Angelica Sinensis Polysaccharide Mediates Sirtl to Inhibit P53/P21 Pathway and Delay Hematopoietic Stem Cell Aging

To study the effect of Angelica sinensis polysaccharide (ASP) on the expression of Sirt1/p53/p21 in radiation-induced aging hematopoietic stem cells (HSCs) of mice, and to explore the possible mechanism of ASP regulating the aging of HSCs. Methods: C57BL/6J mice were randomly divided into control group, model group and ASP group. The model group was irradiated with X-ray 3.0Gy/8F to establish the aging model of HSCs in mice. ASP group was given ASP intragastric administration during irradiation; The control group and the model group were given equal volume of normal saline. HSCs were sorted by immunomagnetic beads, and cell cycle was detected by flow cytometry The aging cells were observed by α-galactosidase staining. The directional differentiation ability of HSCs was observed by mixed colony culture (CFU-Mix). The expression of Sirtl, p53 and p21 protein was detected by Western blot. Results: Compared with the control group. X-ray can significantly increase the proportion of HSCs Gi cells, the rate of SA-α-Gal positive cells and the expression of p53 and p21 protein in aging group (P<0.05).The expression of Sirtl and mixed colony forming ability were decreased (P<0.05). Compared with the model group, ASP inhibited the increase of aging HSCs Gicell ratio, SA-fJ-Gal positive cell rate and p53 and p21 protein expression (P<0.05). At the same time, Sirtl expression and mixed colony forming ability were increased (P<0.05). conclusion: ASP may inhibit p53/p21 pathway and delay the aging of mouse HSCs by regulating Sirtl.

Mechanism of Circular RNA RAD23B for Regulating Glycolysis and Proliferation of Ovarian Cancer Cells by Targeting MicroRNA-519b-3p

We investigated whether circRAD23B regulates glycolysis and proliferation of ovarian cancer cells by targeting miRNA-519b-3p. circRAD23B expression in ovarian cancer tissues was significantly higher than that in paracancerous tissues, and miRNA-519b-3p expression in ovarian cance tissues was significantly lower than that in paracancerous tissues (P < 0.05). Transfection sicircRAD23B or miRNA-519b-3p mimics can greatly attenuate cell viability, glucose consumption, lactic acid level, and CyclinD1 protein level (P < 0.05), and increase p21 protein level (P < 0.05). Double luciferase reporter experiment confirmed that circRAD23B could function as a miRNA-519b-3p sponge molecule. Co-transfection of si-circRAD23B and anti-miRNA-519b-3p could greatly decrease cell viability, glucose consumption, lactic acid level, and CyclinD1 protein level (P < 0.05), and increase p21 protein level by comparison with si-circRAD23B+anti-miRNA-NC group (P < 0.05). Inhibiting circRAD23B expression can, in turn, inhibit glycolysis and the proliferation of ovarian cancer cells by up-regulating miRNA-519b-3p expression.

Effect of Yugan Sanjie decoction on expressions of regulatory T cells, serum P21 protein and vascular endothelial growth factor in mice with hepatocellular carcinoma

Purpose: To investigate the effect of Yugan Sanjie decoction on the expressions of regulatory T cells (Tregs), serum P21 protein and vascular endothelial growth factor (VEGF) in mice with hepatocellular carcinoma. Methods: A total of forty specific-pathogen-free (SPF) Kunming mice were randomly assigned to four groups of 10 mice each. Except for normal control group, the other three groups were transfected with hepatoma-22 (H22) cells to establish a mouse model of liver cancer. Mice in the cyclophosphamide group was given cyclophosphamide at a dose of 20 mg/kg daily intragastrically, while those in decoction group were treated with Yugan Sanjie decoction (0.4 ml/kg/day) intraperitoneally. After 30 days of treatment, serum levels of CD4+ Th17, CD4+CD25+ Treg, Th17/Treg, TNF-α, and VEGF were determined. Results: There was lower serum level of CD4+ Th17 in the decoction group than in negative control and cyclophosphamide groups (p < 0.05). However, higher serum levels of CD4+CD25+ Treg and Th17/Treg were seen in the decoction group, relative to the negative control and cyclophosphamide groups (p < 0.05). Serum TNF-α was also markedly elevated in decoction group, when compared with negative control and cyclophosphamide groups (p < 0.05). Serum VEGF was markedly lower in decoction group than in negative control and cyclophosphamide groups, and was appreciably lower in cyclophosphamide group than in negative control group (p < 0.05). Conclusion: Yugan Sanjie decoction effectively alleviates clinical symptoms of LC, and improves immune function of mice by regulating serum levels of T lymphocytes. These findings provide scientific support for a new treatment strategy.

