Ran Yi Liu

Genetic and Epigenetic Down-regulation of MicroRNA-212 Promotes Colorectal Tumor Metastasis via Dysregulation of MnSOD

BACKGROUND & AIMS Altered functions of microRNAs (miRNAs) have been associated with colorectal cancer (CRC). miR-212 is transcribed from a stable intron of a non-protein coding gene, and is reportedly down-regulated in different tumor types. We investigated the role of miR-212 in colorectal carcinogenesis and progression. METHODS We analyzed the expression of miR-212 by real-time polymerase chain reaction (PCR) analysis of colorectal cell lines and 180 paired tumor samples and surrounding healthy tissue. We overexpressed and knocked down miR-212 in CRC cell lines and assessed the in vitro effects. We also studied the effects of miR-212 overexpression on metastasis of tumors grown from HCT116 cells in nude mice. RESULTS Overexpression of miR-212 inhibited CRC cell migration and invasion in vitro and formation of intrahepatic and pulmonary metastasis in vivo. We identified manganese superoxide dismutase (MnSOD) messenger RNA as a direct target of miR-212, and observed an inverse correlation between the level of miR-212 and MnSOD protein in colorectal tumor samples. MnSOD was required for down-regulation of epithelial markers and up-regulation of mesenchymal markers in CRC cells, indicating that it promoted the epithelial-mesenchymal transition. Overexpression of miR-212 reduced the levels of MnSOD to block the epithelial-mesenchymal transition process. Loss of heterozygosity and promoter hypermethylation each contributed to the down-regulation of miR-212. Reduced levels of miR-212 were associated with a more aggressive tumor phenotype and short disease-free survival times of patients (P = .0045; overall survival, P = .0015). CONCLUSIONS miR-212 is down-regulated in human CRC tissues via genetic and epigenetic mechanisms. miR-212 might prevent tumor progression by targeting MnSOD messenger RNA; reduction of miR-212 could be a prognostic marker for patients with CRC. miR-212 and MnSOD might also be therapeutic targets for cancer.

Overexpression of Sirt7 Exhibits Oncogenic Property and Serves as a Prognostic Factor in Colorectal Cancer

Purpose: Sirtuins play an important role in cancer development. Sirt7, as a member of this family, is frequently overexpressed in certain carcinomas, but the oncogenic mechanism is seldom reported. In this study, Sirt7 was characterized for its role in colorectal cancer aggressiveness and underlying molecular mechanisms. Experimental Design: Quantitative PCR, Western blotting, and immunohistochemistry were performed to study Sirt7 expression in a cohort of colorectal cancer tissues and non-tumor tissues and cells. A series of in vitro and in vivo assays was performed to elucidate the function of Sirt7 in colorectal cancer and its underlying mechanisms. Association between the Sirt7 signature and survival was examined using Kaplan–Meier analysis and log-rank tests. Results: The Sirt7 protein level significantly correlated with tumor stage (P = 0.029), lymph node metastasis (P = 0.046), and poor patient survival (P < 0.05). Sirt7 knockdown significantly inhibited colorectal cancer cell proliferation, colony formation, and motility. Ectopic Sirt7 expression promoted colony formation, induced a more invasive phenotype, and accelerated cell growth both in vitro and in vivo. Moreover, Sirt7 enhanced MAPK pathway activity concomitantly with p-ERK and p-MEK upregulation. In Sirt7-overexpressing cells, the mesenchymal markers vimentin and fibronectin were upregulated, and the epithelial markers E-cadherin and β-catenin were downregulated, which was linked to enhanced invasion by colorectal cancer cells. Conclusion: Our findings suggest that Sirt7 plays an important role in the development and progression of human colorectal cancer and functions as a valuable marker of colorectal cancer prognosis. Clin Cancer Res; 20(13); 3434–45. ©2014 AACR.

