放射诱导胃癌细胞的凋亡及其相关基因的研究

目的观察放射诱导人胃癌细胞株SGC-7901凋亡的作用，并进一步研究bcl-2基因及家族、bax基因、p53基因在此过程中的作用。方法用不同剂量的9 MeV β线照射SGC-7901细胞，观察细胞在受照后的不同时间生长情况。电子透射电镜下观察细胞形态变化。琼脂糖凝胶电泳检测DNA条带变化。流式细胞仪检测受照前后细胞周期及凋亡率的变化。免疫细胞化学法检测受照前后bcl-2、bax、p53基因的表达水平。结果单次剂量照射后，SGC-7901细胞凋亡率与时间、剂量有相关性。在放射诱导SGC-7901细胞凋亡的过程中，bcl-2基因表达水平下降，bax基因表达水平升高，而p53基因表达水平无变化。结论放射能够诱导胃癌细胞株SGC-7901凋亡，凋亡率在72h达高峰。bcl-2及bax基因参与了放射诱导凋亡的调控。细胞凋亡主要是通过p53基因非依赖途径。     

宫颈癌放疗前后肿瘤细胞凋亡及其相关基因的变化

目的:探讨宫颈癌组织放疗前后肿瘤细胞凋亡及凋亡调节基因p53、bcl-2和bax蛋白表达的变化及意义.方法:选择未经治疗的宫颈癌患者20例为试验对象,采集放疗前和放疗10Gy后宫颈癌组织标本,用原位DNA切口末端标记(TUNEL)法检测凋亡细胞;单克隆抗体免疫组化SABC法检测细胞凋亡相关基因p53、bcl-2和bax的蛋白表达水平.结果:1)在宫颈癌放疗前后,肿瘤细胞凋亡阳性率和平均凋亡指数分别为25.00%和0.11%、75.00%和3.40%,放疗前后有显著性差异(P＜0.01);2)放疗前肿瘤细胞凋亡相关基因p53、bax和bcl-2蛋白表达阳性率分别为55%、10%和20%,而放疗后分别为25%、60%和25%,放疗后p53蛋白表达减少,bax蛋白明显增加,bcl-2蛋白无明显变化.结论:放射治疗诱导宫颈癌肿瘤细胞凋亡,可能与凋亡调节基因bax基因表达的诱导密切相关.     

低剂量辐射对人食管癌细胞凋亡相关基因蛋白表达的影响

目的：研究低剂量辐射对人食管癌细胞凋亡相关基因蛋白P^53、bcl-2和bax表达的影响。方法：采用原位杂交技术检测人食管癌细胞系经低剂量辐射处理前后P5。、bcl-2和bax基因蛋白表达的变化。结果：经4cGy射线照射Eca-109细胞后12小时，P^53基因蛋白表达显降低；bcl-2基因蛋白表达有降低趋势，bax基因蛋白表达有增高趋势，但均无统计学意义，然而，bcl-2／bax比值则明显降低。结论：低剂量辐射能引起Eca-109细胞P^53和bcl-2／bax比值的明显降低，而P^53和bcl-2／bax在辐射诱导细胞凋亡中起着重要作用。因此，低剂量辐射有可能影响食管癌放射治疗的敏感性。     

非甾体消炎药诱导胃癌细胞凋亡及其机制的研究

目的：明确非甾体消炎药(NSAIDs)能否诱导胃癌细胞凋亡；明确不同的p53基因表型对NSAIDs诱导的细胞凋亡是否有影响；明确NSAIDs对细胞凋亡相关基因Bcl-2及Bax表达的调控。方法：通过MTT比色法检测NSAIDs对细胞生长活力的影响；应用丫啶橙(AO)染色、Annexin-V／PI双染色、共聚焦显微镜、流式细胞术检测细胞凋亡；应用RT-PCR、Western-blot方法检测bcl-2、bax基因及蛋白水平的改变。结果：NSAIDs药物吲哚美辛(Indo)和阿司匹林(Asp)对胃癌细胞株AGS(p53 ／ )、MKN28(p53-／-)均有显著的生长抑制作用，且呈时间／浓度依赖性增强；在相同作用条件下，AGS细胞的凋亡率明显高于MKN28细胞，处理组MKN28细胞凋亡数量虽有所增多，但与正常对照组相比不具有统计学意义；随着药物作用时间的延长，Bcl-2基因mRNA表达逐渐减弱，Bax基因及蛋白表达逐渐增强，在药物作用6～24小时改变最为明显。结论：一定浓度的NSAIDs作用一定时间后，可诱导胃癌细胞凋亡，这为NSAIDs的抗肿瘤应用增加了理论依据；NSAIDs不能诱导p53基因突变的MKN28胃癌细胞株发生显著的凋亡，p53基因突变可能阻断了NSAIDs的凋亡诱导效应；NSAIDs可能通过调控Bcl-2、Bax的基因及蛋白水平而诱导肿瘤细胞凋亡。     

