MicroRNA-338-3p inhibits colorectal carcinoma cell invasion and migration by targeting smoothened.

OBJECTIVE: To investigate the regulative effect of microRNA-338-3p on colorectal carcinoma cell invasion and migration. METHODS: The microRNA-338-3p expression pattern of colorectal carcinoma tissues and cell lines was detected by real-time reverse transcriptase polymerase chain reaction. The protein level of smoothened was detected by western blot analysis. Furthermore, colorectal carcinoma cells were pretreated with or without anti-smoothened-small interfering ribonucleic acid prior to the addition of pre-microRNA-338-3p or anti-microRNA-338-3p. The status of colorectal carcinoma cell invasion and that of migration were detected by transwell assay and wound healing assay, respectively. RESULTS: The expression of microRNA-338-3p was significantly down-regulated in colorectal carcinoma tissues in comparison with those in the adjacent non-tumorous tissues, and the value was negatively related to advanced tumor, node, metastasis stage and local invasion. The expression of microRNA-338-3p in colorectal carcinoma cells transfected with pre-microRNA-338-3p p was significantly increased. Furthermore, over-expression of microRNA-338-3p inhibited the expression of smoothened protein in colorectal carcinoma cells, which showed obviously suppressed invasion and migration ability. The expression of microRNA-338-3p in colorectal carcinoma cells transfected with anti-microRNA-338-3p was significantly decreased. Moreover, the down-regulated expression of microRNA-338-3p caused the up-regulated expression of smoothened protein in colorectal carcinoma cells, which showed significantly enhanced invasion and migration ability. However, anti-smoothened-small interfering ribonucleic acid largely, but not completely, reversed the effects induced by blockage of microRNA-338-3p, suggesting that the regulative effect of microRNA-338-3p on colorectal carcinoma cell invasion and migration was indeed mediated by smoothened. Additionally, smoothened was identified as a direct target of microRNA-338-3p by luciferase assay. CONCLUSIONS: MicroRNA-338-3p could inhibit colorectal carcinoma cell invasion and migration by inhibiting smoothened expression.

Construction of lentivirus-based inhibitor of hsa-microRNA-338-3p with specific secondary structure.

AIM: To construct a lentivirus-based inhibitor with specific secondary structure that could exert long-term suppression on microRNA-338-3p (miR-338-3p), thus elucidating its molecular function in colorectal carcinoma cells. METHODS: The miR-338-3p inhibitor sequence was synthesized and inserted into pLV-THM plasmid. HEK-293T cells were co-transfected with the lentiviral vectors pLV-THM-miR-338-3p-inhibitor, psPAX2, and pMD2.G. The supernatant containing the lentivirus particles was harvested to determine the viral titer, and then used to infect colorectal carcinoma-derived SW-620 cells. eGFP(+) cells were sorted using flow cytometry. The expression of miR-338-3p in SW-620 cells was determined with real-time RT-PCR, and the expression of the smoothened (SMO) protein was detected using Western blot analysis. The migration ability of the transfected SW-620 cells was assessed with transwell assay. RESULTS: Restriction endonuclease analysis and DNA sequencing demonstrated that the lentiviral vector pLV-THM-miR-338-3p-inhibitor was successfully constructed. The expression of miR-338-3p in SW-620 cells was significantly decreased by infection with the lentivirus pLV-THM-miR-338-3p-inhibitor. Moreover, the down-regulated expression of miR-338-3p caused up-regulated expression of the SMO protein in SW-620 cells, which showed significantly enhanced migration in transwell assay. CONCLUSION: The construction of the lentiviral vector pLV-THM-miR-338-3p-inhibitor with specific secondary structure provides a basis for further studies the molecular function of miR-338-3p in colorectal carcinoma. miR-338-3p may suppress SMO gene expression and thereby inhibit colorectal carcinoma migration.

Two-dimensional electrophoresis for comparative proteomic analysis of human bile.

