The maintenance of hematopoietic stem cells (HSCs) is a complex process involving numerous cell-extrinsic and -intrinsic regulators. The first member of the cyclin-dependent kinase family of inhibitors to be identified, p21, has been reported to perform a wide range of critical biological functions, including cell cycle regulation, transcription, differentiation, and so on. Given the previous inconsistent results regarding the functions of p21 in HSCs in a p21-knockout mouse model, we employed p21-tdTomato (tdT) mice to further elucidate its role in HSCs during homeostasis. The results showed that p21-tdT+ HSCs exhibited increased self-renewal capacity compared to p21-tdT- HSCs. Zbtb18, a transcriptional repressor, was upregulated in p21-tdT+ HSCs, and its knockdown significantly impaired the reconstitution capability of HSCs. Furthermore, p21 interacted with ZBTB18 to co-repress the expression of cKit in HSCs and thus regulated the self-renewal of HSCs. Our data provide novel insights into the physiological role and mechanisms of p21 in HSCs during homeostasis independent of its conventional role as a cell cycle inhibitor.
Animals ; Hematopoietic Stem Cells/cytology* ; Cyclin-Dependent Kinase Inhibitor p21/genetics* ; Mice ; Cell Self Renewal ; Repressor Proteins/genetics* ; Mice, Inbred C57BL ; Mice, Knockout ; Humans ; Gene Expression Regulation

OBJECTIVE: N6-methyladenosine (m ⁶A) is a common epigenetic modification in eukaryotes. In this study, we explore the potential impact of m ⁶A-associated single nucleotide polymorphisms (m ⁶A-SNPs) on heart failure (HF). METHODS: Data from genome-wide association studies (GWAS) investigating HF in humans and from m ⁶A-SNPs datasets were used to identify HF-associated m ⁶A-SNPs. Their functions were explored using expression quantitative trait locus (eQTL), gene expression, and gene enrichment analyses. Mediation protein quantitative trait locus (pQTL)-Mendelian randomization (MR) was used to investigate the potential mechanism between critical protein levels and risk factors for HF. RESULTS: We screened 44 HF-associated m ⁶A-SNPs, including 10 m ⁶A-SNPs that showed eQTL signals and differential expressions in HF. The SNP rs1801270 in CDKN1A showed the strongest association with HF ( P = 7.75 × 10 ^-6). Additionally, MR verified the genetic association between the CDKN1A protein and HF, as well as the mediating effect of blood pressure (BP) in this pathway. Higher circulating level of CDKN1A was associated with a lower risk of HF (odds ratio [ OR] = 0.82, 95% confidence interval [ CI]: 0.69 to 0.99). The proportions of hypertension, systolic BP, and diastolic BP were 48.10%, 28.94%, and 18.02%, respectively. Associations of PDIA6 ( P = 1.30 × 10 ^-2) and SMAD3 ( P = 4.80 × 10 ^-2) with HF were also detected. CONCLUSION Multiple HF-related m ⁶A-SNPs were identified in this study. Genetic associations of CDKN1A and other proteins with HF and its risk factors were demonstrated, providing new ideas for further exploration of the molecular mechanisms of HF.
Humans ; Polymorphism, Single Nucleotide ; Heart Failure/genetics* ; Mendelian Randomization Analysis ; Genome-Wide Association Study ; Cyclin-Dependent Kinase Inhibitor p21/metabolism* ; Quantitative Trait Loci ; Adenosine/metabolism* ; Male ; Female ; Genetic Predisposition to Disease