S100P Interacts with p53 while Pentamidine Inhibits This Interaction

S100P, a small calcium-binding protein, associates with the p53 protein with micromolar affinity. It has been hypothesized that the oncogenic function of S100P may involve binding-induced inactivation of p53. We used 1H-15N HSQC experiments and molecular modeling to study the molecular interactions between S100P and p53 in the presence and absence of pentamidine. Our experimental analysis indicates that the S100P-53 complex formation is successfully disrupted by pentamidine, since S100P shares the same binding site for p53 and pentamidine. In addition, we showed that pentamidine treatment of ZR-75-1 breast cancer cells resulted in reduced proliferation and increased p53 and p21 protein levels, indicating that pentamidine is an effective antagonist that interferes with the S100P-p53 interaction, leading to re-activation of the p53-21 pathway and inhibition of cancer cell proliferation. Collectively, our findings suggest that blocking the association between S100P and p53 by pentamidine will prevent cancer progression and, therefore, provide a new avenue for cancer therapy by targeting the S100P-p53 interaction.

PRRSV Promotes MARC-145 Cells Entry Into S Phase of the Cell Cycle to Facilitate Viral Replication via Degradation of p21 by nsp11

Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most economically significant pathogens that seriously affect the global swine industry. Despite sustained efforts, the factors that affect PRRSV replication in host cells are far from being fully elucidated and thus warrants further investigation. In this study, we first demonstrated that PRRSV infection can cause downregulation of endogenous p21 protein in MARC-145 cells in a virus dose-dependent manner. Next, we analyzed the effect of p21 knockdown by RNA interference on cell cycle progression using flow cytometric analysis, and found that knockdown of p21 promotes MARC-145 cells entry into S phase of the cell cycle. Interestingly, we further discovered PRRSV infection is also able to promote MARC-145 cells entry into the S phase. Subsequently, we synchronized MARC-145 cells into G0/G1, S and G2/M phases, respectively, and then determined PRRSV replication in these cells. Results here show that the MARC-145 cells synchronized into the S phase exhibited the highest viral titer among the cells synchronized to different phases. Additionally, to reliably analyze the potential role of endogenous p21 protein in PRRSV replication, we constructed a p21 gene-knockout MARC-145 cell line (p21−/−) using CRISPR/Cas9 technology and evaluated its capability to support PRRSV replication. Our results indicate that knockout of p21 is conducive to PRRSV replication in MARC-145 cells. Furthermore, through construction of a series of eukaryotic plasmids expressing each of individual PRRSV proteins combined with cell transfection, we demonstrated that the nonstructural protein 11 (nsp11) of PRRSV mediates p21 degradation, which was further confirmed by generating a stable MARC-145 cell line constitutively expressing nsp11 using a lentivirus system. Notably, we further demonstrated that the endoribonuclease activity rather than the deubiquitinating activity of nsp11 is essential for p21 degradation via mutagenic analysis. Finally, we demonstrated that nsp11 mediates p21 degradation via a ubiquitin-independent proteasomal degradation manner. Altogether, our study not only uncovers a new pathogenesis of PRRSV, but also provides new insights into development of novel antiviral strategies.

