ABSTRACT
Objective To investigate the expression level of serine/threonine phosphoprotein phosphatase 4C(PPP4C)in gastric cancer,and analyze its relationship with prognosis and the underlying regulatory mechanism.Methods The clinical data of 104 gastric cancer patients admitted to the First Affiliated Hospital of Bengbu Medical College between January 2012 and August 2016 were collected.Immunohistochemical staining was employed to determine the expression levels of PPP4C and Ki-67 in the gastric cancer tissue.The gastric cancer cell lines BGC823 and HGC27 were cultured and transfected with the vector for PPP4C knockdown,the vector for PPP4C overexpression,and the lentiviral vector(control),respectively.The effects of PPP4C on the cell cycle and proliferation were analyzed and the possible regulatory mechanisms were explored.Results PPP4C was highly expressed in gastric cancer(P<0.001),and its expression promoted malignant progression of the tumor(all P<0.01).Univariate and Cox multivariate analysis clarified that high expression of PPP4C was an independent risk factor affecting the 5-year survival rate of gastric cancer patients(P=0.003).Gene ontology and Kyoto encyclopedia of genes and genomes enrichment analysis suggested that PPP4C may be involved in the cell cycle.The correlation analysis showed that the expression of PPP4C was positively correlated with that of Ki-67 in gastric cancer(P<0.001).The up-regulation of PPP4C expression increased the proportion of tumor cells in the S phase,alleviated the G2/M phase arrest,and promoted the proliferation of gastric cancer cells and the expression of cyclin D1 and cyclin-dependent kinase 6(CDK6)(all P<0.05).The down-regulation of PPP4C decreased the proportion of gastric cancer cells in the S phase,promoted G2/M phase arrest,and inhibited cell proliferation and the expression of cyclin D1,CDK6,and p53(all P<0.05).p53 inhibitors promoted the proliferation of BGC823 and HGC27 cells in the PPP4C knockdown group(P<0.001,P<0.001),while p53 activators inhibited the proliferation of BGC823 and HGC27 cells in the PPP4C overexpression group(P<0.001,P=0.002).Conclusions PPP4C is highly expressed in gastric cancer and affects the prognosis of the patients.It may increase the proportion of gastric cancer cells in the S phase and alleviate the G2/M phase arrest by inhibiting p53 signaling,thereby promoting cell proliferation.
Subject(s)
Humans , Stomach Neoplasms/genetics , Cyclin D1/metabolism , Tumor Suppressor Protein p53 , Phosphoproteins/metabolism , Ki-67 Antigen , Cell Line, Tumor , Prognosis , Cell Proliferation , Phosphoprotein Phosphatases/metabolism , Threonine , SerineABSTRACT
ObjectiveTo study the synergistic effect of p38MAPK and ERK1/2 in bone marrow mesenchymal stem cells (BMSCs), and to explore their influence on osteogenic differentiation in BMSCs cultures. MethodsMouse BMSCs were cultured in phenol red-free α-MEM containing osteogenic supplements (OS) for inducing osteogenic differentiation. The temporal sequence of osteogenic differentiation in BMSCs cultures was assayed by measuring alkaline phosphatase activity (ALP) and calcium deposition gene expression. The activation of p38MAPK and ERK1/2 was detected by western blotting using phospho-specific MAP kinase antibody. BMSCs were treated with the inhibitor of p38MAPK pathway(SB203580) or ERK1/2 pathway (PD98059), and osteogenic differentiation was measured. BMSCs were treated with SB203580 or sodium arsenite(ARS), a strong activator of p38MAPK, and the phosphorylation of ERK 1/2 was measured. BMSCs were treated with PP2A inhibitor, Okadaic acid(OA), the phosphorylation of ERK1/2 and osteogenic differentiation were measured. lmmunoprecipitation was used to test the binding interaction between PP2A and ERK1/2, and the effect of SB203580 on the interaction. ResultsTreatment of BMSCs with osteogenic supplements resulted in activation of p38MAPK and ERK1/2 that coincided with osteogenic differentiation. Inhibition of p38MAPK activation by SB203580, blocked the osteogenic differentiation, whereas inhibition of ERK1/2 activation by PD98059, enhanced the osteogenic differentiation in a dose-dependent manner.SB203580 treatment resulted in increased ERK1/2 phosphorylation. By contrast, ARS treatment resulted in decreased ERK1/2 phosphorylation. Inhibition of PP2A by OA resulted in increased ERK1/2 phosphorylation. OS-induced osteogenic differentiation was also attenuated by PP2A inhibition. Immunoprecipitation confirmed the association of PP2A with ERK1/2 in BMSCs cultures, which was decreased by SB203580 treatment. ConclusionThe present study demonstrates a synergistic effect between p38MAPK and ERK1/2 signaling pathways via PP2A in BMSCs cultures, which may regulate the osteogenic differentiation of BMSCs.
