丁酸钠对子宫内膜癌抑制作用的裸鼠体内实验研究

目的:探讨丁酸钠(NaB)对人 子宫内膜癌细胞株HHUA裸鼠皮下移 植瘤的生长抑制作用及其作用机制。方 法:将2×107个人子宫内膜细胞株 HHUA细胞接种于裸鼠皮下,建立 HHUA皮下移植瘤模型,然后随机分成 两组,实验组用NaB治疗,对照组用 PBS,治疗4～6周。治疗过程中定期测 量肿瘤大小,于治疗结束时取肿瘤组织 切片进行HE染色、电镜观察和TUNEL 标记,取心、肝、肾组织切片进行药物毒 性评估。结果:实验组裸鼠生长良好,无 明显毒性反应。心、肝、肾组织切片光镜 下检查未见异常。在NaB治疗过程中 肿瘤体积逐渐缩小,而对照组肿瘤体积 逐渐增大。光镜和透射电镜下可见实验 组出现大量凋亡细胞,TUNEL法进一步 分析显示实验组肿瘤细胞凋亡率显著高 于对照组,P<0.01。结论:NaB对裸鼠 皮下移植瘤有明显的生长抑制作用,其 机制可能与NaB诱导肿瘤细胞凋亡有 关。治疗剂量的NaB对裸鼠心、肝、肾组 织无毒性。     

丁酸钠诱导食管癌细胞凋亡的体外观察

目的探讨丁酸钠对人食管癌Eca-109细胞凋亡的作用。方法将丁酸钠以1mmol／L、2．5mmol／L和5mmol／L与人食管癌Eca-109细胞共培养,倒置显微镜观察细胞生长情况,免疫组化（SP法）检测凋亡抑制基因survivin蛋白的表达。结果Eca-109细胞经丁酸钠处理后,在倒置显微镜下观察到丁酸钠处理后的Eca-109细胞形态学发生了改变,细胞生长明显受到抑制;免疫组化检测实验组细胞的survivin蛋白表达阳性率低于对照组,具有统计学意义（P〈0．05）。结论丁酸钠可诱导食管癌Eca-109细胞凋亡,其机制与下调凋亡抑制基因survivin蛋白表达有关。     

丁酸钠对结肠癌细胞凋亡活性的影响

目的观察丁酸钠对结肠癌细胞凋亡活性的影响。方法采用流式细胞术(FCM)和DNA末端原位标记染色法(TUNEL)检测细胞凋亡。结果实验48小时检测,对照组和2.5mM、5mM和10mM各浓度丁酸钠作用后的Lovo细胞凋亡率分别为11.71%、21.62%、34.40%和47.83%,各组之间有显著性差异(P<0.01);对照组和5mM丁酸钠组的HT-29细胞,培养24、48、72小时,其凋亡率分别为6.22%、12.00%、14.31%和30.68%、34.60%、41.88%,差异有显著性(P<0.01);本研究中用二倍体的人胚肾293细胞作了对照研究,未发现丁酸钠对293细胞的生长抑制和凋亡有影响。结论一定浓度的丁酸钠可以选择性抑制两种结肠癌细胞增生,诱导凋亡,显示出浓度、时间依赖性。在预防肿瘤发生的过程中发挥重要的作用。     

丁酸钠对人食管癌Eca-109细胞凋亡作用的实验研究

目的体外研究丁酸钠对人食管癌Eca-109细胞的凋亡作用。方法 以1mmol/L、2．5mmol／L、5mmol／L丁酸钠处理Eca-109细胞,透射电镜观察细胞凋亡的形态,TUNEL法检测细胞凋亡率,免疫组化（SP法）检测凋亡抑制基因bcl-2蛋白的表达。结果 Eca-109细胞经丁酸钠处理后,透射电镜见到细胞核染色质浓缩,聚集于核膜处等细胞凋亡的形态特征,并见到凋亡小体;TUNEL法检测发现2．5mamol／L丁酸钠处理24h组与阴性对照组细胞凋亡率分别为5．5％和1．6％,其差异具有显著性（P〈0．05）;免疫组化检测实验组的bcl-2蛋白表达阳性率低于对照组,具有统计学意义（P〈0.05）。结论 丁酸钠可诱导食管癌Eca-109细胞凋亡,其机制与下调凋亡抑制基因bcl-2蛋白表达有关。     

