Differential apoptosis by indomethacin in gastric epithelial cells through the constitutive expression of wild-type p53 and/or up-regulation of c-myc.

Nonsteroidal anti-inflammatory drug (NSAID)-induced apoptosis is considered to be an important mechanism in the antineoplastic effects and damage produced by the drugs in the gastrointestinal tract. In this study, two different gastric cancer cell lines, MKN28 (mutant-type p53) and AGS (wild-type p53), were compared as to growth inhibition, apoptosis, and cell cycle and apoptosis-related gene expression in response to indomethacin treatment. Cell growth was measured by MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide) assay. Apoptosis was characterized by acridine orange staining and DNA fragmentation, and cell cycle kinetics by flow cytometry. The mRNA and protein levels of p53, p21waf1/cip1, and c-myc were determined by Northern and Western blotting. The results showed that indomethacin initiated growth inhibition and apoptosis in both cell lines without cell cycle shifting. AGS cells were more sensitive to growth inhibitory activity and apoptosis of indomethacin than MKN28 cells. In MKN28 cells, the levels of p53, p21waf1/cip1, and c-myc mRNA remained unchanged over the 24-hr treatment with indomethacin, but the p53 protein level was elevated after 4 hr. There was no change in the p21waf1/cip1 and c-myc protein levels in the MKN28 cells. In AGS cells, a progressive increase in c-myc mRNA and protein levels was noted, while p53 and p21waf1/cip1 remained unchanged. It can be concluded that wild-type p53 and/or up-regulation of c-myc is associated with indomethacin-mediated differential apoptosis in gastric epithelial cells.     

Platinum-(IV)-derivative satraplatin induced G2/M cell cycle perturbation via p53-p21(waf1/cip1)-independent pathway in human colorectal cancer cells

Aim:

Platinum-(IV)-derivative satraplatin represents a new generation of orally available anti-cancer drugs that are under development for the treatment of several cancers. Understanding the mechanisms of cell cycle modulation and apoptosis is necessary to define the mode of action of satraplatin. In this study, we investigate the ability of satraplatin to induce cell cycle perturbation, clonogenicity loss and apoptosis in colorectal cancer (CRC) cells.

Methods:

CRC cells were treated with satraplatin, and the effects of satraplatin on apoptosis and the cell cycle were evaluated by flow cytometry. Western blot analysis was used to investigate the effects of satraplatin on cell cycle and apoptosis-related proteins. RT-qPCR was used to evaluate p53-related mRNA modulation.

Results:

Satraplatin induced an accumulation of CRC cells predominantly in the G₂/M phase. Increased p53 protein expression was observed in the p53 wild-type HCT116 and LoVo cells together with p21^waf1/cip1 protein up-regulation. However, p21^waf1/cip1 protein accumulation was not observed in the p53 mutant HCT15, HT29, and WiDr cells, even when p53 protein expression was compromised, suggesting that the cell cycle perturbation is p53-p21^waf1/cip1 independent. Following a candidate approach, we found an elevated expression of 14-3-3σ protein levels in CRC cells, which was independent of the status of p53, further supporting the role of satraplatin in the perturbation of the G₂/M cell cycle phase. Moreover, satraplatin treatment induced apoptosis along with Bcl-2 protein down-regulation and abrogated the clonogenic formation of CRC cells in vitro.

Conclusion:

Collectively, our data suggest that satraplatin induces apoptosis in CRC cells, which is preceded by cell cycle arrest at G₂/M due to the effect of 14-3-3σ and in a p53-p21^waf1/cip1–independent manner. Taken together, these findings highlight the potential use of satraplatin for CRC treatment.     

