p53基因诱导胱癌细胞HTB9凋亡及相关基因的表达

目的 研究野生型p53基因诱导膀胱癌细胞凋亡的作用,及其对凋亡相关基因bcl-2、bax和ICE表达的调控。方法 将野生型p53基因重组腺病毒载体转染人膀胱癌细胞HTB9,应用RT－PCR检测bax的mRNA表达水平,应用免疫组化法检测bcl-2、bax和ICE蛋白表达水平,以DNA琼脂糖凝胶电泳、脱氧核苷酸转移酶介导的dUTP切口末端标记技术（TUNEL）和流式细胞仪检测细胞凋亡。结果 野生型p53基因导入可诱导HTB9细胞凋亡,凋亡细胞百分率可达50．4％;bax mRNA和蛋白水平增高,ICE和Bcl-2蛋白水平分别增高和下降。结论 野生型p53基因很可能是通过调控凋亡相关基因ICE、Bax和Bcl-2的表达来诱导细胞凋亡。     

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.     

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.     

Androgen receptor expression in relation to apoptosis and the expression of cell cycle related proteins in prostate cancer

The expression of several genes involved in the regulation of cell cycle and apoptosis may be regulated via the androgen receptor (AR) in the prostate. AR may have a role in the prognosis of prostatic carcinoma. The aim was to examine AR expression status and its relationship with markers of proliferation, apoptosis and cell cycle control in prostate cancer. Expression of AR, bcl-2, bax, Ki-67 and p53 was examined in paraffin-embedded tissues from 50 cases of prostate carcinoma by immunohistochemistry and evaluated using an index of staining. Detection of apoptotic cells was performed by TUNEL method. Correlation between AR expression and apoptosis, proliferation index, bcl-2, bax and p53 and also clinicopathological parameters including stage, pathological grade and Gleason score were determined. AR expression was observed in all cases with mean expression of 81%±15 and mean staining index of 141±65. No correlation was found between AR expression and apoptosis detected in patients. The mean AR staining index was 170±72 in bcl-2 positive tumors versus 120±53 in bcl-2 negative tumors showing a significant association between AR and bcl-2 expression (p=0.015). AR expression also showed a significant association with bcl-2/bax ratio (r=0.321, p=0.023) and Ki-67 proliferation staining index (r=0.396, p=0.004). Although a significant correlation between Ki-67 and p53 with differentiation status of the tumors was observed (p<0.004) no correlation was found with AR. AR expression showed no prognostic value regarding its correlation with stage and differentiation status of the prostate carcinoma. However, its significant correlation with Ki-67 and bcl-2 that are markers of cell survival suggest its contribution to tumor cell progression.     

Gold nanoparticles induce apoptosis in MCF-7 human breast cancer cells

Background: Gold nanoparticles have recently been investigated with respect to biocompatibility accordingto their interactions with cells. The purpose of this study was to examine cytotoxicity and apoptosis induction bywell-characterized gold nanoparticles in human breast epithelial MCF-7 cells. Methods: Apoptosis was assessedby TUNEL, cytotoxicity by MTT assay and caspase 3, 9, p53, Bax and Bcl expression by real-time PCR assays.Results: Gold nanoparticles at up to 200 μg/mL for 24 hours exerted concentration-dependent cytotoxicity andsignificant upregulation of mRNA expression of p53, bax, caspase-3 & caspase-9, whereas expression of antiapoptoticbcl-2 was down-regulated. Conclusion: To the best of our knowledge this is the first report showingthat gold nanoparticles induce apoptosis in MCF-7cells via p53, bax/bcl-2 and caspase pathways.     

