Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Therapy targeting hypoxia-inducible factor-1 (HIF-1) to reverse the hypoxia-related drug resistance has received much interest. Despite a close interaction between HIF-1 and p53 and that p53 mutation is seen in >50% of tumors, whether HIF-1 silencing by targeted therapy depends on tumor p53 status remains unknown. Two isogenic fibrosarcoma cells HT1080 (wild-type p53) and HT1080-6TG (mutant p53) were transduced with HIF-1alpha-specific RNAi lentiviral vectors and selected with blasticidin. Real-time PCR and western blot analysis of HIF-1alpha mRNA and protein respectively validated the silencing effects. Cells were first preconditioned under hypoxia (0.5% O(2)) for 4 h and then co-treated with cisplatin for another 24 h. MTT was used for assessment of chemosensitivity to cisplatin. Moreover, annexin V and propidium iodide staining was detected on flow cytometry for analysis of cisplatin-induced apoptosis. Furthermore, changes of some Bcl-2 family members were detected on western blotting. Exposure to hypoxia significantly increased resistance to cisplatin than exposure to normoxia. HIF-1alpha knockdown could reverse hypoxia-related resistance to cisplatin and apoptotic resistance only in HT1080 cells, but had little effect on HT1080-6TG cells. With HIF-1alpha knockdown, Bid expression was higher in HT1080 than in HT1080-6TG under hypoxia. In summary, HIF-1 targeted therapy to reverse hypoxia-related cisplatin resistance depends on normal p53 status. Changes of Bid expression levels under hypoxia might contribute in part to the differential response to HIF-1alpha silencing in cells with different p53 status.
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PMID:Effects of lentivirus-mediated HIF-1alpha knockdown on hypoxia-related cisplatin resistance and their dependence on p53 status in fibrosarcoma cells. 1842 7

Theaflavins, the bioactive flavonoids of black tea, have been demonstrated to inhibit proliferation and induce apoptosis in a variety of cancer cells. However, the contribution of p53 in mammary epithelial carcinoma cell apoptosis by theaflavins remains unclear. It has been reported that p53 triggers apoptosis by inducing mitochondrial outer membrane permeabilization through transcription-dependent and -independent mechanisms. Using wild-type and mutant p53-expressing as well as p53-null cells we found a strong correlation between p53 status and theaflavin-induced breast cancer cell apoptosis. Apoptogenic effect was more pronounced in functional p53-expressing cells in which theaflavins raised p53 protein levels that harmonized with Bax up-regulation and migration to mitochondria. However, in the same cells, when p53-mediated transactivation was inhibited by pifithrin-alpha, theaflavins not only failed to increase transcription but also to induce apoptosis although p53 up-regulation was not altered. In contrast, Bax over-expression restored back theaflavin-induced apoptosis in pifithrin-alpha-inhibited/dominant-negative p53-expressing cells. Inhibition of Bax by RNA-interference also reduced theaflavin-induced apoptosis. These results not only indicated the requirement of p53-mediated transcriptional activation of Bax but also its role as down-stream effecter in theaflavin-induced apoptosis. Bax up-regulation resulted in mitochondrial transmembrane potential loss and cytochrome c release followed by activation of caspase cascade. In contrast, mitochondrial translocation of p53 and its interaction with Bcl-2 family proteins or activation of caspase-8 could not be traced thereby excluding the involvement of p53-mediated transcription-independent pathways. Together these findings suggest that in breast cancer cells, p53 promotes theaflavin-induced apoptosis in a transcription-dependent manner through mitochondrial death cascade.
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PMID:Contribution of p53-mediated Bax transactivation in theaflavin-induced mammary epithelial carcinoma cell apoptosis. 1845 16

