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Interaction of TLK1 and AKTIP as a Potential Regulator of AKT Activation in Castration-Resistant Prostate Cancer Progression. PATHOPHYSIOLOGY 2021; 28:339-354. [PMID: 35366279 PMCID: PMC8830441 DOI: 10.3390/pathophysiology28030023] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/14/2021] [Accepted: 07/17/2021] [Indexed: 01/13/2023] Open
Abstract
Prostate cancer (PCa) progression is characterized by the emergence of resistance to androgen deprivation therapy (ADT). AKT/PKB has been directly implicated in PCa progression, often due to the loss of PTEN and activation of PI3K>PDK1>AKT signaling. However, the regulatory network of AKT remains incompletely defined. Here, we describe the functional significance of AKTIP in PCa cell growth. AKTIP, identified in an interactome analysis as a substrate of TLK1B (that itself is elevated following ADT), enhances the association of AKT with PDK1 and its phosphorylation at T308 and S473. The interaction between TLK1 and AKTIP led to AKTIP phosphorylation at T22 and S237. The inactivation of TLK1 led to reduced AKT phosphorylation, which was potentiated with AKTIP knockdown. The TLK1 inhibitor J54 inhibited the growth of the LNCaP cells attributed to reduced AKT activation. However, LNCaP cells that expressed constitutively active, membrane-enriched Myr-AKT (which is expected to be active, even in the absence of AKTIP) were also growth-inhibited with J54. This suggested that other pathways (like TLK1>NEK1>YAP) regulating proliferation are also suppressed and can mediate growth inhibition, despite compensation by Myr-AKT. Nonetheless, further investigation of the potential role of TLK1>AKTIP>AKT in suppressing apoptosis, and conversely its reversal with J54, is warranted.
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Chimento A, Casaburi I, Avena P, Trotta F, De Luca A, Rago V, Pezzi V, Sirianni R. Cholesterol and Its Metabolites in Tumor Growth: Therapeutic Potential of Statins in Cancer Treatment. Front Endocrinol (Lausanne) 2018; 9:807. [PMID: 30719023 PMCID: PMC6348274 DOI: 10.3389/fendo.2018.00807] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/21/2018] [Indexed: 12/13/2022] Open
Abstract
Cholesterol is essential for cell function and viability. It is a component of the plasma membrane and lipid rafts and is a precursor for bile acids, steroid hormones, and Vitamin D. As a ligand for estrogen-related receptor alpha (ESRRA), cholesterol becomes a signaling molecule. Furthermore, cholesterol-derived oxysterols activate liver X receptors (LXRs) or estrogen receptors (ERs). Several studies performed in cancer cells reveal that cholesterol synthesis is enhanced compared to normal cells. Additionally, high serum cholesterol levels are associated with increased risk for many cancers, but thus far, clinical trials with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have had mixed results. Statins inhibit cholesterol synthesis within cells through the inhibition of HMG-CoA reductase, the rate-limiting enzyme in the mevalonate and cholesterol synthetic pathway. Many downstream products of mevalonate have a role in cell proliferation, since they are required for maintenance of membrane integrity; signaling, as some proteins to be active must undergo prenylation; protein synthesis, as isopentenyladenine is an essential substrate for the modification of certain tRNAs; and cell-cycle progression. In this review starting from recent acquired findings on the role that cholesterol and its metabolites fulfill in the contest of cancer cells, we discuss the results of studies focused to investigate the use of statins in order to prevent cancer growth and metastasis.
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Barakat DJ, Zhang J, Barberi T, Denmeade SR, Friedman AD, Paz-Priel I. CCAAT/Enhancer binding protein β controls androgen-deprivation-induced senescence in prostate cancer cells. Oncogene 2015; 34:5912-22. [PMID: 25772238 PMCID: PMC4573387 DOI: 10.1038/onc.2015.41] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 12/19/2014] [Accepted: 01/06/2015] [Indexed: 12/17/2022]
Abstract
The processes associated with transition to castration independent prostate cancer growth are not well understood. Cellular senescence is a stable cell cycle arrest that occurs in response to sublethal stress. It is often overcome in malignant transformation to confer a survival advantage. CCAAT/Enhancer Binding Protein (C/EBP) β function is frequently deregulated in human malignancies and interestingly, androgen dependent prostate cancer cells express primarily the LIP isoform. We found that C/EBPβ expression is negatively regulated by androgen receptor activity and that treatment of androgen dependent cell lines with anti-androgens increases C/EBPβ mRNA and protein levels. Accordingly, we also find that C/EBPβ levels are significantly elevated in primary prostate cancer samples from castration resistant compared with therapy naive patients. Chromatin immunoprecipitation demonstrated enhanced binding of the androgen receptor to the proximal promoter of the CEBPB gene in the presence of dihydroxytestosterone. Upon androgen deprivation, induction of C/EBPβ is facilitated by active transcription as evident by increased histone 3 acetylation at the C/EBPβ promoter. Also, the androgen agonist R1881 suppresses the activity of a CEBPB promoter reporter. Loss of C/EBPβ expression prevents growth arrest following androgen deprivation or anti-androgen challenge. Accordingly, suppression of C/EBPβ under low androgen conditions results in reduced expression of senescence-associated secretory genes, significantly decreased number of cells displaying heterochromatin foci, and increased numbers of Ki67 positive cells. Ectopic expression of C/EBPβ caused pronounced morphological changes, reduced PC cell growth, and increased the number of senescent LNCaP cells. Lastly, we found that senescence contributes to prostate cancer cell survival under androgen deprivation, and C/EBPβ deficient cells were significantly more susceptible to killing by cytotoxic chemotherapy following androgen deprivation. Our data demonstrate that up-regulation of C/EBPβ is critical for complete maintenance of androgen deprivation induced senescence and that targeting C/EBPβ expression may synergize with anti-androgen or chemotherapy in eradicating prostate cancer.