Expression profiles of p53, p21, bax and bcl-2 proteins in all-trans-retinoic acid treated primary and metastatic melanoma cells

We have previously shown that all-trans-retinoic acid (atRA) induces apoptosis in melanoma cells and primary melanoma cells are more sensitive to the exposure of atRA than the matched metastases. However, mechanisms behind the atRA-induced apoptosis have not been studied. In this study, we used a similar cell culture model system of matched primary and metastatic melanoma cells from the same patient to investigate whether p53 and bcl-2 family proteins were involved in atRA-induced apoptosis. The primary and metastatic melanoma cells were exposed to 0.1 and 10 micro M atRA in serum-free RPMI 1640 cell culture medium in the dark for up to 96 h. The protein expression of p53, p21, bax and bcl-2 were examined by Western blotting and immunocytochemistry. Expression of p53, p21 and bax was increased, and bcl-2 was decreased in melanoma cells after exposure to atRA at different concentrations for various periods of time. The changes of p53, p21, bax, and bcl-2 protein levels were dose- and time-dependent. The primary melanoma cells were more sensitive to the atRA treatments than cells from matched metastatic melanoma. These data indicate that p53, p21, bax and bcl-2 proteins were involved in atRA-induced apoptosis in melanoma cells. Modification of these protein levels in the tumour cells might be beneficial for early treatment of melanoma.     

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。     

Damage-induced apoptosis in intestinal epithelia from bcl-2-null and bax-null mice: investigations of the mechanistic determinants of epithelial apoptosis in vivo

The influence of bcl-2 and bax expression on apoptotic cell death in mouse intestinal epithelia was assessed using homozygously null mice. Apoptosis was induced in vivo by the enterotoxin 5-fluorouracil (5FU) or by gamma-irradiation and its cell positional incidence was assessed. 5FU and gamma-radiation treated bax-null mice surprisingly showed no reductions in apoptotic yield in the small intestine or midcolon at 4.5 h at cell positions in which both agents had previously been shown to strongly induce p53 protein expression. The colonic epithelia of 5FU treated bcl-2-null mice showed elevated levels of apoptosis at 4.5 h: from 48 apoptotic events in wild-type mice to 273 in the nulls, scoring 200 half crypts. The increase occurred specifically in the cell positions considered to harbour colonic stem cells, at the base of crypts, where there is selective expression of bcl-2. There was a modest but significant increase in apoptosis in the small intestine of the bcl-2-null mice although the epithelia of wild-type mice here are not immunohistochemically positive for bcl-2 protein. These findings show that bcl-2 plays a key role in determining the sensitivity of colonic stem cells to damage-induced death but that bax is not responsible for the p53-dependent induction of apoptosis in this context.     

Expression of bcl-2 and bax in chewing tobacco-induced oral cancers and oral lesions from India

Deregulation of oncogenes and tumor suppressor genes involved in apoptosis has been associated with tumor development and progression. To investigate the involvement of apoptosis regulating proteins in oral cancer in Indian patients, primarily associated with chewing tobacco habits, immunohistochemical expression of bcl-2 and bax was examined in 63 oral squamous cell carcinomas, and 31 putative premalignant lesions. Our studies revealed overexpression of tumor specific cytoplasmic bcl-2 in 56% and bax in 43% oral cancers. The oral cancers in the Indian patients are preceded by premalignant oral lesions; hence oral lesions were examined for bcl-2 and bax expression. We observed aberrant expression of bcl-2 in 16% oral lesions comprising leukoplakias and SMF and bax in 55% oral lesions. We have already reported, p53 expression in these oral cancers and lesions. It was noteworthy that 30% oral cancers demonstrated a p53+bcl2+ pattern, and 14% samples exhibited p53+bcl2+bax+ pattern. However, none of the oral lesions showed concurrent deregulation of p53 and bcl-2 or all the three genes. Interestingly 45% oral lesions were p53-bax+ as compared to 18% oral cancers; while 39% oral lesions were bcl2-bax+ as compared to 14% oral cancers, indicating overexpression of bax in oral lesions, in the absence of p53 and bcl-2 proteins. Significant correlation was observed between positive nodal status and bcl2+ (p=0.047) and p53+bcl-2+ (p=0.01) in oral cancers. Kaplan Meier survival analysis showed significantly (p=0.059) higher survival in patients with p53- oral tumors than with p53+ tumors. Our studies thus indicate frequent overexpression of apoptosis regulators bcl-2, bax and p53 proteins in oral cancers, and a subset of oral lesions, representing early events in oral car-cinogenesis. The aberrant bcl-2 expression and loss of p53 function observed, may play an important role in the tumorigenesis of oral cancers by allowing escape from apoptosis and enabling additional genetic alterations to accrue.     