(-)-Syringaresinol inhibits proliferation of human promyelocytic HL-60 leukemia cells via G1 arrest and apoptosis

We examined the effect of (-)-syringaresinol, a furofuran-type lignan isolated from Daphne genkwa, on cell cycle regulation in HL-60 human promyelocytic leukemia cells in vitro. (-)-Syringaresinol decreased the viability of HL-60 cells by inducing G(1) arrest followed by apoptosis in a dose- and time-dependent manner. The G(0)/G(1) phase of the cell cycle is regulated by cyclin-dependent kinases (Cdk), cyclins and cyclin-dependent kinase inhibitors (Cdki). We show by western blot analysis, that the (-)-syringaresinol-induced G(1) arrest was mediated through the increased expression of Cdki proteins (p21(cip1/waf1) and p27(kip1)) with a simultaneous decrease in cdk2, cdk4, cdk6, cyclin D(1), cyclin D(2), and cyclin E expression. The induction of apoptosis after treatment with (-)-syringaresinol for 24 h was demonstrated by morphological changes, DNA fragmentation, altered ratio of Bax/Bcl-2, cleavage of poly(ADP-ribose) polymerase and flow cytometry analysis. (-)-Syringaresinol also induced cytochrome c release and activation of caspase-3 and caspase-9. To our knowledge, this is the first time that (-)-syringaresinol has been reported to potently inhibit the proliferation of human promyelocytic HL-60 cells through G(1) arrest and induction of apoptosis. These findings suggest that (-)-syringaresinol may be a potential chemotherapeutic agent for the treatment of cancer.     

Genistein-induced neuronal apoptosis and G2/M cell cycle arrest is associated with MDC1 up-regulation and PLK1 down-regulation

The aim of the present study is to investigate the effect of genistein on human neuroblastoma SK-N-MC cells. MTT proliferation assay, LDH cytotoxicity assay, flow cytometric analysis, real-time quantitative RT-PCR and western blotting were used to investigate the effect of genistein on cell survival, cellular toxicity, cell cycle progression, and mRNA and protein alterations of selected DNA damage-, cell cycle- and apoptosis-related genes in SK-N-MC cells. Genistein suppressed cell proliferation, increased LDH release and modulated cell cycle distribution through accumulation of cells at G2/M- and S-phase and sub-G0 (cell death) with a concurrent decrease of cells at G0/G1 phase. Genistein increased the MDC1 (Mediator of DNA damage Checkpoint protein 1), p53, p21(waf1/cip1), Cdc2 and Bax mRNA levels in a dose-dependent manner. However, PLK1 (Polo-Like Kinase 1) and Cyclin B1 mRNAs were down-regulated after genistein treatment. Furthermore, Genistein did not alter Chk2 (Checkpoint Kinase 2), Bcl-2 and Cdc25C mRNA levels. On western blotting analyses; genistein increased the protein level of MDC1, p53, p21(waf1/cip1), and Bax in a dose-dependent manner. Genistein also increased the phosphorylation of Chk2 and Cdc25C at Thr-68 and Ser-216, respectively. In addition, consistently with PLK1 down-regulation, the phosphorylation of Cdc25C at Ser-198 was markedly decreased after genistein treatment. Additionally, Chk2, Cdc25C, Cyclin B1, p-Cyclin B1 (Ser-147), and Cdc2 as well as Bcl-2 proteins were down-regulated after genistein treatment. Altogether, these results suggest for the first time the involvement of MDC1 up-regulation after genistein treatment in DNA damage-induced Chk2 activation- and PLK1 down-regulation-mediated apoptosis and cell cycle checkpoint pathways.     

