cells was unknown. Herein, we observed a remarkable decrease of miR-365 expression in CD133 or EpCAM-positive liver CSCs as well as in CSC-enriched hepatoma spheres. Up-regulated miR-365 suppressed liver CSC expansion by inhibiting the dedifferentiation of hepatoma cells and decreasing the self-renewal ability of liver CSCs. Mechanistically, bioinformatic and luciferase reporter analysis identified Ras-related C3 botulinum toxin substrate 1 (RAC1) as a direct target of miR-365. Overexpression of miR-365 in hepatoma cells downregulated the RAC1 mRNA and protein expression. RAC1 also could promote the expansion of liver CSCs. The special RAC1 inhibitor EHop-106 or RAC1 overexpression abolished the discrepancy in liver CSC proportion and the self-renewal capacity between miR-365 overexpression hepatoma cells and control cells, which further confirmed that RAC1 was required in miR-365-suppressed liver CSCs expansion. miR-365 was downregulated in liver CSCs and could inhibit HCC cells dedifferentiation and liver CSCs expansion by targeting RAC1 signaling.