OBJECTIVE: To study the effect of knocking down fascin on cervical cancer cell proliferation and tumorigenicity in nude mice. METHODS: Cervical cancer CaSki cells were infected with a lentiviral vector carrying fascin siRNA or with a negative control lentivirus, and fascin mRNA and protein expressions in the cells were detected using qRT-PCR and Western blotting. MTT assay was used to determine the proliferation of CaSki cells with fascin knockdown. CaSki cells transfected with fascin siRNA or the control lentiviral vector and non-transfected CaSki cells were inoculated subcutaneously in nude mice, and the volume and weight of the transplanted tumor were measured; Western blotting was used to detect the expressions of proliferating cell nuclear antigen (PCNA), survivin, cyclin dependent kinase 4 (CDK4) and p21 proteins in the tumor xenograft. RESULTS: Infection with the lentiviral vector carrying fascin siRNA, but not the negative control vector, caused significant reductions in the expression levels of fascin mRNA and protein in CaSki cells ( < 0.05). Fascin knockdown resulted in significantly reduced proliferation of CaSki cells ( < 0.05). The nude mice inoculated with CaSki cells with fascin knockdown showed reduced tumor volume and weight, lowered levels of PCNA, survivin and CDK4, and increased expression of p21 protein in the tumor xenograft compared with the control mice. The negative control lentivirus did not affect the proliferation or tumorigenicity of CaSki cells in nude mice or the expression levels of PCNA, survivin, CDK4 or p21 proteins in the xenografts. CONCLUSIONS Knocking down fascin can inhibit the growth and tumorigenicity of cervical cancer cells in nude mice.
Animals ; Apoptosis ; Carrier Proteins ; genetics ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; Cyclin-Dependent Kinase 4 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Female ; Gene Knockdown Techniques ; Genetic Vectors ; Humans ; Mice ; Mice, Nude ; Microfilament Proteins ; genetics ; metabolism ; Proliferating Cell Nuclear Antigen ; metabolism ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; Survivin ; metabolism ; Transfection ; Tumor Burden ; Uterine Cervical Neoplasms ; etiology ; pathology

Senescence-associated secretory phenotype (SASP) is often a concomitant result of cell senescence, embodied by the enhanced function of secretion. The SASP factors secreted by senescent cells include cytokines, proteases and chemokines, etc, which can exert great influence on local as well as systemic environment and participate in the process of cell senescence, immunoregulation, angiogenesis, cell proliferation and tumor invasion, etc. Relative to the abundance of SASP models in human cells, the in vitro SASP model derived from mouse cells is scarce at present. Therefore, the study aimed to establish a mouse SASP model to facilitate the research in the field. With this objective, we treated the INK4a-deficient mouse NIH-3T3 cells and the wildtype mouse embryonic fibroblasts (MEF) respectively with mitomycin C (MMC), an anticarcinoma drug which could induce DNA damage. The occurring of cell senescence was evaluated by cell morphology, β-gal staining, integration ratio of EdU and Western blot. Quantitative RT-PCR and ELISA were used to detect the expression and secretion of SASP factors, respectively. The results showed that, 8 days after the treatment of NIH-3T3 cells with MMC (1 μg/mL) for 12 h or 24 h, the cells became enlarged and the ratios of β-gal-positive (blue-stained) cells significantly increased, up to 77.4% and 90.4%, respectively. Meanwhile, the expression of P21 protein increased and the integration ratios of EdU significantly decreased (P < 0.01). Quantitative RT-PCR detection showed that the mRNA levels of several SASP genes, including IL-6, TNF-α, IL-1α and IL-1β increased evidently. ELISA detection further observed an enhanced secretion of IL-6 (P < 0.01). On the contrary, although wildtype MEF could also be induced into senescence by MMC treatment for 12 h or 24 h, embodied by the enlarged cell volume, increased ratios of β-gal-positive cells (up to 71.7% and 80.2%, respectively) and enhanced expression of P21 protein, the secretion of IL-6 displayed no significant change. Our study indicated that, although MMC could induce senescence in both mouse NIH-3T3 cells and wildtype MEF, only senescent NIH-3T3 cells displayed the canonical SASP phenomena. Current study suggested that senescent NIH-3T3 cells might be an appropriate in vitro SASP model of mouse cells.
Animals ; Cell Proliferation ; Cellular Senescence ; drug effects ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Cytokines ; genetics ; metabolism ; DNA Damage ; Fibroblasts ; drug effects ; Interleukin-6 ; secretion ; Mice ; Mitomycin ; pharmacology ; NIH 3T3 Cells ; Phenotype

OBJECTIVETo explore the role of p21 in ionizing radiation-induced changes in protein levels during the G2/M transition and long-term G2 arrest.