ABSTRACT
Objective: To investigate the relationship of PPP4R1 gene with the oncogenesis and metastasis of gastric carcinoma by using bioinformatics analysis, and to verify the result by RT-PCR. Methods: IntNetDB was used to search for the neighborhoods of gene PPP4R1 and cliques by CFinder; Chilibot was used to explore the association between the cliques and carcinoma, then the association of PPP4R1 with gastric carcinoma was deduced. Eighteen pairs of primary and metastatic specimens from the same patient and 12 pairs primary carcinoma and the adjacent normal specimens from the same patient were analyzed by RT-PCR for PPP4R1 expression. Results: It was found that the community genes of PPP4R1 included PPP2R5E, MTMR4, PPP3CC, CTDP1, CTDSP1, FLJ22405, PPP1CB, PPP1CC, PPP2R2A, PPP2R5A, PPP2R5C, CTDSP2, and PPP1CA as searched by Cfinder2. 0 when k = 14. Nine of the genes were associated with carcinoma and 2 associated with carcinoma and metastasis. The result of RT-PCR showed that higher expression of PPP4R1 was found in 15 of the 18 primary gastric cancer specimens compared with the paired metastatic specimens (P<0.01); higher expression was also found in 9 of the 12 adjacent normal specimens compared with the paired cancer specimens (P< 0.01). Conclusion: Gene PPP4R1 may be associated with the oncogeriesis and metastasis of gastric carcinoma; bioinformatics is an efficient way to investigate function of new genes.
ABSTRACT
AIM To investigate the role of serine/threonine protein phosphatases 1 and 2A (PP1/2A) in regulation of cell signal transduction involved in the tolerance of human umbilical vein endothelial cells (HUVEC) to hypoxia. METHODS HUVEC tolerance was established by hypoxic preconditioning. The tolerance of HUVEC was evaluated by the cell survival rate, lactic dehydrogenase (LDH) releasing and total antagonistic-oxidative capability (T-AOC). Subcellular localization of nuclear factor E2-related factor 2 (Nrf2) was determined by immunocytochemistry combined with Western blot. The expression of stress protein of heme oxygenase-1 (HO-1) was measured by Western blot. RESULTS Hypoxia 90 min decreased the survival rate and T-AOC of HUVEC significantly, increased the release of LDH in cultured HUVEC. Compared with the hypoxic group, hypoxic preconditioning (4, 8 and 24 h after hypoxia 10 min) up-regulated the tolerance against hypoxia in HUVEC, the survival rate of HUVEC and T-AOC increased and the release of LDH down-regulated when insulted with hypoxia (90 min) in HUVEC. Hypoxic preconditioning established the translocation of Nrf2 from cytoplasm to nucleus and up-regulated the expression of downstream protein HO-1. Pretreatment with okadaic acid (40 nmol·L-1), a powerful inhibitor of PP1/2A, for 10 min in hypoxic preconditioning HUVEC partly inhibited the translocation of Nrf2 from cytoplasm to nucleus and the expression of HO-1, abolished the tolerance of HUVEC established by hypoxic preconditioning. CONCLUSION PP1/2A at least partly take part in Regulation of translocation of Nrf2 and expression of HO-1, with is associated with the tolerance of HUVEC established by hypoxic preconditioning.
ABSTRACT
AIM To investigate the effects of serine/threonine protein phosphatases in regulation of cell signal transduction on voltage-gated potassium and calcium channels in cultured rat trigeminal ganglion (TRG) neurons. METHODS Whole-cell patch clamp technique was used to record the potassium and calcium currents from adult rat TRG neurons before and after perfusion of okadaic acid, a potent inhibitor of the serine/threonine protein phosphatases 1 and 2A. RESULTS Okadaic acid 1 μmol·L-1 inhibited transient outwards potassium currents (IA) by 28.6%, increased delay rectified potassium currents (IK) and calcium currents (ICa) by 22.7% and 20.0%, respectively. okadaic acid 1 μmol·L-1 produced significant hyperpolarizing shifts in the conductance-voltage (G-V) curves and inactivation curves of IA , also produced significant hyperpolarizing shifts in the G-V curves of IK, while it had no effect on the activation and inactivation kinetics of ICa. CONCLUSION Serine/threonine protein phosphatases 1 and 2A may be involved in the modulation of voltage-gated potassium and calcium channels on rat TRG neurons. In addition, voltage-gated potassium and calcium channels show different dependence on the dephosphorylation reactions of PP1 and PP2A phosphatases.
