A Novel Compound,L34, Induced Apoptosis in Human Gastric Cancer Cells

Selectively apoptosis-targeting compounds in gastrointestinal cancers attract broad interest. Here, we investigated a synthetic sulfonamide, 4-bromo-N-(5-ethyl-5H-pyrido[4,3-b]indol-8-yl)benzenesulfonamide (L34). It showed high activity against gastric cancer cells SGC-7901, causing apoptosis, which was associated with downregulation of caspase-3 and XIAP, upegulation of cleaved caspase-3, and cleavage of PARP. Hence, L34 might be a potent chemotherapeutic agent against human gastric cancer.     

Thymoquinone inhibits growth and augments 5-fluorouracil-induced apoptosis in gastric cancer cells both in vitro and in vivo

Thymoquinone (TQ), a component derived from the bioactive constituent of black seed (Nigella sativa), has been shown to exert biological activity on various types of human cancers. However, there are few studies addressing its effects on gastric cancer. Here, we present the first report describing the chemosensitizing effect of thymoquinone and 5-fluorouracil (5-FU) on gastric cancer cells both in vitro and in vivo. Studies have shown that pretreatment with TQ significantly increased the apoptotic effects induced by 5-FU in gastric cancer cell lines in vitro. Moreover, we found that TQ enhanced the 5-FU-induced killing of gastric cancer cells by mediating the downregulation of the anti-apoptotic protein bcl-2, the upregulation of the pro-apoptotic protein bax, and the activation of both caspase-3 and caspase-9. In addition to the in vitro results, it has been shown that the combined treatment of TQ with 5-FU represents a significantly more effective antitumor agent than either agent alone in a xenograft tumor mouse model. These data suggest that the TQ/5-FU combined treatment induces apoptosis by enhancing the activation of both caspase-3 and caspase-9 in gastric cancer cells. These results, which provide molecular evidence both in vitro and in vivo, support our conclusion that thymoquinone can activate caspase-3 and caspase-9 and thus result in the chemosensitisation of gastric cancer cells to 5-FU-induced cell death.     

Identification of an alternative form of caspase-9 in human gastric cancer cell lines: a role of a caspase-9 variant in apoptosis resistance

Overcoming apoptosis resistance to chemotherapy and radiation may lead to a reduction in gastric cancer death. We hypothesize that the apoptotic machinery in gastric cancer cells is dependent upon specific cellular conditions. In the course of our study of the expression of apoptosis-related genes in human gastric cancer cell lines, we have identified a cDNA clone which predicts an alternative form of caspase-9. The caspase-9 variant, which we designated as caspase-9 beta, retained a truncated structure of native caspase-9 without its catalytic domain and was expressed in seven cell lines from human gastric cancer. Among the cell lines examined, MKN-28 cells, which exhibited the most resistance against apoptotic stimuli, expressed the highest level of caspase-9 beta. The induction of apoptosis by staurosporine or actinomycin D was markedly suppressed in caspase-9 beta-transfected HeLa cells. These results are consistent with our hypothesis that the caspase-9 beta may be an endogenous dominant-negative molecule which attenuates apoptotic activity in human gastric cancer cells.     

A forskolin derivative, FSK88, induces apoptosis in human gastric cancer BGC823 cells through caspase activation involving regulation of Bcl-2 family gene expression, dissipation of mitochondrial membrane potential and cytochrome c release

FSK88, a forskolin derivative, was extracted and purified from cultured tropical plant roots, Coleus forskohlii. Our previous studies have demonstrated that FSK88 can inhibit HL-60 cell proliferation and induce the differentiation of HL-60 cells to monocyte macrophages. In this study, we showed that FSK88 can induce apoptotic death of human gastric cancer BGC823 cells in a dose- and time-dependent manner. Results showed that FSK88-induced apoptosis was accompanied by the mitochondrial release of cytochrome c and activation of caspase-3 in BGC823 cells. Furthermore, treatment with caspase-3 inhibitor (z-DEVD-fmk) was capable of preventing the FSK88-induced caspase-3 activity and apoptosis. FSK88-induced apoptosis in human gastric cancer BGC823 cells was also accompanied by the up-regulation of Bax, Bad and down-regulation of Bcl-2. Theses results clearly demonstrated that the induction of apoptosis by FSK88 involved multiple cellular and molecular pathways and strongly suggest that pro- and anti-apoptotic Bcl-2 family genes, mitochondrial membrane potential (Deltapsi(m)), cytochrome c, and caspase-3, participate in the FSK88-induced apoptotic process in human gastric cancer BGC823 cells.     