氧化苦参碱对人食管癌细胞株Eca109增殖及凋亡的影响

目的:观察氧化苦参碱(Oxy)对食管癌细胞株Eca109的抑制增殖及诱导凋亡作用。方法:培养食管癌细胞株(Eca109),以MTT比色法、生长曲线、及流式细胞术测定Oxy对食管癌细胞株Eca109抑制增殖及诱导凋亡的作用。免疫沉淀法并ERK活性试剂盒测定ERK活性;免疫印记法测定p-ERK1/2、Cyclin D1、p21waf/cip1、Bax及Bcl-2表达。结果:MTT实验及生长曲线显示Oxy明显抑制Eca109细胞增殖,流式细胞术显示Oxy可诱导Eca109细胞凋亡;免疫沉淀法显示Oxy可抑制ERK活性,免疫印记法显示Oxy抑制p-ERK1/2、Cyclin D1及Bcl-2表达,同时上调p21waf/cip1和Bax表达,Bax/Bcl-2比值增加。结论:氧化苦参碱可以抑制食管癌细胞株Eca109增殖,机制与影响ERK及下游CyclinD1、p21waf/cip1表达有关;其诱导凋亡途径与上调Bax表达,降低Bcl-2表达有关。     

Effects of genistein on cell proliferation and cell cycle arrest in nonneoplastic human mammary epithelial cells: involvement of Cdc2, p21(waf/cip1), p27(kip1), and Cdc25C expression

Genistein, a soy isoflavone, has been reported to inhibit the multiplication of numerous neoplastic cells, including those in the breast. However, there is limited information on the effect of genistein on nonneoplastic human breast cells. In the present studies, genistein inhibited proliferation of, and DNA synthesis in, the nonneoplastic human mammary epithelial cell line MCF-10F with an IC(50) of approximately 19-22 microM, and caused a reversible G2/M block in cell cycle progression. Genistein treatment (45 microM) increased the phosphorylation of Cdc2 by 3-fold, decreased the activity of Cdc2 by 70% after 8 hr, and by 24 hr reduced the expression of Cdc2 by 70%. In addition, genistein enhanced the expression of the cell cycle inhibitor p21(waf/cip1) by 10- to 15-fold, increased p21(waf/cip1) association with Cdc2 by 2-fold, and increased the expression of the tumor suppressor p53 by 2.8-fold. Genistein did not alter the expression of p27(kip1) significantly. Furthermore, genistein inhibited the expression of the cell cycle-associated phosphatase Cdc25C by 80%. From these results, we conclude that genistein inhibits the growth of nonneoplastic MCF-10F human breast cells by preventing the G2/M phase transition, induces the expression of the cell cycle inhibitor p21(waf/cip1) as well as its interaction with Cdc2, and inhibits the activity of Cdc2 in a phosphorylation-related manner. Down-regulation of the cell cycle-associated phosphatase Cdc25C combined with up-regulation of p21(waf/cip1) expression appear to be important mechanisms by which genistein decreases Cdc2 kinase activity and causes G2 cell cycle arrest.     

紫草素诱导A375-S2细胞凋亡的分子机制研究

目的　研究紫草素诱导人黑色素瘤A375 S2细胞凋亡的分子机制。方法　MTT法、Hoechst33258荧光染色、DNA片段化分析、Westernblot、流式细胞分析以及caspase活力分析等。结果　10μmol·L-1紫草素可明显地抑制A375 S2细胞的生长,其半数有效抑制浓度IC50为 (10 9±1 8)μmol·L-1。10μmol·L-1紫草素可诱导A375 S2细胞凋亡,并经历了caspase 9和caspase 3的激活。紫草素促进p53蛋白的积聚,Bax蛋白表达的上调和Bcl xL蛋白表达的下调,进而导致细胞色素C的释放,致使细胞凋亡。紫草素可使细胞周期停止在G1 期。结论　紫草素可诱导A375 S2细胞周期停止在G1 期,其诱导细胞凋亡的途径经过p53介导的Bax和caspase 9的激活。     

Induction of G0/G1 arrest and apoptosis by 3-hydroxycinnamic acid in human cervix epithelial carcinoma (HeLa) cells

The present studies were undertaken to analyze the factors regulating 3-hydroxycinnamic acid-induced apoptosis and cell cycle arrest. Treatment of human cervix HeLa cells with 3-hydroxycinnamic acid induced apoptosis and G0/G1-phase arrest. The percentage of apoptosis induced by 3-hydroxycinnamic acid in HeLa cells was increased with incubation time. The results also demonstrated that 3-hydroxycinnamic acid increased the expression of p53, caspase-3, Bax and cyclin B. These results demonstrated that 3-hydroxycinnamic acid induced apoptosis through p53- and caspase-3-dependent pathways.     