SIRT1 is significantly elevated in mouse and human prostate cancer

Evidence suggests that the histone deacetylase, SIRT1, is a mediator of life span extension by calorie restriction; however, SIRT1 may paradoxically increase the risk of cancer. To better understand the relationship among SIRT1, energy balance, and cancer, two experiments were done. First, a transgenic mouse model of prostate cancer (transgenic adenocarcinoma of mouse prostate; TRAMP) was used to determine the role of energy balance on SIRT1 expression and the effect of cancer stage on SIRT1 and hypermethylated in cancer-1 (HIC-1). Second, immunohistochemistry was done on human prostate tumors to determine if SIRT1 was differentially expressed in tumor cells versus uninvolved cells. Results show that SIRT1 is not increased in the dorsolateral prostate (DLP) of calorie-restricted mice during carcinogenesis. In contrast, when examined in the DLP as a function of pathologic score, SIRT1 was significantly elevated in mice with poorly differentiated adenocarcinomas compared with those with less-advanced disease. HIC-1, which has been shown to regulate SIRT1 levels, was markedly reduced in the same tumors, suggesting that a reduction in HIC-1 may be in part responsible for the increased expression of SIRT1 in prostatic adenocarcinomas. Furthermore, immunostaining of human prostate tumors showed that cancer cells had greater SIRT1 expression than uninvolved cells. In conclusion, DLP SIRT1 expression from calorie-restricted mice was not altered during carcinogenesis. However, SIRT1 expression was increased in mice with poorly differentiated adenocarcinomas and in human prostate cancer cells. Because SIRT1 may function as a tumor promoter, these results suggest that SIRT1 should be considered as a potential therapeutic target for prostate cancer.     

Testosterone is a potential augmentor of antioxidant-induced apoptosis in human prostate cancer cells

We have investigated the effect of antioxidant-induced apoptosis in human prostate cancer cell lines that is augmented by testosterone (T). In this study, DU-145 (androgen unresponsive), ALVA-101 (partially androgen responsive), and LNCaP (androgen responsive) were grown in tissue culture with RPMI 1640 medium, 5-10% fetal bovine serum (FBS), antibiotics and 5% CO2. Treatment with 2.5-20 microg/ml of PDTC significantly (P < 0.05, n = 6) lowered cell growth in all three cells 2-60% following treatment for 1-7 days. T (10(-12) M) alone enhances cell growth in androgen responsive cells. In contrast, the combination of PDTC and T significantly (P < 0.05, n = 6) augmented the PDTC induction of apoptosis in the androgen responsive cells, (ALVA-101 and LNCaP), but not in the androgen unresponsive cells (DU-145). PDTC reduced the nuclear NF-KB, as determined with an electrophoretic mobility shift assay (EMSA), to 50% of the control in LNCaP cells, 65% in ALVA-101 cells and 45% in DU-145 cells, but the combination of PDTC and T was not more potent than PDTC alone in any of the cell lines. PDTC suppressed both the AR mRNA and protein expression and reversed the stimulatory effect of T on androgen receptor (AR) protein synthesis in LNCaP and AVLA-101 cells. In conclusion, PDTC is a potent growth inhibitor and an inducer of apoptosis in human prostate cancer cells by reducing nuclear NF-kappaB and AR protein expression. PDTCs suppression of AR synthesis and nuclear NF-kappaB in response to T may contribute to its enhancement of apoptosis observed with T and PDTC compared to PDTC alone.     