METHODSProtein expression levels were assessed by western blot in the human uveal melanoma 92-1 cells after treatment with ionizing radiation. Depletion of p21 was carried out by employing the siRNA technique. Cell cycle distribution was determined by flow cytometry combined with histone H3 phosphorylation at Ser28, an M-phase marker. Senescence was assessed by senescence- associated-β-galactosidase (SA-β-gal) staining combined with Ki67 staining, a cell proliferation marker.

RESULTSAccompanying increased p21, the protein levels of G2/M transition genes declined significantly in 92-1 cells irradiated with 5 Gy of X-rays. Furthermore, these irradiated cells were blocked at the G2 phase followed by cellular senescence. Depletion of p21 rescued radiation-induced G2 arrest as demonstrated by the upregulation of G2/M transition kinases, as well as the high expression of histone H3 phosphorylated at Ser28. Knockdown of p21 resulted in entry into mitosis of irradiated 92-1 cells. However, cells with serious DNA damage failed to undergo cytokinesis, leading to the accumulation of multinucleated cells.

CONCLUSIONOur results indicated that p21 was responsible for the downregulation of G2/M transition regulatory proteins and the bypass of mitosis induced by irradiation. Downregulation of p21 by siRNA resulted in G2-arrested cells entering into mitosis with serious DNA damage. This is the first report on elucidating the role of p21 in the bypass of mitosis.

Cell Cycle Checkpoints ; radiation effects ; Cell Line, Tumor ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; DNA Damage ; Down-Regulation ; Fibroblasts ; metabolism ; radiation effects ; Gene Expression Regulation ; radiation effects ; Humans ; Mitosis ; radiation effects ; RNA Interference ; RNA, Small Interfering ; Radiation, Ionizing ; Up-Regulation

To investigate the effect of jianpi-jiedu (JPJD) prescription-contained serum on colorectal cancer SW48 cell proliferation and the underlying mechanisms.
 Methods: Crude extract from JPJD was made by water extract method and the main components of crude extract from JPJD were analyzed by ultra-performance liquid phase high resolution time of flight mass spectrometry (UPLC-Q-TOF/MS). The low, medium, and high-concentration of JPJD-contained serum were prepared by the serum pharmacological method. The effect of serum containing JPJD on SW48 cell proliferation was determined by MTT assay. The cell cycle was detected by flow cytometric method. The protein levels of mammalian target of rapamycin (mTOR), phospho-mTOR, P-P53, and -P21, and the mRNA level of mTOR were examined by Western blot and RT-PCR, respectively.
 Results: Seven compounds including calycosin-7-glucoside, astragaloside, ginsenoside-Re, ginsenoside-Rb1, glycyrrhizinic acid, apigenin, atractylenolide-II were identified. MTT assays demonstrated that the SW48 cell proliferation was inhibited by medium and high concentration of JPJD-contained serum and the percentages of cells at G1 phase in SW48 cell cultured in the medium and high concentration of JPJD serum group were significantly higher than those in the control group (P<0.05). Meanwhile, the levels of mTOR mRNA and phospho-mTOR protein in the medium and high concentration of JPJD serum groups were substantially lower than those in the control group (P<0.05). Conversely, the expressions of phospho-P53 and P21 protein were significantly increased in the medium and high concentration of JPJD serum group compared with those in the control group.
 Conclusion: JPJD prescription-contained serum can inhibit SW48 cell proliferation, which may be related to mTOR-P53-P21 signaling pathways.
Animals ; Apigenin ; Blotting, Western ; Cell Cycle ; Cell Division ; Cell Proliferation ; drug effects ; genetics ; Colorectal Neoplasms ; Cyclin-Dependent Kinase Inhibitor p21 ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Flow Cytometry ; Ginsenosides ; Glycyrrhizic Acid ; Humans ; Lactones ; Phosphorylation ; genetics ; RNA, Messenger ; Saponins ; Sesquiterpenes ; Signal Transduction ; TOR Serine-Threonine Kinases ; drug effects ; Triterpenes ; Tumor Suppressor Protein p53 ; drug effects

