In vivo and in vitro studies of anticancer actions of alpha-TEA for human prostate cancer cells

BACKGROUND: Vitamin E analog, 2,5,7,8-tetramethyl-2R-(4R,8R, 12-trimethyltridecyl) chroman-6-yloxyacetic acid, referred to as alpha-TEA induces apoptosis in a variety of human cancer cells in cell culture and reduces tumor burden and metastases in preclinical animal models of breast and ovarian cancer. The goal of this study was to determine in vivo anticancer efficacy of alpha-TEA against human prostate cancer cells and identify mechanisms of action. METHODS: A PC-3-GFP xenograft model was used to assess the effects of alpha-TEA formulated in liposomes and administered orally on tumor burden and metastases. Tumor tissue was examined by immunohistochemical staining for percentage of cells undergoing apoptosis by TUNEL or cell proliferation by Ki-67. In vitro analyses of mechanisms employed western immunoblotting to examine effects of alpha-TEA-treatments in LNCaP and PC-3-GFP cells on levels of pro-survival and pro-death factors. Functional significance was determined using ectopically expressed constitutively active forms, inhibitors, or siRNA. RESULTS: alpha-TEA significantly reduced tumor burden and metastases, increased apoptosis and decreased proliferation of tumor cells (P < 0.05). alpha-TEA treatment of both LNCaP and PC-3-GFP cells in vitro reduced levels of pAkt1, pAkt2; FOXO1, c-FLIP(L) and survivin. Constitutively active Akt1, Akt2, c-FLIP or survivin reduced alpha-TEA-induced apoptosis. PI3K inhibitor enhanced apoptosis. Constitutively active FOXO1 enhanced alpha-TEA induced Fas ligand expression; whereas, FOXO1 siRNA reduced alpha-TEA induced Fas ligand expression. CONCLUSIONS: alpha-TEA is an effective anticancer agent for human prostate cancer cells. Downregulation of pro-survival and upregulation of pro-death factors play roles in alpha-TEA-induced apoptosis.     

Fas-Fas ligand signaling pathway mediates an interleukin-12-induced rejection of a murine prostate tumor system

BACKGROUND: Recent data suggest that anti-tumor activities of interleukin-12 (IL-12) involve the induction of apoptosis. Fas (APO-1/CD95) is a type I membrane protein that is capable of initiating an apoptosis signaling pathway when bound to its ligand (FasL). We undertook this study to test the hypothesis that Fas-FasL-mediated apoptosis plays a role in IL-12-induced tumor regression. METHODS: An mIL-12 expression vector driven by cytomegalovirus promoter was used to express murine IL-12 cDNA in the RM-9 murine prostate carcinoma cell line. Control RM-9 cells and RM-9 cells stably transfected with IL-12 gene (RM-9-IL12) were inoculated subcutaneously in 4- to 6-week-old male C57BL/J6 mice. Tumor size was measured every 3 days. Western blot and immunohistochemical assays were used to evaluate Fas and FasL protein expression. In situ fluorescent end labeling was used to label apoptotic cells. RESULTS: IL-12-expressing RM-9 prostate carcinoma cells transplanted into C57BL/J6 mice grew more slowly than control RM-9 cells and vector control RM-9-Luc cells. The average survival time of the RM-9-IL12 mice was longer than 53 days, whereas the mean survival for mice transplanted with control RM-9 cells was only 16 days. Apoptotic cells were more numerous in RM-9-IL12 tumors: 10.3% vs. 1.5% in control (P = 0.001). Fas and FasL proteins were increased approximately twofold in the RM-9-IL12 tumors compared with the RM-9 control tumors as determined by Western blot and immunohistochemical analyses (P < 0.05). CONCLUSION: The Fas-FasL-mediated apoptosis pathway may contribute to the IL-12-induced rejection of prostate carcinoma.     

