A "through-shell" binding isotope effect.
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Binding Sites↗
Biomedical subjects
Yong Liu
Publications and source records attributed to Yong Liu.
An autoimmune domain-reduced HCV core gene remains effective in stimulating anti-core cytotoxic T lymphocyte activity.
Chronic hepatitis C virus (HCV) infection cases resistant to conventional therapies might be treated by immunotherapy as cytotoxic T lymphocytes (CTL) are the main mechanism through which viral infections are cleared. The HCV core gene, with the highest homology between HCV types, deleted of its autoimmune-stimulating regions (pseudo-GOR and pseudo-p450), may be an appropriate antigen for targeting HCV-infected cells. Two recombinant adeno-associated virus (rAAV) vectors, carrying either the full length (aa 1-190) or truncated (aa 49-180, deleted of the pseudo-GOR and pseudo-p450 sequences) versions of core, were generated. Both AAV/core (l-190) and AAV/core (49-180) were used to transduce/load dendritic cells (DC) at high levels (88-95%). These two genetically altered DC types then stimulated anti-core CTL. The DC and CTL were analyzed by FACS and for killing efficiency (percent target killing). The rAAV-altered DC displayed higher levels of CD80, CD83, CD86, and CD 1a than control DC. The truncated core (aa 49-180) gene stimulated equivalent and strong killing of synthetic core-positive autologous peripheral blood lymphocyte (PBL) targets to that stimulated by the full length core gene. However, the smaller core (49-180) antigen gene stimulated lower levels of killing of core-negative "self" PBL targets (GOR- and p450-positive) (p = 0.002). These AAV/core: DC-stimulated CTL displayed higher IFN-gamma expression, higher CD8:CD4 ratios, and lower CD56:CD8 ratios than controls. The rAAV-loading derived CD8+ T cells had more CD69+ cells and the CD4+ T populations had fewer CD25+ cells than controls. We conclude that the core (49-180) gene is an effect antigen, but has the advantage of stimulating less self-recognition. Thus, core (49-180) may be useful for further translational immunotherapy studies against HCV.
Autoimmunity↗
Cryptotanshinone inhibits endothelin-1 expression and stimulates nitric oxide production in human vascular endothelial cells.
The Chinese herb Salvia miltiorrhiza (SM) has been found to have beneficial effects on the circulatory system. In the present study, we investigated the effects of cryptotanshinone (derived from SM) on endothelin-1 (ET-1) expression in human umbilical vein endothelial cells (HUVECs). The effect of cryptotanshinone on nitric oxide (NO) in HUVECs was also examined. We found that cryptotanshinone inhibited basal and tumor necrosis factor-alpha (TNF-alpha) stimulated ET-1 secretion in a concentration-dependent manner. Cryptotanshinone also induced a concentration-dependent decrease in ET-1 mRNA expression. Cryptotanshinone increased basal and TNF-alpha-attenuated NO production in a dose-dependent fashion. Cryptotanshinone induced a concentration-dependent increase in endothelial nitric oxide synthase (eNOS) expression without significantly changing neuronal nitric oxide synthase (nNOS) expression in HUVECs in the presence or absence of TNF-alpha. NOS activities in the HUVECs were also induced by cryptotanshinone. Furthermore, decreased ET-1 expression in response to cryptotanshinone was not antagonized by the NOS inhibitor l-NAME. A gel shift assay further showed that TNF-alpha-induced Nuclear Factor-kappaB (NF-kappaB) activity was significantly reduced by cryptotanshinone. These data suggest that cryptotanshinone inhibits ET-1 production, at least in part, through a mechanism that involves NF-kappaB but not NO production.
Cells, Cultured↗
Carbonic anhydrase inhibitors: inhibition of the human isozymes I, II, VA, and IX with a library of substituted difluoromethanesulfonamides.