姜黄素对HaCaT细胞凋亡过程中相关基因表达的影响

目的： 研究姜黄素对人永生化表皮HaCaT细胞凋亡过程中相关基因表达的影响。方法：通过免疫细胞化学法和免疫印迹检测姜黄素对HaCaT细胞凋亡过程中相关基因表达的影响。结果：免疫细胞化学染色结果显示,经7.5 μg/mL姜黄素处理之后,与细胞凋亡相关的抑凋亡蛋白Bcl-2表达减弱,促凋亡蛋白P53、Fas、Bax表达增强。Western blot检测结果显示,经7.5 μg/mL姜黄素处理之后,与细胞凋亡相关的抑凋亡蛋白Bcl-2表达下调,促凋亡蛋白P53、Fas、Bax表达上调。结论：姜黄素诱导HaCaT细胞凋亡过程中伴随着抑凋亡基因bcl-2表达的抑制和促凋亡基因p53、Bax和Fas基因的激活。由此证明姜黄素通过多种凋亡相关基因的调控,激活凋亡信号传导途径,诱使细胞凋亡。     

重组腺病毒p53影响口腔黏膜异常增生细胞生长的分子机制

[目的]探讨重组腺病毒p53(rAd-p53)影响口腔黏膜异常增生细胞(POE-9n)生长、诱导凋亡的分子机制。[方法]利用RT-PCR及Westernblot技术检测rAd-p53转染POE-9n细胞后p53、p21CIP/WAF及bcl-2mRNA和蛋白的表达变化。[结果]POE-9n细胞经rAd-p53转染后,p53、p21CIP/WAF和bcl-2mRNA和蛋白水平的表达均出现明显变化。转染24h后,p53、p21CIP/WAFmRNA及蛋白表达显著增高(P<0.01),而bcl-2则在转染72h后表达明显降低(P<0.01)。[结论]rAd-p53转染POE-9n细胞后,外源性p53的导入使p21CIP/WAF激活,并抑制bcl-2的表达,从而诱导细胞凋亡。     

胃癌细胞MKN28(p53-/-)对NSAIDs诱导凋亡敏感性的研究

目的1.明确非甾体消炎药(NSAIDs)能否诱导p53基因突变的胃癌细胞MKN28凋亡.2.明确NSAIDs对MKN28细胞凋亡相关基因bcl-2、bax表达的调控.方法1.通过MTT比色法检测NSAIDs对细胞生长活力的影响.2.应用丫啶橙染色、Annexin-Ⅴ/PI双染色、共聚焦显微镜、流式细胞术检测细胞凋亡.3.应用RT-PCR(逆转录-聚合酶链反应)方法检测bcl-2、bax基因水平的改变.结果1.NSAIDs药物吲哚美辛(Indo)和阿斯匹林(Asp)对胃癌细胞株MKN28均有生长抑制作用,且呈时间/浓度依赖性增强.2.在Indo 800μmol/L、Asp8 mmol/L作用48～96 h后,MKN28细胞凋亡数量稍有增多,但不具有统计学意义.3.随着药物作用时间的延长,MKN28细胞的bcl-2基因mRNA表达逐渐减弱,bax基因表达逐渐增强.结论1.NSAIDs可抑制MKN28胃癌细胞株增殖.2.NSAIDs不能诱导p53基因突变的MKN28胃癌细胞株发生显著的凋亡,提示p53基因突变可能阻断了NSAIDs诱导的细胞凋亡.3.NSAIDs可使MKN28细胞凋亡相关基因bcl-2和bax的水平呈现促进凋亡倾向的改变.     

