Oridonin Dose-Dependently Modulates the Cell Senescence and Apoptosis of Gastric Cancer Cells
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ABSTRACT:
SUBMITTER: Wang Y
PROVIDER: S-EPMC8595004 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Gastric cancer is the third most frequent cause of cancer-associated mortality and almost all patients who respond initially to cisplatin (DDP) later develop drug resistance, indicating multi-drug resistance (MDR) is an essential aspect of the failure of treatment. The natural diterpenoid component Oridonin (Ori) has exhibited efficient inhibition in several types of human cancer. However, the effect and potential mechanism of Ori-reversed MDR in human gastric cancer has not been fully elucidated. In the present study, it was found that Ori significantly suppressed DDP-resistant human SGC7901/DDP cell proliferation, growth and colony formation, causing increased caspase-dependent apoptosis, decreased expression of P-glycoprotein (P-gp), encoded by the MDR gene, multi-drug resistance-associated protein (MRP1), and cyclin D1. SGC7901/DDP cells were cultured with different groups of drugs (Ori, DDP alone, or the combination of Ori and DDP). The drug sensitivity, cell apoptosis and effects on MDR were detected by MTT assay and western blot analysis. The results revealed that Ori is able to reverse the DDP resistance and has a clear synergistic effect with DDP in SGC7901/DDP cells by decreasing the levels of P-gp, MRP1, cyclin D1 and cancerous inhibitor of protein phosphatase 2A. Thus, Ori may be a novel effective candidate to treat DDP-resistant human gastric cancer cells.
| S-EPMC5530171 | biostudies-other
Project description:BackgroundRadio- and chemotherapy (RT/CT) resistance hampers success in combating small and non-small cell lung cancers (SCLC/NSCLC). The underlying molecular mechanisms of RT/CT resistance of LCs are multifactorial and have been understood in part hitherto. miRNAs, key regulators of mRNAs, are well-recognised oncomirs; however, their role in regulating RT response remains poorly understood.MethodsSix human NSCLC and five SCLC cell lines with different SF2 values were investigated. Using microarray we examined whether expression of miRNAs is linked to the RT resistance of NSCLCs or SCLCs. Obtained data were validated by quantitative real-time PCR. Apoptosis and senescence were analysed using siRNA transfection, western blot and flow cytometry.ResultsmiRNA-21, miRNA-1827, miRNA-214, miRNA-339-5p, miRNA-625, miRNA-768-3p, miRNA-523-3p, miRNA-1227, miRNA-324-5p, miRNA-423-3p, miRNA-1301 and miRNA-1249 are differentially expressed in LC cells. miRNA-214 is upregulated in RT-resistant NSCLC cells relative to radiosensitive counterparts. Considering miRNA-214 as a putative regulator of RT resistance, we demonstrate that knockdown of miRNA-214 in radioresistant NSCLCs sensitised them to RT by stimulation of senescence. Consistently, overexpression of miRNA-214 in radiosensitive NSCLCs protected against RT-induced apoptosis. Protection was mediated by p38MAPK, as downregulation of this kinase could reverse the miRNA-214 overexpression-induced resistance of NSCLC cells.ConclusionmiRNA profiling of LC revealed putative RT resistance signalling circuits, which might help in sensitisation of LC to RT.
| S-EPMC3494421 | biostudies-literature
Project description:Lung adenocarcinoma (LAC), predominant subclassfication of lung cancer, leads high incidence and mortality annually worldwide. During the premalignant transition from lung adenomas to LAC, cellular senescence is regard as a critical physiological barrier against tumor progression. Nevertheless, the role of senescence in tumorigenesis is controversial and few senescence inducers are extensively determined. In this study, we used two classical cell lines A549 and H1299 and two NSCLC xenograft models on Balb/c-nude mice to reveal the pro-senescence effects of shikonin and the corresponding underlying mechanism in LAC. Shikonin, a pure compound isolated from the herbal medicine Lithospermum erythrorhizon, remarkably stimulated cellular senescence including increased SAHF formation, enlarged cellular morphology, and induced SA-?-Gal positive staining. Further mechanism study revealed that the pro-senescence effect of shikonin was dependent on the increased intercellular ROS generation, which subsequently triggered DNA damage-p53/p21waf axis without activating oncogenes such as Ras and MEK-1. Meanwhile, Kdm2b, an H3K36me2-specific demethylase effectively suppressed ROS generation, was also notably suppressed by shikonin treatment. Moreover, shikonin at 10 mg/kg significantly inhibited tumor weights by 55.84% and 50.98% in A549 and H1299 xenograft model, respectively (P < 0.05) through activating cellular senescence. Our study suggested that shikonin, a ROS-dependent senescence inducer, could serve as a promising agent for further lung cancer treatment.