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Affiliation(s)
- D J Barakat
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - J Zhang
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - T Barberi
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - S R Denmeade
- Division of Medical Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - A D Friedman
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - I Paz-Priel
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
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Pan T, Gao L, Wu G, Shen G, Xie S, Wen H, Yang J, Zhou Y, Tu Z, Qian W. Elevated expression of glutaminase confers glucose utilization via glutaminolysis in prostate cancer. Biochem Biophys Res Commun 2014; 456:452-8. [PMID: 25482439 DOI: 10.1016/j.bbrc.2014.11.105] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 11/26/2014] [Indexed: 11/17/2022]
Abstract
Cancer cells reprogram their metabolism towards aerobic glycolysis and elevated glutaminolysis, which contributes to the aggressive phenotype. Understanding how these metabolic pathways are regulated may provide critical targets for therapeutic intervention. Glutaminase (GLS1) is a key enzyme that converts glutamine to glutamate. In this study, we show the loss of GLS1 function by RNA interference or inhibitor diminished the rates of glucose utilization, growth and invasiveness of prostate cancer cells. We propose that GLS1 positively regulates glucose uptake in addition to glutaminolysis. Further, GLS1 involves the transcriptional repression of thioredoxin interacting protein (TXNIP), which is a potent negative regulator of glucose uptake and aerobic glycolysis. Most importantly, we provided direct evidence that elevated GLS1 expression was highly correlated with the tumor stage and progression in prostate cancer patients. Together, we defined a key role for GLS1 in coupling glutaminolysis of the TCA cycle with elevated glucose uptake and consequently the growth of prostate cancer cells. These data extends the role of GLS1 in regulating cell metabolism and the clinical utility of GLS1 inhibitors in the restriction of essential nutrients.
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Affiliation(s)
- Tiejun Pan
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Lei Gao
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China.
| | - Guojun Wu
- Department of Urology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Guoqiu Shen
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Sen Xie
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Handong Wen
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Jiarong Yang
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Yu Zhou
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Zhong Tu
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
| | - Weihong Qian
- Department of Urology, Wuhan General Hospital of Guangzhou Military Region, Wuhan, Hubei, China
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Giusiano S, Baylot V, Andrieu C, Fazli L, Gleave M, Iovanna JL, Taranger-Charpin C, Garcia S, Rocchi P. TP53INP1 as new therapeutic target in castration-resistant prostate cancer. Prostate 2012; 72:1286-94. [PMID: 22213058 DOI: 10.1002/pros.22477] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Accepted: 12/01/2011] [Indexed: 11/09/2022]
Abstract
BACKGROUND Prostate cancer (PC) is one of the most common malignancies in industrialized countries, and the second leading cause of cancer-related death in the United States. We recently showed that over-expression of tumor protein 53-induced nuclear protein 1 (TP53INP1), a cell stress response protein, is a worse prognostic factor in PC, particularly predictive of biological cancer relapse. Moreover, treatment of castration-sensitive (CS) LNCaP tumor cells with a TP53INP1 antisense oligonucleotide (TP53INP1 ASO) inhibits proliferation and induces apoptosis. The aim of this study was to investigate variations of TP53INP1 expression in PC during androgen withdrawal therapy and in castration-resistant prostate cancer (CRPC). METHODS Quantitative measurements of immunohistochemical expression of TP53INP1 using high-throughput densitometry, assessed on digitized microscopic tissue micro-array images were correlated with hormone therapy (HT) status in human PC. Northern blot analysis of TP53INP1 after castration was performed in LNCaP xenograft. Treatment of CR C4-2 tumor cells in vitro with TP53INP1 ASO was analyzed. We also analyzed the effect of TP53INP1 ASO treatment in vivo on tumor xenograft growth. RESULTS TP53INP1 protein expression decreases during HT and increases after HT in human CRPC. TP53INP1 mRNA increases significantly in CR tumors of LNCaP xenograft. Moreover, treatment of CR C4-2 cells with TP53INP1 ASO downregulates TP53INP1 protein level, inhibits proliferation, and induces apoptosis. Finally, in vivo, TP53INP1 ASO treatment significantly inhibits the tumoral progression of CR C4-2 xenograft and enhances docetaxel cytotoxicity. CONCLUSIONS These results suggest that TP53INP1 could be considered as a relevant-specific target for molecular therapy of CRPC.
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Affiliation(s)
- Sophie Giusiano
- Department of Pathology, Hôpital Nord, Chemin des Bourrellys, 13915 Marseille, France.
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Liu X, Fu YM, Meadows GG. Differential effects of specific amino acid restriction on glucose metabolism, reduction/oxidation status and mitochondrial damage in DU145 and PC3 prostate cancer cells. Oncol Lett 2011; 2:349-355. [PMID: 21415930 DOI: 10.3892/ol.2011.237] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Selective amino acid restriction targets mitochondria to induce apoptosis of DU145 and PC3 prostate cancer cells. Biochemical assays and flow cytometry were uitilized to analyze the glucose consumption, lactate production, pyruvate dehydrogenase (PDH), nicotinamide adenine dinucleotide (NAD)/NADH and nicotinamide adenine dinucleotide phosphate (NADP)/NADPH ratios, mitochondrial glutathione peroxidase (GPx), manganese superoxide dismutase (SOD), glutathione, reactive oxygen species (ROS) and DNA damage in DU145 and PC prostate cancer cells cultured under various amino acid deprived conditions. Restriction of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln) or methionine (Met) differentially modulated glucose metabolism and PDH and antioxidant enzyme activity in the mitochondria of the two prostate cancer cell lines. In DU145 cells, Gln and Met restriction increased glucose consumption and decreased lactate production, but Tyr/Phe restriction did not. The examined restrictions increased mitochondrial PDH activity and accumulation of ROS. Gln and Met restriction increased GPx activity. Tyr/Phe and Met restriction increased SOD during the first 2 days of the restriction, and the activity returned to the basal level on day 4. All amino acid restrictions decreased reduced glutathione (GSH) and induced mitochondrial DNA damage. In PC3 cells, all amino acid restrictions reduced glucose consumption and lactate production. Gln restriction increased ROS and elevated GPx activity. Tyr/Phe restriction increased SOD activity. The amino acid restriction decreased GSH, but did not cause mitochondrial DNA damage. Specific amino acid dependency differentially regulates glucose metabolism, oxidation-reduction reactions of mitochondria and mitochondrial damage in DU145 and PC3 prostate cancer cell lines.