Effects of anthocyanidin on the inhibition of proliferation and induction of apoptosis in human gastric adenocarcinoma cells.

Anthocyanins are naturally occurring reddish pigments that abundant in fruits and vegetables. To investigate the mechanistic basis for the anti-tumor properties of anthocyanins, five aglycone (cyanidin, delphinidin, malvidin, pelargonidin, and peonidin) and four glycosylated (cyanidin-3-glucoside, malvidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside) anthocyanins were used to examine their effects on cell cycle progression and induction of apoptosis in human gastric adenocarcinoma AGS cells. The data from cell viability assay showed that malvidin exhibited the most potent anti-proliferation effect on AGS cells in a time- and dose-dependent manner (P<0.05). This event is accompanied the arrest of AGS cells at the G0/G1 phase by malvidin at the tested concentrations of 0-200 microM. Cellular uptake of anthocyanin and anthocyanidin was confirmed by HPLC analysis and the intracellular accumulation of malvidin (24.9+/-1.1 microM/mg protein) was observed when treatment of AGS cells with malvidin for 12 h. In addition, an accumulation of AGS cells in sub-G1 phase (20% and 30% increase for 100 and 200 microM of malvidin, respectively) was observed as well as by the appearance of a fraction of cells with an aneudiploid DNA content. The occurrence of apoptosis induced by malvidin was confirmed by morphological and biochemical features, including apoptotic bodies formation, caspase-3 activation and poly(ADP-ribose) polymerase proteolysis. Furthermore, the mitochondrial membrane potential of apoptotic cells after treatment with malvidin was significantly lost and resulted in the elevation of Bax/Bcl-2 ratio for 1.6-fold against control for 100 microM treatment. In addition, the malvidin treatment significantly increased the p38 kinase expression and inhibited the ERK activity, and the effects of malvidin on caspase-3 activation were blocked, respectively, by the ERK and p38 inhibitors. These findings suggest that growth inhibition and cytotoxicity of AGS cells by malvidin is involved in the induction of apoptosis rather than necrosis.     

P53-mediated cell cycle arrest and apoptosis through a caspase-3- independent, but caspase-9-dependent pathway in oridonin-treated MCF-7 human breast cancer cells

Aim： To study the caspase-3-independent mechanisms in oridonin-induced MCF-7 human breast cancer cell apoptosis in vitro. Methods： The viability of oridonin- treated MCF-7 cells was measured by MTT （thiazole blue） assay. Apoptotic cells with condensed nuclei were visualized by phase contrast microscopy. Nucleosomal DNA fragmentation was assayed by agarose gel electrophoresis. The apoptotic ratio was determined by lactate dehydrogenase assay. Cell cycle alternation and mitochondrial membrane potential were measured by flow cytometric analysis. Bax, Bcl-2, caspase-3, caspase-9, heat shock protein （Hsp）90, p53, p-p53, p21, Poly （ADP-ribose） polymerase （PARP）, and the inhibitor of caspase-activated DNase （ICAD） protein expressions were detected by Western blot analysis. Results： Oridonin inhibited cell growth in a time- and dose-dependent manner. Cell cycle was altered through the upregulation of p53 and p21 protein expressions. Pancaspase inhibitor Z-VAD-fmk and calpain inhibitor II both decreased cell death ratio. Nucleosomal DNA fragmentation and the downregulation of △ψmit were detected in oridonin-induced MCF-7 cell apoptosis, which was involved in a postmitochondrial caspase-9-dependent pathway. Decreased Bcl-2 and Hsp90 expression levels and increased Bax and p21 expression levels were positively correlated with elevated levels of phosphorylated p53 phosphorylation. Moreover, PARP was partially cleaved by calpain rather than by capase-3. Condusion： DNA damage provoked alternations in the mitochondrial and caspase-9 pathways as well as p53-mediated cell cycle arrest, but was not related to caspase-3 activity in oridonin-induced MCF-7 cells.     