Fas and Fas-ligand expression in human pancreatic cancer

OBJECTIVE: To investigate Fas and FasL expression in pancreatic tissues and cultured pancreatic cancer cell lines, and to assess the ability of anti-Fas antibodies to induce apoptosis. SUMMARY BACKGROUND DATA: Activation of the Fas receptor by Fas-ligand (FasL) results in apoptosis, and dysregulation of this pathway may contribute to abnormal cell proliferation. METHODS: Northern blotting and immunohistochemistry were used to compare Fas and FasL expression in normal and cancerous tissues. DNA 3'-OH end labeling was used to detect apoptotic cells. The effects of Fas activation on cell growth and signaling pathways were investigated in culture. RESULTS: Pancreatic cancers exhibited increased Fas RNA levels, whereas FasL mRNA levels were similar in both groups. Despite the colocalization of Fas and FasL in the cancer cells, an apoptotic signal was present in approximately 10% of these cells in only 2 of 16 cancer samples. Fas and FasL were coexpressed in all four cell lines, whereas Fas-associated phosphatase 1 was below the level of detection in all cell lines. Only COLO-357 cells underwent apoptosis after Fas activation. Apoptosis was associated with enhanced activation of jun kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). In the presence of actinomycin D, Fas antibody also induced apoptosis in the other three cell lines. CONCLUSIONS: These results suggest that pancreatic cancer cells are resistant to Fas-mediated apoptosis by mechanisms excluding receptor downregulation or Fas-associated phosphatase upregulation and raise the possibility that Fas-mediated apoptosis may be dependent on the activation of the JNK/p38 MAPK pathway in these cells.     

c-Jun NH2-terminal kinase-dependent Fas activation contributes to etoposide-induced apoptosis in p53-mutated prostate cancer cells

BACKGROUND: The death receptor, Fas, has recently been demonstrated to contribute the chemotherapeutic agents-induced apoptosis, however, the detail mechanisms have yet to be fully understood, especially in prostate cancer cells. METHODS: PC-3 and DU145 stably transfected with dominant negative form of Fas-associated death domain (FADD) or specific kinase of c-Jun NH2-terminal kinase (JNK) (mitogen-activated protein kinase kinase, MKK7) were selected in the presence of hygromycin B (Hyg B). Cell viability was examined by (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphonyl)-2H-tetrazolium, inner salt (MTS) assay or flowcytometric analysis using green fluorescent protein (GFP). Apoptosis was examined by DNA ladder, Western blotting analysis of cleaved caspases, or morphological analysis. The expression of Fas and JNK activation were investigated by Western blotting/flowcytometric analysis and in vitro kinase assay, respectively. RESULTS: Stimulation with etoposide significantly up-regulated Fas, and the death-inducing signaling complex (DISC) was formed in PC-3 and DU145. Stable transfection with dominant-negative FADD inhibited etoposide-induced apoptosis. In addition, stable transfection with dominant-negative MKK7, by which JNK activation was inhibited, canceled both the up-regulation of Fas and the formation of DISC by etoposide. Re-introduction of wild type p53 into PC-3 and DU145 completely suppressed these inhibitory effects. CONCLUSIONS: These results suggest that, in p53-mutated prostate cancer, JNK-initiated Fas-mediated apoptotic signals may play an important role in chemosensitivity.     

FasL, Fas, and death-inducing signaling complex (DISC) proteins are recruited to membrane rafts after spinal cord injury

The Fas/CD95 receptor-ligand system plays an essential role in apoptosis that contributes to secondary damage after spinal cord injury (SCI), but the mechanism regulating the efficiency of FasL/Fas signaling in the central nervous system (CNS) is unknown. Here, FasL/Fas signaling complexes in membrane rafts were investigated in the spinal cord of adult female Fischer rats subjected to moderate cervical SCI and sham operation controls. In sham-operated animals, a portion of FasL, but not Fas was present in membrane rafts. SCI resulted in FasL and Fas translocation into membrane raft microdomains where Fas associates with the adaptor proteins Fas-associated death domain (FADD), caspase-8, cellular FLIP long form (cFLIPL ), and caspase-3, forming a death-inducing signaling complex (DISC). Moreover, SCI induced expression of Fas in clusters around the nucleus in both neurons and astrocytes. The formation of the DISC signaling platform leads to rapid activation of initiator caspase-8 and effector caspase-3, and the modification of signaling intermediates such as FADD and cFLIP(L) . Thus, FasL/Fas-mediated signaling after SCI is similar to Fas expressing Type I cell apoptosis.     