Resistance to cytotoxic chemotherapy-induced apoptosis in human prostate cancer cells is associated with intracellular clusterin expression

We recently reported the powerful antiapoptotic activity of clusterin against various apoptotic stimuli in prostate cancer model systems; however, the precise mode of clusterin action in target cells remains largely unknown. In the present study, we therefore investigated whether intracellular or extracellular action of clusterin plays a crucial role in cytotoxic chemotherapy-induced apoptosis in androgen-independent human prostate cancer PC3 cells, which express a high level of clusterin. The sensitivity of PC3 cells to paclitaxel was increased by pretreatment with monoclonal antibody (mAb) to clusterin or antisense (AS) oligodeoxynucleotide (ODN) targeting the clusterin gene in a dose-dependent manner at up to 50 microg/ml or 1 microM, respectively. However, clusterin mAb failed to further enhance the sensitivity to paclitaxel of PC3 cells simultaneously treated with 1 microM AS clusterin ODN, whereas AS clusterin ODN further induced the apoptosis of cells treated with 50 microg/ml clusterin mAb. Moreover, the effects of clusterin mAb and AS clusterin ODN on PC3 cells were not reversed by additional treatment with exogenous recombinant clusterin protein. These findings suggest that the sensitivity of PC3 cells to paclitaxel-induced cytotoxicity may be regulated by the intracellular rather than extracellular level of clusterin.     

Sodium butyrate and tributyrin induce in vivo growth inhibition and apoptosis in human prostate cancer

Histone deacetylase inhibitors (HDACs) are known to exhibit antiproliferative effects on various carcinoma cells. In this study, the in vivo efficiency of two HDACs, sodium butyrate and tributyrin, on prostate cancer growth inhibition were investigated. To gain an insight into the possible underlying pathways, cell culture experiments were performed focusing on the expression of p21, Rb and c-myc. For in vivo testing, prostate cancer cell lines (PC3 and TSU-Pr1) were seeded on the chorioallantois membrane (CAM) and implanted in a xenograft model using nude mice. Standard Western blot analysis was performed for protein expression of p21, Rb and c-myc in HDAC-treated vs untreated prostate cancer cells. Both sodium butyrate and tributyrin had a considerable treatment effect on microtumours on the chicken egg at already very low concentrations of 0.1 mM. Tributyrin-treated tumours showed the strongest effect with 38% apoptotic nuclei in the prostate cancer cell line PC3. In the mouse model, there was almost no difference between sodium butyrate and tributyrin. In untreated animals the tumours were almost double the size 4 weeks after implantation. Tumours of the treatment groups had a significantly lower percentage of Ki-67-positive-stained nuclei. As demonstrated by Western blot analysis, these effects seem to be independent of p53 status and a pathway via p21-Rb-c-myc is possibly involved. In this study we have demonstrated a substantial in vivo treatment effect, which can be induced by the application of sodium butyrate or the orally applicable tributyrin in human prostate cancer. The given results may provide the rationale to apply these drugs in well-controlled clinical trials in patients being at high risk of recurrence after specific therapy or in patients with locally or distant advanced prostate cancer.     

Toll-like receptor 3 triggers apoptosis of human prostate cancer cells through a PKC-alpha-dependent mechanism