2-acetyl furanonaphthoquinone (FNQ) is a naturally occurring drug with enhanced toxicity versus glucose-starved tumor cells, which frequently show topoisomerase II drug resistance. Since loss of p53 tumor suppressor function or overexpression of the anti-apoptotic bcl-2 gene can decrease susceptibility to some cancer therapies, we now investigated the effect of FNQ against genetically matched C8161 melanoma cell lines transduced to express unequal levels of Bcl-2, or engineered to harbour a functional wt p53 for comparison with dominant-negative mutant p53 R175H. Cells with differing p53 genotype showed susceptibility to FNQ. However, this response was attenuated in those overexpressing mutant p53, although a brief p53 induction was early seen in FNQ-treated wt p53 cells. Cells susceptible to FNQ showed cleavage of anti-apoptotic Mcl-1, sustained activation of the c-Jun N-terminal Kinase (p-JNK), and apoptosis-associated PARP fragmentation, all of which were counteracted in bcl-2 overexpressing cells. Suppression of JNK activation with the specific inhibitor, SP600125 also prevented FNQ-mediated cell death. Our data suggests that Bcl-2, persistent JNK phosphorylation and cleavage of anti-apoptotic Mcl-1 are key events controlling susceptibility to FNQ.
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PMID:Mcl-1 cleavage and sustained phosphorylation of c-Jun-N-terminal kinase mediate melanoma apoptosis induced by 2-acetyl furanonaphthoquinone: roles of Bcl-2 and p53. 1845 32

Gene therapy for a variety of human cancers containing the mutant p53 (mt-p53) gene has been performed by direct injection of a retroviral or adenoviral vector containing the wild-type p53 (wt-p53) gene. Because many individuals with skin squamous cell carcinoma (SCC) have been shown to carry the p53 gene mutation, these patients are candidates for p53 gene therapy. For this reason, we established ponasterone A-inducible the wild-type p53 (wt-p53) protein-expressing clones by transfecting a ponasterone-inducible vector containing the wt-p53 gene into HSC-1 cells, which harbor the mutated p53 (m/w) at codon 173 (GTG --> TTG in one allele). Upon the induction of the wt-p53 protein, severe growth suppression was observed. Based on the results of the expression patterns of the p21, p16, RB, BAX and Bcl-2 proteins, as well as on the results of senescence-associated beta-galactosidase staining, the suppression was caused by senescence-like growth arrest of the cells. Although it is generally accepted that the suppression of tumor cell growth is caused by p53-induced apoptosis, permanent G1 arrest induced by p53 is also an important part of the growth-suppression mechanism in p53 gene therapy. The present results should expand the possibilities for p53 gene therapy for human skin SCCs containing the mutant p53 gene.
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PMID:Establishment of ponasterone A-inducible the wild-type p53 protein-expressing clones from HSC-1 cells, cell growth suppression by p53 expression and the suppression mechanism. 1900 4

Radiation-induced bystander effects are established consequences of exposure to ionizing radiation. The operation of this mechanism has been seen in vitro and also between fish, mammals, and plants in vive where stress signals from treated organisms induce responses in neighbors. In vitro research shows that DNA repair deficient cells produce more toxic bystander responses. To test this in vivo two strains of Japanese medaka were tested. One is a mutant, repair deficient strain (ric2) and the other, the wildtype repair proficient strain (CAB). Irradiated fish swam with unirradiated partners in a strain mix and match protocol. The data suggest that medaka produce signals, when exposed to radiation, that induce unirradiated fish ofthe same strain swimming with them to produce an altered response to that seen in bystanders to sham irradiated fish. More apoptosis was seen in bystanders to repair deficient fish. When the strains are mixed, the bystanders of either strain respond like the donor strain. Measurements of Bcl-2 and cmyc proteins in the explants confirmed these observations. A possible role for p53 was also identified in that the use of reporters with mutant p53 demonstrated that CAB signals killed all the reporter cells by apoptosis. Use of a similar but p53 wildtype cell line had no such effect. The data add to the body of knowledge showing that bystander signals operate at hierarchical levels of organization greater than the individual and may therefore have relevance in radioecology and (eco)systems biology.
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PMID:Communication of radiation-induced signals in vivo between DNA repair deficient and proficient medaka (Oryzias latipes). 1953 55