川楝素诱导人胃癌MGC-803细胞凋亡及其机制

目的: 本研究旨在探讨川楝素诱导人胃癌MGC-803细胞凋亡及其机制。方法: 将人胃癌MGC-803细胞分为5组,每组3个复孔,采用氟尿嘧啶(5-FU)和0 nmol/L川楝素(TSN)分别作为阳性对照和阴性对照。其余3组分别加入终浓度为30 nmol/L、50 nmol/L、70 nmol/L的川楝素。川楝素处理细胞48 h后,利用激光共聚焦显微镜观察细胞形态结构变化;流式细胞术检测线粒体膜电位变化;酶标法检测Caspase-3和Caspase-9活性;利用qRT-PCR和Western blot检测凋亡相关基因Bcl-2、Bax、Cyt c和APAF-1 mRNA和蛋白水平。结果: 与0 nmol/L TSN组相比,30 nmol/L、50 nmol/L、70 nmol/L的川楝素作用于人胃癌MGC-803细胞48 h,可见细胞体积缩小,细胞核裂解,部分染色质凝集等形态学变化;Caspase-3和Caspase-9活性升高(P＜0.05);而线粒体膜电位明显下降(P＜ 0.05);Bax、Cyt c和APAF-1 基因mRNA及蛋白表达量显著升高(P＜0.05),Bcl-2 基因mRNA及蛋白表达量显著降低(P＜0.05)。结论: 川楝素通过上调Bax、Cyt c和APAF-1的表达,下调Bcl-2基因表达,增强Caspase-3、Caspase-9活性诱导人胃癌MGC-803细胞凋亡。     

Skeletal muscle apoptosis is not increased in gastric cancer patients with mild-moderate weight loss

Numerous experimental and clinical studies have shown that skeletal muscle apoptotis may increase in wasting conditions and suggest that apoptosis might contribute to the loss of lean body mass. Data in cancer patients are still lacking. The present study aimed at verifying whether apoptosis was enhanced in the skeletal muscle of 16 patients with gastric cancer with respect to controls. A biopsy specimen was obtained from the rectus abdominis muscle. The occurrence of apoptosis in muscle biopsies was determined morphologically by the fluorescent transferase-mediated dUTP nick end labeling assay and by immunohistochemistry for caspase-3 and caspase-1. Mean weight loss was 6+/-2% in cancer patients and 0.5+/-0.1% in controls (p<0.0001). Serum albumin levels (g/dL) were 3.7+/-0.3 in cancer patients and 4.1+/-0.2 in controls (p<0.05). The percentage of apoptotic myonuclei was similar in cancer patients and in controls (1.5+/-0.3 versus 1.4+/-0.2, respectively; p=ns), in gastric cancer patients with mild (1.6+/-0.4) or moderate-severe weight loss (1.4+/-0.5) (p=ns), and in the different stages of disease (stages I-II: 1.5+/-0.7; stage III: 1.3+/-0.4; stage IV: 1.6+/-0.3; p=ns). By immunohistochemistry, caspase-1 and caspase-3 positive fibers were absent in controls and in neoplastic patients. Poly-ADP-ribosyl polymerase, a typical caspase-3 substrate whose processing is indicative of caspase-3 activation, was not cleaved in muscle biopsies of cancer patients. These data suggest that skeletal muscle apoptosis is not increased in neoplastic patients with mild-moderate weight loss and argue against the hypotheses that caspase-3 activation might be an essential step of myofibrillar proteolysis in cancer-related muscle wasting.     

Transforming growth factor beta-dependent sequential activation of Smad, Bim, and caspase-9 mediates physiological apoptosis in gastric epithelial cells

Transforming growth factor beta (TGF-beta) has been implicated in the maintenance of homeostasis in various organs, including the gastric epithelium. In particular, TGF-beta-induced signaling was shown to be required for the differentiation-associated physiological apoptosis of gastric epithelial cells, but its mechanism has not been well understood. In this study, the molecular mechanism of TGF-beta-induced apoptosis was analyzed in a human gastric epithelial cell line, SNU16, as an in vitro model. Expression of Smad7 and Bcl-X(L), but not viral FLIP, was shown to prevent TGF-beta-induced apoptosis, indicating an exclusive requirement of the activation of Smad signaling pathway and mitochondrial dysfunction followed by activation of caspase-9. In addition, treatment with TGF-beta induced binding of Bim, a proapoptotic Bcl-2 homology domain 3 (BH3)-only protein, to Bcl-X(L), which is dependent on the activation of Smad, and reduction in the expression of Bim by RNA interference decreased the sensitivity to TGF-beta-induced apoptosis. Moreover, we found abnormalities in the gastric epithelium of both Bim and caspase-9 knockout mice; these abnormalities were associated with a defect of physiological apoptosis in gastric epithelial cells. These results indicate for the first time that TGF-beta is involved in the physiological loss of gastric epithelial cells by activating apoptosis mediated by Smad, Bim, and caspase-9.     

