CCT4 suppression inhibits tumor growth in hepatocellular carcinoma by interacting with Cdc20 / 中华医学杂志(英文版)

BACKGROUND@#The chaperonin containing t-complex (CCT) proteins play an important role in cell cycle-related protein degradation in yeast and mammals. The role of the chaperonin containing t-complex 4 (CCT4), one subtype of CCT proteins, in the progress of hepatocellular carcinoma (HCC) was not fully elucidated. Here, we aimed to explore the mechanisms of CCT4 in HCC.@*METHODS@#In this study, we used the UALCAN platform to analyze the relationship between CCT4 and HCC, and the association of CCT4 with the overall survival (OS) of HCC patients was also analyzed. CCT4 expression in HCC tumor tissues and normal tissues was also determined by western blot (WB) assay. Lentivirus vector was used to knock down the CCT4 expression, and quantitative polymerase chain reaction and WB were used to determine the level of CCT4 in HCC cell lines. Cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to detect the cell proliferation, and flow cytometry (FCM) was performed to evaluate the effect of CCT4 on the apoptosis of HCC cells. Co-immunoprecipitation (co-IP) assay and WB were used to explore the mechanisms of CCT4 regulating the growth of HCC. Data were calculated from at least three replicate experiments and expressed as mean ± standard deviation. Student's t test, paired t test, and Kaplan-Meier analysis were used to compare across different groups.@*RESULTS@#We found CCT4 was upregulated in HCC tissues compared with normal tissues, and its high expression was associated with poor prognosis (P < 0.001). CCT4 was significantly increased in HCC tumor tissues compared with normal tissues (0.98 ± 0.12 vs. 0.23 ± 0.05, t = 7.73, P < 0.001). After being transfected with CCT4 short-hairpin RNA (shRNA), CCT4 was decreased in mRNA level and protein level in both Huh7 (mRNA level: 0.41 ± 0.07 vs. 1.01 ± 0.11, t = 8.09, P = 0.001; protein level: 0.61 ± 0.03 vs. 0.93 ± 0.07, t = 7.19, P = 0.002) and Hep3b cells (mRNA level: 0.55 ± 0.11 vs. 1.04 ± 0.15, t = 4.51, P = 0.011; protein level: 0.64 ± 0.10 vs. 0.95 ± 0.08, t = 4.32, P = 0.012). CCK8 assay indicated that CCT4 knockdown inhibited cell proliferation in both Huh7 (OD value of 3 days: 0.60 ± 0.14 vs. 0.97 ± 0.16, t = 3.13, P = 0.036; OD value of 4 days: 1.03 ± 0.07 vs. 1.50 ± 0.12, t = 5.97, P = 0.004) and Hep3b (OD value of 3 days: 0.69 ± 0.14 vs. 1.10 ± 0.11, t = 3.91, P = 0.017; OD value of 4 days: 1.12 ± 0.12 vs. 1.48 ± 0.13, t = 3.55, P = 0.024) cells. EdU assay showed that CCT4 knockdown inhibited the cell proliferation in both Huh7 (EdU positive rate: [31.25 ± 3.41]% vs. [58.72 ± 3.78]%, t = 9.34, P = 0.001) and Hep3b cells (EdU positive rate: [44.13 ± 7.02]% vs. [61.79 ± 3.96]%, t = 3.79, P = 0.019). FCM assay suggested that CCT4 knockdown induced apoptosis in HCC cells (apoptosis rate of Huh7: [9.10 ± 0.80]% vs. [3.66 ± 0.64]%, t = -9.18, P = 0.001; apoptosis rate of Hep3b: [6.69 ± 0.72]% vs. [4.20 ± 0.86]%, t = -3.84, P = 0.018). We also found that CCT4 could regulate anaphase-promoting complex (APC)Cdc20 activity via interacting with Cdc20. Furthermore, CCT4 knockdown induced securin (0.65 ± 0.06 vs. 0.44 ± 0.05, t = -4.69, P = 0.009) and B-cell lymphoma-2 (Bcl-2) interacting mediator of cell death (Bim; 0.96 ± 0.06 vs. 0.61 ± 0.09, t = -5.65, P = 0.005) accumulation. The upregulation of securin inhibited cell growth by downregulating cyclin D1 (0.65 ± 0.05 vs. 1.04 ± 0.07, t = 8.12, P = 0.001), and the accumulation of Bim inhibited Bcl-2 (0.77 ± 0.04 vs. 0.87 ± 0.04, t = 3.00, P = 0.040) and activated caspase 9 (caspase 9: 0.77 ± 0.04 vs. 0.84 ± 0.05, t = 1.81, P = 0.145; cleaved caspase 9: 0.64 ± 0.06 vs. 0.16 ± 0.07, t = 1.81, P = 0.001), which led to elevated apoptosis.@*CONCLUSIONS@#Overall, these results showed that CCT4 played an important role in HCC pathogenesis through, at least partly, interacting with Cdc20.