BACKGROUND: Proteomic analysis of bile fluid holds promise as a method to identify biomarkers of bile tract diseases, especially for tumors. Two-dimensional electrophoresis (2-DE) is a popular and proven separation technique for proteome analysis, but using this strategy for bile fluid analysis is still not fully developed. This study was undertaken to (a) establish a reliable method for general clean-up to make bile fluid samples suitable for 2-DE; (b) obtain 2-D biliary maps with high reproducibility and resolution; and (c) identify protein patterns present in 2-D biliary maps for potential tumor biomarker discovery, with the intention of distinguishing malignant from benign causes of bile duct obstruction. METHODS: Bile fluid samples were obtained from two patients suffering from malignant and benign bile tract obstruction (one patient with cholangiocarcinoma as the experimental case, the other with cholelithiasis as control). A variety of sample preparation options, including delipidation, desalination and nucleic acid removal, were adopted to remove contaminants that affect 2-DE results. After that, each 350 microg purified sample was loaded onto nonlinear IPG strips (18 cm, pH 3-10 and pH 4-7) for first-dimension isoelectric focusing, and 12.5% SDS-PAGE electrophoresis for second dimension separation. Then 2-D maps were visualized after silver staining and analyzed with the Image Master 2-D software. RESULTS: A large number of protein spots were separated in 2-D maps from the experimental and control groups, with means of 250 and 216 spots on pH 3-10 IPG strips, and 182 and 176 spots on pH 4-7 strips, respectively. Approximately 16 and 23 spots were differentially expressed in matched pairs from the experimental and control cases using pH 3-10 and pH 4-7 strips. CONCLUSIONS: This study established a reliable sample preparation process suitable for 2-DE of bile fluid. By this method, 2-D biliary maps with high reproducibility and resolution were obtained. The differentially displayed proteomes in the 2-D biliary maps from the experimental and control groups indicated the potential application for bile fluid analysis to identify disease-associated biomarkers, especially for biliary tract tumors.

Effect of antisense DNMT3b gene eukaryotic expression plasmid on expression of the DNMT3b gene in human biliary tract carcinoma cells.

BACKGROUND: Hypermethylation of the promoter region is one of the major mechanisms of tumor suppressor gene inactivation. DNA methyltransferase 3b (DNMT3b), an enzyme that participates in the establishment of de novo methylation patterns, is highly expressed in many tumor cells and tissues, and it is closely associated with hypermethylation of the promoter of tumor suppressor genes. The aim of this study was to explore the effect of transfection with antisense DNMT3b gene eukaryotic expression plasmid on the expression of the DNMT3b gene in human biliary tract carcinoma cell. METHODS: The constructed antisense DNMT3b gene eukaryotic expression plasmid was transfected into the human biliary tract carcinoma cell line QBC-939 with lipofectamine transfection reagent, and positive cell clones were formed using G418 selection after transfection. The constructed recombinant plasmid was transfected into QBC-939 cells successfully and was confirmed by amplification of the exogenous neoR gene with the polymerase chain reaction method. The expression of DNMT3b gene mRNA and protein was detected by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and flow cytometry respectively. RESULTS: Following transfection, the mRNA level of the DNMT3b gene decreased from 0.956+/-0.053 to 0.209+/-0.023, and the protein level of the DNMT3b gene also decreased from (75.38+/-3.22)% to (29.87+/-3.46)%. Very significant differences were observed both at the transcription and post-transcription levels in the expression of the DNMT3b gene between the non-transfection group and the antisense DNMT3b gene eukaryotic expression plasmid transfection group (P<0.01). CONCLUSIONS: Transfection with the antisense DNMT3b gene eukaryotic expression plasmid can significantly reduce the expression level of the DNMT3b gene in the human biliary tract carcinoma cell line QBC-939. This study may provide a valid method to investigate the function of the DNMT3b gene and its role in biliary tract carcinoma.

[Effect of adenovirus-mediated mutant exogenous P27kip1 gene expression on the chemosensitivities of cholangiocarcinoma cell line].

OBJECTIVE: To investigate the effects of mutant exogenous P27(kip1) gene on chemosensitivity of human cholangiocarcinoma cell line. METHODS: The recombinant vector was constructed and the mutant P27(kip1) gene was transfected into human cholangiocarcinoma cell line (QBC(939)). RT-PCR and Western blot were used to determine the expression of target genes. The effects of 5-fluorouracil (5-FU), mitomycin C (MMC) and cyclophosphamide (CTX) on the transfected cells were detected by assaying the apoptotic rate and growth inhibition by methabenzthiazuron (MTT) assay and flow cytometry (FCM). RESULTS: The mutant exogenous P27(kip1) gene was expressed effectively in the cells, and the expression enhanced the apoptosis and growth inhibition of QBC(939) inducted by 5-FU, MMC and CTX. The ratio of growth inhibiting increased significantly from 41.89% (5-FU), 45.59% (MMC), 38.91% (CTX) to 56.15% (5-FU), 55.65% (MMC), 51.69% (CTX), and apoptosis index from 13.76% +/- 3.03% (5-FU), 11.76% +/- 3.99% (MMC), 10.46% +/- 2.10% (CTX) to 41.39% +/- 4.32% (5-FU), 35.94% +/- 2.71% (MMC), 34.46% +/- 2.32% (CTX) (P < 0.05). CONCLUSIONS: The exogenous P27(kip1) gene transfer can remarkably increase the drug sensibility of the cholangiocarcinoma cells. The strategy targeted to control the cell cycle may be more effective in cancer treatment by combination of P27(kip1) gene therapy.

miRNA-338-3p suppresses cell growth of human colorectal carcinoma by targeting smoothened.