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Affiliation(s)
- Xiaoyi Liu
- Department of Pharmaceutical Sciences, College of Pharmacy, Washington State University, Pullman, WA 99164-6534, USA
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Memon AA, Munk M, Nexo E, Sorensen BS. Calcium-induced apoptosis is delayed by HER1 receptor signalling through the Akt and PLCγ pathways in bladder cancer cells. Scandinavian Journal of Clinical and Laboratory Investigation 2010; 71:45-51. [PMID: 21087080 DOI: 10.3109/00365513.2010.536250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The level of extracellular calcium has been demonstrated to regulate important physiological processes like cell growth and apoptosis. We demonstrate that in the bladder cancer cell line RT4, an increased extracellular calcium level induces apoptosis and that the HER1 receptor functions as a cell survival factor and delays apoptosis. After 12 h of calcium treatment (10 mM) apoptosis was detected in the RT4 cells. Increased activation of the HER1 receptor was detected as soon as 30 min after calcium addition, and the activation decreased again after 12 h of incubation, coinciding with the time when apoptosis was detectable. Inhibition of HER1 with Gefitinib (5 μM) or Tyrphostin (AG1478) (20 μM) augmented the calcium-induced apoptosis, and with HER1 inhibition apoptosis was detectable after 6 h. Analysis of downstream signalling molecules showed an increased activation of Akt, PLCγ and MAPK in response to calcium treatment. The activation of Akt and PLCγ was abolished by inhibition of HER1 with Gefitinib (5 μM), whereas this had no effect on the activity of MAPK. In addition, incubation with inhibitors of Akt and PLCγ significantly augmented calcium-induced apoptosis, whereas this was not seen with MAPK inhibition. Finally a significant increase in PKCδ activity was observed with calcium treatment alone and was augmented further with HER1 inhibition. In conclusion we show that calcium-induced apoptosis in bladder cancer cells is delayed by HER1 receptor activation involving the Akt and PLCγ signalling pathways.
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Affiliation(s)
- Ashfaque A Memon
- Department of Clinical Biochemistry, NBG, AS, Aarhus University Hospital, Aarhus C, Denmark.
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8
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Méndez-López LF, Zapata-Benavides P, Zavala-Pompa A, Aguado-Barrera ME, Pacheco-Calleros J, Rodríguez-Padilla C, Cerda-Flores RM, Cortés-Gutiérrez EI, Dávila-Rodríguez MI. Immunohistochemical analysis of prostate apoptosis response-4 (Par-4) in Mexican women with breast cancer: a preliminary study. Arch Med Res 2010; 41:261-8. [PMID: 20637369 DOI: 10.1016/j.arcmed.2010.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 05/13/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND AIMS We undertook this study to compare the expression level of prostate apoptosis response-4 (Par-4) among patient outcome in two groups of women with breast cancer (short and long survival) and two groups without breast cancer (benign lesion and control). METHODS We included breast specimens with nonhistological abnormalities (eight samples) as a control group. Semiquantitative and quantitative analysis of immunohistochemical staining by image analysis software were used to study the intensity of Par-4 expression. Both methods produced similar results (p>0.05). RESULTS No significant expression of Par-4 was observed in normal breast tissue. Benign lesions and breast cancer tissue showed strong nuclear expression of Par-4, predominantly on epithelial cells and specifically in ductal cells. Par-4 expression was lower in myoepithelial cells and there was no appreciable stromal staining. Significantly less Par-4 reactivity was detected in tissue from patients with a short survival compared with patients with benign lesions and those with a long survival. CONCLUSIONS Our findings suggest that a lower expression level of Par-4 is related to an unfavorable prognosis. A larger prospective study of samples of all patient groups with a longer follow-up is needed to validate this finding.
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Affiliation(s)
- Luis Fernando Méndez-López
- División de Genética, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, Mexico
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Sharma PK, Singh R, Novakovic KR, Eaton JW, Grizzle WE, Singh S. CCR9 mediates PI3K/AKT-dependent antiapoptotic signals in prostate cancer cells and inhibition of CCR9-CCL25 interaction enhances the cytotoxic effects of etoposide. Int J Cancer 2010; 127:2020-30. [PMID: 20127861 DOI: 10.1002/ijc.25219] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite recent advances in treatment and management of prostate cancer (PCa), it remains the second leading cause of cancer-related deaths among men in the US. Chemotherapy is one of the treatment alternatives for hormone refractory metastatic PCa. However, current chemotherapeutic regimens provide palliative benefit but relatively modest survival advantage primarily due to chemo-resistance and upregulated antiapoptotic machineries in PCa cells. Therefore, blocking the mechanisms responsible for suppression of apoptosis might improve current chemotherapeutic regimens. In this study, we show that CC chemokine receptor-9 (CCR9) and its natural ligand CCL25 interaction upregulates antiapoptotic proteins (i.e., PI3K, AKT, ERK1/2 and GSK-3beta) and downregulate activation of caspase-3 in PCa cells. Significant downregulation of these CCR9-mediated antiapoptotic proteins in the presence of a PI3K inhibitor (wortmannin), further suggests that the antiapoptotic action of CCR9 is primarily regulated through PI3K. Furthermore, the cytotoxic effect of etoposide was significantly inhibited in the presence of CCL25, and this inhibitory effect of CCL25 was abrogated when CCR9-CCL25 interaction was blocked using anti-CCR9 monoclonal antibodies. In conformation to these in vitro studies, significant reduction in tumor burden was found in mice receiving CCL25 neutralizing antibodies and etoposide together as compared to both as a single agent. These results suggest that the CCR9-CCL25 axis mediates PI3K/AKT-dependent antiapoptotic signals in PCa cells and could be a possible reason for low apoptosis and modest chemotherapeutic response. Therefore, targeting CCR9-CCL25 axis with cytotoxic agents may provide better therapeutic outcomes than using cytotoxic agents alone.