Topoisomerase I inhibitor (camptothecin)-induced apoptosis in human gastric cancer cells and the role of wild-type p53 in the enhancement of its cytotoxicity

Camptothecin (CPT), a human topoisomerase I inhibitor, blocks DNA replication in human cancer cells. It represents a promising new class of chemotherapeutic agents with broad anti-tumor activity. However, its effect on gastric cancer cells remains unknown. We examined cell growth, apoptosis and cell cycle phase distribution in gastric cancer cells by exposing these cells to CPT for up to 72 h. Cell viability was determined by the Trypan blue exclusion assay. Cell cycle phase distribution and apoptosis were measured using flow cytometry, fluorescence microscopy and DNA ladder assay. Exposure of exponentially growing gastric AGS cancer cells to CPT induced time-dependent apoptosis and growth inhibition. Serum starvation-synchronized AGS cells (about 60% cells in G0/G1 phase) showed similar cellular responses. Analysis of cell cycle phase distribution of AGS cells treated with CPT for up to 72 h showed no obvious differences compared to untreated control cells. Although the induction of apoptosis was noticed in gastric cancer cell lines both with and without p53, cells lacking p53 showed less apoptosis compared to those cell lines possessing p53. Our data show that CPT is capable of inducing gastric cancer cell growth inhibition and apoptosis. Wild-type p53 may enhance the cytotoxicity of CPT against gastric carcinoma.     

Isokotomolide A, a new butanolide extracted from the leaves of Cinnamomum kotoense, arrests cell cycle progression and induces apoptosis through the induction of p53/p21 and the initiation of mitochondrial system in human non-small cell lung cancer A549 cells

This study is the first to investigate isokotomolide A (IKA), a butanolide compound isolated from the leaves of Cinnamomum kotoense Kanehira & Sasaki (Lauraceaee), which exhibits an anti-proliferative activity in human non-small cell lung cancer A549 cells. The results show that IKA inhibits the proliferation of A549 by blocking cell cycle progression in the G0/G1 phase and inducing apoptosis. Blockade of cell cycle was associated with increased p21/WAF1 levels and reduced amounts of cyclin D1, cyclin E, Cdk2, Cdk4, and Cdk6 in a p53-mediated manner. IKA treatment also increased p53 phosphorylation (Ser15) and decreased the interaction of p53-MDM2. IKA treatment triggered the mitochondrial apoptotic pathway, indicated by changing Bax/Bcl-2 ratios, cytochrome c release and caspase-9 activation. In addition, pre-treatment of cells with caspase-9 inhibitor inhibited IKA-induced apoptosis, indicating that caspase-9 activation was involved in A549 cells' apoptosis induced by IKA. Our study reports here for the first time that the induction of p53/p21 and the initiation of the mitochondrial apoptotic system may participate in the anti-proliferative activity of IKA in human non-small cell lung cancer cells.     

Induction of apoptosis by Saussurea lappa and Pharbitis nil on AGS gastric cancer cells

We performed this study to understand the molecular basis underlying the antitumor effects of Saussurea lappa, Pharbitis nil, Plantago asiatica and Taraxacum mongolicum, which have been used for herbal medicinal treatments against cancers in East Asia. We analyzed the effects of these medicinal herbs on proliferation and on expression of cell growth/apoptosis related molecules, with using an AGS gastric cancer cell line. The treatments of Saussurea lappa and Pharbitis nil dramatically reduced cell viabilities in a dose and time-dependent manner, but Plantago asiatica and Taraxacum mongolicum didn't. FACS analysis and Annexin V staining assay also showed that both Saussurea lappa and Pharbitis nil induce apoptotic cell death of AGS. Expression analyses via RT-PCR and Western blots revealed that Saussurea lappa, but not Pharbitis nil, increased expression of the p53 and its downstream effector p21Waf1, and that the both increased expression of apoptosis related Bax and cleavage of active caspase-3 protein. We also confirmed the translocation of Bax to mitochondria. Collectively, our data demonstrate that Saussurea lappa and Pharbitis nil induce growth inhibition and apoptosis of human gastric cancer cells, and these effects are correlated with down- and up-regulation of growth-regulating apoptotic and tumor suppressor genes, respectively.     