An inhibition study of the human cytosolic isozymes I, and II, the mitochondrial isoform VA, and the tumor-associated, transmembrane isozyme IX of carbonic anhydrase (CA, EC 4.2.1.1) with a library of aromatic/heteroaromatic/polycyclic difluoromethanesulfonamides is reported. Most of the inhibitors were derivatives of benzenedifluoromethanesulfonamide incorporating substituted-phenyl moieties, or were methylsulfonamide and difluoromethyl-sulfonamide derivatives of the sulfamates COUMATE and EMATE, respectively. Except for the methylsulfonamide-COUMATE derivative which behaved as a potent CA II inhibitor (K(I) of 32nM), these sulfonamides were moderate inhibitors of all isozymes, with inhibition constants in the range of 96-5200nM against hCA I, of 80-670nM against hCA II, and of 195-9280nM against hCA IX, respectively. Remarkably, some derivatives, such as 3-bromophenyl-difluoromethanesulfonamide, showed a trend to selectively inhibit the mitochondrial isoform CA VA, showing selectivity ratios for inhibiting CA VA over CA II of 3.53; over CA I of 6.84 and over CA IX of 9.34, respectively, although it is a moderate inhibitor (K(I) of 160nM). Some of these derivatives may be considered as leads for the design of isozyme selective CA inhibitors targeting the mitochondrial isozyme CA VA, with potential use as anti-obesity agents.
Antigens, Neoplasm↗
Multiple human papillomavirus genes affect the adeno-associated virus life cycle.
The risk of cervical cancer, one of the most prevalent cancers in the world, is determined by two viruses. Human papillomavirus (HPV) is the main risk factor for developing cervical cancer. However, although little known, it is well substantiated that the human Parvovirus adeno-associated virus type 2 (AAV), and its encoded Rep78 protein, interacts with HPV and lowers the risk of cervical cancer. HPV also contributes to AAV inhibition by serving as a helper virus for AAV and stimulating higher AAV replication levels. Here we surveyed four HPV-16 early genes, E1, E2, E6 and E7, for their ability to increase/decrease the basal level of AAV replication in stratifying squamous epithelium (the epithelial raft culture system). It was found that the HPV-16 E1, E2 and E6 genes were able to help/enhance AAV-2 replication in epithelial raft cultures. Under these conditions, with all the HPV genes being expressed from the AAV p5 promoter, E1 appeared to have the strongest enhancing effect on AAV DNA replication (Southern blot), RNA expression (RT-PCR), protein expression (Western blot) and AAV virion production (2 plate-Southern blot). Further study of E1 mutants showed that the carboxy-half of E1, the putative helicase/ATPase domain, was the main contributor of helper activity. These data are important for understanding the HPV-AAV interaction and its effect on modifying cervical cancer risk. These data also suggest the possibility that the identified HPV helper genes may be useful in the generation of recombinant (r)AAV virions for gene therapy, as rAAV is increasing in popularity for such purposes.
Capsid Proteins↗
[The expression of collagen type I, II and TGF-beta1 in the articular processes of scoliosis patients].
OBJECTIVE: To look into the characteristic of the expression of collagen type I, II and transforming growth factor-beta(1) (TGF-beta(1)) in the processes of scoliosis patients. METHODS: The articular processes of 9 IS patients and 10 CS patients were collected. The techniques of HE staining and immunohistochemistry were adopted in this research. The images of immunohistochemistry were analyzed semi-quantitatively. RESULTS: For collagen type I: The expression at the concave side of the apical vertebrae of both IS and CS patients is significantly higher than that of the convex side, 193 +/- 64 vs 151 +/- 45 and 199 +/- 86 vs 179 +/- 78, P < 0.05, and the apical vertebrae higher than the end vertebrae. In the lower end vertebrae of the IS patients, the expression at the concave side is significantly higher than that of the convex side; and the convex side of the apical vertebrae of IS patients is lower than that of CS patients. For collagen type II: The expression at the concave side in the lower end vertebrae of CS patients is higher than that of convex side; and for both IS and CS patients, the apical vertebrae is higher than the end vertebrae. For TGF-beta(1): The expression at the concave side of the apical vertebrae of both IS and CS patients is significantly higher than that of the convex side, 145 +/- 43 vs 112 +/- 50 and 120 +/- 61 vs 89 +/- 32, P < 0.05. For IS patients, the lower end vertebrae at the concave side is higher than concave side; the apical vertebrae is higher than the end vertebrae. For CS patients, the concave side of the apical vertebrae is higher than the end vertebrae; while for the apical vertebrae, IS patients higher than CS patients. CONCLUSION: Articular processes cartilage of the apical vertebrae of scoliosis patients shows degenerative sign. The expression of collagen type I, II and TGF-beta(1) is significantly higher at the concave side and the apical vertebrae of both IS and CS patients. Abnormal press and stress power may play a very important role.