OTUB1 promotes metastasis and serves as a marker of poor prognosis in colorectal cancer

BackgroundOTUB1 (OTU deubiquitinase, ubiquitin aldehyde binding 1) is a deubiquitinating enzyme (DUB) that belongs to the OTU (ovarian tumor) superfamily. The aim of this study was to clarify the role of OTUB1 in colorectal cancer (CRC) and to identify the mechanism underlying its function.MethodsTwo hundred and sixty CRC samples were subjected to association analysis of OTUB1 expression and clinicopathological variables using immunohistochemical (IHC) staining. Overexpression of OTUB1 was achieved in SW480 and DLD-1 cells, and downregulation of OTUB1 was employed in SW620 cells. Then, migration and invasion assays were performed, and markers of the epithelial-mesenchymal transition (EMT) were analyzed. In addition, hepatic metastasis models in mice were used to validate the function of OTUB1 in vivo.ResultsOTUB1 was overexpressed in CRC tissues, and the expression level of OTUB1 was associated with metastasis. A high expression level of OTUB1 was also associated with poor survival, and OTUB1 served as an independent prognostic factor in multivariate analysis. OTUB1 also promoted the metastasis of CRC cell lines in vitro and in vivo by regulating EMT.ConclusionsOTUB1 promotes CRC metastasis by facilitating EMT and acts as a potential distant metastasis marker and prognostic factor in CRC. Targeting OTUB1 may be helpful for the treatment of CRC.

Adenovirus-mediated intra-tumoral delivery of the human endostatin gene inhibits tumor growth in nasopharyngeal carcinoma

The growth and metastasis of nasopharyngeal carcinoma (NPC), one of the most common cancers in southern China, is closely related to neovascularization. Here, we examined whether intra‐tumoral delivery of endostatin gene could lead to long‐term local expression of bioactive endostatin at therapeutic levels. We constructed a recombinant adenoviral vector carrying the human endostatin gene (Ad/hEndo), which expressed high‐level endostatin protein in NPC CNE‐2 cells, and significantly inhibited the proliferation and migration of vascular endothelial cells in vitro. Tumor growth and angiogenesis in NPC CNE‐2 xenografted tumors were significantly inhibited after 5 courses of intra‐tumoral treatment with Ad/hEndo in vivo. Endostatin mRNA in tumor tissues peaked at 1–2 days after intra‐tumoral administration and disappeared within 1 week, whereas the plasma endostatin protein levels peaked at 3 days after administration and lasted 2–3 weeks. The therapeutically relevant endostatin transgene expression was achieved during the course of multiple intra‐tumoral administrations with Ad/hEndo. Multiple injections with adenoviral vectors did not lead to continuous increases of adenovirus neutralizing antibodies in serum. Thus, adenovirus‐mediated intra‐tumoral introduction of the human endostatin gene may form a viable new treatment for NPC, although readministration every 2–3 weeks may be necessary for the best effect.

Adenoviral expression of a truncated S1 subunit of SARS-CoV spike protein results in specific humoral immune responses against SARS-CoV in rats

Abstract The causative agent of severe acute respiratory syndrome (SARS) has been identified as SARS-associated coronavirus (SARS-CoV), but the prophylactic treatment of SARS-CoV is still under investigation. We constructed a recombinant adenovirus containing a truncated N-terminal fragment of the SARS-CoV Spike (S) gene (from −45 to 1469, designated Ad-SN), which encoded a truncated S protein (490 amino-acid residues, a part of 672 amino-acid S1 subunit), and investigated whether this construct could induce effective immunity against SARS-CoV in Wistar rats. Rats were immunized either subcutaneously or intranasally with Ad-SN once a week for three consecutive weeks. Our results showed that all of the immunized animals generated humoral immunity against the SARS-CoV spike protein, and the sera of immunized rats showed strong capable of protecting from SARS-CoV infection in vitro. Histopathological examination did not find evident side effects in the immunized animals. These results indicate that an adenoviral-based vaccine carrying an N-terminal fragment of the Spike gene is able to elicit strong SARS-CoV-specific humoral immune responses in rats, and may be useful for the development of a protective vaccine against SARS-CoV infection.