Fas/FasL表达和细胞凋亡在人类同种异体移植肾急性排斥中的作用

目的探讨移植肾急性排斥（ＡＲ）时细胞凋亡与Ｆａｓ和Ｆａｓ配体（ＦａｓＬ）表达的作用及其临床意义。方法分别用原位末端标记技术（ＴＵＮＥＬ法）和免疫组织化学方法检测２６例移植肾ＡＲ标本中细胞凋亡和Ｆａｓ／ＦａｓＬ表达情况。结果细胞凋亡和Ｆａｓ／ＦａｓＬ表达主要在ＡＲ移植肾小管上皮发生,且凋亡指数和Ｆａｓ／ＦａｓＬ表达与肾组织病理损伤程度平行,与正常肾对照组和移植肾功能稳定组比较差异显著（Ｐ＜０．０１）。结论肾小管上皮细胞凋亡在ＡＲ所致的移植肾损伤中起重要作用,Ｆａｓ／ＦａｓＬ系统可能参与移植肾ＡＲ,是造成肾小管上皮细胞凋亡的重要因素。ＴＵＮＥＬ法检测细胞凋亡可作为判断移植肾病理变化和预后的重要指标     

LIGHT／INF—γ基因配比转染HepG2细胞对其凋亡及Fas／FasL系统表达的影响

目的：观察脂质体介导的LIGHT和IFN—γ配比转染HepG2细胞后对其凋亡及Fas和FasL表达的影响。方法：将HepG2细胞分为LIGHT单独转染组、LIGHT和IFN—γ联合转染组和空白对照组，以脂质体为中介转染HepG2细胞；分别于转染后12、24和48h收集HepG2细胞，流式细胞术检测转染后HepG2细胞的凋亡率及Fas和FasL的表达。结果：LIGHT基因转染HepG2细胞能明显促进其凋亡，随时间延长凋亡率增加；Fas和FasL在HepG2细胞高表达，以Fas升高程度显著。结论：LIGHT和IFN—γ联合转染HepG2，其凋亡效果优于LIGHT单独转染，主要是通过上调Fas的表达来促进HepG2细胞凋亡。     

Prognostic Significance of Fas and Fas Ligand System-Associated Apoptosis in Gastric Cancer

Background: Previous studies indicate that gastric carcinomas express Fas ligand and downregulate Fas to escape from the host immune attack; however, the prognostic importance of Fas/FasL expression in this tumor is yet to be evaluated.Methods: Specimens from 87 gastric carcinoma patients of different stages treated in a defined period with curative intent were evaluated for apoptosis, Fas, FasL, and CD8 expression using an immunohistochemical method.Results: The percentage of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive apoptotic cells expressed as apoptotic index (AI) was higher in 43 patients when the cut-off value was set at the median value. There were no significant correlations between AI and clinicopathologic parameters. Thirty-nine patients showed a high number of CD81 cells within cancer nests. Positive FasL and Fas expression was seen in 53 and 72 patients, respectively. CD8 and FasL expressions were related only to patients age. Fas expression had significant correlations with tumor invasion and Lauren classification. There were significant direct correlations between AI and number of nest CD81 cells and between AI and grade of Fas expression. Apoptotic index, pT stage, CD8 expression, and Fas expression were identified as independent prognostic factors.Conclusions: Spontaneous apoptosis in gastric carcinoma may be an independent prognosticator for survival and is significantly influenced by tumor Fas expression and number of nest CD81 cells.     

Fas、FasL和Bcl-2在膀胱癌组织的表达及意义

目的　研究Fas蛋白 (CD95 /Apol 1,Fas)、Fas配体 (Fasligand ,FasL)及Bcl 2在膀胱癌组织中的表达 ,并探讨其临床意义。方法　采用免疫组化LSAB法检测 5 0例膀胱癌组织及 6例正常膀胱黏膜中Fas、FasL和Bcl 2的表达。结果　Fas、FasL及Bcl 2在膀胱癌组织中的阳性表达率分别为 5 0 %、38%、4 2 %。膀胱癌组织FasL和Bcl 2的阳性表达率明显高于正常组织 (P <0 .0 5 ) ,Fas明显低于正常组织 (P <0 .0 5 )。Fas的表达与膀胱癌病理分级、复发有关 (P <0 .0 5 ) ;FasL、Bcl 2表达与各项病理指标均无关 (P >0 .0 5 )。结论　Fas的表达降低与膀胱肿瘤的恶性化程度有关。     