5-Hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone,a polymethoxyflavone,exerts antitumor effect on PI3K/Akt signaling pathway in human gastric cancer cell BGC-7901

5-Hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone (5HHMF), a polymethoxyflavone (PMF) mainly found in citrus plants, exhibits excellent physiological functions. In this study, we aimed to investigate the anticancer activity of 5HHMF against human gastric cancer cell BGC-7901 both in vitro and in vivo and illustrate the potential mechanisms. The proliferation of BGC-7901 cells was assessed by MTT assay. Reactive oxygen species (ROS) level was determined by ELISA kit. The protein expression was determined by western blot analysis. Antitumor activity of 5HHMF in vivo was evaluated in BALB/c nude mice. The results showed that treatment with 5HHMF significantly suppressed BGC-7901 cells proliferation, increased ROS generation, and upregulated cytochrome c release from the mitochondria to the cytosol. Western blot analysis demonstrated that 5HHMF significantly downregulated the expression of procaspase-3, procaspase-9, and PARP and upregulated cleaved caspase-3, cleaved caspase-9, cleaved PARP, and Bax/Bcl-2 ratio. Meanwhile, 5HHMF treatment markedly decreased the expression of PI3K and p-Akt. In addition, 5HHMF effectively inhibited tumor growth in xenograft models in BALB/c nude mice without major side action. In summary, 5HHMF-induced apoptosis via targeting PI3K/Akt, indicating 5HHMF is a potential antitumor agent for gastric cancer.     

miR-30b,Down-Regulated in Gastric Cancer,Promotes Apoptosis and Suppresses Tumor Growth by Targeting Plasminogen Activator Inhibitor-1

Background

Gastric cancer is one of the most common malignant diseases worldwide. Emerging evidence has shown that microRNAs (miRNAs) are associated with tumor development and progression. Our previous studies have revealed that H. pylori infection was able to induce the altered expression of miR-30b in gastric epithelial cells. However, little is known about the potential role of miR-30b in gastric cancer.

Methods

We analyzed the expression of miR-30b in gastric cancer cell lines and human gastric cancer tissues. We examined the effect of miR-30b mimics on the apoptosis of gastric cancer cells in vitro by flow cytometry (FCM) and caspase-3/7 activity assays. Nude mouse xenograft model was used to determine whether miR-30b is involved in tumorigenesis of gastric cancer. The target of miR-30b was identified by bioinformatics analysis, luciferase assay and Western blot. Finally, we performed the correlation analysis between miR-30b and its target expression in gastric cancer.

Results

miR-30b was significantly down-regulated in gastric cancer cells and human gastric cancer tissues. Enforced expression of miR-30b promoted the apoptosis of gastric cancer cells in vitro, and miR-30b could significantly inhibit tumorigenicity of gastric cancer by increasing the apoptosis proportion of cancer cells in vivo. Moreover, plasminogen activator inhibitor-1 (PAI-1) was identified as the potential target of miR-30b, and miR-30b level was inversely correlated with PAI-1 expression in gastric cancer. In addition, silencing of PAI-1 was able to phenocopy the effect of miR-30b overexpression on apoptosis regulation of cancer cells, and overexpression of PAI-1 could suppressed the effect of promoting cell apoptosis by miR-30b, indicating PAI-1 is potentially involved in miR-30b-induced apoptosis on cancer cells.

Conclusion

miR-30b may function as a novel tumor suppressor gene in gastric cancer by targeting PAI-1 and regulating the apoptosis of cancer cells. miR-30b could serve as a potential biomarker and therapeutic target against gastric cancer.     

