Over-expression of SATB1 mediates invasion and metastasis of nasopharyngeal carcinoma cells through epithelial-mesenchymal transition

AIM:To analyze the high expression of special AT-rich sequence-binding protein 1 (SATB1) in nasopharyngeal carcinoma (NPC) and its role in tumor invasion and metastasis. METHODS:The method of immunohistochemistry was used to detect the expression of SATB1 and epithelial-mesenchymal transition (EMT)-related molecules E-cadherin and vimentin in 76 cases of NPC and 61 cases of nasopharyngeal chronic inflammation (NPI), and the correlations of over-expression of SATB1 with NPC patients' clinical parameters as well as the expression of E-cadherin and vi-mentin were analyzed. Variously differentiated NPC cell lines CNE1, CNE2Z and C666-1 were cultured in vitro, and then SATB1-overexpressing cell line was screened. After interfering with SATB1 expression by siRNA, the expression of EMT-related molecules and the change of cell invasiveness were analyzed. RESULTS:The expression of SATB1 in the nasopharyngeal tissue was dominantly localized in the nuclei. The positive rate of SATB1 in NPC group was significantly higher than that in NPI group (P<0.01). E-cadherin was membrane-positive in NPI epithelial cells, while membrane E-cadherin in NPC was decreased but cytoplasmic expression was increased. The positive expression rate of membrane E-cadherin in NPI was significantly higher than that of NPC (P<0.01). Vimentin was localized in cytoplasm and negative in NPI epithelial cells, but the positive rate in NPC parenchymal cells was significant higher than that in NPI (P<0.01). The high expression of SATB1 in NPC was not related to the patents' sex, age, clinical classification and N classification, but positively correlated with T and M classification (P<0.05). Besides, high expression of SATB1 was positively correlated with vi-mentin in NPC tissues (r=0.358, P=0.009). SATB1 expression in NPC cell lines was negatively correlated with the levels of cell differentiation. Knockdown of SATB1 expression in C666-1 cells with siRNA was accompanied by an increase in E-cadherin and a decrease in vimentin levels, as well as a decrease in cell invasiveness. CONCLUSION:High expression of SATB1 promotes the clinical progress of NPC through EMT mechanism.     

Expression of molecular markers Jab1 and Akt1 in recurrent nasopharyngeal carcinoma

AIM：To analyze the expression of Jab1 and Akt1 in paired human primary and recurrent nasopharyngeal carcinoma (NPC) tissues, to explore the relationships between their expression and molecular mechanism and further to identify the potential treatment target of rNPC. METHODS：Paired primary and recurrent NPC archival samples (n=45) from Affiliated Foshan Hospital and Affiliated Shantou Hospital of Sun Yat-sen University were collected. The expression of Jab1 and Akt1 was determined by the method of immunohistochemistry (SABC). The expression of Jab1 and Akt1 in CNE-1, CNE-2, CNE-2R and HONE1 cells before and after ionizing radiation (IR) was detected by Western blotting. RESULTS：The expression of Jab1 and Akt1 increased in recurrent NPC tissues compared with the primary tumors (both P<0.05). The expression of Jab1 and Akt1 increased in CNE-1, CNE-2R and HONE1 cells in comparison with CNE-2 cells. Furthermore, Jab1 expression was elevated in CNE-1, CNE-2, CNE-2R and HONE1 cells after receiving IR. CONCLUSION：Over-expression of Jab1 and Akt1 contributes to the resistance of NPC cells with irradiation, and induces recurrence of NPC. Therefore, Jab1 and Akt1 serve as potential tumor targets for the treatment of recurrent NPC.     

Effect of transketolase-like protein 1 on proliferation of human nasopharyngeal carcinoma cells

AIM: To investigate the effect of transketolase-like protein 1 (TKTL1) on proliferation of human nasopharyngeal carcinoma cells in vitro. METHODS: The siRNA against TKTL1 mRNA was constructed and transfected into human nasopharyngeal carcinoma cells (CNE cell line). The activity of transketolase was detected before and after RNA interference.Real-time PCR was used to determine the mRNA expression of transketolase (TKT) gene family in the CNE cells.Flow cytometry and MTT test were used to detect the effect of anti-TKTL1 siRNA on cell proliferation and cell cycle in the CNE cells. RESULTS: The total transketolase activity was significantly decreased in the CNE cells transfected with siRNA TKTL1 construct compared with the cells transfected with control vector or untransfected CNE cells. No significant difference in the expression level of TKT and TKTL2 gene between the CNE cells transfected with siRNA TKTL1 construct and the cells transfected with control vector or untransfected CNE cells was observed (P>0.05). However, the expression level of TKTL1 gene was significantly downregulated in the CNE cells transfected with siRNA TKTL1 construct compared with the cells transfected with control vector.Cancer cells were arrested in G0/G1 phase, and cancer cell proliferation was significantly inhibited in the CNE cells transfected with siRNA TKTL1 construct. CONCLUSION: TKTL1 plays an important role in the total transketolase activity and cell proliferation of human nasopharyngeal carcinoma. TKTL1 may be considered as a potential target for novel anti-cancer therapy.     

