BackgroundATAD2 is associated with many cellular processes, such as cell growth, migration and invasion. However, no studies have been conducted on the molecular biological function of the ATAD2 gene in hepatocellular carcinoma (HCC).MethodsThe protein and mRNA level expression of ATAD2 was examined in tissues and cell lines. Prognostic significance was analyzed by the Kaplan-Meier survival method and Cox regression. ATAD2 knockdown was used to analyze cell proliferation and invasion. The upstream and downstream of ATAD2 was analyzed by RT2 Profiler™ PCR array and luciferasex fluorescence system.ResultsATAD2 was highly expressed in liver cancer samples and correlated with poor survival. High ATAD2 expression was positively correlated with metastasis (P = 0.005) and was an independent prognostic factor in HCC (P = 0.001). ATAD2 depletion by RNA interference reduced their capacity for invasion and proliferation and led to a G1 phase arrest in vitro. Further study revealed that miR-372 was an upstream target of ATAD2 as miR-372 was bound directly to its 3′ untranslated region (3′ UTR). In addition, ATAD2 knockdown was found to extremely up-regulate APC expression and down-regulate CTNNA1 at the mRNA level.ConclusionsThe findings demonstrated that miR-372 suppressed the expression of ATAD2, which was highly expressed in HCC and exerted a proto-oncogene effect in hepatic carcinogenesis. In conclusion, ATAD2 may promote HCC progression.

BackgroundIncreasing evidence suggests that microRNAs (miRNAs) play critical roles in malignant transformation, tumor progression and metastasis. Aberrant miR-655-3p expression has been associated with several cancers. However, the role and underlying mechanism of miR-655-3p in the development of hepatocellular carcinoma (HCC) remains unclear.MethodsMiR-655-3p expression was detected by quantitative RT-PCR (qRT-PCR) in human HCC tissues and cell lines. Cell proliferation was investigated using MTT and colony formation assays, and cell migration and invasion abilities were evaluated by transwell assay. ADAM10 protein expression was detected by immunohistochemical assay. The target gene and downstream of miR-655-3p were determined by qRT-PCR, western blot and dual-luciferase reporter assays.ResultsmiR-655-3p was significantly down-regulated in HCC tissues and HCC cell lines. Low miR-655-3p expression was negatively related to tumor size, portal vein tumor thrombosis (PVTT) status, TNM stage and metastasis status. In addition, miR-655-3p overexpression and depletion decreased and increased HCC cell proliferation, migration and invasion, respectively. Moreover, ADAM10 was identified as a direct target of miR-655-3p, and miR-655-3p down-regulated E-cadherin protein level and inhibits β-catenin pathway by mediating ADAM10.ConclusionsMiR-655-3p might functions as a tumor suppressor by directly targeting ADAM10 and indirectly regulating β-catenin pathway in the development of progression of HCC. It may be a novel therapeutic candidate target to in HCC treatment.

ATAD2 is associated with many cellular progresses such as cell growth, differentiation and apoptosis. Some studies suggest ATAD2 is highly expressed in cancer cells. In our previous studies, we found that ATAD2 is highly expressed in HCC tissues, compared with adjacent normal tissues, and patients with high expression of ATAD2 had a poorer prognosis. Moreover, we found mir-372 can regulate the expression of ATAD2 in HCC cell lines. We also detected a relationship between the mRNA expression of ATAD2 and Ptch1 by gene microarray. Here, we completed the function studies of ATAD2 in vivo and in vitro, and tested whether ATAD2 could regulate the Hh pathway. ATAD2 and Hh pathway protein expressions in 80 HCC specimens were examined by immunohistochemistry (IHC). The mRNA expression of ATAD2 and Hh pathway members in paired-HCC tissues and cell lines were, respectively, analyzed using quantitative PCR. ATAD2‑RNAi was transduced into HCCLM3 and Huh7 cells, using a lentiviral vector. The effect of ATAD2 in HCC cell lines on cell cycle and apoptosis were evaluated by flow cytometry. Tumorigenicity experiments in nude mice were performed to test the function of ATAD2 in vivo. Pharmacological regulation of Hh signaling was performed to test the relation between the ATAD2 and Hh pathways and C-myc. We found that ATAD2 and Ptch1 were both highly expressed in HCC tissues, compared with paired normal hepatic tissues. In addition, we found that ATAD2 could affect the expression of the Hh pathway by PCR and western blot anaysis in HCC cell lines, by observing the outcome before and after transfection. We speculate that ATAD2 cooperates with the MYC gene to regulate the expression of SMO and Gli, activating the Hh pathway and inducing an active feedback of the Hh pathway.