小分子RNA干扰 MTA1基因对乳腺癌MDA-MB-231细胞生物活性及相关蛋白表达的影响

目的:采用短发夹状RNA(short hairpin RNA,shRNA)干扰技术沉默乳腺癌细胞MDA-MB-231中转移相关基因(metastasis-associated gene 1,MTA1)的表达,并观察其对15-脂氧合酶-2(15-lipoxygenase-2,15-LOX-2)、p53及bcl-2表达的影响.方法:将shRNA-MTA1载体质粒稳定转染MDA-MB-231细胞,MTT法检测细胞增殖抑制情况,FCM法检测细胞周期及凋亡情况,RT-PCR和Western印迹法检测MTAl、15-LOX-2、p53及bcl-2 mRNA和蛋白表达情况.结果:shRNA-MTA1能明显降低MTA1基因在MDA-MB-231细胞中的表达量;抑制MDA-MB-231细胞的增殖,诱导其凋亡,并使细胞被阻滞在G1期,与对照组相比,差异有统计学意义(P<0.01).转染shRNA-MTA1可使MDA-MB-231细胞中15-LOX-2和p53 mRNA及蛋白的表达明显增强(P<0.01),而 MTA1和bcl-2 mRNA表达明显减弱(P <0.01).结论:MTA1基因可抑制乳腺癌MDA-MB-231细胞的增殖,诱导其凋亡,该作用可能与上调细胞中15-LOX-2和p53的表达,下调bcl-2的表达有关.     

红毛五加多糖对胃癌细胞的诱导凋亡作用

目的：研究红毛五加多糖对胃癌的诱导凋亡作用及其作用机制。方法：采用流式细胞术检测凋亡细胞百分比及基因和细胞因子蛋白含量。结果：该多糖使癌基因bcl-2蛋白表达降低,而使抑癌基因p53、bax、Fas、Fas-L及细胞因子TGFβ1蛋白表达增高。结论：该多糖通过降低原癌基因蛋白表达,增高抑癌基因和细胞因子蛋白表达,从而诱导胃癌细胞SGC-7901凋亡。     

野生型p53基因蛋白在氨肽酶抑制剂诱导人白血病细胞株K562细胞凋亡的实验研究

目的研究野生型p53基因蛋白对国产氨肽酶抑制剂乌苯美司(ubenimex)诱导人白血病细胞凋亡的影响及其作用机制。方法真核转导试剂FuGEMNE^TM6转导入K562细胞，免疫组化法检测细胞p53蛋白的表达，DNA片段原位末端标记及流式细胞仪(FCM)检测细胞凋亡，Rhodamin(Rh)123染色后，FCM检测细胞线粒体跨膜电位。结果p53基因cDNA转导的细胞p53蛋白表达增加；p53基因转导能促进ubenimex诱导K562细胞凋亡并增加ubenimex诱导的K562细胞线粒体跨膜电位(△ψm)的下降。结论野生型p53基因转导能促进ubenimex诱导K562细胞凋亡，并可能参与线粒体信号传导通路的调控。     

Tamoxifen-induced apoptosis in breast cancer cells relates to down-regulation of bcl-2, but not bax and bcl-X(L), without alteration of p53 protein levels.

Tamoxifen (TAM) has been shown to induce apoptosis in breast cancer cells. bcl-2 family genes, which can interact with each other, have been shown to interfere with apoptosis after various stimuli. In this study, we investigated the effects of TAM on bcl-2 family gene products bcl-2, bax, and bcl-X(L) and on p53 levels in estrogen receptor-positive MCF-7 breast cancer cells. We found that TAM induced time- and concentration-dependent down-regulation of bcl-2 at both the mRNA and protein level. Down-regulation of bcl-2 correlated with TAM-induced apoptosis. In addition, estradiol treatment significantly increased bcl-2 protein expression and blocked the reduction of bcl-2 by TAM. TAM did not, however, affect bax, bcl-X(L), or p53 expression at the mRNA or protein level. Our results demonstrate that TAM can induce apoptosis in a time- and dose-dependent manner by modulating bcl-2 levels in breast cancer cells, and down-regulation of bcl-2 induced by TAM was not accompanied by alterations in p53 levels.     