Adolescent↗
Salvianolic acid B attenuates plasminogen activator inhibitor type 1 production in TNF-alpha treated human umbilical vein endothelial cells.
Plasminogen activator inhibitor type 1 (PAI-1), which plays a role in the development of atherosclerosis, is produced by endothelial cells following stimulation with various inflammatory cytokines such as tumor necrosis factor (TNF-alpha). In the present study, we investigated the effects of a potent water-soluble antioxidant, salvianolic acid B (SalB; derived from the Chinese herb, Salvia miltiorrhiza), on the expression of PAI-1 in TNF-alpha-treated human umbilical vein endothelial cells (HUVECs). We found that SalB inhibited TNF-alpha-induced PAI-1 mRNA production and protein secretion in HUVECs. Treatment with SalB (0.05 and 0.15 microM) notably attenuated TNF-alpha induced expression of PAI-1 to 90.5% and 74.6%, respectively, after 12 h, and to 75.1% and 64.2%, respectively, after 18 h. We also observed a dose-dependent decrease in PAI-1 protein production in the presence of SalB. We then used pathway inhibitors to investigate which step of the TNF-alpha induced signaling pathway was targeted by SalB. We found that the c-Jun N-terminal kinase (JNK) inhibitor, SP600125, increased the inhibitory effects of SalB on TNF-alpha-induced PAI-1 secretion, whereas the nuclear factor-kappaB (NF-kappaB) inhibitor, emodin, and the extracellular signal-regulated kinase (ERK) inhibitor, PD98059, did not. A gel shift assay further showed that SalB inhibited the TNF-alpha-activated NF-kappaB and AP-1 DNA binding activities in a dose-dependent manner. Collectively, these results indicate that the NF-kappaB and ERK-AP-1 pathways are possible targets of SalB in the regulation of TNF-alpha-stimulated PAI-1 production in HUVECs.
Benzofurans↗
Expression of transforming growth factor and basic fibroblast growth factor and core protein of proteoglycan in human vertebral cartilaginous endplate of adolescent idiopathic scoliosis.
STUDY DESIGN: To compare the expression of cytokines and core protein of proteoglycan in the scoliotic concave and convex cartilaginous endplate using immunohistochemical staining. OBJECTIVES: To define the possible role of transforming growth factor beta 1 (TGFbeta1), basic fibroblast growth factor (bFGF), and core protein of proteoglycan in the development of adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Changes in the endplate composition have been implicated as possible etiologic factors in the pathogenesis of adolescent idiopathic scoliosis. Cytokines have exclusive effects on cartilage. Thus comparing the expression of the cytokines and matrix on the convex and concave sides of scoliotic endplate tissues may help to understand the role of endplate tissues in the induction and/or progression of idiopathic scoliosis. METHODS: The convex and concave half of cartilage endplate was collected at the apex and end vertebrae from 12 patients. The expression of TGFbeta1, bFGF, and core protein on both sides was examined with the immunohistochemistry method, and results were analyzed with the image analysis system. RESULTS: TGFbeta1, bFGF, and core protein of proteoglycan were all expressed in the cytoplasm of chondrocytes in the cartilaginous endplate. The area density and quantity density of TGFbeta1 and bFGF on the concave side are expressed in an even significantly higher level than that on the convex side (P > or = 0.05). The expression of the core protein of proteoglycan on the convex side is higher than that on the concave side, the difference is not significant (P > 0.05). CONCLUSION: There was a significantly higher expression of TGFbeta1 and bFGF, although a lower expression of the core protein on the concave side, which suggests a possible etiological factor or a secondary change in the development of adolescent idiopathic scoliosis.
Adolescent↗
Adhesion molecule expression in fibroblasts: alteration in fibroblast biology after transfection with LOX-1 plasmids.