| S-EPMC5974149 | biostudies-literature
Project description:Acetylation is an important post translational modification of histone that plays a role in regulation of physiological and pathological process in the body. We have recently shown that the inhibition of histone deacetylases (HDAC) by low concentrations of HDAC inhibitors (HDACis), belinostat (up to 0.25 µM) and panobinostat (up to 0.04 µM) promote histone acetylation (e.g., AcH4) and neutrophil extracellular trap formation (NETosis). Clinical use of belinostat and panobinostat often leads to neutropenia and the in vivo concentrations vary with time and tissue locations. However, the effects of different concentrations of these HDACis on neutrophil death are not fully understood. We considered that increasing concentrations of belinostat and panobinostat could alter the type of neutrophil death. To test this hypothesis, we treated human neutrophils with belinostat and panobinostat in the presence or absence of agonists that promote NOX-dependent NETosis (phorbol myristate acetate or lipopolysaccharide from Escherichia coli 0128) and NOX-independent NETosis (calcium ionophores A23187 or ionomycin from Streptomyces conglobatus). Increasing concentrations of HDACis induced histone acetylation in a dose-dependent manner. ROS analyses showed that increasing concentrations of HDACis, increased the degree of NOX-derived ROS production. Higher levels (>1 µM belinostat and >0.2 µM panobinostat) of AcH4 resulted in a significant inhibition of spontaneous as well as the NOX-dependent and -independent NETosis. By contrast, the degree of neutrophil apoptosis significantly increased, particularly in non-activated cells. Collectively, this study establishes that increasing concentrations of belinostat and panobinostat initially increases NETosis but subsequently reduces NETosis or switches the form of cell death to apoptosis. This new information indicates that belinostat and panobinostat can induce different types of neutrophil death and may induce neutropenia and regulate inflammation at different concentrations.
| S-EPMC6571947 | biostudies-literature
Project description:The present study aims to investigate whether gastrokine 1 (GKN1) induces senescence and apoptosis in gastric cancer cells by regulating telomere length and telomerase activity. Telomere length, telomerase activity, and hTERT expression decreased significantly in AGSGKN1 and MKN1GKN1 cells. Both stable cell lines showed increased expression of TRF1 and reduced expression of the hTERT and c-myc proteins. In addition, TRF1 induced a considerable decrease in cell growth, telomerase activity, and expression of hTERT mRNA and protein. GKN1 completely counteracted the effects of c-myc on cell growth, telomere length, and telomerase activity. Interestingly, GKN1 directly bound to c-myc and down-regulated its expression as well as inhibited its binding to the TRF1 protein and a hTERT promoter. Furthermore, GKN1 triggered senescence, followed by apoptosis via up-regulating the p53, p21, p27, and p16 proteins and down-regulating Skp2. Telomere length in 35 gastric cancers was shortened significantly compared with the corresponding gastric mucosae, whereas GKN1 expression was inversely correlated with telomere length and c-myc and hTERT mRNA expression. Taken together, these results suggest that GKN1 may shorten telomeres by acting as a potential c-myc inhibitor that eventually leads to senescence and apoptosis in gastric cancer cells.
| S-EPMC4294346 | biostudies-literature
Project description:MicroRNAs have been shown to be involved in a variety of different human cancers, including gastric cancer, functioning as post-transcriptional regulators of oncogenes or tumor suppressors. This study aimed to clarify the role of miR-422a in gastric cancer and further elucidate the pathogenesis thereof. To this end, miR-422a expression was initially determined in gastric cancer tissues and cells. Our results showed decreased miR-422a and increased cell division cycle 40 (CDC40) expression in gastric cancer. Dual-luciferase reporter assay further confirmed that miR-422a targeted CDC40. Altogether, this study showed that miR-422a downregulated CDC40, thereby affecting cell cycle progression. Moreover, restoration of miR-422a inhibited gastric cancer cell proliferation. In summary, this study has been the first to show that miR-422a was associated with CDC40 levels in human gastric cancer cells and that disease development may be attributed to CDC40.
| S-EPMC7476107 | biostudies-literature
Project description:ObjectivesEnhancer of zeste homologue 2 (EZH2) is crucially involved in epigenetic silencing by acting as a histone methyltransferase. Although EZH2 is overexpressed in many cancers and is involved in malignant cell proliferation and invasion, the role of EZH2 in senescence induced by DNA damage has up to now remained largely unknown. In this study, we sought to explore the outcome of EZH2 depletion along with exposure of doxorubicin (DOX), and related mechanisms, in gastric cancer cells.Materials and methodsHere, senescence induced by DNA damage was achieved in gastric cancer cells by DOX treatment. EZH2 was downregulated by transfection with siRNA or treated with (-)-epigallocatechin-3-gallate, a targeted inhibitor. Senescence-associated β galactosidase (SA-β-gal) and formation of senescence-associated heterochromatin foci were used to identify cell senescence. To investigate effects of EZH2 depletion on the cell cycle, apoptosis and proliferation, flow cytometry and MTT analysis were employed. Changes in p53-p21 axis activation were detected by Western blotting.ResultsWe found that cell proliferative arrest caused by DOX could be promoted by EZH2 depletion. Mechanistically, EZH2 depletion not only worked in coordination with DNA damage during the progression of cell senescence but also promoted apoptosis in p53 mutant cells. However, it had no cooperative relationship with DOX in p53 wild-type cells.ConclusionsThese data help unravel a crucial role for EZH2 in senescence and apoptosis in gastric cancer cells and that p53 genomic status was associated with different cell responses to EZH2 silencing.