AIM: To investigate the regulative effect of miRNA-338-3p (miR-338-3p) on cell growth in colorectal carcinoma (CRC). METHODS: The lentiviral vector pLV-THM-miR-338-3p and pLV-THM-miR-338-3p-inhibitor were constructed. The recombinant viral vector encoding the pre-miR-338-3p or miR-338-3p-inhibitor and the two packaging plasmids psPAX2 and pMD2.G were cotransfected into human embryonic kidney 293T cells to package lentivirus. The supernatant containing the lentivirus particles was harvested to determine the viral titer, and this supernatant was then used to transduce CRC-derived cell line, SW-620. Flow cytometry was utilized for sorting the green fluorescent protein (GFP)⁺ cells to establish the SW-620 cell line stably expressing pre-miR-338-3p or miR-338-3p-inhibitor. Moreover, the expression of miR-338-3p was determined by real-time reverse transcriptase polymerase chain reaction, and Western blotting was used to detect the expression of the smoothened (SMO, the possible target of miR-338-3p) protein in SW-620 cells. Furthermore, the status of CRC cell proliferation and apoptosis were detected by 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay and flow cytometry, respectively. RESULTS: Restriction enzyme digestion and DNA sequencing demonstrated that the lentiviral vector pLV-THM-miR-338-3p and pLV-THM-miR-338-3p-inhibitor were constructed successfully. GFP was expressed after the SW-620 cells were transduced by the lentivirus. Expression of miR-338-3p in SW-620 cells transduced with the lentivirus pLV-THM-miR-338-3p was significantly increased (relative expression 3.91 ± 0.51 vs 2.36 ± 0.44, P < 0.01). Furthermore, overexpression of miR-338-3p inhibited the expression of SMO protein in SW-620 cells, which showed obviously suppressed proliferation ability [cellular proliferation inhibition rate (CPIR) 61.9% ± 5.2% vs 41.6% ± 4.8%, P < 0.01]. Expression of miR-338-3p in SW-620 cells transduced with the lentivirus pLV-THM-miR-338-3p-inhibitor was significantly decreased (relative expression 0.92 ± 0.29 vs 2.36 ± 0.44, P < 0.01). Moreover, the downregulated expression of miR-338-3p caused upregulated expression of the SMO protein in SW-620 cells, which showed significantly enhanced proliferation ability (CPIR 19.2% ± 3.8% vs 41.6% ± 4.8%, P < 0.01). However, anti-SMO-siRNA largely, but not completely, reversed the effects induced by blockage of miR-338-3p, suggesting that the regulative effect of miR-338-3p on CRC cell growth was indeed mediated by SMO. CONCLUSION: miR-338-3p could suppress CRC growth by inhibiting SMO protein expression.

Anti-miRNA-221 sensitizes human colorectal carcinoma cells to radiation by upregulating PTEN.

AIM: To investigate the regulative effect of miRNA (miR)-221 on colorectal carcinoma (CRC) cell radiosensitivity and the underlying mechanisms. METHODS: A human CRC-derived cell line was cultured conventionally and exposed to different doses of X-rays (0, 2, 4, 6 and 8 Gy). The total RNA and protein of the cells were extracted 24 h after irradiation, and the alteration of miR-221 and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene mRNA expression was detected by real-time reverse transcriptase polymerase chain reaction (PCR). The protein alteration of PTEN in the cells was detected by Western blotting. Caco2 cells were pretreated with or without anti-PTEN-siRNA prior to the addition of pre-miR-221 or anti-miR-221 using Lipofectamine 2000. Colony formation assay and flow cytometry analysis were used to measure the surviving cell fraction and the sensitizing enhancement ratio after irradiation. Additionally, PTEN 3'-untranslated region fragment was PCR amplified and inserted into a luciferase reporter plasmid. The luciferase reporter plasmid construct was then transfected into CRC cells together with pre-miR-221 or anti-miR-221, and the luciferase activity in the transfected cells was detected. RESULTS: The X-ray radiation dose had a significant effect on the expression of miR-221 and PTEN protein in human Caco2 cells in a dose-dependent manner. The miR-221 expression level improved gradually with the increase in irradiation dose, while the PTEN protein expression level reduced gradually. miR-221 expression was significantly reduced in the anti-miR-221 group compared with the pre-miR-221 and negative control groups (P < 0.01). Anti-miR-221 upregulated expression of PTEN protein and enhanced the radiosensitivity of Caco2 cells (P < 0.01). Moreover, the inhibitory effect was dramatically abolished by pretreatment with anti-PTEN-siRNA, suggesting that the enhancement of radiosensitivity was indeed mediated by PTEN. A significant increase of luciferase activity was detected in CRC cells that were cotransfected with the luciferase reporter plasmid construct and anti-miR-221 (P < 0.01). CONCLUSION: Anti-miR-221 can enhance the radiosensitivity of CRC cells by upregulating PTEN.