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Czubaty A, Piekiełko-Witkowska A. Protein kinases that phosphorylate splicing factors: Roles in cancer development, progression and possible therapeutic options. Int J Biochem Cell Biol 2017; 91:102-115. [PMID: 28552434 DOI: 10.1016/j.biocel.2017.05.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 11/30/2022]
Abstract
Disturbed alternative splicing is a common feature of human tumors. Splicing factors that control alternative splicing are phosphorylated by multiple kinases, including these that specifically add phosphoryl groups to serine-arginine rich proteins (e.g. SR-protein kinases, cdc2-like kinases, topoisomerase 1), and protein kinases that govern key cellular signaling pathways (i.e. AKT). Phosphorylation of splicing factors regulates their subcellular localization and interactions with target transcripts and protein partners, and thus significantly contributes the final result of splicing reactions. In this review we aim to summarize the current knowledge on the role of splicing kinases in cancer. Published studies and recently released data of The Cancer Genome Atlas demonstrate that expressions and activities of splicing kinases are commonly disturbed in cancers. Aberrant functioning of splicing kinases results in changed alternative splicing of tumor suppressors (e.g. p53) and regulators of cell signaling (e.g. MAPKs), apoptosis (e.g. MCL), and angiogenesis (VEGF). Splicing kinases act in complicated regulatory networks in which they mutually affect each other's activity to provide tight control of cellular signaling. Dysregulation of these regulatory networks contributes to oncogenic transformation, uncontrolled proliferation, enhanced migration and invasion. Furthermore, the activities of splicing kinases significantly contribute to cellular responses to genotoxic stress. In conclusion, published data provide strong evidence that splicing kinases emerge as important regulators of key processes governing malignant transformation, progression, and response to therapeutic treatments, suggesting their potential as clinically relevant targets.
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Affiliation(s)
- Alicja Czubaty
- Department of Molecular Biology, Faculty of Biology, University of Warsaw, ul. Miecznikowa 1, 02-096 Warsaw, Poland
| | - Agnieszka Piekiełko-Witkowska
- Department of Biochemistry and Molecular Biology, Centre of Postgraduate Medical Education, ul. Marymoncka 99/103, 01-813 Warsaw, Poland.
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Ali Y, Abd Hamid S. Human topoisomerase II alpha as a prognostic biomarker in cancer chemotherapy. Tumour Biol 2015; 37:47-55. [DOI: 10.1007/s13277-015-4270-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/15/2015] [Indexed: 12/12/2022] Open
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Feng Y, Zhang H, Gao W, Wen S, Huangfu H, Sun R, Bai W, Wang B. Expression of DNA topoisomerase II-α: Clinical significance in laryngeal carcinoma. Oncol Lett 2014; 8:1575-1580. [PMID: 25202370 PMCID: PMC4156233 DOI: 10.3892/ol.2014.2367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 06/19/2014] [Indexed: 01/03/2023] Open
Abstract
DNA topoisomerase II-α (Topo II-α) is essential for numerous cell processes, including DNA replication, transcription, recombination, and chromosome separation and condensation. Altered Topo II-α expression may lead to carcinogenesis and cancer progression. The aim of the present study was to investigate the association between Topo II-α expression levels and clinicopathological data from laryngeal cancer patients. Immunohistochemistry was used to analyze Topo II-α expression in laryngeal squamous cell carcinoma and distant healthy tissues obtained from 70 patients. In addition, fluorescence in situ hybridization was used to detect Topo II-α amplification and chromosome 17 ploidy using a laryngeal cancer tissue microarray. The expression of Topo II-α protein was detected in 71.43% (50/70) of laryngeal carcinoma tissues, in contrast to 9% of healthy tissues (2/22). Furthermore, the expression of Topo II-α protein was found to be associated with tumor de-differentiation and advanced tumor T stage. However, the expression of Topo II-α protein was not identified to be associated with Topo II-α amplification in laryngeal carcinoma, although was found to positively correlate with chromosome 17 aneuploidy (P<0.05). A higher aneuploidy rate contributed to increased expression levels of Topo II-α protein. Aberrant Topo II-α expression and chromosome 17 aneuploidy contributed to the development and progression of laryngeal cancer, indicating that targeting Topo II-α may provide a treatment strategy for patients with laryngeal cancer.