| S-EPMC6495717 | biostudies-literature
Project description:Staphylococcus aureus is one of the major human bacterial pathogens causing a broad spectrum of serious infections. Myeloid-derived suppressor cells (MDSC) represent an innate immune cell subset capable of regulating host-pathogen interactions, yet their role in the pathogenesis of S. aureus infections remains incompletely defined. The aim of this study was to determine the influence of different S. aureus strains and associated virulence factors on human MDSC generation. Using an in vitro MDSC generation assay we demonstrate that low concentrations of supernatants of different S. aureus strains led to an induction of functional MDSC, whereas increased concentrations, conversely, reduced MDSC numbers. The concentration-dependent reduction of MDSC correlated with T cell proliferation and cytotoxicity. Several findings supported a role for staphylococcal enterotoxins in modulating MDSC generation. Staphylococcal enterotoxins recapitulated concentration-dependent MDSC induction and inhibition, T cell proliferation and cytotoxicity, while an enterotoxin-deficient S. aureus strain largely failed to alter MDSC. Taken together, we identified staphylococcal enterotoxins as main modulators of MDSC generation. The inhibition of MDSC generation by staphylococcal enterotoxins might represent a novel therapeutic target in S. aureus infections and beyond in non-infectious conditions, such as cancer.
| S-EPMC6146041 | biostudies-literature
Project description:MicroRNAs (miRNAs) are a new class of gene expression regulators that have been implicated in tumorigenesis and modulation of the responses to cancer treatment including that of human non-small cell lung cancer (NSCLC). However, the role of miR-34a in ionizing radiation (IR)-induced senescence in NSCLC cells remains poorly understood. Here we report that IR-induced premature senescence correlates with upregulation of miR-34a expression in NSCLC cells. Ectopic overexpression of miR-34a by transfection with synthetic miR-34a mimics markedly enhances IR-induced senescence, whereas inhibition of miR-34a by transfection with a synthetic miR-34a inhibitor attenuates IR-induced senescence. Clonogenic assays reveal that treatment with miR-34a mimics augments IR-induced cell killing in human NSCLC cells. Mechanistically, we found that the senescence-promoting effect of miR-34a is associated with a dramatic down-regulation of c-Myc (Myc) expression, suggesting that miR-34a may promote IR-induced senescence via targeting Myc. In agreement with this suggestion, knockdown of Myc expression by RNAi recapitulates the senescence-promoting effect of miR-34a and enhances IR-induced cell killing in NSCLC cells. Collectively, these results demonstrate a previously unrecognized role for miR-34a in modulating IR-induced senescence in human NSCLC cells and suggest that pharmacological intervention of miR-34a expression may represent a new therapeutic strategy for improving the efficacy of lung cancer radiotherapy.
| S-EPMC5642517 | biostudies-literature
Project description:Defects in natural killer (NK) cell functions are necessary for tumor immune escape, but their underlying regulatory mechanisms in human cancers remain largely unknown. Here we showed, in detailed studies of NK cells from 235 untreated patients with gastric cancer (GC), the NK cell density in GC tissues could predict improved survival of patients. However, NK cells were significantly decreased in number with advanced-stage GC. A multivariate Cox analysis revealed that the intratumoral NK cell density was an independent prognostic factor for overall survival and disease-free survival in the GC patients. Most of the intratumoral NK cells exhibited a normal phenotype and secreted normal levels of cytokines, but the expression of Ki67 was decreased compared with NK cells from nontumoral regions. Moreover, the levels of intratumoral NK cells were negatively correlated with the intratumoral expression of cyclooxygenase-2. Furthermore, we found that PGE2 derived from GC cells suppressed NK cell proliferation and increased apoptosis in vitro. These data reveal that tumor-derived PGE2 is critical for inducing NK cell dysfunction in GC and demonstrate that an extensive infiltration of NK cells predicts a good prognosis in patients with GC. Our findings suggest that immunosuppressive barriers erected by tumors greatly hamper the antitumor activity of human NK cells, thereby favoring tumor outgrowth and progression.
| S-EPMC4801461 | biostudies-literature