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Affiliation(s)
- Praveen K Sharma
- James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, USA
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Saegusa M, Hashimura M, Kuwata T, Okayasu I. Transcriptional regulation of pro-apoptotic Par-4 by NF-kappaB/p65 and its function in controlling cell kinetics during early events in endometrial tumourigenesis. J Pathol 2010; 221:26-36. [PMID: 20186924 DOI: 10.1002/path.2680] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prostatic apoptosis response-4 (Par-4) was first identified in prostatic cancer cells that were induced to undergo apoptosis. Recently, Par-4 has been suggested to be a tumour suppressor gene that plays a role in the development of endometrial carcinomas (ECs), but the exact mechanism remains to be clarified. Here we examined gene activation signalling cascades and influence on cell kinetics during endometrial tumourigenesis. In normal endometrium, constitutively high levels of Par-4 expression were observed in epithelial cells through the menstrual cycle, in contrast to the transient up-regulation in stromal components in the menstrual stage, correlated positively with the phospho-p65 (pp65) status and apoptosis. In contrast, most ECs exhibited significant down-regulation as compared to normal endometrium, with positive links only to pp65 expression. In EC cell lines, transfection of the NF-kappaB subunit p65 led to transactivation of Par-4 through specific binding to its promoter region, in contrast to the suppression by active Akt, suggesting that the balance between the two signals may be important to determine Par-4 expression levels. In addition, transient overexpression of Par-4 resulted in the induction of not only apoptosis but also senescence, through changes in the expression of bcl-2 and p21$;{{\rm WAF1}}$, respectively. Together, these findings suggest that a signalling cascade involving sequential activation of NF-kappaB/p65 and Par-4 may participate in relatively early events of endometrial tumourigenesis, leading to modulation of cell kinetics including apoptosis and cell cycle progression.
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Affiliation(s)
- Makoto Saegusa
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555, Japan.
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Vergis R, Corbishley CM, Thomas K, Horwich A, Huddart R, Khoo V, Eeles R, Sydes MR, Cooper CS, Dearnaley D, Parker C. Expression of Bcl-2, p53, and MDM2 in localized prostate cancer with respect to the outcome of radical radiotherapy dose escalation. Int J Radiat Oncol Biol Phys 2010; 78:35-41. [PMID: 20092961 DOI: 10.1016/j.ijrobp.2009.07.1728] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 07/10/2009] [Accepted: 07/16/2009] [Indexed: 02/04/2023]
Abstract
PURPOSE Established prognostic factors in localized prostate cancer explain only a moderate proportion of variation in outcome. We analyzed tumor expression of apoptotic markers with respect to outcome in men with localized prostate cancer in two randomized controlled trials of radiotherapy dose escalation. METHODS AND MATERIALS Between 1995 and 2001, 308 patients with localized prostate cancer received neoadjuvant androgen deprivation and radical radiotherapy at our institution in one of two dose-escalation trials. The biopsy specimens in 201 cases were used to make a biopsy tissue microarray. We evaluated tumor expression of Bcl-2, p53, and MDM2 by immunohistochemistry with respect to outcome. RESULTS Median follow-up was 7 years, and 5-year freedom from biochemical failure (FFBF) was 70.4% (95% CI, 63.5-76.3%). On univariate analysis, expression of Bcl-2 (p < 0.001) and p53 (p = 0.017), but not MDM2 (p = 0.224), was significantly associated with FFBF. Expression of Bcl-2 remained significantly associated with FFBF (p = 0.001) on multivariate analysis, independently of T stage, Gleason score, initial prostate-specific antigen level, and radiotherapy dose. Seven-year biochemical control was 61% vs. 41% (p = 0.0122) for 74 Gy vs. 64 Gy, respectively, among patients with Bcl-2-positive tumors and 87% vs. 81% (p = 0.423) for 74 Gy vs. 64 Gy, respectively, among patients with Bcl-2-negative tumors. There was no statistically significant interaction between dose and Bcl-2 expression. CONCLUSIONS Bcl-2 expression was a significant, independent determinant of biochemical control after neoadjuvant androgen deprivation and radical radiotherapy for prostate cancer. These data generate the hypothesis that Bcl-2 expression could be used to inform the choice of radiotherapy dose in individual patients.
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Affiliation(s)
- Roy Vergis
- Academic Urology Unit, Institute of Cancer Research, Royal Marsden NHS Foundation Trust, Surrey, UK
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Risek B, Bilski P, Rice AB, Schrader WT. Androgen receptor-mediated apoptosis is regulated by photoactivatable androgen receptor ligands. Mol Endocrinol 2008; 22:2099-115. [PMID: 18562628 DOI: 10.1210/me.2007-0426] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We have studied nonsteroidal ligands of the human androgen receptor (hAR) and have shown elsewhere that when photoactivated by visible light they collide with O2 to yield singlet oxygens (1O2) in vitro. Here we report cell killing after brief light activation (405 nm) of 1,2,3,4-tetrahydro-2,2-dimethyl-6-(trifluoromethyl)-8-pyridono[5,6-g]quinoline (TDPQ) in human prostate tumor cells. TDPQ/AR complexes were required for the death response because AR-positive LNCaP cells were killed, whereas AR-negative PC-3 cells were resistant. Excess dihydrotestosterone (DHT) blocked the TDPQ effect when the two were added together; irradiation of cells containing DHT alone had no effect. When LNCaP AR expression was suppressed using small interfering oligonucleotides targeting AR, photocytotoxicity was diminished. Conversely, stable transfection of hAR into PC-3 cells made the cells photosensitive to TDPQ. Similar results were obtained using a structural isomer of TDPQ, and also the synthetic steroidal AR ligand R1881. Cell death occurred via apoptosis as demonstrated by annexin V immunostaining, nuclear condensation, and caspase inhibition. Death involved oxidative stress, because it was prevented by addition of the antioxidant ascorbic acid during photoactivation. Detection of elevated levels of 8-hydroxy-2'-deoxyguanosine in nuclei of irradiated cells indicated oxidative DNA damage. Apoptosis spread into adjacent nonirradiated cells by direct cell-cell contacts, indicative of a bystander effect. Other photoactivatable ligands are described, implying a general method for ablation of cells bearing specific nuclear hormone receptors.