Proteasome inhibitor inhibits proliferation and induces apoptosis in renal interstitial fibroblasts

BackgroundThe ubiquitin proteasome pathway plays a pivotal role in controlling cell proliferation, apoptosis and differentiation in a variety of normal and tumor cells. This study aimed to investigate the role of a proteasome inhibitor on proliferation, apoptosis and related proteins in renal interstitial fibroblasts (NRK-49F).MethodsNRK-49F cells were induced using transforming growth factor-β1 (TGF-β1) and pretreated with the proteasome inhibitor MG-132. Cell proliferation was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The cell cycle and apoptosis were analyzed using flow cytometry. Apoptosis was also analyzed using a DNAladder. The protein expression of p53, p27, p21, caspase-3, Bcl-2 and Bax was examined using western blots.ResultsThe results showed that TGF-β1 (5 ng/ml) can stimulate the proliferation of NRK-49F cells.MG-132 (0.25–5 μM) inhibited TGF-β1-induced proliferation in a dose-dependent manner through G1-arrest; TGF-β1 alone did not induce apoptosis (3.8 ± 0.4% vs. 4.7 ± 1.6%). However, pretreatment with MG-132 significantly induced apoptosis in TGF-β1-stimulated NRK-49F cells in a dosedependentmanner. AtypicalDNAladderwas also confirmed in these two groups.Western blot analysis showed thatMG-132 activated p53, p21, caspase-3 and Bax, and inhibited Bcl-2 in a dose-dependent manner, while p27 expression remained unchanged.ConclusionsA proteasome inhibitor inhibited proliferation and induced apoptosis in renal interstitial fibroblasts stimulated by TGF-β1. The mechanism may relate to the p53, p21, caspase-3, Bcl-2 and Bax pathways. Our results suggest that a proteasome inhibitor could be a new strategy to treat renal interstitial fibrosis.     

绒毛膜促性腺激素治疗对隐睾患儿生殖细胞p53和细胞周期调节基因表达的影响

目的观察绒毛膜促性腺激素(HCG)治疗对隐睾患儿生殖细胞肿瘤抑制蛋白p53和细胞周期调节基因(p21waf/cip1)表达的影响,探讨隐睾患儿HCG治疗是否损伤睾丸生殖细胞及其机制。方法 60名隐睾患儿随机分为单纯手术组(30例)和HCG加手术组(30例),单纯手术组患儿只接受手术治疗,HCG加手术组患儿于手术前给予HCG治疗。两组患儿术后均采用RT-PCR技术检测睾丸生殖细胞p53和p21waf/cip1 mRNA表达水平。结果与单纯手术组相比,HCG加手术组p53mRNA表达增加,且两者差异有统计学意义(P<0.05);但p21waf/cip1mRNA的表达HCG加手术组较单纯手术组下降,且差异有统计学意义(P<0.05)。结论隐睾患儿给予HCG干预后,可使p53基因表达增加,p21waf/cip1基因表达下降,进而可能会导致睾丸生殖细胞增殖障碍。     

Iron-induced oxidative damage and apoptosis in cerebellar granule cells: attenuation by tetramethylpyrazine and ferulic acid