A biochemical mechanism for resistance of intervertebral discs to metastatic cancer: Fas ligand produced by disc cells induces apoptotic cell death of cancer cells

Metastatic spinal cancer is characterized by the maintenance of normal disc structure until the vertebral body is severely destroyed by cancer cells. Anatomic features of the discs have been thought to be the main factor which confer the discs their resistance to metastatic cancer. However, little is known about the biochemical mechanism to prevent or attenuate the local infiltration of cancer cells into the discs. The purpose of this study was to investigate whether Fas ligand (FasL) produced by disc cells can kill Fas-bearing breast cancer cells by Fas and FasL interaction. Two human breast cancer cells (MCF-7 and MDA-MB-231) were obtained and cultured (1 × 10⁶ cells/well), and the expression of Fas was investigated by western blot analysis. Annulus fibrosus cells were isolated and cultured, and the presence of FasL was quantified in the supernatants of three different numbers of annulus fibrosus cells (1×, 2×, and 4 × 10⁶ cells/well) by ELISA assay. The MCF-7 and MDA-MB-231 cancer cells were cultured with supernatants of annulus fibrosus cells for 48 h. As controls, MCF-7 and MDA-MB-231 cancer cells were also cultured by themselves for 48 h. Finally, we determined and quantified the apoptosis rates of MCF-7 and MDA-MB-231 cancer cells by Annexin V–FITC and PI and TUNEL at 48 h, respectively. The expression of Fas was identified in MCF-7 and MDA-MB-231 cancer cells. The mean concentrations of FasL in supernatants of annulus fibrosus cells (1×, 2×, and 4 × 10⁶ cells/well) were 10.8, 29.6, and 56.4 pg/mL, respectively. After treatment with the supernatant of three different numbers of annulus fibrosus cells, the mean apoptosis rate of MCF-7 cancer cells was increased (2.8%, P < 0.01; 6.7%, P < 0.001; 31.0%, P < 0.001) in a dose-dependent manner of FasL compared to that of control (1.1%). The mean apoptosis rate of MDA-MB-231 cancer cells was also increased (5.7%, P < 0.01; 11.1%, P < 0.001; 25.3%, P < 0.001) in a dose-dependent manner of FasL compared to that of control (2.1%). TUNEL also demonstrated direct evidence of apoptoses of MCF-7 and MDA-MB-231 cancer cells. Our results demonstrate that Fas-bearing cancer cells undergo apoptosis by FasL produced by disc cells, which may be considered as a potential biochemical explanation for the disc’s resistance to metastatic cancer. This is the EuroSpine Winning Paper 2007 on Basic Science.     

The impact of altered annexin I protein levels on apoptosis and signal transduction pathways in prostate cancer cells

BACKGROUND: Although reduced expression levels of annexin I (ANX I) protein is a common finding in all stages of prostate cancer a causative relationship between ANX I dysregulation and prostate cancer development has yet to be established. METHODS: Annexin I expression was restored in LNCaP and MDA PCa 2b that normally express low or undetectable levels of ANX I protein. The impact of restoring ANX I expression on cell viability, colony formation in soft agar, apoptosis, and extracellular signal-regulated kinases (ERK), p38, c-Jun N-terminal kinases (JNK) activation was examined. RESULTS: Restoring ANX I expression reduced cell viability, colony formation, in addition to inducing apoptosis. The proliferative response of epidermal growth factor was blocked by restoring ANX I expression. Furthermore, increasing basal and induced levels of phosphorylated p38 and JNK were observed in prostate cancer cells following restoration of ANX I expression. CONCLUSIONS: Annexin I may have tumor suppressor functions in prostate cancer. The pro-apoptotic effect of ANX I involves the activation of p38 and JNK, which appears to shift the balance of signal transduction away from proliferation and toward apoptosis.     