The endothelial lectinlike, oxidatively (ox-) modified LDL receptor LOX-1 is a critical player in the pathogenesis of atherosclerosis and myocardial ischemia. Ox-LDL binding of LOX-1 results in the expression of various adhesion molecules, which attract monocytes to endothelial cells, an initial step in atherogenesis. We wished to examine the role of the ox-LDL/LOX-1 signaling pathway in fibroblasts, which naturally express low levels of LOX-1. Rat cardiac fibroblasts were transfected with either cytomegalovirus (CMV)-LOX-1wt (amino acids [aa] 1 to 273) or CMV-LOX-1(1-261) (an ox-LDL-binding negative mutant, aa 1 to 261) plasmid. Western blots showed that LOX-1 protein expression was increased significantly in cells transfected with CMV-LOX-1wt or CMV-LOX-1(1-261) plasmid (P<0.01 vs control). Fibroblasts transfected with CMV-LOX-1wt showed ox-LDL binding, whereas fibroblasts without transfection and those transfected with CMV-LOX-1(1-261) did not bind ox-LDL. Compared with untransfected cells, ox-LDL treatment (50 microg/mL, 24 hours) markedly induced the expression of the leukocyte adhesion molecules intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM)-1 as well as matrix metalloproteinase (MMP)-1 in cells transfected with CMV-LOX-1wt (P<0.05) but not in cells transfected with CMV-LOX-1(1-261). Concurrently, ox-LDL treatment enhanced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) (P<0.05 vs control) in CMV-LOX-1wt-transfected cells. These data suggest that in cardiac fibroblasts, ox-LDL binds to LOX-1 and activates p38 MAPK, followed by the expression of ICAM-1, VCAM-1, and MMP-1. Thus, fibroblasts transform into an endothelial phenotype on transfection with CMV-LOX-1wt and subsequent exposure to ox-LDL. This study provides a useful model system (plasmid-transfected fibroblasts) to study the molecular biology of LOX-1.
Animals↗
Synthesis of a non-hydrolyzable estrone sulfate analogue bearing the difluoromethanesulfonamide group and its evaluation as a steroid sulfatase inhibitor.
Steroid sulfatase (STS) catalyzes the hydrolyis of steroidal sulfates such as estrone sulfate (ES1) and is considered to be an attractive target in the treatment of steroid dependent cancers. A non-hydrolyzable estrone sulfate (ES1) analogue bearing an alpha,alpha-difluorosulfonamide moiety at the 3-position on the A-ring, compound , was synthesized. Key to the success of this synthesis was the first use of the allyl group as a sulfonamide protecting group. The pK(a) of this ES1 mimic in 0.1 M bis-tris propane, 10% DMSO was determined to be 8.05 using 19F NMR. Compound is a reversible inhibitor with a K(i) similar to that of its sulfonate analogue at pH 7.0. It is more potent than its non-fluorinated sulfonamide analogue and, its inhibitory potency increases with increasing pH, a trend opposite to that of other STS inhibitors. Possible reasons for this are presented.
Journal Article↗
Quasi-classical trajectory simulations of intramolecular vibrational energy redistribution in HONO2 and DONO2.
By use of an analytic potential energy surface developed in this work for nitric acid, the quasi-classical trajectory method was used to simulate intramolecular vibrational energy redistribution (IVR). A method was developed for monitoring the average vibrational energy in the OH (or OD) mode that uses the mean-square displacement of the bond length calculated during the trajectories. This method is effective for both rotating and nonrotating molecules. The calculated IVR time constant for HONO(2) decreases exponentially with increasing excitation energy, is almost independent of rotational temperature, and is in excellent agreement with the experimental determination (Bingemann, D.; Gorman, M. P.; King, A. M.; Crim, F. F. J. Chem.Phys. 1997, 107, 661). In DONO(2), the IVR time constants show more complicated behavior with increasing excitation energy, apparently due to 2:1 Fermi-resonance coupling with lower frequency modes. This effect should be measurable in experiments.
Journal Article↗
Protocatechuic aldehyde suppresses TNF-alpha-induced ICAM-1 and VCAM-1 expression in human umbilical vein endothelial cells.