To study the effect of the combined administration of different doses of Glycyrrhizae Radix et Rhizoma and Atractylodis Macrocephalae Rhizoma on the proliferation of DFMO-treated intestinal epithelial cells (IEC-6) and p53, p21 mRNA and protein expressions, in order to define the molecular basis for the effect of the combined administration of different doses of Glycyrrhizae Radix et Rhizoma and Atractylodis Macrocephalae Rhizoma on the cell proliferation. The effect of the drugs on the cell division rate and cell cycle of IEC-6 cells was detected by FCM. Quantitative Real-time PCR (qRT-PCR) was used to analyze the effect of the drugs on mRNA of p2l and p53 related to IEC-6 proliferation. Western blot was used to analyze the effect of the drugs on p2l and p53 protein expressions of IEC-6 cells. Atractylodis Macrocephalae Rhizoma could increase p53, p21 mRNA and proteins expression in DFMO-treated IEC-6 cells. The combined administration of different ratios of Atractylodis Macrocephalae Rhizoma and Glycyrrhizae Radix et Rhizoma could significantly down-regulate Atractylodis Macrocephalae Rhizoma's effect on p53, p21 mRNA and proteins expression in DFMO-treated IEC-6 cells and promote the proliferation of IEC-6 cells. The combined administration of Atractylodis Macrocephalae Rhizoma and Glycyrrhizae Radix et Rhizoma could down-regulate Atractylodis Macrocephalae Rhizoma's effect on DFMO-treated intestinal epithelial cells (IEC-6).
Animals ; Atractylodes ; chemistry ; Cell Line ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Epithelial Cells ; drug effects ; metabolism ; Gene Expression ; drug effects ; Glycyrrhiza ; chemistry ; Intestines ; drug effects ; metabolism ; Rats ; Rhizome ; chemistry ; Tumor Suppressor Protein p53 ; genetics ; metabolism

Neural stem cells (NSCs) proliferation can be influenced by repetitive transcranial magnetic stimulation (rTMS) in vivo via microRNA-106b-25 cluster, but the underlying mechanisms are poorly understood. This study investigated the involvement of microRNA-106b-25 cluster in the proliferation of NSCs after repetitive magnetic stimulation (rMS) in vitro. NSCs were stimulated by rMS (200/400/600/800/1000 pulses per day, with 10 Hz frequency and 50% maximum machine output) over a 3-day period. NSCs proliferation was detected by using ki-67 and EdU staining. Ki-67, p21, p57, cyclinD1, cyclinE, cyclinA, cdk2, cdk4 proteins and miR-106b, miR-93, miR-25 mRNAs were detected by Western blotting and qRT-PCR, respectively. The results showed that rMS could promote NSCs proliferation in a dose-dependent manner. The proportions of ki-67+ and Edu+ cells in 1000 pulses group were 20.65% and 4.00%, respectively, significantly higher than those in control group (9.25%, 2.05%). The expression levels of miR-106b and miR-93 were significantly upregulated in 600-1000 pulses groups compared with control group (P<0.05 or 0.01 for all). The expression levels of p21 protein were decreased significantly in 800/1000 pulses groups, and those of cyclinD1, cyclinA, cyclinE, cdk2 and cdk4 were obviously increased after rMS as compared with control group (P<0.05 or 0.01 for all). In conclusion, our findings suggested that rMS enhances the NSCs proliferation in vitro in a dose-dependent manner and miR-106b/p21/cdks/cyclins pathway was involved in the process.
Animals ; Animals, Newborn ; Biomarkers ; metabolism ; Cell Proliferation ; genetics ; Cyclin-Dependent Kinase 2 ; genetics ; metabolism ; Cyclin-Dependent Kinase 4 ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p57 ; genetics ; metabolism ; Cyclins ; genetics ; metabolism ; Gene Expression Regulation ; Hippocampus ; cytology ; metabolism ; Ki-67 Antigen ; genetics ; metabolism ; Magnetic Fields ; MicroRNAs ; genetics ; metabolism ; Neural Stem Cells ; cytology ; metabolism ; Primary Cell Culture ; Rats ; Rats, Sprague-Dawley ; Signal Transduction