Recombinant adenovirus vector-mediated functional expression of neurotropin-3 receptor (TrkC) in neural stem cells

We have constructed a recombinant adenovirus expression vector carrying the human neurotrophin-3 (NT-3) receptor TrkC (tyrosine protein kinase C) gene (rAd-TrkC; 2478 bp) and confirmed the expression of the encoded TrkC in green fluorescent protein (GFP)-murine neural stem cells (NSCs) by reverse transcription polymerase chain reaction (RT-PCR), Western blot analysis, and immunocytochemistry. The activity of the expressed rAd-TrkC was verified in vitro by evaluating dose-related responses of NSCs to NT-3, a TrkC specific ligand. TrkC-GFP-NSCs had a significantly higher percentage of neuronal differentiation when treated with NT-3 relative to the rAd-LacZ control cells (55.2% vs. 29.8%; P<0.05, chi(2) test). Thus, our rAd-TrkC vector can transfect NSCs and produce functional TrkC receptors to promote neuronal differentiation of NSCs.

Interaction of NS2 with AIMP2 Facilitates the Switch from Ubiquitination to SUMOylation of M1 in Influenza A Virus-Infected Cells

ABSTRACT Influenza A viruses (IAVs) rely on host factors to support their life cycle, as viral proteins hijack or interact with cellular proteins to execute their functions. Identification and understanding of these factors would increase our knowledge of the molecular mechanisms manipulated by the viruses. In this study, we searched for novel binding partners of the influenza A virus NS2 protein, the nuclear export protein responsible for overcoming host range restriction, by a yeast two-hybrid screening assay and glutathione S-transferase-pulldown and coimmunoprecipitation assays and identified AIMP2, a potent tumor suppressor that usually functions to regulate protein stability, as one of the major NS2-binding candidates. We found that the presence of NS2 protected AIMP2 from ubiquitin-mediated degradation in NS2-transfected cells and AIMP2 functioned as a positive regulator of IAV replication. Interestingly, AIMP2 had no significant effect on NS2 but enhanced the stability of the matrix protein M1. Further, we provide evidence that AIMP2 recruitment switches the modification of M1 from ubiquitination to SUMOylation, which occurs on the same attachment site (K242) on M1 and thereby promotes M1-mediated viral ribonucleoprotein complex nuclear export to increase viral replication. Collectively, our results reveal a new mechanism of AIMP2 mediation of influenza virus replication. IMPORTANCE Although the ubiquitination of M1 during IAV infection has been observed, the precise modification site and the molecular consequences of this modification remain obscure. Here, we demonstrate for the first time that ubiquitin and SUMO compete for the same lysine (K242) on M1 and the interaction of NS2 with AIMP2 facilitates the switch of the M1 modification from ubiquitination to SUMOylation, thus increasing viral replication.

High expression of XPA confers poor prognosis for nasopharyngeal carcinoma patients treated with platinum-based chemoradiotherapy

In this study, we tried to explore if xeroderma pigmentosum complementation group-A (XPA) expression is likely a prognostic prediction factor for locally advanced nasopharyngeal carcinoma (NPC) patients treated with platinum-based chemoradiotherapy, which was considered to bring chemotherapy-related severe toxicity compared with radiotherapy alone. Firstly, MTT assay revealed that downregulating XPA expression in NPC HONE1 and CNE1 cells decreased IC50 of cisplatin and sensitized cells to cisplatin. XPA expression was detected by immunohistochemistry in cancer tissues from locally advanced NPC patients treated with platinum-based chemoradiotherapy. The relationships between XPA expression and clinicopathologic features, overall survival and progression-free survival of patients were evaluated. The results showed that XPA expression was not associated with clinicopathologic parameters, but was likely an independent prognostic factor for patient survival. High XPA level predicts a poor prognosis, and the prediction values were higher in subgroups of younger, higher EBV antibody titer, or treated with concurrent chemoradiotherapy. Combining XPA levels and T/N classifications, we successfully classified these patients into low, medium and high risk groups for platinum-based chemoradiotherapy. These findings suggest that XPA levels may be a potential predictor of prognosis in locally advanced NPC patients treated with platinum-based chemoradiotherapy, and helpful for selecting patients likely to need and benefit from this treatment in future.