Adhesion molecules, which play a crucial role in the development of atherogenesis, are produced by endothelial cells following stimulation with various inflammatory cytokines. The current studies examined the effect of a potent water-soluble antioxidant, protocatechuic aldehyde (derived from the Chinese herb, Salvia miltiorrhiza), on the expression of adhesion molecules in human umbilical vein endothelial cells (HUVECs) stimulated with tumor necrosis factor-alpha (TNF-alpha). Protocatechuic aldehyde appeared to specifically downregulate the TNF-alpha-induced cell surface expression of vascular adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) on HUVECs as well as the release of soluble VCAM-1and ICAM-1 from HUVECs in a dose-response manner at pharmacologically relevant concentrations (0.15-1.35 mM). We also observed a dose-dependent lowering of mRNA expression of VCAM-1 and ICAM-1 in the presence of protocatechuic aldehyde. Furthermore, protocatechuic aldehyde (0.15, 0.45, and 1.35 mM) notably inhibited TNF-alpha-induced upregulation of U937 cell adhesion to HUVECs to 83.7%, 60.9%, and 40.8%, respectively. A gel shift assay further showed that protocatechuic aldehyde inhibited the TNF-alpha-activated NF-kappaB and AP-1 DNA binding activities in a dose-dependent manner. Collectively, these results indicate that protocatechuic aldehyde inhibits TNF-alpha-stimulated VCAM-1 and ICAM-1expression in HUVECs through a mechanism that involves NF-kappaB and AP-1.
Benzaldehydes↗
Species- and disposition model-dependent metabolism of raloxifene in gut and liver: role of UGT1A10.
Caco-2 cell lysate, and intestinal and liver microsomes derived from female humans and rats were used to compare and contrast the metabolism and disposition of raloxifene. In Caco-2 cell lysate, raloxifene 6-beta-glucuronide (M1) was the main metabolite, although raloxifene 4'-beta-glucuronide (M2) was formed in comparable abundance (58% versus 42%). In rat liver and intestinal microsomes, M1 represented about 76 to 86% of glucuronidated metabolites. In contrast, raloxifene 4'-beta-glucuronide (M2) was the predominant metabolite in expressed UGT1A10 (96%) and human intestinal (92%) microsomes. Intrinsic clearance for M2 (CLint, M2) in human intestinal microsomes was 33- to 72-fold higher than in rat microsomes, whereas intrinsic clearance for M1 (CLint, M1) was 3- to 4-fold lower. Taken together, total intrinsic clearance (CLint, M1 + CLint, M2) in human intestinal microsomes was 3- to 6-fold higher than that in rat intestinal microsomes, but was similar in liver microsomes. In addition, intrinsic clearance in small intestinal microsomes was 2- to approximately 5-fold higher than that in hepatic microsomes, regardless of species. To account for the difference in species- and disposition model-dependent intestinal metabolism, we probed the presence of various UGT1A isoforms in Caco-2 cells using real-time reverse transcriptase-polymerase chain reaction and, as expected, detected no UGT1A10. In conclusion, the lack of UGT1A10 may explain why Caco-2 cell and rat intestinal microsomes metabolized raloxifene differently from human intestinal microsomes. The presence of human intestinal UGT1A10 and the higher overall intrinsic clearance value in the human intestine as the result of UGT1A10 expression could explain why raloxifene has much lower bioavailability in humans (2%) than in rats (39%).
Animals↗
Engineered allosteric ribozymes that respond to specific divalent metal ions.
In vitro selection was used to isolate five classes of allosteric hammerhead ribozymes that are triggered by binding to certain divalent metal ion effectors. Each of these ribozyme classes are similarly activated by Mn2+, Fe2+, Co2+, Ni2+, Zn2+ and Cd2+, but their allosteric binding sites reject other divalent metals such as Mg2+, Ca2+ and Sr2+. Through a more comprehensive survey of cations, it was determined that some metal ions (Be2+, Fe3+, Al3+, Ru2+ and Dy2+) are extraordinarily disruptive to the RNA structure and function. Two classes of RNAs examined in greater detail make use of conserved nucleotides within the large internal bulges to form critical structures for allosteric function. One of these classes exhibits a metal-dependent increase in rate constant that indicates a requirement for the binding of two cation effectors. Additional findings suggest that, although complex allosteric functions can be exhibited by small RNAs, larger RNA molecules will probably be required to form binding pockets that are uniquely selective for individual cation effectors.
Allosteric Regulation↗
Suppression of Pyk2 attenuated the increased tyrosine phosphorylation of NMDA receptor subunit 2A after brain ischemia in rat hippocampus.