Tetramethylpyrazine and ferulic acid are two active ingredients of a Chinese herbal medicine Ligusticum wallichi Franchat. In the present investigation, iron-induced oxidative neuronal damage and the protective effects of tetramethylpyrazine and ferulic acid against this induction were studied in primary cultures of rat cerebellar granule cells. When neurons were treated with 200 microM of FeSO(4) for 1 h, lipid peroxidation in neurons increased time dependently, as measured with the thiobarbituric acid assay. Thirty-six hours after iron treatment, the cell viability decreased to 43.6% and the percentage of apoptotic cells increased to 50.6%. Transmission electron microscopic examination showed a disrupted nuclear envelope and condensed chromatin in iron-treated neurons. Analysis of DNA extracted from iron-treated cells by agarose gel electrophoresis showed the typical "ladder pattern", which indicated the formation of mono- and oligonucleosomes. After iron treatment, caspase 3 activity increased significantly, as measured in a fluoregenic assay. The results above suggested that iron treatment triggered oxidative stress and apoptosis in neurons. Western blot revealed that iron treatment up-regulated the apoptosis-related gene p53 as well as its effector gene p21(waf1/cip1). Pretreatment of the cells with 100 microM of tetramethylpyrazine or ferulic acid effectively decreased the activation of caspase 3 as well as the expression of p53 and p21(waf1/cip1), and attenuated iron-induced oxidative damage and apoptosis. The results suggest that tetramethylpyrazine and ferulic acid might be used as preventive agents against neuronal diseases associated with oxidative stress.     

Taiwan cobra cardiotoxin III inhibits Src kinase leading to apoptosis and cell cycle arrest of oral squamous cell carcinoma Ca9-22 cells

Cardiotoxin III (CTX III), a basic polypeptide with 60-amino acid residues isolated from Naja naja atra venom, has been reported to have cytotoxic activity. CTX III exerted cytotoxicity with the S-phase cell cycle arrest, correlated with a marked decrease in the expression levels of cyclin A, cyclin B, and cyclin-dependent kinase 1 (CDK1), and apoptosis, accompanied with Bax and Bad up-regulation, and the down-regulation of Bcl-2, p-Bad, and X-linked inhibitor of apoptosis (XIAP) with cytochrome c release and sequential activation of caspase-9 and caspase-3 in Ca9-22 cells. Mechanistic studies showed that CTX III suppressed the phosphorylation of Src, EGFR, STAT3, STAT5, Akt, and activation of PI3 K (p110). Moreover, Src inactivation was observed earlier than that of the EGFR and the Src inhibitor PP2 suppressed the levels of phospho-EGFR, phospho-STAT3, phospho-STAT5, phospho-Akt, and PI3 K(p110). The PP2 also caused the S-phase arrest and apoptosis, and led to down-regulation of Bcl-2, p-Bad, XIAP, cyclin A, cyclin B, and CDK1, and up-regulation of Bax and Bad, similar to that observed in CTX III treatment. Taken together, these results indicate that CTX III induces apoptosis and S-phase arrest in Ca9-22 cells via concomitant inactivation of the Src, EGFR, STAT3, STAT5, PI3 K(p110), and Akt signaling pathways.     