Th2 predominance and CD8+ memory T cell depletion in patients with severe acute respiratory syndrome.

Abstract The immune spectrum of severe acute respiratory syndrome (SARS) is poorly understood. To define the dynamics of the immune spectrum in SARS, serum levels of cytokines, chemokines, immunoglobulins, complement and specific antibodies against SARS-associated coronavirus (SARS-CoV) were assayed by enzyme-linked immunosorbent assay (ELISA), and phenotypes of peripheral lymphocytes were analyzed by flow cytometry in 95 SARS-infected patients. Results showed that interleukin (IL)-10 and transforming growth factor β (TGF-β) were continuously up-regulated during the entirety of SARS. Regulated on activation normally T cell-expressed and secreted (RANTES) levels were decreased, while monocyte chemoattractant protein-1 (MCP-1) was elevated in acute patients. Immunoglobulins and complement were elevated during the first month of SARS. Both serum-positive rates and titers of specific IgM and IgG antibodies responding to SARS-CoV peaked at days 41–60 from the onset of SARS. CD4+ and CD8+ T lymphocytes decreased significantly in acute-phase. CD3+CD8+CD45RO+ T lymphocytes were decreased by 36.78% in the convalescent patients. Conclusion: SARS-CoV seemed to elicit effective humoral immunity but inhibited cellular immunity, especially CD8+ memory T lymphocytes over time. Prolonged overproduction of IL-10 and TGF-β may play an important role in the disease.

Adenovirus-mediated delivery of interferon-γ gene inhibits the growth of nasopharyngeal carcinoma

BackgroundInterferon-γ (IFN-γ) is regarded as a potent antitumor agent, but its clinical application is limited by its short half-life and significant side effects. In this paper, we tried to develop IFN-γ gene therapy by a replication defective adenovirus encoding the human IFN-γ (Ad-IFNγ), and evaluate the antitumoral effects of Ad-IFNγ on nasopharyngeal carcinoma (NPC) cell lines in vitro and in xenografts model.MethodsThe mRNA levels of human IFN-γ in Ad-IFNγ-infected NPC cells were detected by reverse transcription-polymerase chain reaction (RT-PCR), and IFN-γ protein concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in the culture supernatants of NPC cells and tumor tissues and bloods of nude mice treated with Ad-IFNγ. The effects of Ad-IFNγ on NPC cell proliferation was determined using MTT assay, cell cycle distribution was determined by flow cytometry analysis for DNA content, and cells apoptosis were analyzed by Annexin V-FITC/7-AAD binding assay and hoechst 33342/PI double staining. The anti-tumor effects and toxicity of Ad-IFNγ were evaluated in BALB/c nude mice carrying NPC xenografts.ResultsThe results demonstrated that Ad-IFNγ efficiently expressed human IFN-γ protein in NPC cell lines in vitro and in vivo. Ad-IFNγ infection resulted in antiproliferative effects on NPC cells by inducing G1 phase arrest and cell apoptosis. Intratumoral administration of Ad-IFNγ significantly inhibited the growth of CNE-2 and C666-1 cell xenografts in nude mice, while no significant toxicity was observed.ConclusionsThese findings indicate IFN-γ gene therapy mediated by replication defective adenoviral vector is likely a promising approach in the treatment of nasopharyngeal carcinoma.