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Affiliation(s)
- Boris Risek
- Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, III T.W. Alexander Drive, Research Triangle Park, North Carolina 27709, USA
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Goswami A, Ranganathan P, Rangnekar VM. The phosphoinositide 3-kinase/Akt1/Par-4 axis: a cancer-selective therapeutic target. Cancer Res 2006; 66:2889-92. [PMID: 16540633 DOI: 10.1158/0008-5472.can-05-4458] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Activation of the phosphoinositide 3-kinase (PI3K)/Akt cell survival pathway in many cancers makes it an appealing target for therapeutic development. However, because this pathway also has an important role in the survival of normal cells, tactics to achieve cancer selectivity may prove important. We recently showed that the cancer-selective proapoptotic protein Par-4 is a key target for inactivation by PI3K/Akt signaling. Additionally, we found that Par-4 participates in mediating apoptosis by PTEN, the tumor suppressor responsible for blocking PI3K/Akt signaling. As a central player in cancer cell survival, Par-4 may provide a useful focus for the development of cancer-selective therapeutics.
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Affiliation(s)
- Anindya Goswami
- Department of Radiation Medicine, University of Kentucky, Lexington, KY 40536, USA
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Coffey RNT, Morrissey C, Taylor CT, Fitzpatrick JM, Watson RWG. Resistance to caspase-dependent, hypoxia-induced apoptosis is not hypoxia-inducible factor-1 alpha mediated in prostate carcinoma cells. Cancer 2005; 103:1363-74. [PMID: 15719438 DOI: 10.1002/cncr.20918] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Hypoxia occurs in association with cancer development, the result being a more aggressive and metastatic cancer phenotype. Hypoxia, which activates hypoxia-inducible factor-1 alpha (HIF-1alpha), is associated with a number of cellular changes including increased apoptotic resistance. The authors hypothesized that HIF-1alpha is central to the cell's ability to resist apoptosis induced during the hypoxia selection process. METHODS PWR-1E, LNCaP, LNCaP-HOF, PC-3, and DU-145 cells were cultured in normoxic and hypoxic conditions. Apoptosis was assessed by propidium iodide DNA staining. Cleavage of specific substrates was used to assess caspase activity and Western blotting was used to assess mitochondrial release of cytochrome c and second mitochondria-derived activator caspase (SMAC)/Diablo. A dominant negative HIF-1alpha construct was transfected into the PC-3 and LNCaP cells to block HIF-1alpha activity. RESULTS PC-3 and DU-145 were resistant to apoptosis induced by exposure to hypoxia, but the PWR-1E and LNCaP cells were susceptible. This induction of apoptosis in the LNCaP cells was caspase dependent but independent of cytochrome c release. Blocking the activity of HIF-1alpha had no effect on increased apoptotic susceptibility in the PC-3 cells. LNCaP-HOF cells, which were resistant to hypoxia-induced apoptosis, showed no increase in HIF-1alpha expression or activity. CONCLUSIONS Apoptotic resistance is already established in cells that survive a hypoxic insult and whereas increased HIF-1alpha activity may be essential for the development of a more aggressive cancer phenotype, it may not be responsible for the initial selection of an apoptotic resistance phenotype.
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Affiliation(s)
- Ronan N T Coffey
- Department of Surgery, Mater Misericordiae University Hospital, Conway Institute of Biomedical and Biomolecular Research, University College Dublin, Ireland
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Fu YM, Yu ZX, Li YQ, Ge X, Sanchez PJ, Fu X, Meadows GG. Specific amino acid dependency regulates invasiveness and viability of androgen-independent prostate cancer cells. Nutr Cancer 2003; 45:60-73. [PMID: 12791506 DOI: 10.1207/s15327914nc4501_8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Androgen-independent prostate cancer is resistant to therapy and is often metastatic. Here we studied the effect of deprivation of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln), or methionine (Met), in vitro on human DU145 and PC3 androgen-independent prostate cancer cells, and on nontumorigenic human infant foreskin fibroblasts and human prostate epithelial cells. Deprivation of the amino acids similarly inhibited growth of DU145 and PC3 cells, arresting the cell cycle at G0/G1. Met and Tyr/Phe deprivation induces apoptosis in DU145, but only Met deprivation induces apoptosis in PC3 cells. The growth of normal cells is inhibited, but no apoptosis is induced by amino acid deprivation. Tyr/Phe deprivation inhibits expression and phosphorylation of focal adhesion kinase (FAK) and extracellular-regulated kinase (ERK) in DU145 but not PC3 or normal cells. Met deprivation inhibits phosphorylation but not protein expression of FAK and ERK in PC3. Therefore, apoptosis of DU145 and PC3 cells by amino acid restriction is FAK and ERK dependent. Tyr/Phe and Met deprivation inhibits invasion of DU145 and PC3, but Gln deprivation only inhibits invasion of DU145 cells. This indicates that the inhibition of invasion is not dependent on induction of apoptosis. The inhibition of invasion by Tyr/Phe restriction in DU145 and Met restriction in PC3 is consistent with the inhibition on FAK/ERK signaling. The inhibition of Tyr/Phe restriction in PC3 and Gln restriction in DU145 is not associated with inhibition of FAK/ERK. This indicates that FAK/ERK-dependent and independent pathways are modulated by specific amino acid restriction. This study shows the potential for specific amino acid restriction to treat prostate cancer.
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Affiliation(s)
- Ya-Min Fu
- Cancer Prevention & Research Center, Department of Pharmaceutical Sciences, College of Pharmacy, Washington State University, Pullman, WA 99164-6510, USA
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Zhang L, Brereton HM, Hahn M, Froscio M, Tilley WD, Brown MP, Barritt GJ. Expression of Drosophila Ca2+ permeable transient receptor potential-like channel protein in a prostate cancer cell line decreases cell survival. Cancer Gene Ther 2003; 10:611-25. [PMID: 12872143 DOI: 10.1038/sj.cgt.7700608] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The effects of expression of Drosophila melanoga ster Ca(2+) permeable transient receptor potential-like (TRPL) channels, under the control of the cytomegalovirus (CMV) or prostate cell-specific promoters, on cell survival and apoptosis in the androgen-sensitive LNCaP prostate cancer cell line were investigated. A prostate-specific antigen (PSA) promoter construct (designated PSAEn/PSAPr) composed of a 0.6 kb region of the promoter and a 1.45 kb region of the enhancer resulted in androgen-dependent and prostate-specific expression of a luciferase reporter gene in transiently transfected LNCaP cells. Expression of the enhanced green fluorescence protein-TRPL chimeric protein under the control of the CMV promoter was confirmed by Western blot. Whereas the majority of the expressed protein was located in the cytoplasmic space, confocal microscopy with the CD-9 protein as a plasma membrane marker demonstrated that approximately 10% of the expressed TRPL protein was located in a band in the plasma membrane. Using recombinant adenoviruses, expression of the TRPL protein was associated with an increase in both the initial and sustained rates of Ca(2+) inflow. Expression of TRPL under the control of the CMV promoter for 96 hours decreased cell number and increased the number of cells undergoing apoptosis by 23 and 27%, respectively. Apoptosis was inhibited by a caspase-3 inhibitor, Z-DEVD-fmk. It is concluded that, when heterologously expressed in LNCaP cells, the TRPL protein leads to a reduction in cell survival due, in part, to the induction of apoptosis. The effects of TRPL are likely caused by enhanced Na(+) and Ca(2+) inflow to the cells. This finding suggests a novel approach to modify the growth of prostate cancer cells that fail to undergo apoptosis following androgen ablation therapy.