Effects of suppressing the protein expression of Pyk2 on increased tyrosine phosphorylation of N-methyl-D-aspartate (NMDA) receptor subunit 2A (NR2A) after brain ischemia in rat hippocampus were studied with immunoprecipitation and immunoblot. Transient (15 min) brain ischemia and reperfusion (I/R) was induced by four-vessel occlusion in Sprague-Dawley (SD) rats. I/R led to increases of tyrosine phosphorylation of NR2A and interaction of Pyk2 and Src kinase with NR2A after 6 h of reperfusion. The increases were attenuated by Pyk2 antisense oligonucleotides intracerebroventricularly infused every 24 h for 4 days before ischemia, but not missense oligonucleotides or vehicle. The antisense also inhibited the increased auto-phosphorylation of Pyk2 and Src kinase, while the protein expression of NR2A or Src kinase had no obvious change under the above conditions. The data suggested that Pyk2 may be involved in facilitating NR2A tyrosine phosphorylation by Src kinase after I/R.
Animals↗
["Subclinical hypothyroidism" has to be handled with care].
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Humans↗
Configurations of germinal vesicle (GV) chromatin in the goat differ from those of other species.
Configuration of germinal vesicle (GV) chromatin has been studied and found correlated with the developmental competence of oocytes in several mammalian species. A common feature in the configuration of GV chromatin in the species studied so far is that the diffuse chromatin (the so called "NSN" pattern) condenses into a perinucleolar ring (the so called "SN" configuration) with follicular growth. However, no study has been published on the configuration of GV chromatin in the goat. Nor is it known whether the perinucleolar ring of condensed chromatin (CC) in an oocyte represents a step toward final maturation or atresia. Changes in configurations of GV chromatin and RNA synthesis during goat oocyte growth, atresia and maturation in vivo and in vitro were investigated in this study. Based on both the size of nucleoli and the degree of chromatin condensation, the GV chromatin of goat oocytes was classified into GV1 characterized by large nucleoli and diffuse chromatin, GV2 with medium-sized nucleoli and condensed net-like (GV2n) or clumped (GV2c) chromatin, GV3 with small nucleoli and net-like (GV3n) or clumped (GV3c) chromatin, and GV4 with no nucleolus but clumped chromatin. The results showed that (i) the configurations of GV chromatin in the goat differ from those of other species in that the chromatin did not condense into a perinucleolar ring; (ii) most of the goat oocytes are synchronized at the GV3n configuration before GVBD; (iii) the GVn pattern might represent a healthy state, but the GVc an atretic state; (iv) in both goats and mice, the GC-specific (Chromomycin A3, CMA3) and the AT-specific (Hoechst 33342) fluorochromes followed the same pattern of distribution in GV chromatin; (v) the nucleolar size decreased significantly with oocyte growth and maturation in vivo and in vitro; and (vi) goat oocytes began GVBD at 8 hr and had completed it by 20 hr after onset of estrus. The peculiar configuration of GV chromatin of goat oocytes can be a useful model for studies of morphological and functional changes of different nuclear compartments during the cell cycle and cell differentiation, and the functional differentiation between GV3n and GV3c might be used for reference to the question whether the "SN" configuration in other species inclines toward ovulation or atresia.
Animals↗
Effect of exogenous p16ink4a and hRb1 genes on cell cycle regulation of osteosarcoma cell.
To study the effect on regulation of cell cycle of osteosarcoma cell line MG63 tranceduced with exogenous p16ink4a and hRb1 genes, pIRES-p16ink4a-hRb1, pIRES-p16ink4a and pIRES-hRb1 plasmids were constructed by gene recombination technology. The recombinant plasmid was transferred into osteosarcoma cell line MG63 by metafectene, and the resistant clones were selected by G418 selective medium. mRNA and protein expression of osteosarcoma cell line were assayed by RT-PCR and Western-Blot respectively. Cell cycle and apoptosis were analyzed by subG1 flow cytometric. Cell proliferation was tested by MTT. In the genome of these transfected target cells, the expression of p16ink4a and hRb1 mRNA and protein were detected respectively in vitro. It was demonstrated with subG1 flow cytometric analysis and MTT method that p16ink4a and hRb1 genes cooperation more significantly inhibited cell growth and induced a more marked G1 arrest and apoptosis than p16ink4a/hRb1 alone (P < 0.01). Coexpression of exogenous p16ink4a with hRb1 broke the regulatory feedback loop of p16ink4a-cyclinD1 /CDK-hRb1 and played a more significant role in inhibiting cell growth as well as inducing cell apoptosis than p16ink4a or hRb1 did alone in vitro.
Apoptosis↗