全反式维甲酸对食管癌细胞系EC109作用的研究

目的 探讨不同浓度全反式维甲酸(ATRA)对食管癌细胞系EC109的生长抑制作用及其机理.方法 不同浓度ATRA作用于细胞EC109,采用MTT法检测细胞生长;通过流式细胞仪检测和DNA梯状电泳证实凋亡存在;用RT-PCR方法检测凋亡诱导过程中p53、bcl-2和bax基因表达变化.结果 ATRA呈剂量及时间依赖性抑制细胞生长;琼脂糖电泳呈现凋亡DNA梯状条带;流式细胞仪分析存在明显的凋亡峰;ATRA处理组bax和p53基因表达上调,但bcl-2基因表达下调.结论 ATRA具有抑制食管癌细胞株EC109生长作用,其机理可能是诱导细胞凋亡,其分子机制可能与bcl-2/bax和p53的表达相关.     

p53-Independent induction of apoptosis in human melanoma cells by a bcl-2/bcl-xL bispecific antisense oligonucleotide.

Mutations in the p53 tumor suppressor gene are implicated in defective apoptotic response of tumors to genotoxic damage and, thus, are major determinants of resistance to a variety of anticancer agents. Because even melanomas harboring wild-type (wt) p53 show an abnormal response to radiation and p53 mutations occur late during melanoma progression, we investigated whether the effect of the bcl-2/bcl-xL bispecific antisense oligonucleotide 4625 is dependent on the p53 status in human C8161 melanoma cells. Upon treatment with oligonucleotide 4625, p53-mut C8161 cells showed earlier DNA damage, which occurred concomitantly with the reduction of bcl-2 and bcl-xL expression and the increase in the expression of proapoptotic bax. Loss of cell viability, bcl-2 down-regulation, and poly(ADP-ribose) polymerase cleavage, indicative of apoptosis, also occurred in wt p53 C8161 cells on treatment with oligonucleotide 4625. These effects, however, were mediated by strong induction of p53 without changes in p21 WAF1 expression in wt p53 cells, whereas a 70% decrease in p21 WAF1 expression was observed in mut p53 cells. In contrast to many other anticancer agents to which the apoptotic response is decreased because of p53 mutations, our data suggest that the bcl-2/bcl-xL bispecific antisense oligonucleotide 4625 effectively induces p53-independent apoptosis in human C8161 melanoma cells.     

Topoisomerase-I inhibitors for human malignant glioma: Differential modulation of p53, p21, bax and bcl-2 expression and of CD95-mediated apoptosis by camptothecin and β-lapachone