Toll-like receptors (TLRs) are known to play a key role in the innate immune system particularly in inflammatory response against invading pathogens. Recent reports strongly indicate that they play important roles in cancer cells. Prostate cancer represents one of the most common cancer for which no cure is available once metastatic and androgen refractory. Since TLR3 has been recently suggested as a possible therapeutic target in some cancer cell lines, we studied TLR3 expression and functionality in two human prostate cancer cell lines, LNCaP and PC3. We report that both cell lines express TLR3 and that the TLR3 agonist poly (I:C) activates mitogen-activated protein kinases and induces inhibition of proliferation as well as caspase-dependent apoptosis. By using pharmacological and genetic approaches, we demonstrate the involvement of TLR3 in poly (I:C)-induced effects. We also show that a novel interferon-independent pathway involving protein kinase C (PKC)-alpha activation, upstream of p38 and c-jun N-terminal kinase, is responsible for poly (I:C) pro-apoptotic effects on LNCaP cells. To our knowledge, this is the first report describing a role of PKC-alpha in poly (I:C)-mediated apoptosis. The comprehension of the mechanisms underlying TLR3-mediated apoptosis can contribute tools to develop new agonists useful for the treatment of prostate cancer.     

Apoptosis induced by the sodium butyrate in human gastric cancer TMK-1 cells

The effects of sodium butyrate on cell proliferation, gene expression, and apoptosis were investigated. Upon exposure to sodium butyrate the cells exhibited marked morphological changes, reduced cell proliferation and most cells died through apoptosis within 48 hours. In the presence of dexamethasone, however, the sodium butyrate-triggered apoptosis was markedly reduced. Studies using the glucocorticoid receptor antagonist RU486 indicated that the protective effect of dexamethasone was mediated through glucocorticoid receptor. Sodium butyrate markedly induced the c-jun proteins level, whereas the c-Myc protein was down-regulated rapidly. c-Jun protein may play an important role in the action of sodium butyrate since its induction preceded the onset of DNA fragmentation. In addition, preincubation of the cells with dexamethasone markedly delayed the induction of c-jun levels by sodium butyrate. Analysis of the expression of bel-2-related genes indicated that the Bcl-xS protein level was increased in the presence of sodium butyrate and the up-regulation of Bcl-xS by sodium butyrate was also blocked by dexamethasone. Taken together, these results indicate that c-myc, c-jun and Bcl-xS proteins may be involved in the mechanism of sodium butyrate-triggered apoptosis in these cells.     

Growth inhibitory and differentiating effects of sodium butyrate on human neuroblastoma cells in culture.

The effect of sodium butyrate (NaB) on cell growth and expression of morphological and biochemical properties was examined in the human neuroblastoma cell lines AF8 and SJ-N-KP. The obtained data show that NaB induced a marked growth inhibition and morphological differentiation, while it was ineffective in inducing biochemical differentiation.     

Effects of phenylbutyrate on proliferation and apoptosis in human prostate cancer cells in vitro and in vivo

Phenylbutyrate (PB) is a potent differentiating agent and currently under investigation for the treatment of prostate cancer (CaP) and other malignancies. We have studied the impact of PB in vitro and in vivo on differentiation, proliferation and apoptosis in the LNCaP and LuCaP 23.1 prostate cancer xenograft models. In vitro we found that i) PB increased PSA secretion/cell, ii) inhibited cell proliferation in a time- and dose-dependent manner resulting in a cell cycle arrest in G1-phase and iii) induced apoptosis at concentrations of 2.5 mM after 3 days of treatment. In PB treated animals tumor growth stabilized or regressed. Combination of castration and PB treatment had a synergistic antiproliferative effect. The growth-inhibitory and differentiating properties and a low toxicity profile of PB provide rationale for further clinical studies in patients with CaP.     

Induction of apoptosis by thiosulfinates in primary human prostate cancer cells

Thiosulfinates, a substance of Allium tuberosum L., is a known folk medicine that has been extensively used in diet to treat diseases. In the present study, we have evaluated the effect of thiosulfinates from Allium tumberosum L. on proliferation of metastasis (DU145) and primary malignant tumor (RC-58T/h/SA#4)-derived human prostate cancer cells. Thiosulfinates decrease viable cell numbers in a dose- and time-dependent manner and induce apoptosis. The apoptosis induced by thiosulfinates is associated with the activation of initiator caspase-8, and -9, and the effector caspase-3. Thiosulfinates stimulated Bid cleavage, indicating that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. Thiosulfinates decreased the expression of the anti-apoptotic protein Bcl-2, and increased the expression of the pro-apoptotic protein Bax. Thiosulfinates also increased the expression of AIF, a caspase-independent mitochondrial apoptosis factor, in RC-58T/h/#4 cells and induced DNA fragmentation and chromatin condensation. These results indicate that thiosulfinates from Allium tuberosum L. inhibit cell proliferation by inducing apoptosis in RC-58T/h/#4 cells which may be mediated via both caspase-dependent and caspase-independent pathways.     