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Affiliation(s)
- Lei Zhang
- Department of Medical Biochemistry, School of Medicine, Faculty of Health Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia
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Rothermund CA, Kondrikov D, Lin MF, Vishwanatha JK. Regulation of Bcl-2 during androgen-unresponsive progression of prostate cancer. Prostate Cancer Prostatic Dis 2003; 5:236-45. [PMID: 12496988 DOI: 10.1038/sj.pcan.4500582] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2001] [Accepted: 02/27/2002] [Indexed: 11/09/2022]
Abstract
The progression of prostate cancer from androgen-responsive to an androgen-unresponsive state remains the greatest obstacle in the treatment of this disease. Androgen-unresponsive prostate cancer is highly resistant to chemotherapy and radiation treatment that kill cells by the induction of apoptosis. Elucidating the molecular mechanisms of apoptosis regulation in prostate cancer can be useful in the development of new strategies for effective therapy of androgen-unresponsive cancer. We analyzed the Bcl-2 family of apoptosis regulators using various passages of the LNCaP prostate cancer cell line, which serve as an in vitro model for the progression of prostate cancer from androgen-responsive to androgen-unresponsive. In our model, progressively higher passages of LNCaP cells represent the progression to androgen-unresponsiveness. We examined the basal mRNA expression of the Bcl-2 family of apoptosis regulators. Under normal growth conditions, both androgen-responsive and androgen-unresponsive LNCaP cells express the Bcl-2 family of genes at similar levels. Western blot analysis showed the presence of Bcl-2 protein in androgen-responsive cells but not in androgen-unresponsive cells. Both androgen-responsive and androgen-unresponsive cells expressed Bax protein at similar levels. When exposed to oxidative stress, androgen-responsive cells underwent apoptosis but androgen-unresponsive cells exhibited resistance suggesting that the progression to androgen-unresponsiveness was associated with altered regulation of apoptosis. Treatment with paclitaxel or sodium butyrate induced apoptosis in both androgen-responsive and androgen-unresponsive cells suggesting that the apoptotic machinery is still intact in androgen-unresponsive LNCaP cells.
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Affiliation(s)
- C A Rothermund
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198-4525, USA
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Mimeault M, Pommery N, Hénichart JP. New advances on prostate carcinogenesis and therapies: involvement of EGF-EGFR transduction system. Growth Factors 2003; 21:1-14. [PMID: 12795332 DOI: 10.1080/0897719031000094921] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The prostate cancers (PCs) are among the major causes of death because therapeutic treatments are not effective against advanced and metastatic forms of this cellular hyperproliferative disorder. In fact, although androgen-deprivation therapies permit to cure localized PC forms, the metastatic PC cells have acquired multiple functional features that confer to them resistance to ionizing radiations and anticarcinogenic drugs currently used in therapy. The present review describes last advances on molecular mechanisms that might be responsible for sustained growth and survival of PC cells. In particular, emphasis is on intracellular signaling cascades which are involved in the mitogenic and antiapoptotic effects of epidermal growth factor EGF-EGFR system. Of therapeutic interest, recent advances and prospects for development of new treatments against incurable forms of metastatic PC forms are also discussed.
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Affiliation(s)
- Murielle Mimeault
- Institut de Chimie Pharmaceutique Albert Lespagnol, Faculté de Pharmacie, 3 Rue du Professeur Laguesse, BP83, 59006 Lille, Cédex, France.
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Ghafar MA, Anastasiadis AG, Chen MW, Burchardt M, Olsson LE, Xie H, Benson MC, Buttyan R. Acute hypoxia increases the aggressive characteristics and survival properties of prostate cancer cells. Prostate 2003; 54:58-67. [PMID: 12481256 DOI: 10.1002/pros.10162] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Androgen withdrawal, the standard therapeutic strategy for advanced prostate cancer, induces a rapid reduction of blood flow to prostate and prostate cancer tissues and the concomitant onset of a hypoxic environment in these tissues. To establish whether hypoxia-responsiveness (by means of the action of hypoxia inducible factor [HIF] -1alpha protein) might affect the tumorigenic or survival properties of prostate cancer cells, we studied how acute exposure of cultured human prostate cancer cells (LNCaP cell line) to hypoxia might alter their pattern of gene expression and their in vitro behavior. METHODS LNCaP cultures were placed in a hypoxia chamber for up to 24 hr and were compared with control (normoxic) cells for the expression of gene products by Western blotting and semiquantitative reverse transcription-polymerase chain reaction techniques. RESULTS Exposure of LNCaP cells to acute hypoxia activated a typical cellular hypoxia response characterized by up-regulation of HIF-1alpha and vascular endothelial growth factor protein expression. In contrast, expression of differentiation-specific proteins (prostate specific antigen and androgen receptor) or proliferative-regulatory proteins (c-myc, cyclin D1, p27) were down-regulated by hypoxia. Some of these latter changes (reduction of c-myc and cyclin D expression) were not accompanied by corresponding reduction of mRNAs and were abrogated by a proteosome inhibitor (MG132), suggesting that their loss was associated with their increased degradation rather than through transcriptional controls. The phosphorylation of Akt/protein kinase B and its downstream target, forkhead protein, was highly up-regulated by hypoxia, and cells exposed to transient periods of hypoxia became significantly less sensitive to an apoptotic stimulus (exposure to phorbol ester) when compared with normoxic cells. CONCLUSION This study demonstrates that even acute hypoxia has the potential to drastically alter the growth, differentiation characteristics, and apoptotic sensitivity of a prostate cancer cell.