Radix Tetrastigma Hemsleyani Flavone Inhibits the Occurrence and Development of Ovarian Cancer Cells by Regulating miRNA-4458 Expression

Ovarian cancer (OC) has been identified to have the highest mortality rate among gynecological tumors. Most patients are diagnosed at an advanced stage because of its asymptomatic nature and a lack of effective early diagnostic methods. Advanced-stage cancer cells are prone to metastasis which reduces the efficacy of standard therapies. Thus, we evaluated the effect of different concentrations of radix tetrastigma hemsleyani flavone (RTHF) on SKOV3 OC cells. Our findings indicated a significant inhibition in cell proliferation, migration, and invasion. RTHF treatment resulted in a significant increase in p21 protein expression, whereas the expression of cyclin D1, MMP-2, and MMP-9 has reportedly decreased. In addition, the expression of miRNA-4458 expression increased significantly in a dose-dependent manner. Co-transfection of miRNA-4458 mimics into SKOV3 cells revealed that overexpressed miRNA-4458 can increase SKOV3 cell proliferation and p21 protein expression. Reduced cell migration and invasion were also observed along with decreased expression of cyclin D1, MMP-2, and MMP-9. Furthermore, inhibition of miRNA-4458 expression reversed the RTHF effect on SKOV3 cell proliferation, migration, invasion, and cyclin D1, MMP-2, and MMP-9 expression. These results indicate that RTHF reduces the proliferation, migration, and invasion of OC cells, and the underlying mechanism is associated with the upregulation of miRNA-4458 expression. These findings provide a new treatment strategy for advanced OC.

IGFBP2 protects against pulmonary fibrosis through inhibiting P21-mediated senescence

Accumulation of senescent cells contributes to age related diseases including idiopathic pulmonary fibrosis (IPF). Insulin-like growth factor binding proteins (IGFBPs) are evolutionarily conserved proteins that play a vital role in many biological processes. Overall, little is known about the functions of IGFBP2 in the epigenetic regulation of cellular senescence and pulmonary fibrosis. Here, we show that Igfbp2 expression was significantly downregulated at both mRNA and protein levels in a low-dose bleomycin-induced pulmonary fibrosis model of aged mice. Using the reduced representation of bisulfite sequencing technique, we demonstrated Igfbp2 downregulation is attributed to DNA methylation of CpG islands in fibrotic lungs of aged mice. Furthermore, Igfbp2 siRNA knockdown increased both P53 and P21 protein levels in mouse lung epithelial cells exposed to hypoxia treatment. Lentiviral mediated expression of Igfb2 decreased P21 protein levels and significantly reduced beta galactosidase activity in mouse lung epithelial cells challenged with a senescent drug (atazanavir) and hypoxia treatments. Using the RT2 Profiler PCR Array, we found that P21, PAI-1, IRF-5 and IRF-7, important regulators of senescence pathway, were significantly downregulated specifically in type-II alveolar epithelial cells (AECs) of aged human-Igfbp2 transgenic mice after bleomycin challenge. Finally, transgenic expression of human-Igfbp2 in type-II AECs from aged bleomycin challenged mice significantly decreased senescent associated secretory phenotype factors and also reduced extracellular matrix markers compared to aged wild-type mice challenged with bleomycin injury. Collectively, these findings reveal that epigenetic repression of Igfbp2 promotes pulmonary fibrosis and that restoring IGFBP2 in fibrotic lungs could prove effective in IPF treatment.

Resveratrol in the treatment of neuroblastoma: a review

Resveratrol, polyphenol naturally occurring in grapes or nuts, has anti-cancer properties in the treatment of neuroblastoma – the most common childhood solid tumor. It affects cancer cells by increasing apoptosis, inducing cell necrosis and reducing tumor mass. Mechanism of action – (1) converting procaspases, mainly procaspases three and nine into active forms – caspases, (2) blocking kinases, and also (3) leading the cell to the S-cell cycle, where it is most effective while increasing the concentration of cyclin E and lowering the concentration of p21 protein. In vitro, as well as, rodent animal models studies are available and show promising results. Therapeutic doses, currently within 10–100 μmol/L, are also being tested, as well as other forms of resveratrol, such as its trans-4,4′-dihydroxystilbene analog and polyphenol lipoconjugates. In our review, we presented the known molecular mechanisms of polyphenol anti-tumor activity against neuroblastoma and discussed the studies confirming its effectiveness.

Sensitive and selective monitoring of the DNA damage-induced intracellular p21 protein and unraveling the role of the p21 protein in DNA repair and cell apoptosis by surface plasmon resonance

Sensitive and selective monitoring of DNA damage-induced intracellular p21 protein is proposed using surface plasmon resonance. The method serves as a viable means for unraveling the role of p21 protein in DNA repair and cell apoptosis.