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Objective@#To investigate the effect of chrysotile exposure on ribosomal DNA (rDNA) copy number and DNA damage response, so as to provide insights into the mechanism of asbestos-induced carcinogenesis. @*Methods@#Human pleural mesothelial MeT-5A cells were treated with chrysotile suspensions at doses of 1.25, 2.5 and 5 μg/cm2 (low-, medium-, high-dose group), while PBS served as controls. MeT-5A cells were harvested 6, 24, 48 and 72 h post-treatment, and the rDNA copy numbers and the BIRC5, HRAS, GINS4 and RRM2 mRNA expression were determined using a quantitative real-time PCR (qPCR) assay. The apoptosis of MeT-5A cells and DNA damage were detected using Muse cell analyzer. The rDNA copy numbers, DNA damage responses and BIRC5, HRAS, GINS4 and RRM2 mRNA expression were compared in MeT-5A cells treated with different doses of chrysotile suspensions.@*Results@#There were significant differences in 45S rDNA copy numbers among low-, medium-, high-dose groups and the control groups 6, 48 and 72 h post-treatment with chrysotile suspensions, and significantly lower 45S rDNA copy numbers were measured in low-, medium- and high-dose groups than in the control group 6 h post-treatment, while significantly higher 45S rDNA copy numbers were found in the high-dose group than in low- and medium-dose groups 48 and 72 h post-treatment (all P<0.05). There were significant differences in 5S rDNA copy numbers among low-, medium-, high-dose groups and the control groups 24, 48 and 72 h post-treatment with chrysotile suspensions, and significantly lower 5S rDNA copy numbers were measured in medium- and high-dose groups than in the control group 24 and 48 h post-treatment, while significantly lower 5S rDNA copy numbers were found in medium- and high-dose groups than in the low-dose group 24, 72 h post-treatment (all P<0.05). There were significant differences in the overall apoptotic rate of MeT-5A cells among groups at different time points, and the overall apoptotic rate of MeT-5A cells were significantly higher in medium- and high-dose groups than in the control group (all P<0.05), with late-stage apoptosis predominantly detected. There were significant differences in the rates of ATM activation and DNA double-strand break in MeT-5A cells among groups 72 h post-treatment, and higher rates of ATM activation and DNA double-strand break were measured in medium- and high-dose groups than in the control group (all P<0.05). In addition, there were significant differences in the relative mRNA expression of BIRC5, HRAS, GINS4 and RRM2 genes among groups 24 and 48 h post-treatment, and significantly lower BIRC5, HRAS, GINS4 and RRM2 mRNA expression was quantified in medium- and high-dose groups than in the control group (all P<0.05).@*Conclusion@#Exposure to chrysotile may induce rDNA copy number variations and altered expression of nucleolar proteins in human pleural mesothelial cells, which may be involved in the regulation of DNA damage responses.
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Objective To evaluate the effect of nucleolar protein 14 (NOP14) on angiogenesis in melanoma.Methods Melanoma tissues were collected from 40 patients with pathologically diagnosed melanoma in Guangzhou First People's Hospital from January 2016 to December 2018,and immunohistochemical study was conducted to determine the expression of NOP14 and CD31 (expressed as microvessel density [MVD]).Melanoma cell lines A375 and SK-MEL-1 were both divided into 4 groups:empty vector group transfected with the empty vector,NOPI4 group transfected with a NOP14-overexpressing vector,siNOP14 group transfected with the siRNA targeting NOP14,and siNC group transfected with a negative control siRNA.Fluorescence-based quantitative PCR and Western blot analysis were performed to determine the mRNA and protein expression of NOP14 respectively,and Western blot analysis and enzyme-linked immunosorbent assay (ELISA) to measure the expression of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) in cells and their culture media.Coculture models of human umbilical vein endothelial cells (HUVECs) and A375/SK-MEL-1 cells in the above groups were established in Transwell chambers,and cell counting kit-8 (CCK8) assay,Transwell migration and invasion assays and Matrigel-based vasculogenic mimicry assay were performed to evaluate the cellular proliferative,migratory,invasive activity and tube formation capacity respectively.A linear regression model was used to analyze the relationship between NOP14 expression and MVD in melanoma tissues,multi-way analysis of variance to analyze the difference in cellular proliferative activity,and