Cisplatin is a first-line chemotherapeutic agent and a powerful component of standard treatment regimens for several human malignancies including bladder cancer. DNA-Pt adducts produced by cisplatin are mainly responsible for cellular toxicity and induction of apoptosis. Identification of the mechanisms that control sensitivity to cisplatin is central to improving its therapeutic index and to successfully encountering the acquired resistance frequently emerging during therapy. In the present study, using MTT-based assays, Western blotting and semi-quantitative RT-PCR, we examined the apoptosis-related cellular responses to cisplatin exposure in two human urinary bladder cancer cell lines characterized by different malignancy grade and p53 genetic status. Both RT4 (grade I; wild-type p53) and T24 (grade III; mutant p53) cell types proved to be vulnerable to cisplatin apoptotic activity, albeit in a grade-dependent and drug dose-specific manner, as demonstrated by the proteolytic processing profiles of Caspase-8, Caspase-9, Caspase-3, and the Caspase repertoire characteristic substrates PARP and Lamin A/C, as well. The differential resistance of RT4 and T24 cells to cisplatin-induced apoptosis was associated with an RT4-specific phosphorylation (Ser15; Ser392) pattern of p53, together with structural amputations of the Akt and XIAP anti-apoptotic regulators. Furthermore, cisplatin administration resulted in a Granzyme B-mediated proteolytic cleavage of Hsp90 molecular chaperone, exclusively occurring in RT4 cells. To generate functional networks, expression analysis of a number of genes, including Bik, Bim, Bcl-2, FAP-1, Fas, FasL, TRAIL, Puma, Caspase-10, ATP7A, ATP7B and MRP1, was performed, strongly supporting the role of p53-dependent and p53-independent transcriptional responses in cisplatin-induced apoptosis of bladder cancer cells.
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PMID:Human bladder cancer cells undergo cisplatin-induced apoptosis that is associated with p53-dependent and p53-independent responses. 1957 56

New cytotoxic agents are urgently needed for the treatment of advanced ovarian cancer because of the poor long-term response of this disease to conventional chemotherapy. Curcumin, obtained from the rhizome of Curcuma longa, has potent anticancer activity; however, the mechanism of curcumin-induced cytotoxicity in ovarian cancer cells remains a mystery. In this study we show that curcumin exhibited time- and dose-dependent cytotoxicity against monolayer cultures of ovarian carcinoma cell lines with differing p53 status (wild-type p53: HEY, OVCA429; mutant p53: OCC1; null p53: SKOV3). In addition, p53 knockdown or p53 inhibition did not diminish curcumin killing of HEY cells, confirming p53-independent cytotoxicity. Curcumin also killed OVCA429, and SKOV3 cells grown as multicellular spheroids. Nuclear condensation and fragmentation, as well as DNA fragmentation and poly (ADP-ribose) polymerase-1 cleavage in curcumin-treated HEY cells, indicated cell death by apoptosis. Procaspase-3, procaspase-8, and procaspase-9 cleavage, in addition to cytochrome c release and Bid cleavage into truncated Bid, revealed that curcumin activated both the extrinsic and intrinsic pathways of apoptosis. Bax expression was unchanged but Bcl-2, survivin, phosphorylated Akt (on serine 473), and total Akt were downregulated in curcumin-treated HEY cells. Curcumin also activated p38 mitogen-activated protein kinase (MAPK) without altering extracellular signal-regulated kinase 1/2 activity. We conclude that p53-independent curcumin-induced apoptosis in ovarian carcinoma cells involves p38 MAPK activation, ablation of prosurvival Akt signaling, and reduced expression of the antiapoptotic proteins Bcl-2 and survivin. These data provide a mechanistic rationale for the potential use of curcumin in the treatment of ovarian cancer.
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PMID:Curcumin-induced apoptosis in ovarian carcinoma cells is p53-independent and involves p38 mitogen-activated protein kinase activation and downregulation of Bcl-2 and survivin expression and Akt signaling. 1967 5

In breast cancer, maspin, a serine protease inhibitor, can suppress tumor growth and metastasis in vivo and tumor cell motility and invasion in vitro. The clinical significance of maspin expression in breast cancer, especially in the sequence of ductal carcinoma in situ (DCIS)-invasive cancer-lymph node metastasis is well known in the Western countries, but its status in the rapidly increasing breast cancers in India remains unknown. The present study was designed to determine the clinical significance of maspin expression in invasive ductal carcinomas of breast (IDCs) in North Indian population and modulation of its expression by curcumin. Immunohistochemical analysis of maspin showed loss or reduced cytoplasmic expression in 36 of 59 (61%) tumors. Furthermore, breast cancer cells (MCF-7 (wild type p53) and MDA-MB-231 (mutant p53)) were treated with curcumin and the effect on expression of maspin gene at transcription and translation levels was analyzed by RT-PCR, immunofluorescence and Western blotting. Maspin expression was also correlated with p53 and Bcl-2 levels. Curcumin inhibited cell growth, induced apoptosis and upregulated maspin gene expression in MCF-7 cells and these findings were further correlated with the upregulation of p53 protein and downregulation of Bcl-2, suggesting maspin mediated apoptosis in MCF-7 cells. To our knowledge this is the first report showing the upregulation of maspin expression by curcumin in breast cancer cells and taken together with the clinical data suggests a potential therapeutic role for curcumin in inducing maspin mediated inhibition of invasion of breast carcinoma cells.
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PMID:Expression analysis of maspin in invasive ductal carcinoma of breast and modulation of its expression by curcumin in breast cancer cell lines. 1994 74