Latent membrane protein 1 regulates expression of p27 and RPLP0 in nasopharyngeal epithelial and nasopharyngeal carcinoma tissues

AIM: To observe the protein expression of p27 and ribosomal phosphoprotein large P0(RPLP0) regulated by latent membrane protein 1 (LMP1) in nasopharyngeal epithelial and nasopharyngeal carcinoma tissues. METHODS: The protein levels of p27 and RPLP0 and the relationship with LMP1 were analyzed by Western blotting. The protein expression of LMP1, p27 and RPLP0 was also detected by the method of immunohistochemistry in 30 nasopharyngeal epithelial and 60 nasopharyngeal poorly-differentiated squamous-cell carcinoma tissues. Meanwhile, the significance of clinical pathology was evaluated. RESULTS: The positive rate of LMP1 protein was 73.3% and 90.0% in nasopharyngeal epithelial and nasopharyngeal poorly-differentiated squamous-cell carcinoma tissues, respectively. Compared with the LMP1-negative tissues, the protein levels of RPLP0 were low in the nasopharyngeal epithelial and nasopharyngeal poorly-differentiated squamous-cell carcinoma tissues with LMP1-positive expression, but the levels of RPLP0 protein were overexpressed. The protein expression of RPLP0 and RPLP0 was related to the age of nasopharyngeal carcinoma patients, the protein level of LMP1, the metastasis of lymph nodes and the TNM classification. The positive expression of p27 protein at high level was usually observed in the patients with young age, or had the characteristics of LMP1 (-), non-metastasis of lymph nodes, and in I or II stage of TNM classification. However, the protein expression of RPLP0 was low (P<0.05). CONCLUSION: LMP1 down-regulates p27 and up-regulates RPLP0 in nasopharyngeal epithelial and nasopharyngeal poorly-differentiated squamous-cell carcinoma tissues.     

Construction of shRNA targeting AGR2 gene and effect of AGR2 on biological function of nasopharyngeal carcinoma cells

AIM: To construct the shRNA targeting anterior gradient protein 2 (AGR2) gene for exploring the effect of AGR2 on the biological behavior of nasopharyngeal carcinoma (NPC) cells.METHODS: The expression of AGR2 at mRNA and protein levels in NPC cell lines 6-10B and 5-8F was detected by real-time PCR and Western blot. The pSR-GFP/Neo-AGR2-shRNA expression vector targeting AGR2 was constructed. Based on the interference targeting AGR2, the cell migration and motility were determined by Transwell migration and motility assays.RESULTS: The expression of AGR2 was increased in NPC cell line 5-8F compared with NPC cell line 6-10B (P<0.05). When the AGR2 expression in 5-8F cells was interfered, the cell migration, invasion and tumorigenicity were weakened.CONCLUSION: The expression of AGR2 is up-regulated in NPC cell line 5-8F. pSR-GFP/Neo-CLU-shRNA successfully inhibits the expression of AGR2 in NPC cell line 5-8F. AGR2 inhibits the migration, invasion and tumorigenicity of 5-8F cells in vivo.     

Inhibitory effect of JIP on AP-1 activity induced by LMP1 in nasopharyngeal carcinoma cells and its mechanism

AIM: To investigate the mechanism of the AP-1 signal transduction pathway inhibited by JIP in nasopharyngeal carcinoma cells. METHODS: AP-1 activity was triggered by Dox-induced LMP1 expression in Tet-on-LMP1-HNE₂ cells (L7). The retention of phospho-JNK in the cytoplasm caused by JIP was examined with immunofluroscence assay. RESULTS: 24 h after transfection of L7 cells with the JIP expression plasmid, the translocation of activated JNK was inhibited, which resulted in the retention of phospho-JNK in the cytoplasm and down-regulation of the AP-1 activity. CONCLUSION: JIP down-regulates the activity of AP-1 through the inhibition of the translocation of JNK.     