Parathyroid hormone-related protein regulates apoptosis in lung cancer cells through protein kinase A

Parathyroid hormone-related protein (PTHrP)-(1–34) and PTHrP-(140–173) protect lung cancer cells from apoptosis after ultraviolet (UV) irradiation. This study evaluated upstream signaling in PTHrP-mediated alteration of lung cancer cell sensitivity to apoptosis. The two peptides increased cAMP levels in BEN lung cancer cells by 15–35% in a dose-dependent fashion, suggesting signaling through protein kinase A (PKA). In line with this view, the PKA inhibitor H89 abrogated the protective effects of PTHrP-(1–34) and PTHrP-(140–173) against caspase activation and DNA loss. PKA activation by forskolin, 3-isobutyl-1-methylxanthine (IBMX), or 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate attenuated and H89 augmented apoptosis after UV exposure as indicated by caspase-3 activation, cell DNA loss, and morphological criteria. Studies with IBMX and varying doses of forskolin indicated that small increases in cAMP, on the order of those generated by IBMX alone and the PTHrP peptides, were sufficient to protect lung cancer cells from apoptosis. In summary, PTHrP-(1–34) and PTHrP-(140–173) stimulate PKA in lung carcinoma cells and protect cells against UV-induced caspase-3 activation and DNA fragmentation. PKA activation by other means also induces resistance to apoptosis, and the protective effect of the PTHrP peptide is blocked by PKA inhibition. Thus PKA appears to have a role in the regulatory effects of PTHrP on lung cancer cell survival. caspases; cell surface receptors; growth substances; signal transduction     

Parathyroid hormone-related protein ameliorates death receptor-mediated apoptosis in lung cancer cells

Parathyroid hormone-related protein (PTHrP) is expressed in more advanced, aggressive tumors and may play an active role in cancer progression. This study investigated the effects of PTHrP on apoptosis after UV irradiation, Fas ligation, or staurosporine treatment in BEN human squamous lung carcinoma cells. Cells at 70% confluency were treated for 24 h with 100 nM PTHrP-(1-34), PTHrP-(38-64), PTHrP-(67-86), PTHrP-(107-139), or PTHrP-(140-173) in media with serum, exposed for 30 min to UV-B radiation (0.9 mJ/cm²), and maintained for another 24 h. Caspase-3, caspase-8, and caspase-9 activities increased fivefold. Pretreatment with PTHrP-(1-34) and PTHrP-(140-173) ameliorated apoptosis after UV irradiation, as indicated by reduced caspase activities, increased cell protein, decreased nuclear condensation, and increased clonal survival. Other peptides had no effect on measures of apoptosis. PTHrP-(140-173) also reduced caspase activities after Fas ligation by activating antibody, but neither peptide had effects on caspase-3 or caspase-9 activity after 1 µM staurosporine. These data indicate that PTHrP-(1-34) and PTHrP-(140-173) protect against death receptor-induced apoptosis in BEN lung cancer cells but are ineffective against mitochondrial pathways. PTHrP contributes to lung cancer cell survival in culture and could promote cancer progression in vivo. The mechanism for the protective effect against apoptosis remains to be determined. caspases; cell surface receptors; growth substances     

Upregulation of periostin prevents P53-mediated apoptosis in SGC-7901 gastric cancer cells

Periostin is frequently upregulated in human cancers including gastric cancer and implicated in cancer cell proliferation, invasion, and epithelial–mesenchymal transition. This study was undertaken to investigate the effects of periostin overexpression on the chemosensitivity of gastric cancer cells. We constructed a stable cell line overexpressing periostin in SGC-7901 human gastric cancer cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that periostin had no influence on the proliferation of SGC-7901 cells. Compared to empty vector-transfected cells, overexpression of periostin rendered SGC-7901 cells more resistant to cisplatin or 5-fluorouracil (5-FU)-induced apoptosis, accompanying with less release of cytochrome c from mitochondria and diminished cleavage of caspase-3 and poly (ADP-ribose) polymerase. Periostin-overexpressing cells treated with cisplatin or 5-FU showed significantly (p < 0.05) decreased expression of Bax and p53 proteins and increased expression of Bcl-2 protein, when compared to drug-treated mock counterparts. Restoration of p53 expression by delivering wild-type p53 gene resulted in a marked increase in drug-induced apoptosis in periostin-overexpressing SGC-7901 cells. Periostin overexpression elevated the phosphorylation of Akt. Pretreatment of periostin-overexpressing cells with an Akt inhibitor, MK-2206, partially rescued periostin-mediated inhibition of p53 expression and drug resistance. Taken together, our data indicate that periostin confers protection against cisplatin or 5-FU-induced apoptosis in SGC-7901 cells, likely through modulating the Akt/p53 pathway, and thus represents a potential therapeutic target in gastric cancer.     