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Affiliation(s)
- Mohamed A Ghafar
- The Department of Urology, The College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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Tombal B, Denmeade SR, Gillis JM, Isaacs JT. A supramicromolar elevation of intracellular free calcium ([Ca(2+)](i)) is consistently required to induce the execution phase of apoptosis. Cell Death Differ 2002; 9:561-73. [PMID: 11973614 DOI: 10.1038/sj.cdd.4400999] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2001] [Revised: 11/30/2001] [Accepted: 12/05/2001] [Indexed: 11/08/2022] Open
Abstract
Many agents, such as the endoplasmic reticulum Ca(2+) ATPase inhibitor, thapsigargin, or the ionophore, ionomycin, induce apoptosis by transiently elevating [Ca(2+)](i). The role of [Ca(2+)](i) in apoptosis induced by agents that do not immediately increase [Ca(2+)](i), such as 5-FdUr, TGF beta-1, doxorubicin, or radiation, is far more controversial. In the present paper, [Ca(2+)](i) was measured continuously for 120 h. in prostate and bladder cancer cell lines exposed to these four agents: 5-FdUR, TGF beta-1, doxorubicin, or radiation. Each of them consistently induced a delayed [Ca(2+)](i) rise associated with the morphological changes that characterize the execution phase of apoptosis (i.e. rounding, blebbing). This [Ca(2+)](i) rise occurred in two consecutive steps (< or = 10 microM and >10 microM) and resulted from a Ca(2+) influx from the extracellular medium. This delayed supramicromolar [Ca(2+)](i) rise was also observed previously in breast, prostate and bladder cancer cell lines exposed to thapsigargin. This influx regulated transcriptional reprogramming of Gadd153 and is required to activate cytochrome c release, caspase-3 activation, loss of clonal survival and DNA fragmentation. When cells were maintained in low extracellular Ca(2+) media, these phenomena were temporarily delayed but occurred on return to normal Ca(2+) medium. Similarly, apoptosis could be delayed by overexpressing the Ca(2+)-binding proteins, Calbindin-D(28K) and parvalbumin. As this delayed >or = 10 microM [Ca(2+)](i) elevation was observed in a number of cell lines exposed to a variety of different agents, we conclude that such elevation constitutes a key and general event of apoptosis in these malignant cells.
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Affiliation(s)
- B Tombal
- Johns Hopkins Oncology Center, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA.
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22
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Coffey RN, Watson RW, Hegarty PK, Watson CL, Wolohan L, Brady HR, O'Keane C, Fitzpatrick JM. Priming prostate carcinoma cells for increased apoptosis is associated with up-regulation of the caspases. Cancer 2001; 92:2297-308. [PMID: 11745284 DOI: 10.1002/1097-0142(20011101)92:9<2297::aid-cncr1576>3.0.co;2-b] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The potential to prime prostatic carcinoma cell lines for apoptosis represents an exciting strategy for the treatment of patients with this disease. The ability and the underlying molecular mechanisms involved in sensitizing both androgen-sensitive and androgen-insensitive cell types to a range of apoptotic-inducing agents are investigated by the authors. METHODS Primary and secondary cell lines were pretreated with diethyl-maleate (DEM) prior to the induction of apoptosis by Fas antibody (1 microg/mL), cycloheximide (1 microg/mL), etoposide (62.5 microM), and radiation (5 grays). It was demonstrated previously that DEM (50 microM) increases the sensitivity to apoptosis induced by these agents. The effects of DEM on both protein and RNA expression was determined by Western blot analysis and a ribonuclease protection assay, respectively. The effects of DEM on intracellular glutathione (GSH) levels and its intracellular distribution also were assessed. RESULTS DEM did not affect the expression of the caspases at the transcriptional level but was associated with increased procaspase-3 and caspase-8 protein levels. DEM preincubation restored sensitivity to Fas antibody and radiation-induced apoptosis in cells from the LNCaP-bcl-2 transfectant cell line that, normally, are resistant to these apoptotic stimuli. It is that DEM chemically depletes intracellular thiol levels. Although no depletion in total intracellular thiol GSH was observed at these concentrations of DEM, trafficking of GSH from the nucleus to the cytosol was demonstrated. CONCLUSIONS Identification of the caspases as a potential target for chemical manipulation may serve as an effective, adjuvant-based approach in the treatment of patients with prostate carcinoma and, in particular, for immunotherapy and radiation-based strategies that rely on the activation of these death-effector proteases.
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Affiliation(s)
- R N Coffey
- Department of Surgery, Mater Misericordiae Hospital, University College Dublin, 47 Eccles Street, Dublin 7, Ireland.
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Chaudhary KS, Abel PD, Stamp GW, Lalani E. Differential expression of cell death regulators in response to thapsigargin and adriamycin in Bcl-2 transfected DU145 prostatic cancer cells. J Pathol 2001; 193:522-9. [PMID: 11276013 DOI: 10.1002/1096-9896(2000)9999:9999<::aid-path821>3.0.co;2-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Functional overexpression of Bcl-2 has been reported to confer an anti-apoptotic potential in a variety of cell types. The role of Bcl-2 in epithelial cell-cycle control and in interactions with other cell-cycle regulators is not clearly understood. Its expression has been correlated with the hormono- and chemo-resistant phenotype in advanced prostate cancer. The aim of this study was to investigate the mechanisms through which Bcl-2 mediates increased cytotoxic chemoresistance by assessing alterations in the expression of cell death regulatory molecules. The DU145 human prostatic adenocarcinoma cell line was stably transfected with a Bcl-2 encoding expression plasmid. Two Bcl-2 transfectants, DKC9 and DKC11, were expanded for further study. The effects of Bcl-2 expression on cellular proliferation, cell death (+/- adriamycin or thapsigargin), and expression of cell-cycle/death regulators (p53, PCNA, Bax, Bak, Bcl-X(L)) were evaluated. Compared with controls, Bcl-2 transfectants showed no difference in the rate of proliferation, a decrease in p53 (approximately two-fold), an increase in Bax (approximately two-fold) and PCNA (approximately three-fold), and no change in the levels of Bcl-X(L) and Bak proteins. DKC9 and DKC11 also exhibited a significantly increased chemoresistance to adriamycin (0.0025-5 microM) and thapsigargin (0.0025-5 microM) compared with controls. In the presence of thapsigargin or adriamycin, levels of Bcl-2 and its heterodimeric partner Bax were elevated approximately two-fold with no change in Bak in Bcl-2 transfectants in contrast to controls, where Bak was increased (two-fold). This is the first study to demonstrate that Bcl-2 transfection modulates the expression of mutant p53, Bax, and PCNA in prostate cancer cells. Moreover, Bcl-2 overexpression conferred a significant cytotoxic chemoresistance and altered the balance of expression of death promoters (from Bak, a dominant death promoter in controls, to Bax) in response to thapsigargin and adriamycin.