In this study, one immortalized human normal prostatic epithelial cell line (BPH) and four human prostate cancer cell lines (LNCaP, 22Rv1, PC-3, and DU-145) were treated with Ganoderma Lucidum triterpenoids (GLT) at different doses and for different time periods. Cell viability, apoptosis, and cell cycle were analyzed using flow cytometry and chemical assays. Gene expression and binding to DNA were assessed using real-time PCR and Western blotting. It was found that GLT dose-dependently inhibited prostate cancer cell growth through induction of apoptosis and cell cycle arrest at G1 phase. GLT-induced apoptosis was due to activation of Caspases-9 and -3 and turning on the downstream apoptotic events. GLT-induced cell cycle arrest (mainly G1 arrest) was due to up-regulation of p21 expression at the early time and down-regulation of cyclin-dependent kinase 4 (CDK4) and E2F1 expression at the late time. These findings demonstrate that GLT suppresses prostate cancer cell growth by inducing growth arrest and apoptosis, which might suggest that GLT or Ganoderma Lucidum could be used as a potential therapeutic drug for prostate cancer.
Antineoplastic Agents, Phytogenic ; isolation & purification ; pharmacology ; Apoptosis ; drug effects ; Caspase 3 ; genetics ; metabolism ; Caspase 9 ; genetics ; metabolism ; Cell Line, Tumor ; Cell Survival ; drug effects ; Cyclin D1 ; genetics ; metabolism ; Cyclin-Dependent Kinase 4 ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Dose-Response Relationship, Drug ; E2F1 Transcription Factor ; genetics ; metabolism ; G1 Phase Cell Cycle Checkpoints ; drug effects ; genetics ; Gene Expression Regulation, Neoplastic ; Humans ; Male ; Nucleosomes ; drug effects ; metabolism ; pathology ; Plant Extracts ; chemistry ; Prostate ; drug effects ; metabolism ; pathology ; Reishi ; chemistry ; Signal Transduction ; Triterpenes ; isolation & purification ; pharmacology

Senescence is an important obstacle to cancer development. Engaging a senescent response may be an effective way to cure acute myeloid leukemia (AML). The aim of this study was to examine the effect of resveratrol-downregulated phosphorylated liver kinase B1 (pLKB1) on the senescence of acute myeloid leukemia (AML) stem cells. The protein expressions of pLKB1 and Sirtuin 1 (SIRT1), a regulator of pLKB1, were measured in CD34(+)CD38(-) KG1a cells treated with resveratrol (40 μmol/L) or not by Western blotting. Senescence-related factors were examined, including p21 mRNA tested by real-time PCR, cell morphology by senescence-associated β-galactosidase (SA-β-gal) staining, cell proliferation by MTT assay and cell cycle by flow cytometry. Besides, apoptosis was flow cytometrically determined. The results showed that pLKB1 was highly expressed in CD34(+)CD38(-) KG1a cells, and resveratrol, which could downregulate pLKB1 through activation of SIRT1, induced senescence and apoptosis of CD34(+)CD38(-) KG1a cells. It was concluded that resveratrol-downregulated pLKB1 is involved in the senescence of AML stem cells.
Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cellular Senescence ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; Down-Regulation ; Gene Expression Regulation, Neoplastic ; drug effects ; Humans ; Leukemia, Myeloid, Acute ; enzymology ; genetics ; pathology ; Neoplastic Stem Cells ; drug effects ; Phosphorylation ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Sirtuin 1 ; genetics ; metabolism ; Stilbenes ; pharmacology