Involvement of bcl-2 and bax gene expression in apoptosis and differentiation of the non-tumorigenic murine hematopoietic cell line, 32DC13(G)

32DCl3(G) is an interleukin-3 (IL-3) dependent, non-tumorigenic murine hematopoietic cell line which undergoes terminal differentiation into granulocytes when exposed to granulocyte-colony stimulating factor (G-CSF). This line therefore offers a convenient system to study the expression of genes involved in apoptosis and differentiation. In our experiments we have acquired evidence that during the differentiation pathway, likewise in apoptosis induced by IL-3 deprivation, detectable levels of bax mRNA appear, while bcl-2 expression decreases. These events are under the control of the p53 tumor-suppressor gene. In these cells, an overexpression of exogenous wild-type p53 leads to a decrease in bcl-2 mRNA and to the appearance of box mRNA, which instead is absent in the parental cells growing in IL-3 conditioned medium. Furthermore, results from experiments on p53 transfected cells demonstrate that excess wild-type p53 activity, on its own, fails to elicit apoptosis as long as IL-3 is present and does not induce differentiation if G-CSF is not added to the culture medium. We conclude that in apoptosis and differentiation of 32DCl3(G) the alterate ratio of bcl-2 and box gene expression, modulated by p53, is an early event dependent on IL-3 withdrawal and that the appearance of bax and the decrease of bcl-2 expression are necessary, but not sufficient for the acquisition of a completely mature granulocytic phenotype.     

Prognostic value of bax, bcl-2, and p53 staining in primary osteosarcoma

BACKGROUND AND OBJECTIVES: To investigate the immunohistochemical expression of three apoptosis-related genes (bax, bcl-2, and p53) and apoptosis (TUNEL) in patients with primary osteosarcoma, and examine potential correlations between gene expression and clinicopathological characteristics in these patients. MATERIALS AND METHODS: Thirty-five primary osteosarcoma specimens and 18 tissue specimens deriving from non-malignant osseous lesions were immunohistochemically stained for bax, bcl-2, and p53 proteins, while apoptosis was investigated by the TUNEL method. The results were statistically analyzed. RESULTS: P53, bax, and bcl-2 protein expression was observed in 22 (62.9%), 29 (82.9%), and 18 (51.4%) osteosarcoma patients, respectively. Non-specific positive TUNEL staining (+/-) was observed in two primary osteosarcoma cases (5.7%). None of the benign controls expressed any of the genes studied. None of the apoptosis-related genes studied was able to predict overall or disease-free survival in our group of patients. Nevertheless, increased bax/bcl-2 protein expression ratio was associated with a decreased 4-year survival and disease free survival (P = 0.0229 and P = 0.0370, respectively). Furthermore, all the patients who were bax(+)/bcl-2(-)/p53(+) relapsed within the 4-year follow-up period (P = 0.0385). CONCLUSIONS: The increased apoptotic rate as determined by an elevated bax/bcl-2 protein expression ratio or by the bax(+)/bcl-2(-)/p53(+) protein expression pattern, appears to identify groups of osteosarcoma patients with unfavorable prognosis.     

Molecular determinants of cell death induction following adenovirus-mediated gene transfer of wild-type p53 in prostate cancer cells

Adenoviral vectors expressing wild-type p53 (Ad-p53) induce apoptosis in different types of cancer cells. The therapeutic utility of Ad-p53 is now being evaluated in prostate-cancer patients. Bcl-2 is frequently expressed by prostate-cancer cells and has previously been shown to inhibit p53-mediated cell death following genotoxic stress. We studied the impact of bcl-2 on Ad-p53-induced cell death in human prostate-cancer cells. Human prostate-cancer cell lines LNCaP (p53 wt) and PC3 (p53 mut) were stably transfected with bcl-2. After p53 transduction, cell viability, apoptosis induction and modulation of specific apoptosis-regulatory proteins were assessed. LNCaP vector control and bcl-2-expressing cells underwent similar decreases in viability associated with apoptosis induction following Ad-p53 infection. Increased bcl-2 expression provided significant protection to PC3 cells transduced with Ad-p53. These findings are correlated with modulations in bax, bcl-2, bcl-x(L) and p21 protein levels. These data suggest that Ad-p53 may be useful in the treatment of some prostate cancers.     