independent-sample t test to compare other experimental indices between 2 groups.Results The expression of CD31 (MVD) was 44 ± 13 in the group with high NOP14 expression (n =20),58 ± 16 in that with moderate NOP14 expression (n =17),and 62 ± 11 in that with low NOP14 expression (n =3).The NOP14 expression was negatively correlated with MVD (r =-0.525,P =0.017).Compared with the empty vector group,the expression of VEGF and VEGFR in A375 and SK-MEL-1 cells and their culture media significantly decreased in the NOP14 group (all P ＜ 0.05).Compared with the siNC group,the expression of VEGF and VEGFR in the A375 and SK-MEL-1 cells and their culture media significantly increased in the siNOP14 group(all P ＜ 0.05).In the co-culture models of A375 cells and HUVECs,the NOP14 group showed significantly decreased proliferative activity of HUVECs (F =131.85,P ＜ 0.05),and numbers of migratory cells (22 ± 5 vs.63 ± 8,t =7.07,P =0.002),invasive cells (14 ± 5 vs.45 ± 10,t =4.94,P =0.008) and branch points (8 ± 2 vs.14 ± 3,t =5.06,P ＜ 0.001) compared with the empty vector group;compared with the siNC group,the siNOP14 group showed significantly increased proliferative activity of HUVECs (F =79.92,P ＜ 0.01),and numbers of migratory cells (152 ± 30 vs.59 ± 4,t =5.36,P =0.006),invasive cells (134 ± 21 vs.50 ± 8,t =6.40,P ＜ 0.001) and branch points (27 ± 3 vs.15 ± 4,t =6.10,P ＜ 0.001).In the co-culture models of SK-MEL-1 cells and HUVECs,the 4 groups showed the same trend of changes in the cellular proliferative,migratory,invasive activity and tube formation capacity of HUVECs as the above groups in the co-culture models of A375 cells and HUVECs.Conclusion The NOP14 expression is negatively correlated with MVD in melanoma tissues,and NOP14 can inhibit angiogenesis in melanoma.
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Objective@#To investigate expression of nucleolar protein 14(NOP14) and CD31 in pancreatic cancer mouse model and its correlation with tumor progression.@*Methods@#Clinicopathological data of 5 patients with pathologically confirmed pancreatic ductal adenocarcinoma(PDAC) and hepatic metastasis between January 2013 and December 2015 was collected in Department of General Surgery, Peking Union Medical College Hospital. Immunohistochemistry staining was employed to detect the expression of NOP14 in matched primary PDAC and relevant metastasis.Pancreatic cancer cells with NOP14 stably knocked down were established by transfecting lentivirus with NOP14 targeted silencing RNA.The inhibition efficacy was detected by quantitative real time PCR and western blot.Microvascular density(MVD) in pancreatic cancer transplantation mouse model was determined by CD31 immunohistochemistry staining analysis and correlated with NOP14 expression and tumor progression.@*Results@#NOP14 had a significant higher expression in liver metastasis than primary pancreatic adenocarcinoma (2.09±0.45 vs. 1.31±0.27, P=0.028). NOP14 was knocked down 86 percent on mRNA level determined by qPCR and 78 percents on protein level detected by western blot. MVD was significantly decreased in NOP14-inhibited tumor from both pancreatic cancer cells subcutaneously and orthotopically grafted tumor mouse model with the value of 61.40±13.85 vs. 85.53±14.59 (P=0.041) and 38.33±10.91 vs. 59.33±15.37(P =0.037), respectively. Besides, MVD was positively associated with tumor volume(r=0.842, P<0.01) and metastasis (r=0.726, P=0.008).@*Conclusion@#NOP14 presents higher expression in hepatic metastasis of pancreatic adenocarcinoma and might promote tumor progression by increasing microvascular density.
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Using an anti-nucleolar protein B23 monoclonal antiboby, we examined the changes of protein B23 content in NIH3T3 fibroblasts during serum-induced proliferation and the difference in protein B23 content between mitotic and interphase NIH3T3 fibroblasts by immunofluorescence and im-munoblot methods. When NIH3T3 cells grew confluent, the serum containing medium was removed and replaced by serum-free medium,and the cells were cultured for another 24h. Then cells were refed with serum and further cultured. The results showed that protein B23 content was low in serum-starved NIH3T3 cells,and it markedly increased after serum addition. Furthermore,the increase occurred early at 6h after serum treatment. It was also showed that protein B23 content in mitotic cells blocked by the microtubule inhibitor colcemid was much higher than that in interphase ones. Our results suggested that nucleolar protein B23 might play some roles in the early stage of serum- induced proliferation and during transition from G2 to mitosis in cell cycle.