Effects of Arsenic Trioxide on Cdc20 and Mad2 in Acute Myeloid Leukemia HL-60 Cell Line / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the effects of arsenic trioxide (AsO) on Cdc20 and Mad2 in process of AML HL-60 cell proliferation.</p><p><b>METHODS</b>The proliferation of HL-60 cells was detected by CCK-8 method at different concentrations of arsenic trioxide for 24, 48 and 72 hours. The cell morphological changes were observed by inverted microscopy. The expressions of Mad2 and Cdc20 mRNA and protein in HL-60 cells treated with AsO for 48 h were detected by real-time PCR and Western blot respectively.</p><p><b>RESULTS</b>Arsenic trioxide significantly inhibited the HL-60 cell proliferation and displayed a good time-dose correlation. RT-PCR and Western blot showed that the expression of Mad2 was up-regulated and the expression of Cdc20 was down-regulated in HL-60 cells treated with arsenic trioxide of different concentration (4,8,10 µmol/L).</p><p><b>CONCLUSION</b>Arsenic trioxide can inhibit the human acute myeloid leukemia HL-60 cell proliferation, and its mechanism may be related with up-regulation of Mad2 expression and down-regulation of Cdc20 expression.</p>

DNA replication components as regulators of epigenetic inheritance--lesson from fission yeast centromere

Genetic information stored in DNA is accurately copied and transferred to subsequent generations through DNA replication. This process is accomplished through the concerted actions of highly conserved DNA replication components. Epigenetic information stored in the form of histone modifications and DNA methylation, constitutes a second layer of regulatory information important for many cellular processes, such as gene expression regulation, chromatin organization, and genome stability. During DNA replication, epigenetic information must also be faithfully transmitted to subsequent generations. How this monumental task is achieved remains poorly understood. In this review, we will discuss recent advances on the role of DNA replication components in the inheritance of epigenetic marks, with a particular focus on epigenetic regulation in fission yeast. Based on these findings, we propose that specific DNA replication components function as key regulators in the replication of epigenetic information across the genome.

Human KIAA1018/FAN1 nuclease is a new mitotic substrate of APC/C(Cdh1) / 癌症

A recently identified protein, FAN1 (FANCD2-associated nuclease 1, previously known as KIAA1018), is a novel nuclease associated with monoubiquitinated FANCD2 that is required for cellular resistance against DNA interstrand crosslinking (ICL) agents. The mechanisms of FAN1 regulation have not yet been explored. Here, we provide evidence that FAN1 is degraded during mitotic exit, suggesting that FAN1 may be a mitotic substrate of the anaphase-promoting cyclosome complex (APC/C). Indeed, Cdh1, but not Cdc20, was capable of regulating the protein level of FAN1 through the KEN box and the D-box. Moreover, the up- and down-regulation of FAN1 affected the progression to mitotic exit. Collectively, these data suggest that FAN1 may be a new mitotic substrate of APC/CCdh1 that plays a key role during mitotic exit.