Abstract
Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. Ubiquitin-proteasome system has been shown to play a pivotal role in the pathophysiology of HCC and other malignancies. UBE2Q1 is a putative E2 ubiquitin conjugating enzyme, and may be involved in the regulation of cancer-related proteins. In this study, we investigated the expression pattern of UBE2Q1 in HCC cell lines and human HCC specimens, and its potential clinical and biological significance in HCC. Western blot and immunohistochemical analyses revealed that UBE2Q1 was significantly upregulated in HCC tumorous tissues compared with the adjacent noncancerous ones. Next, univariate and multivariate survival analyses were performed to determine the prognostic significance of UBE2Q1 in HCC. The results showed that upregulated expression of UBE2Q1 was positively correlated with high histological grades of HCC and predicted poor prognosis. In addition, the expression of UBE2Q1 was progressively increased in serum-refed HCC cells. UBE2Q1 depletion by small interfering RNA inhibited cell proliferation and led to G1 phase arrest in HepG2 and BEL-7404 cells. Furthermore, we showed that cells transfected with UBE2Q1-targeting siRNA resulted in significant increase in the levels of p53, p21 in HepG2 and BEL-7404 cells. These data imply that UBE2Q1 is upregulated in liver cancer cell lines and tumorous samples and may play a role in the development of HCC.
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Acknowledgments
This work was supported by Medical Innovation Team Project funded of Jiangsu Province LJ201134, Clinical special fund of Jiangsu Province SBL2014020017 and "Science and Education Guardian" leading talent and innovative engineering team project of Jiangsu Province LJ201134.
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Renan Chang and Lixian Wei contributed equally to this work.
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Supplementary material 1
The expression of UBE2Q1 in proliferating BEL-7404 cells. A. Cells synchronized at G1 progressed into the cell cycle when serum was refed for 0, 4, 8, 12, 24 h. Data are presented as mean ± SEM of three independent experiments. *,#P < 0.05, compared with control cells serum starved for 72 h (S72 h). S, serum starvation; R, serum release. B. The S72 h BEL-7404 cells were released by refeeding with serum, and cell lysates were prepared and analyzed by Western blot using antibodies against UBE2Q1, p53, PCNA and GAPDH (a). The bar graph indicates density of UBE2Q1/p53/PCNA versus GAPDH at each time point (b). Data are presented as mean ± SEM of 3 independent experiments. *,#,^ P < 0.05, compared with control cells serum starved for 72 h (S72 h) (TIFF 8969 kb)
Supplementary material 2
Low expression of UBE2Q1 resulted in reduced cell growth in BEL-7404 cells. A. The S72 h BEL-7404 cells were released by refeeding with serum, and cell lysates were prepared and analyzed by Western blot using antibodies against UBE2Q1, p53 and GAPDH (a). The bar graph indicates density of UBE2Q1/p53 versus GAPDH at each time point (b). Data are presented as mean ± SEM of 3 independent experiments. *,#P < 0.05, compared with control cells serum starved for 72 h (S72 h). B. The expression of UBE2Q1 was decreased after cells were transfected with UBE2Q1-targeting siRNAs (a). The bar chart indicates the ratio of UBE2Q1 protein expression to GAPDH by densitometry (b). The data are mean ± SEM (*,#P < 0.05 compared with the negative control). The experiments were repeated 3 times. C. UBE2Q1, cyclin D expression were downregulated, while p53, p21 were increased in cells infected with UBE2Q1-siRNA (a). The bar chart below demonstrated the ratio of UBE2Q1/cyclin D protein to GAPDH by densitometry (b). The data are mean ± SEM (*, %,#, ^P < 0.05 compared with the control). The experiments were repeated three times. D. Cell proliferation was attenuated in UBE2Q1-siRNA-treated BEL-7404 cells using the CCK-8 assay. Data are mean ± SEM (* P < 0.05 compared with the control). The experiments were repeated three times. E. Cell cycle analysis by flow cytometry showed a corresponding augment of cell percentage in G1 phase in UBE2Q1-depleted BEL-7404 cells (TIFF 9658 kb)
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Chang, R., Wei, L., Lu, Y. et al. Upregulated expression of ubiquitin-conjugating enzyme E2Q1 (UBE2Q1) is associated with enhanced cell proliferation and poor prognosis in human hapatocellular carcinoma. J Mol Hist 46, 45–56 (2015). https://doi.org/10.1007/s10735-014-9596-x
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DOI: https://doi.org/10.1007/s10735-014-9596-x