硒对淋巴细胞杀伤大肠癌细胞过程中Fas/FasL表达的影响

目的　探讨硒对淋巴细胞抗大肠癌过程中凋亡相关基因Fas/FasL表达的影响。方法　以半胱氨酸硒作为影响因素,人T淋巴细胞为效应细胞及人结肠癌细胞（LoVo细胞株）为靶细胞,采用四甲基偶氮唑蓝(MTT)比色法、凋亡细胞荧光计数检测凋亡细胞的数量,逆转录-聚合酶链(RT-PCR)反应、原位杂交技术检测,硒对效应细胞杀伤肿瘤细胞过程中Fas/FasL表达的影响。结果　不同浓度的半胱氨酸硒（0.5、1.0　mg/L）作用48h后,可增强人T淋巴细胞抗肿瘤活性［分别为（25.12±3.91）%,（46.17±3.68）%,P＜0.05］,且肿瘤细胞的凋亡比例上升［分别为(18.6±4.1)%,（32.7±2.1）%,P＜0.05］;能使免疫效应细胞和肿瘤细胞表达FasL和Fas水平增高。结论　硒可提高淋巴细胞的抗肿瘤作用,可能通过Fas/FasL途径起作用。     

皮肤鳞状细胞癌Fas和FADD表达的差异性分析

目的：观察死亡受体（Fas）、Fas相关死亡结构域（Fas-associ ated death domain,FADD）在皮肤鳞状细胞癌（SCC）组织中的表达情况,分析其表达差异及意义。方法：应用免疫组织化学SABC法对27例SCC组织的石蜡切片及10例正常皮肤组织的切片分别进行Fas、FADD染色,在光学显微镜下观察并计数其阳性细胞,根据阳性细胞平均表达积分来判定。结果采用t检验和等级相关分析。结果：①Fas、FADD在10例正常皮肤组织中表达均为阳性,平均表达积分3.10±0.87、3.20±0.63;②Fas在27例SCC组织中的平均表达积分2.19±1.14,低于正常对照组,差异有统计学意义（P〈0.05）;FADD在27例SCC组织中的平均表达积分2.15±1.40,低于正常对照组,差异有统计学意义（P〈0.05）;③在27例SCC组织中,Fas、FADD蛋白表达程度与病理分级呈正相关,有统计学意义（P〈0.05）。结论：①Fas和FADD共同的低表达,可能参与了皮肤SCC的发生发展;②Fas、FADD蛋白的异常表达程度与皮肤SCC的恶性程度有关,同时检测两个蛋白的表达情况,有助于判断皮肤SCC的病理分级,有可能作为反映鳞状细胞癌预后的指标。     

复方苦参注射液诱导胃癌细胞凋亡的机制

目的探讨复方苦参注射液对胃癌SGC-7901细胞凋亡的影响及其可能机制。方法体外培养胃癌细胞系SGC-7901，四甲基偶氮唑盐（MTT）法测定药物对SGC-7901细胞生长的抑制作用；透射电镜下观察肿瘤细胞的超微结构变化；应用流式细胞术（FCM）检测肿瘤细胞凋亡情况和Fas、FasL蛋白的表达；分光光度法检测半胱氨酸天冬氨酸蛋白酶（caspase）-3活性的变化。结果不同浓度复方苦参注射液对SGC-7901细胞生长均有一定的抑制作用。0．5g／L、1．0g／L和1．5g／L复方苦参注射液组SGC-7901细胞凋亡率分别为39．80％、58．11％和79．00％，呈明显的量效关系；复方苦参注射液组以早期凋亡细胞为主，氟尿嘧啶对照组以晚期凋亡细胞为主。Fas蛋白表达及FasL蛋白表达与凋亡均呈显著正相关：Fas蛋白表达及FasL蛋白表达之间呈显著正相关。复方苦参注射液组caspase．3酶活性随着药物浓度而升高，且酶活性变化与细胞凋亡率变化呈正相关。结论复方苦参注射液可有效诱导胃癌SGC-7901细胞凋亡，其机制可能与上调Fas／FasL蛋白表达、激活caspase-3酶有关。     

Valproic Acid Sensitizes TRAIL-Resistant Anaplastic Thyroid Carcinoma Cells to Apoptotic Cell Death

Background

Anaplastic thyroid carcinoma (ATC) is an aggressive human tumor associated with a median survival of 2–6 months. TRAIL, as a ligand of death receptors, is known to induce apoptotic cell death in several cancer cells. However, TRAIL treatment alone is not effective against TRAIL-resistant cancer cells. This study was designed to investigate whether valproic acid (VPA) enhances apoptotic cell death of TRAIL-resistant ATC cells and to identify the mechanism of cell death of ATC cells by combination treatment with VPA and TRAIL.