Inhibitory role of epigallocatechin-3-gallate in proliferation of human nasopharyngeal carcinoma cells by targeting P53/miR-34a

AIM: To study the effect of epigallocatechin-3-gallate(EGCG) on the proliferation of human nasopharyngeal carcinoma(NPC) cells, and to explore its mechanism by targeting miR-34a.METHODS: Nasopharyngeal carcinoma CNE-2Z cells were treated with various concentrations of EGCG. The ability of cell proliferation was detected by CCK-8 assay, 5-ethynyl-2-deoxyuridine(EdU) incorporation assay and colony-forming assay. The cell cycle distributions were analyzed by flow cytometry. The protein levels of P53 and Notch1 were detected by Western blot. The expression of miR-34a and Notch1 mRNA was measured by real-time PCR.RESULTS: EGCG effectively inhibited the proliferation and colony formation of CNE-2Z cells in a dose-dependent manner, which was related to its induction of cell cycle arrest at G₀/G₁ phase. The expression of P53 and miR-34a in CNE-2Z cells was significantly increased after treated with EGCG, while the expression of Notch1 at mRNA and protein levels was markedly suppressed.CONCLUSION: EGCG induces cell cycle arrest and suppresses cell proliferation by regulating the P53/miR-34a/Notch1 pathway in NPC cells.     

Differences of genome-wide methylation level and methylated genes between nasopharyngeal carcinoma cells in same genetic background but different radiation resistance

AIM: To compare the differences of the genome-wide methylation levels and methylated regions between nasopharyngeal carcinoma (NPC) cells in the same genetic background but different radiation resistance (CNE-2 cells and CNE-2R cells). METHODS: Using the method which was developed by Doctor Zhao Cun-you, based on using methyl-sensitive restriction enzyme to measure the genome-wide methylation levels. In addition, MeDIP-Seq was used to analyze the methylated regions in 6 gene functional elements, including the upstream 2k sequence, 5'UTR, coding sequence, intron, 3'UTR and downstream 2k sequence, between CNE-2 cells and CNE-2R cells. RESULTS: The genome-wide methylation level was approximately 30% lower in CNE-2R cells than that in CNE-2 cells. No obvious difference on the amount of genes and the coverage of the peak in the 6 gene functional elements was observed. However, the methylation pattern of plentiful genes had altered in the gene function elements. CONCLUSION: The genome-wide methylation levels and methylated regions between NPC cells in the same genetic background but different radiation resistance were quite different, indicating that the DNA methylation may be associated with NPC radioresistance.     

Detection and clinical significance of circulating tumor cells in peripheral blood of nasopharyngeal cancer patients with modified immunomagnetic enrichment and fluorescent immunocytochemistry

AIM: To investigate the clinical significance of the new method of modified immunomagnetic enrichment of tumor cells in combination with fluorescent immunocytochemistry to detect circulating tumor cells (CTCs) in peripheral blood samples of patients with nasopharyngeal cancer (NPC). METHODS: Peripheral blood samples were obtained from 76 histology-proven patients with NPC before the initial therapy. After isolation of the mononuclear cells, the CTCs expressing cytokeratin (CK)8/18 in the blood samples were detected by the method of immunomagnetic enrichment in combination with fluorescent immunocytochemistry. The magnetic beads covalent binding with epithelial cell adhesion molecule (EpCAM) antibody were used to enrich the tumor cells which expressed EpCAM. After median following-up for 25 months, the effects of CTCs and other prognostic factors on patient prognosis were thoroughly investigated. RESULTS: None of the positive CK8/18 cells was detected in 20 normal blood samples. The CTCs were detected in 82.9% of the patients (P<0.01). Relapse patients had significantly higher number of median CK8/18⁺ CTCs than the patients without relapse (P<0.01). No association of viral capsid antigen (VCA)-IgA (P>0.05) was observed between the patients with and without relapse. Relapse-free survival rates were lower when the number of peripheral blood CK8/18⁺ CTCs was more than 3. The 2-year relapse-free survival rates were 100%, 100%, 100%, 94.1%, 71.4%, 53.3% and 44.4%(P<0.01) when the numbers of peripheral blood CK8/18⁺ CTCs were 0, 1, 2, 3, 4, 5, 6 before treatment, respectively. Overall survival rates were lower when the number of peripheral blood CK8/18⁺ CTCs was more than 5, but the difference was not significant. The 2-year overall survival rates were 100%, 100%, 100%, 100%, 100%, 100%, 80% and 77.8% (P>0.05) when the numbers of peripheral blood CK8/18⁺ CTCs were 0, 1, 2, 3, 4, 5, 6 before treatment,respectively. The VCA-IgA titer could not predict survivals. Cox multivariate analysis also showed the same results. CONCLUSION: Peripheral blood CK8/18⁺ CTCs are a prognostic factor for initial treatment of NPC.     