ABSTRACT
Objective To explore the alterations of protein phosphatase-2A (PP-2A) in lymphocytes in mild cognition impairment (MCI) and Alzheimer's disease (AD).Methods The activity PP-2A of was measured by ~(32)p liquid seintillography for incorporated radioactivity in control group(n=11) , the MCI group(n=11),and the AD group(n=11).The expression of PP-2A was determined by Western blot.Results In the control group,the activity of PP-2A (1.01?0.09) and the expression of PP-2A (0.96?0.07) were high while in the MCI group,the activity of PP-2A (0.71?0.12) and the expression of PP-2A (0.80?0.05) were decreased (both P
ABSTRACT
AIMTo investigate the role of serine/threonine protein phosphatases in regulation of cell signal transduction on voltage-dependent sodium channels in rat trigeminal ganglion (TRG) neurons. METHODSWhole-cell patch clamp techniques were used to record the total sodium current (INa-T) and the tetrodotoxin-resistant sodium current (INa-TTX-R) before and after okadaic acid, a potent inhibitor of the serine/threonine protein phosphatases 1 and 2A, perfusion on adult rat TRG neurons. RESULTS1μmol*L-1 okadaic acid inhibited INa-T by (20±13)% (n=9, P<0.05) and INa-TTX-R by (4±3)% (n=6, P<0.05), respectively. The inhibition on INa-T was significantly greater than that on INa-TTX-R (P<0.05). Furthermore, 1μmol*L-1 okadaic acid produced significant 3-4 mV hyperpolarizing shifts in the conductance-voltage curves of INa-T, while it had no effect on that of INa-TTX-R. CONCLUSIONThe serine/threonine protein phosphatases take part in the regulation of total and TTX-R sodium channels on rat TRG neurons. In addition, small-diameter TRG neurons express various voltage-gated sodium channel with different sensitivity to okadaic acid.
ABSTRACT
CPTP1 is a nontransmembrane chicken protein tyrosine phosphatase having 92% sequence homology to the corresponding 321 amino acids of human protein tyrosine phosphatase 1B (HPTP1B). Using anti-CPTP1 antibody, we identified CPTP1-like rat PTP1 of 51 kappa Da in Rat-1 and v-src-transformed Rat-1 fibroblasts. Here we show that CPTP1-like rat PTP1 binds to p60v-src in vivo and CPTP1 also can associate with p60v-src in cell lysate of v-src- transformed Rat-1 fibroblasts. Interaction between HPTP1B-type PTPs, CPTP1-like rat PTP1 and CPTP1, and p60v-src was reduced by vanadate treatment for 13 h due to down regulation of the protein level of p60v-src in vivo. Interestingly, CPTP1-like rat PTP1 was coimmunoprecipitated with a 70-kappa Da protein which has a possibility to be tyrosine- phosphorylated by p60v-src in v-src-transformed Rat- 1 fibroblasts. These results suggest that HPTP1B- type PTPs may play an important role in p60src dependent signal pathway in eucaryotic cells.
Subject(s)
Animals , Female , Rabbits , Rats , Blotting, Western , Cell Line, Transformed , Chickens , Fibroblasts , Oncogene Protein pp60(v-src)/metabolism , Phosphoprotein Phosphatases/genetics , Precipitin Tests , Protein Binding , Protein Tyrosine Phosphatases/genetics , Recombinant Fusion Proteins/geneticsABSTRACT
Objective Many studies showed that Ca~(2+) channel blocker could prevent and treat right ventricular hypertrophy(RVH) induced by chronic hypoxia.To further identify the mechanism,we investigated the effect of Ca~(2+) channel blocker on the levels of myocardial calcineurin A?mRNA(CnA?)in RV and plasma nitric oxide(NO),NO synthase and endothelin-1(ET-1) in rats with chronic hypoxia.Methods 30 rats were divided into three groups by randomized block design: treatment group with Amlodipine Besylate ablets [(30 mg?kg~(-1)?d~(-1)),administered via gavage],chronic hypoxia group,and control group.The rats in treatment group and chronic hypoxia group were exposed to normobaric chronic hypoxia [(10.0?0.5)% O_2 ] for 21 days.On the 21st day of experiment,all rats were sacrificed and the hearts were collected for measuring the weight.Blood samples were also drawn from the ventricles for measuring plasma NO,iNOS and ET-1 levels.CnA?mRNA levels in RV were measured by RT-PCR.Results ⑴The RV/(LV+S)、RV/BW ratios were significantly higher in chronic hypoxia group than those of control group and treatment group(P
ABSTRACT
AIM: The purpose of this study was to determine whether the signal transduction systems were activated at the molecular atrial tissue level in patients with atrial fibrillation (AF) and whether atrial expression of extracellular-signal regulated kinase (ERK) and protein phosphatases is altered. METHODS: Atrial tissue sample of 30 patients undergoing cardiac surgery were examined. 20 patients had AF, 10 patients had no history of AF. The mRNA expression of calcineurin B and MKP-1 were detected by semi-quantitative RT-PCR. ERK1 and phospho-ERK1 were analyzed at the protein level by Western blot. RESULTS: Western blot analysis showed that atrial fibrillation did not induce significant change in ERK1 expression level in the left atrium. In contrast , phospho-ERK1 content was increased in the patients with AF in comparison with those who had sinus rhythm (SR). The mRNA expression of calcineurin B and MKP-1 in the patients with AF were significantly higher than that in patients with SR. CONCLUSION: The activation of extracellular-signal regulated kinase and protein phosphatases may have correlation with the initiation or maintenance of atrial fibrillation.