β-lapachone and camptothecin are structurally unrelated agents thought to inhibit topoisomerase-I activity through distinct mechanisms. We find that β-lapachone is much more potent than camptothecin in inducing acute cytotoxic effects on human malignant glioma cells. Acute cytotoxicity induced by both drugs is apoptotic by electron microscopy, but not blocked by inhibitors of RNA or protein synthesis and not associated with changes in the expression of bcl-2, bax, p53, p21 or GADD45 proteins. In contrast, prolonged exposure of glioma cells to both drugs for 72 hr results in growth inhibition and apoptosis, with EC₅₀ values around 1 μM. None of 7 glioma cell lines tested were resistant to either drug. LN-229 cells which have partial p53-wild-type activity show enhanced expression of p53, p21 and bax protein, whereas bcl-2 levels decrease, after exposure to camptothecin. In contrast, β-lapachone increases bax protein expression in the absence of p53 activation. T98G cells are mutant for p53. In these cells, p53 levels do not change and p21 is not induced. bax accumulation in T98G cells is induced by both drugs, with bcl-2 levels unaltered. Surprisingly, ectopic expression of murine bcl-2 fails to abrogate the toxicity of either drug. Camptothecin, but not β-lapachone, sensitizes human malignant glioma cells to apoptosis induced by the cytotoxic cytokines, tumor necrosis factor-α and CD95 ligand. Thus, both drugs have potent anti-glioma activity that may be mediated by enhanced bax expression but is not inhibited by ectopic bcl-2 expression. Camptothecin-like agents are particularly promising for immunochemotherapy of malignant glioma using cytotoxic drugs and CD95 ligand. Int. J. Cancer 73:707–714, 1997. © 1997 Wiley-Liss, Inc.     

Apoptotic activity is increased in parallel with the metaplasia-dysplasia-carcinoma sequence of the bronchial epithelium

A high level of apoptotic activity and an independence of apoptosis from the expression of p53 and bcl-2 have been observed in non-small-cell lung carcinoma. We examined 44 samples of normal, metaplastic and premalignant (i.e. mild, moderate and severe dysplasias and carcinoma in situ) bronchial epithelia to evaluate whether differences in the apoptotic activity could already be seen in the stages preceding squamous cell carcinoma of the lung (SQCLC). Apoptotic cells and bodies were visualized by 3' end labelling. The expression of p53 and members of the bcl-2 gene family, such as bcl-2, bax and mcl-1, were determined immunohistochemically with specific antibodies. The relative number of apoptotic cells and bodies [apoptotic index (AI%)] was already increased threefold as the normal bronchial epithelium changed to squamous metaplasia, and the AIs of the dysplastic lesions were about four times higher than those of the normal epithelium. Apoptosis was significantly associated with cell proliferation, as determined by proliferating cell nuclear antigen (PCNA) immunohistochemistry. However, the extent of apoptosis did not correlate with the expression of p53, bcl-2, bax and mcl-1. We conclude that, in the metaplasia-dysplasia-carcinoma sequence in the lung, the elevation of the AI% is an early event associated with cell proliferation activity, but is independent of the expression of p53, bcl-2, mcl-1 and bax.     

Neoplastic cell apoptosis in nude mice transplants with nasopharyngeal carcinoma cell lines

We know that tumor growth speed is criticallyinfluenced by the ratio of neoplastic cell proliferation andcell death, and there are two patterns of cell death, namely,necrosis and apoptosis. What is the proportion of necrosisand apoptosis seen in nude mice transplants ofnasopharyngeal carcinoma (NPC) cell lines, CNE-1 andCNE-2? Does the apoptosis play an important role inneoplastic cell death? If so, what is the pathway ofapoptosis developed in those transplants?MATERIALS AND METHODS…     

In vivo expression of p53 and Bcl-2 and their role in programmed cell death in premalignant and malignant lung lesions.

Forty-four specimens of non-malignant and malignant human lung tissue, taken from patients with non-small cell lung cancer (NSCLC), were examined for the expression of wild-type p53, mutant p53, and bcl-2 and the occurrence of programmed cell death (apoptosis). Wild-type p53 expression peaked in peritumoral and metaplastic samples, whereas mutant p53, bcl-2 and apoptosis were first detected in metaplasia and increased with progression to carcinoma. Bcl-2 positive samples had lower levels of apoptosis than bcl-2 negative samples and was independent of wild-type or mutant p53 expression. These results suggest that the over-expression of wild-type p53 may be an early cellular response to an alteration in normal cellular homeostasis. The ensuing increase in apoptosis appears to be relatively independent of mutant or wild-type p53 expression, but does not occur in cells expressing bcl-2.     

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.