Modulation of MDR-1 gene in human breast cancer cells by sodium butyrate and DMSO

The drug resistance of cancer cells is one of the main obstacles in cancer chemotherapy. In the recent years, the reverse study of multidrug resistance has received some successes. Many substances can modulate MDR pheno-type such as calcium channel antagonists, cyclosporin A, antimalarials and steroids. Although there are some reports in phase I/II clinical trials, most of the results are indefinite and controversial. There are severe side effects during experiments, such as cardiovascular …     

Nuclear translocation of apoptosis inducing factor is associated with cisplatin induced apoptosis in LNCaP prostate cancer cells

Prostate cancer (PC) is considered resistant to cisplatin chemotherapy. In order to identify novel causes of resistance to cisplatin, we explored the role of Apoptosis Inducing Factor (AIF) that mediates caspase independent apoptosis in cisplatin induced cell death in PC. Similar to treatment with pancaspase inhibitor Z-VAD-fmk, cisplatin induced apoptosis in LNCaP cells was inhibited by AIF inhibitor N-acetyl-L-cysteine (NAC), treatment of LNCaP cells with NAC prevented AIF translocation to the nucleus and over-expression of recombinant AIF gene increased apoptosis. Our results suggest that AIF is associated with cisplatin induced apoptosis in PC.     

藤黄酸抑制前列腺癌PC-3细胞增殖并诱导其细胞凋亡

目的:研究中药藤黄的有效成分藤黄酸(gambogic acid,GA)对前列腺癌PC-3细胞增殖和凋亡的影响。方法:采用不同浓度的GA作用前列腺癌PC-3细胞后,在体外通过CCK-8比色法分析细胞的增殖情况,吖啶橙/溴化乙啶(acridine orange/ethidium bromide,AO/EB)双重染色法和FCM法分析细胞的凋亡情况;蛋白质印迹法检测细胞中凋亡相关蛋白P53、Bax和Bcl-2的表达变化。结果:GA不仅能抑制PC-3细胞的增殖,而且能有效诱导其细胞凋亡,与对照组比较差异有统计学意义(P<0.05),并且其抑制增殖和促凋亡作用呈浓度依赖性。CCK-8法检测结果表明,GA浓度>1μmol/L时,细胞的增殖能力受到明显抑制。AO/EB染色法显示,GA处理后的前列腺癌PC-3细胞核呈致密浓染橘红色,并伴有核浓缩和偏向。FCM法检测结果显示,GA处理后的前列腺癌PC-3细胞凋亡峰明显。蛋白质印迹法进一步表明,GA能够上调PC-3细胞中Bax和P53的表达水平,下调Bcl-2表达水平。结论:GA对前列腺癌PC-3细胞具有明显的抑制增殖和诱导凋亡作用。     

Valproic acid and butyrate induce apoptosis in human cancer cells through inhibition of gene expression of Akt/protein kinase B

Background  

In eukaryotic cells, the genomic DNA is packed with histones to form the nucleosome and chromatin structure. Reversible acetylation of the histone tails plays an important role in the control of specific gene expression. Mounting evidence has established that histone deacetylase inhibitors selectively induce cellular differentiation, growth arrest and apoptosis in variety of cancer cells, making them a promising class of anticancer drugs. However, the molecular mechanisms of the anti-cancer effects of these inhibitors have yet to be understood.