The anthracycline antibiotic doxorubicin (DOX) is a potent cancer chemotherapeutic agent that exerts both acute and chronic cardiotoxicity. Here we show that in adult mouse cardiomyocytes, DOX activates (i) the pro-apoptotic p53, (ii) p38MAPK and JNK, (iii) Bax translocation, (iv) cytochrome c release, and (v) caspase 3. Further, it (vi) inhibits expression of anti-apoptotic Akt, Bcl-2 and Bcl-xL, and (vii) induces internucleosomal degradation and cell death. WNT1-inducible signaling pathway protein-1 (WISP1), a CCN family member and a matricellular protein, inhibits DOX-mediated cardiomyocyte death. WISP1 inhibits DOX-induced p53 activation, p38 MAPK and JNK phosphorylation, Bax translocation to mitochondria, and cytochrome c release into cytoplasm. Additionally, WISP1 reverses DOX-induced suppression of Bcl-2 and Bcl-xL expression and Akt inhibition. The pro-survival effects of WISP1 were recapitulated by the forced expression of mutant p53, wild-type Bcl-2, wild-type Bcl-xL, or constitutively active Akt prior to DOX treatment. WISP1 also induces the pro-survival factor Survivin via PI3K/Akt signaling. Overexpression of wild-type, but not mutant Survivin, blunts DOX cytotoxicity. Further, WISP1 stimulates PI3K-Akt-dependent GSK3beta phosphorylation and beta-catenin nuclear translocation. Importantly, WISP1 induces its own expression. Together, these results provide important insights into the cytoprotective effects of WISP1 in cardiomyocytes, and suggest a potential therapeutic role for WISP1 in DOX-induced cardiotoxicity.
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PMID:WNT1-inducible signaling pathway protein-1 activates diverse cell survival pathways and blocks doxorubicin-induced cardiomyocyte death. 2007 38

Genotoxic stress triggers the p53 tumor suppressor network to activate cellular responses that lead to cell cycle arrest, DNA repair, apoptosis or senescence. This network functions mainly through transactivation of different downstream targets, including cell cycle inhibitor p21, which is required for short-term cell cycle arrest or long-term cellular senescence, or proapoptotic genes such as p53 upregulated modulator of apoptosis (PUMA) and Noxa. However, the mechanism that switches from cell cycle arrest to apoptosis is still unknown. In this study, we found that mice harboring a hypomorphic mutant p53, R172P, a mutation that abrogates p53-mediated apoptosis while keeping cell cycle control mostly intact, are more susceptible to ultraviolet-B (UVB)-induced skin damage, inflammation and immunosuppression than wild-type mice. p53(R172P) embryonic fibroblasts (MEFs) are hypersensitive to UVB and prematurely senesce after UVB exposure, in stark contrast to wild-type MEFs, which undergo apoptosis. However, these mutant cells are able to repair UV-induced DNA lesions, indicating that the UV hypersensitive phenotype results from the subsequent damage response. Mutant MEFs show an induction of p53 and p21 after UVR, while wild-type MEFs additionally induce PUMA and Noxa. Importantly, p53(R172P) MEFs failed to downregulate anti-apoptotic protein Bcl-2, which has been shown to play an important role in p53-dependent apoptosis. Taken together, these data demonstrate that in the absence of p53-mediated apoptosis, cells undergo cellular senescence to prevent genomic instability. Our results also indicate that p53-dependent apoptosis may play an active role in balancing cellular growth.
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PMID:Absence of p53-dependent apoptosis leads to UV radiation hypersensitivity, enhanced immunosuppression and cellular senescence. 2070 98


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