Effects of Danshensu on TGF-β1/Smads signaling pathways in rats with pulmonary fibrosis

AIM: To study the preventive and curative roles of Danshensu (DA) in bleomycin (BLM)-induced pulmonary fibrosis in rats. METHODS: Pulmonary fibrosis was induced in SD rats by intratracheal instillation of BLM. The rats were intraperitoneally injected with dexamethasone (1 mg·kg-1·d-1, DXM group), DA (15 mg·kg-1·d-1, DA group), or physiological saline (2 mL·d-1, BLM group). Normal controls (NC group) received physiological saline both intratracheally and intraperitoneally. At the 28th day after modeling, the histological changes of the lungs were evaluated by hematoxylin-eosin (HE) and Masson’s trichrome staining. The protein levels of α-smooth muscle actin (α-SMA) in the lung tissues were detected by the method of immunohistochemistry. The mRNA expression of transforming growth factor beta 1 (TGF-β1), Smad3 and Smad7 was assessed by real-time fluorescence quantitative PCR. RESULTS: Compared with BLM group, the degree of inflammation and fibrosis of the lung in DA group was obviously reduced, and so was the expression of α-SMA in the lung tissues. The mRNA expression of TGF-β1 and Smad3 in the lung tissues of the rats decreased and the mRNA expression of Smad7 increased. CONCLUSION: DA alleviates BLM-induced pulmonary fibrosis in rats in the early stage by inhibiting the expression of TGF-β1/Smad3 and stimulating the expression of Smad7 in the lung tissues.     

Relationship between expression of MKK-4 and MMP-9 genes in primary hepatic carcinoma with or without invasion and metastasis

AIM：To investigate the expression of mitogen activated protein kinase kinase 4 (MKK-4) and MMP-9 mRNA in primary hepatic carcinoma (PHC), and to analyze its relationship with invasion and metastasis. METHODS：The expression of MKK-4 and MMP-9 mRNA in 34 cases of hepatic carcinoma tissues and adjacent tissues,and in 12 cases of normal liver tissues were detected with RT-PCR. RESULTS：(1) The expression level of MMP-9 mRNA was higher in metastatic cancer tissues than that in other tissuses (P<0.01). (2) There was significant statistical difference among the expression level of MKK-4 mRNA, but the level in metastatic cancer was low (P<0.01). (3) There was no statistical difference among the expression level of MKK-4 or MMP-9 mRNA among the adjacent tissues and normal tissues (P>0.05). (4) MMP-9 mRNA had a tendency to rise as PHC became invasive and metastatic.The expression level of MKK-4 had a tendency to decline in PHC became invasive and metastatic. (5) The expression level of MMP-9 or MKK-4 mRNA had no correlations with tumor volume,or cell differentiation (P>0.05). (6) There were correlations between expressions of MKK-4 and MMP-9 mRNA in PHC (Pearson Correlation, r=-0.925, P<0.01). CONCLUSION：There are high MMP-9 mRNA expression and low MKK-4 mRNA expression in PHC.The expression level of MKK-4 or MMP-9 mRNA is correlated with tumor metastasis.     

Effects of astragaloside IV combined with ginsenoside Rg1 on autophagy and PI3K signaling pathways of PC12 cells induced by oxygen glucose deprivation/reoxygenation

ATM: To probe the effect and the mechanism of astragaloside IV and ginsenoside Rg1 on autophagy of PC12 cells induced by oxygen glucose deprivation/reoxygenation (OGD/R). METHODS: The autophagy injury model of PC12 cells induced by OGD/R was established(PC12 cells were exposed to 2 h of OGD followed by 24 h of reoxygenation). The effects of astragaloside IV combined with ginsenoside Rg1 on autophagy of PC12 cells were observed, and the mechanism was studied through PI3K Ⅰ/Akt/mTOR and PI3K Ⅲ/becline-1/Bcl-2 signaling pathways. RESULTS: After OGD/R, LC3-Ⅱ/LC3-Ⅰin PC12 cells was increased. Astragaloside IV, ginsenoside Rg1 and astragaloside IV combined with ginsenoside Rg1 restrained the increase in LC3-Ⅱ/LC3-Ⅰ, the effect of the combination was greater than using the drug alone. Ginsenoside Rg1, astragaloside IV combined with ginsenoside Rg1 up-regulated the phosphorylation level of PI3K Ⅰ, Akt and mTOR. The effects of the combination were stronger than those of using the drug alone. Astragaloside IV, astragaloside IV combined with ginsenoside Rg1 inhibited the protein expression of PI3K Ⅲ and becline-1, the effects of the combination were better than those of single astragaloside IV and single ginsenoside Rg1. Meanwhile, the combination treatment increased Bcl-2 protein expression. CONCLUSION: The autophagy of PC12 cells induced by OGD/R is inhibited by astragaloside IV and ginsenoside Rg1. Furthermore, astragaloside IV combined with ginsenoside Rg1 plays synergitic inhibition on autophagy, the mechanism may be related to PI3K Ⅰ/Akt/mTOR and PI3K Ⅲ/becline-1/Bcl-2 signaling pathways.