G1P3, an interferon inducible gene 6-16, is expressed in gastric cancers and inhibits mitochondrial-mediated apoptosis in gastric cancer cell line TMK-1 cell

Expression of an interferon inducible gene 6-16, G1P3, increases not only in type I interferon-treated cells but also in human senescent fibroblasts. However, the function of 6-16 protein is unknown. Here we report that 6-16 is 34 kDa glycosylated protein and localized at mitochondria. Interestingly, 6-16 is expressed at high levels in gastric cancer cell lines and tissues. One of exceptional gastric cancer cell line, TMK-1, which do not express detectable 6-16, is sensitive to apoptosis induced by cycloheximide (CHX), 5-fluorouracil (5-FU) and serum-deprivation. Ectopic expression of 6-16 gene restored the induction of apoptosis and inhibited caspase-3 activity in TMK-1 cells. Thus 6-16 protein has anti-apoptotic function through inhibiting caspas-3. This anti-apoptotic function is expressed through inhibition of the depolarization of mitochondrial membrane potential and release of cytochrome c. By two-hybrid screening, we found that 6-16 protein interacts with calcium and integrin binding protein, CIB/KIP/Calmyrin (CIB), which interacts with presenilin 2, a protein involved in Alzheimers disease. These protein interactions possibly play a pivotal role in the regulation of apoptosis, for which further detailed analyses are need. These results overall indicate that 6-16 protein may have function as a cell survival protein by inhibiting mitochondrial-mediated apoptosis.     

人参皂苷Rg5对胃癌细胞周期和侵袭的影响及其机制

目的:观察ginsenoside-Rg5 (Rg5) 对胃癌细胞周期和侵袭的影响,并探讨其机制。方法:采用不同浓度人参皂苷ginsenoside-Rg3 (Rg3)和Rg5 (10、20、30、40、50 μmol/L) 处理人正常胃粘膜细胞GES-1和胃癌细胞株AGS、MKN-45 24 h,每个浓度设3个复孔。通过CCK-8检测细胞存活率。通过流式细胞仪检测细胞周期、Transwell小室分析迁移和免疫印迹法及ELISA法检测相关蛋白。结果:CCK8 实验结果显示人参皂苷Rg3和Rg5 对GES-1细胞无毒副作用,但可以抑制胃癌细胞AGS和MKN-45的增值。且Rg5抗胃癌细胞的活性强于Rg3。 20 μmol/L Rg5诱导MKN-45细胞发生S期阻滞通过降低CyclinA1/CDK2/PCNA 的表达和升高P21^CIPI蛋白表达。Rg5还可以抑制MKN-45癌细胞的迁移通过降低MMP2和MMP9的表达。WB结果显示Rg5抑制胃癌增殖及迁移主要是通过抑制Notch1蛋白的表达从而调控其下游的周期及侵袭相关蛋白。结论:Rg5抗胃癌细胞活性高于Rg3且通过调控Notch1通路抑制细胞增殖和迁移。     

蛇床子素通过促进胃癌细胞N87凋亡和细胞周期阻滞而抑制细胞增殖

蛇床子素是从伞形科植物蛇床中提取的一类具有生物活性的化合物。研究显示,蛇床子素对多种肿瘤细胞具有抑制作用,然而尚未有研究揭示其对胃癌N87细胞的抗肿瘤活性。本文研究了蛇床子素在体外和荷瘤小鼠体内对胃癌N87细胞的抗肿瘤效应,并进一步利用流式细胞术、TUNEL试验及Western印迹检测分析其对细胞周期及细胞凋亡的影响,以探索其作用机制。研究结果表明,蛇床子素有效地抑制了体外培养的N87细胞生长,并呈浓度依赖效应。本文还建立了N87的荷瘤小鼠模型。结果显示,无论是在低剂量(50 mg/kg)或高剂量(100 mg/kg)情况下,蛇床子素均显示了有效的肿瘤生长抑制效果。流式细胞术及Western印迹的结果表明,蛇床子素诱导N87细胞阻滞在G_2/M期。通过流式细胞术、TUNEL测试及Western印迹结果证明,蛇床子素通过激活胱天蛋白酶-3依赖的凋亡通路,最终导致了N87细胞凋亡的发生。综上所述,本研究显示,蛇床子素在胃癌N87细胞中通过促进细胞凋亡而发挥其抗肿瘤活性,这将为其应用于胃癌的临床治疗提供理论参考。     