THE CORRELATION BETWEEN THE EXPRESSION OF MULTIDRUG RESISTANCE RELATED GENE AND CELL APOPTOSIS AND CLINICAL SIGNIFICANCE IN NON-SMALL CELL LUNG CANCER

The mechanisms about multidrug resistance (MDR) which are studied widely in present include overexpression of multidrug resistance protein such as MDR1/P-gp, MRP (multidrug resistance related protein), LRP (lung resistance protein), increased detoxification of Glutathione / Glutathione - S - transferase II.[1-3] Recent studies have showed that inhibition of cell apoptosis and overexpression of apoptosis related gene is another reason for the MDR.[4] But there are few reports about the …     

Prognostic significance of p53, bax and bcl-2 gene expression in patients with laryngeal carcinoma.

AIM: This study was designed to examine the prognostic significance of the coexpression of three genes (bax, bcl-2 and p53) which play a critical role in the apoptotic mechanisms in patients with squamous cell laryngeal carcinoma. MATERIALS AND METHODS: The immunohistochemical expression of bcl-2, bax and p53 genes was retrospectively examined in 38 patients with squamous cell laryngeal carcinoma and in five controls (necrotomic tissue). Tissue specimens were obtained both during the diagnostic biopsy and at the time of surgery. Clinicopathological and survival data were correlated with the staining results. RESULTS: Bcl-2 protein expression (P=0.0472), stage (P=0.0087) and lymph-node involvement (P=0.0488) were found to be independent prognostic factors. Increased bcl-2 protein expression correlated with a better 5-year survival (P=0.0472). Patients who were bcl-2(-)/p53(-) (n=25) or bax(+)/bcl-2(-) (n=13) had a significantly worse overall survival (P=0.0305 and P=0.0482, respectively). Similarly, patients who were bax(+)/bcl-2(-)/p53(-) (n=11) also had a worse 5-year survival compared with the rest of the group (P=0.0088). Changes that were noticed in bax and p53 protein expression from the time of biopsy until the time of surgery did not correlate with a significant increase in the overall survival. CONCLUSIONS: The expression of bcl-2 gene appears to be an independent prognostic factor for patients with laryngeal carcinoma. The coexpression of the genes studied can be used to determine aggressive clinical phenotypes.     

端粒酶基因与凋亡相关基因在乳腺导管非典型增生中表达的相关性研究

背景与目的:近年研究表明端粒酶的激活及凋亡抑制基因的过度表达与多种肿瘤发生有关,本研究观察端粒酶基因(hTR,hTRT)、凋亡相关基因(p53,bcl-2)在乳腺导管非典型增生中的表达及相互关系,旨在探讨端粒酶活性及凋亡相关基因的变化在乳腺导管非典型增生上皮癌变过程中的作用和意义。方法:应用原位杂交方法检测端粒酶基因(hTR,hTRT)和凋亡相关基因(p53,bcl-2)mRNA在44例乳腺导管非典型增生组织中的表达,应用免疫组化方法检测p53蛋白在上述病例中的表达,并与6例良性乳腺增生及26例乳腺癌病例进行了比较。结果:端粒酶基因(hTR,hTRTmRNA)在乳腺导管重度非典型增生组织中表达增强(60.9%,52.1%),其表达与在轻、中度非典型增生(22.2%,11.1%;33.3%,25.0%),乳腺癌(88.5%,80.8%)组织中的表达差异显著(P<0.05)。p53mRNA在乳腺导管非典型增生组织中的表达随着异型性的增加而下降(轻度:55.6%;中度:41.7%;重度:26.1%),而p53蛋白则相应增加(轻度:11.1%;中度:25.0%;重度:34.8%)。bcl-2在乳腺导管非典型增生组织中呈中度表达,其中以在重度非典型增生组织中表达明显。结论:端粒酶基因(hTR,hTRT)的表达与乳腺非典型增生细胞的恶性转化密切相关,同时可检测到p53mRNA的表达缺失、p53蛋白突变及bcl-2mRNA的过表达,且表达水平与端