大萼香茶菜甲素通过线粒体途径诱导HL-60白血病细胞凋亡

目的：观察大萼香茶菜甲素（macrocalyxinA,MA）体外诱导HL-60细胞凋亡,并探讨其作用机制。方法：不同浓度的MA与HL-60细胞进行培养,采用MTT比色法观察其对HL-60细胞增殖的抑制作用;细胞形态学、DNA含量、DNA梯度电泳及细胞周期分析、Annexin—V／PI双标记和Hoechst 33258荧光染色等分析其促细胞凋亡效应;流式细胞术和RT-PCR分别检测Bcl-2、Bax、P53、Fas、线粒体膜蛋白（Ap02．7）、线粒体跨膜电位（AWm）与Bcl-2、Bax、P53、caspase-3 mRNA变化水平,研究其促凋亡机制。结果：MA呈现作用时间和剂量依赖性地抑制HL-60细胞增殖和活力;HL-60细胞经MA作用后,Wright—Giemsa染色和Hoechst荧光染色后细胞出现典型的凋亡小体,细胞阻滞于G0／G1期,DNA片段化,亚二倍体明显增高,Annexin—V／PI标记升高;MA诱导HL-60细胞凋亡过程中,Bcl-2、Fas、P53表达无明显变化,Bax、线粒体膜蛋白（Apo2．7）、caspase-3表达显著增加,Bax／Bcl-2比值升高,龇下降。结论：MA能抑制HL-60细胞增殖和细胞活力、诱导细胞凋亡,其机制通过上调Bax基因和Bax／Bcl-2比值,使线粒体膜电位下降、膜通透性增高,最终使caspase-3激活而促进凋亡。     

Irinotecan activates p53 with its active metabolite, resulting in human hepatocellular carcinoma apoptosis

The topoisomerase I inhibitor irinotecan is widely used in anticancer therapy, although the detailed mechanism is still unclear. We investigated the apoptotic mechanisms of irinotecan in human hepatocellular carcinoma (HCC) cell lines (Huh7). SN-38 caused a significant decrease in cell proliferation and induced apoptosis in Huh7 cells and HepG2 cells. SN-38 significantly increased the expression of p53 protein and its phosphorylation at Ser(15) in the nucleus and apoptosis-inducing proteins Bax, caspase-9, and caspase-3, while it significantly decreased the antiapoptosis protein Bcl-xL of Huh7 cells. SN-38-induced apoptosis was recovered after p53 antisense oligodeoxynucleotide (AS ODN) pretreatment, while Huh7 cells were precultured with p53 AS ODN, followed by the addition of SN-38 for 24 h. Furthermore, increases in p53 DNA-binding activity were observed in the nuclei of Huh7 cells after SN-38 treatment as shown by electrophoretic mobility shift analysis. SN-38 binding motifs were detected in the proximal promoter of p53 (bases -433 to -317 and -814 to -711). These results suggest that the p53-mediated apoptosis pathway is important in the anticancer effects of irinotecan in hepatocellular carcinoma.     

Humic acid induces G1 phase arrest and apoptosis in cultured vascular smooth muscle cells

Humic acid (HA) in well water used by the inhabitants for drinking is one of the possible etiological factors for Blackfoot disease (BFD). In this study, the ability of HA to inhibit cell cycle progression and induce apoptosis in cultured smooth muscle cells (SMCs; A7r5) was investigated. Treatment of the SMCs at various HA concentrations (25-200 microg/mL) resulted in sequences of events marked by apoptosis, as shown by loss of cell viability, morphology change, and internucleosomal DNA fragmentation. HA-induced apoptotic cell death that is associated with loss of mitochondrial membrane potential (Delta Psi m), cytochrome c translocation, caspase-3, -8, and -9 activation, poly ADP-ribose polymerase (PARP) degradation, dysregulation of Bcl-2 and Bax, and upregulation of p53 and phospholyrated p53 (p-p53) in SMCs. Flow cytometry analysis demonstrated that HA blocked cell cycle progress in the G1 phase in SMCs. This blockade of cell cycle was associated with reduced amounts of cyclin D1, CDK4, cyclin E, CDK2, and hyperphosphorylated retinoblastoma protein (pRb) in a time-dependent manner. Apparent DNA strand breaks (DNA damage) were also detected in a dose-dependent manner using Single-cell gel electrophoresis assay (comet assay). Furthermore, HA induced dose-dependent elevation of reactive oxygen species (ROS) level in SMCs, and antioxidant vitamin C and Trolox effectively suppressed HA-induced DNA damage and dysregulation of Bcl-2/Bax. Our findings suggest that HA-induced DNA damage, cell cycle arrest, and apoptosis in SMCs may be an underlying mechanisms for the atherosclerosis and thrombosis observed in the BFD endemic region.