MicroRNA-34A inhibits the growth,invasion and metastasis of gastric cancer by targeting PDGFR and MET expression

Within the family of RTKs (receptor tyrosine kinases), PDGFR (platelet-derived growth factor receptor) has been implicated in carcinogenesis and tumour development. miRNAs (microRNAs), which can target the mRNAs (messenger RNAs) of cancer-associated genes, are abnormally expressed in various cancers. In this study, our aim was to identify the miRNAs that target PDGFR-α/β and to study the functions of these miRNAs. miR-34a was predicted to target PDGFR, and luciferase reporter assays showed that miR-34a could directly target PDGFR. Meanwhile, we found that miR-34a was down-regulated in gastric cancer tissues and was associated with metastasis. Our findings showed that miR-34a could inhibit gastric cancer cell migration, invasion and proliferation, but these tumourigenic properties were only partially restored when PDGFR-α/β was overexpressed. In subsequent experiments, we found that the overexpression of both PDGFR and MET could completely restore the gastric cancer tumourigenic properties. Moreover, the cancer-associated cell signalling pathway was studied, and we found that miR-34a could inhibit Akt [PKB (protein kinase B)] phosphorylation, which was restored by the overexpression of both PDGFR and MET. In conclusion, miR-34a may act as a potential tumour suppressor in gastric cancer and is associated with the mechanisms of gastric cancer metastasis; miR-34a can inhibit gastric cancer tumourigenesis by targeting PDGFR and MET through the PI3K (phosphoinositide 3-kinase)/Akt pathway.     

gamma-Tocotrienol induces mitochondria-mediated apoptosis in human gastric adenocarcinoma SGC-7901 cells

Tocotrienols are naturally occurring isoprenoid compounds highly enriched in palm oil, rice bran, oat, wheat germ, barley and rye. Tocotrienols have antioxidant properties as well as potent anticancer properties. In this study, the mechanisms underlying the apoptosis of gamma-tocotrienol on human gastric adenocarcinoma SGC-7901 cells were further studied, especially in correlation with the involvement of the apoptotic pathway. gamma-Tocotrienol inhibited SGC-7901 cell growth in a concentration- and time-dependent manner. The inhibitory effects of SGC-7901 cells were correlated with the DNA damage and arresting cell cycle at G(0)/G(1) phase in a time-dependent manner at 60 mumol/L concentration of gamma-tocotrienol. gamma-Tocotrienol induced activation of caspase-3 and increased the cleavage of the downstream substrate poly(ADP-ribose) polymerase. Furthermore, gamma-tocotrienol-induced apoptosis on SGC-7901 cells was mediated by activation of caspase-9. The data in this study suggested that gamma-tocotrienol could induce the apoptosis on human gastric cancer SGC-7901 cells via mitochondria-dependent apoptosis pathway. Thus, our findings revealed gamma-tocotrienol as a potential, new chemopreventive agent for human gastric cancer.     

Identification of signature genes associated with 5-fluorouracil-resistance in human gastric cancer cells

A comparative cDNA microarray analysis was carried out using human gastric cancer cells and their derivative cells made resistant to 5-fluorouracil. Three genes, SRP72, DNA primase, and caspase-6, were identified that were transiently induced by 5-fluorouracil and also overexpressed in 5-fluorouracil-resistant gastric cancer cells.     

C-FLIP(L) contributes to TRAIL resistance in HER2-positive breast cancer

Breast cancers with HER2 amplification have a poorer prognosis than the luminal phenotypes. TRAIL activates apoptosis upon binding its receptors in some but not all breast cancer cell lines. Herein, we investigated the expression pattern of c-FLIP(L) in a cohort of 251 invasive breast cancer tissues and explored its potential role in TRAIL resistance. C-FLIP(L) was relatively high-expressed in HER2-positive breast cancer in comparison with other molecular subtypes, co-expressed with TRAIL death receptors, and inversely correlated with the apoptosis index. Downregulation of c-FLIP(L) sensitized SKBR3 cells to TRAIL-induced apoptosis in a concentration- and time-dependent manner and enhanced the activities and cleavages of caspase-8 and caspase-3, without altering the surface expression of death receptors. Together, our results indicate that c-FLIP(L) promotes TRAIL resistance and inhibits caspase-3 and caspase-8 activation in HER2-positive breast cancer.