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Affiliation(s)
- K S Chaudhary
- Department of Histopathology, Hammersmith Hospital Campus, Imperial College School of Medicine, Du Cane Road, London W12 0NN, UK.
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Abstract
PURPOSE The caspases are an evolutionary conserved family of cell death proteases. Their activation during apoptosis is an important underlying theme in prostate cancer therapy. We summarize the signaling pathways leading to the recruitment of the caspases and address the importance of recent therapeutic strategies aimed at specifically targeting these proteases in relation to prostate cancer. MATERIALS AND METHODS We present a background introduction into the role of the caspases in apoptosis and how failure to signal effectively their activation may contribute to prostate cancer progression. Key studies aimed at specifically targeting the caspases as cancer therapy are discussed. RESULTS Prostate carcinogenesis and apoptosis are related. The deregulation of apoptosis contributes to tumor initiation, metastasis and progression to the androgen insensitive state. Conversely the effectiveness of therapy often depends on its ability to induce apoptosis in prostate cancer cells. Identifying abnormalities in the apoptotic signaling pathway has greatly contributed to understanding the biology of prostate cancer. Elucidating caspase regulation has contributed to the design of novel therapies for prostate cancer. CONCLUSIONS We summarize the physiological and pathological pathways leading to caspase activation in the prostate and describe novel approaches that target these proteases.
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Affiliation(s)
- R N Coffey
- Department of Surgery, University College Dublin, Mater Misericordiae Hospital, Dublin, Ireland
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Abstract
BACKGROUND Glutathione (GSH) maintains an optimum cellular redox potential. Chemical depletion, physical efflux from the cell, or intracellular redistribution of this thiol antioxidant is associated with the onset of apoptosis. The aim of this study was to determine the effects of a thiol-depleting agent, diethylmaleate (DEM), on androgen sensitive and insensitive prostate carcinoma cells. METHODS LNCaP and PC-3 cell lines were induced to undergo apoptosis by DEM and diamide. Apoptosis was quantified by annexin V binding and propidium iodide incorporation using flow cytometry and was confirmed by DNA gel electrophoresis. Intracellular GSH was quantified using a thiol quantitation kit and the generation of reactive oxygen intermediates was measured using dihydrorhodamine 123. Western blot assessed caspase-3, caspase-8, Bcl-2, and Bcl-XL protein expression. Mitochondrial permeability was measured using DiOC6 and stabilized using bongkrekic acid. RESULTS DEM and diamide induced apoptosis in both androgen sensitive and insensitive cells. Apoptosis was also induced in an LNCaP transfectant cell line overexpressing Bcl-2. Apoptosis was caspase-3 dependent and caspase-8 independent. Bongkrekic acid partially prevented the effects of DEM on mitochondrial permeability but was unable to prevent the induction of apoptosis. Decreased Bcl-2 and Bci-XL protein expression was observed at the time of initial caspase-3 activation. CONCLUSIONS This study demonstrates that thiol depletion can be used as an effective means of activating caspase-3 in both androgen sensitive and insensitive prostate carcinoma cells. Direct activation of this effector caspase may serve as a useful strategy for inducing apoptosis in prostate carcinoma cells.
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Affiliation(s)
- R N Coffey
- Department of Surgery, University College Dublin, Mater Misericordiae Hospital, Ireland
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Wertz IE, Dixit VM. Characterization of calcium release-activated apoptosis of LNCaP prostate cancer cells. J Biol Chem 2000; 275:11470-7. [PMID: 10753965 DOI: 10.1074/jbc.275.15.11470] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Apoptosis inhibition rather than enhanced cellular proliferation occurs in prostate cancer (CaP), the most commonly diagnosed malignancy in American men. Therefore, it is important to characterize residual apoptotic pathways in CaP cells. When intracellular Ca(2+) stores are released and plasma membrane "store-operated" Ca(2+) entry channels subsequently open, cytosolic [Ca(2+)] increases and is thought to induce apoptosis. However, cells incapable of releasing Ca(2+) stores are resistant to apoptotic stimuli, indicating that Ca(2+) store release is also important. We investigated whether release of intracellular Ca(2+) stores is sufficient to induce apoptosis of the CaP cell line LNCaP. We developed a method to release stored Ca(2+) without elevating cytosolic [Ca(2+)]; this stimulus induced LNCaP cell apoptosis. We compared the apoptotic pathways activated by intracellular Ca(2+) store release with the dual insults of store release and cytosolic [Ca(2+)] elevation. Earlier processing of caspases-3 and -7 occurred when intracellular store release was the sole Ca(2+) perturbation. Apoptosis was attenuated in both conditions in stable transfected cells expressing antiapoptotic proteins Bclx(L) and catalytically inactive caspase-9, and in both scenarios inactive caspase-9 became complexed with caspase-7. Thus, intracellular Ca(2+) store release initiates an apoptotic pathway similar to that elicited by the dual stimuli of cytosolic [Ca(2+)] elevation and intracellular store release.
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Affiliation(s)
- I E Wertz
- Department of Human Physiology, School of Medicine, University of California, Davis, California 95616, USA
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