Methods

To evaluate the cytotoxic effect of TRAIL and/or VPA on ATC cells, we used the MTT assay. The effects of VPA and TRAIL on apoptosis were assessed using FACS analysis (Annexin-V/PI stain) and Western blotting.

Results

The combination of VPA with TRAIL significantly induced apoptotic cell death compared with 8505C and ARO cells treated with TRAIL alone. The protein levels of cleaved caspase-8, -3, and PARP were increased in VPA and TRAIL co-treated ARO cells. The combination induced the activation of JNK and the phosphorylation of FADD and c-Jun but not p38. However, pretreatment with caspase inhibitors reduced the expression of cleaved caspase-8, -3, and PARP in co-treated ARO cells. SP600125 remarkably reduced the expression of cleaved caspase-8, -3, and PARP and the phosphorylation of FADD and c-Jun, as well as apoptotic cell death.

Conclusions

VPA sensitized TRAIL-resistant ATC cells to apoptotic cell death through involvement of the JNK pathway. Thus, the combination of VPA and TRAIL may be a promising therapy for ATC.

     

Fas介导细胞凋亡通路在慢性排斥反应所致移植物血管病变中的作用

目的 通过建立小鼠心脏及主动脉移植模型探讨Fas途径介导细胞凋亡在慢性排斥反应所致移植物血管病变形成中的作用。方法 (1)正常B6及B6．MRL(Fas-／-)→B10．2R小鼠腹腔异位心脏移植。B10．2R→B6小鼠胸主动脉异位移植。定期获取移植物。观察移植物存活率与组织形态学改变；TUNEL及FITC Annexin V／PI双染色方法检测移植物中凋亡细胞形态及分布；B6小鼠主动脉体外培养。人重组的可溶性FasL诱导平滑肌细胞凋亡。结果 B6．MRL(Fas-／-)供体来源移植物存活期显著延长，其血管平滑肌细胞凋亡明显减少。新生血管内膜中的平滑肌细胞具有抗Fas介导凋亡的特性。结论 在慢性排斥反应所致移植物血管病变形成中Fas途径及平滑肌细胞对Fas介导凋亡的敏感性具有重要作用。     

A non-cleavable mutant of Fas ligand does not prevent neutrophilic destruction of islet transplants

BACKGROUND: Fas ligand (FasL) mediates apoptosis of susceptible Fas-expressing lymphocytes, and may contribute to the maintenance of peripheral tolerance. In transplantation models, however, artificial expression of FasL on cellular as well as islet transplants results in accelerated rejection by neutrophils. The mechanism of the neutrophilic response to FasL expression is unknown. FasL, like other members of the tumor necrosis factor family, is cleaved to a soluble form by metalloproteases. We tested the hypothesis that soluble FasL (sFasL) was responsible for neutrophil migration by creating a non-cleavable mutant of FasL. METHODS: Three mutants of FasL with serial deletions in the putative proteolytic cleavage site of human FasL were made using inverse polymerase chain reaction. The relative fractions of sFasL and membrane-bound FasL were assessed by Western blot and immunoprecipitation, as well as by cytotoxicity assay using Fas-expressing target cells. The fully non-cleavable mutant was transduced into murine islets as well as myoblasts and tumor cell lines, and tested in a murine transplantation model. RESULTS: Serial deletions in the putative metalloprotease site of FasL resulted in a fully non-cleavable mutant of FasL (ncFasL). Expression of ncFasL in tumor lines induced higher levels of apoptosis in Fas bearing targets than wild-type FasL. Transplantation of ncFasL-expressing islets under the kidney capsule of allogenic mice resulted in accelerated rejection identical to that seen with wild-type Fas ligand-expressing islets. Myoblasts and tumor cell lines expressing ncFasL also induced neutrophil infiltration. CONCLUSIONS: Membrane-bound Fas ligand is fully capable of inducing a neutrophilic response to transplants, suggesting an activation by Fas ligand of neutrophil chemotactic factors.