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Affiliation(s)
- Yan Feng
- Department of Otolaryngology, Head and Neck Surgery, The First Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China ; Nursing College of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Haili Zhang
- Department of Otolaryngology, Head and Neck Surgery, The First Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Wei Gao
- Department of Otolaryngology, Head and Neck Surgery, The First Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Shuxin Wen
- Department of Otolaryngology, Head and Neck Surgery, The First Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Hui Huangfu
- Department of Otolaryngology, Head and Neck Surgery, The First Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Ruifang Sun
- Department of Pathology, Shanxi Cancer Hospital, Taiyuan, Shanxi 030013, P.R. China
| | - Wei Bai
- Department of Pathology, Shanxi Cancer Hospital, Taiyuan, Shanxi 030013, P.R. China
| | - Binquan Wang
- Department of Otolaryngology, Head and Neck Surgery, The First Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China ; Nursing College of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
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Ben Abdelkrim S, Rammeh S, Ziadi S, Tlili T, Jaidane M, Mokni M. Expression of Topoisomerase II Alpha, ki67, and p53 in Primary Non-Muscle-Invasive Urothelial Bladder Carcinoma. J Immunoassay Immunochem 2014; 35:358-67. [DOI: 10.1080/15321819.2014.899254] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Stenvang J, Kümler I, Nygård SB, Smith DH, Nielsen D, Brünner N, Moreira JMA. Biomarker-guided repurposing of chemotherapeutic drugs for cancer therapy: a novel strategy in drug development. Front Oncol 2013; 3:313. [PMID: 24400218 PMCID: PMC3872326 DOI: 10.3389/fonc.2013.00313] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Accepted: 12/10/2013] [Indexed: 12/29/2022] Open
Abstract
Cancer is a leading cause of mortality worldwide and matters are only set to worsen as its incidence continues to rise. Traditional approaches to combat cancer include improved prevention, early diagnosis, optimized surgery, development of novel drugs, and honing regimens of existing anti-cancer drugs. Although discovery and development of novel and effective anti-cancer drugs is a major research area, it is well known that oncology drug development is a lengthy process, extremely costly and with high attrition rates. Furthermore, those drugs that do make it through the drug development mill are often quite expensive, laden with severe side-effects and unfortunately, to date, have only demonstrated minimal increases in overall survival. Therefore, a strong interest has emerged to identify approved non-cancer drugs that possess anti-cancer activity, thus shortcutting the development process. This research strategy is commonly known as drug repurposing or drug repositioning and provides a faster path to the clinics. We have developed and implemented a modification of the standard drug repurposing strategy that we review here; rather than investigating target-promiscuous non-cancer drugs for possible anti-cancer activity, we focus on the discovery of novel cancer indications for already approved chemotherapeutic anti-cancer drugs. Clinical implementation of this strategy is normally commenced at clinical phase II trials and includes pre-treated patients. As the response rates to any non-standard chemotherapeutic drug will be relatively low in such a patient cohort it is a pre-requisite that such testing is based on predictive biomarkers. This review describes our strategy of biomarker-guided repurposing of chemotherapeutic drugs for cancer therapy, taking the repurposing of topoisomerase I (Top1) inhibitors and Top1 as a potential predictive biomarker as case in point.
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Affiliation(s)
- Jan Stenvang
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen , Copenhagen , Denmark ; Danish Centre for Translational Breast Cancer Research , Copenhagen , Denmark
| | - Iben Kümler
- Department of Oncology, Center for Cancer Research, Herlev Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Sune Boris Nygård
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen , Copenhagen , Denmark
| | - David Hersi Smith
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen , Copenhagen , Denmark ; DAKO A/S , Glostrup , Denmark
| | - Dorte Nielsen
- Department of Oncology, Center for Cancer Research, Herlev Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Nils Brünner
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen , Copenhagen , Denmark ; Danish Centre for Translational Breast Cancer Research , Copenhagen , Denmark
| | - José M A Moreira
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, Section for Molecular Disease Biology and Sino-Danish Breast Cancer Research Centre, University of Copenhagen , Copenhagen , Denmark ; Danish Centre for Translational Breast Cancer Research , Copenhagen , Denmark
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Zhou S, Li N, Wang X, Li C, Tian F, Ren S, Zhang Y, He Y, Qiu Z, Zhao D, Chen X. In vitrocytotoxicity, pharmacokinetics and tissue distribution in rats of MXN-004, a novel conjugate of polyethylene glycol and SN38. Xenobiotica 2013; 44:562-9. [DOI: 10.3109/00498254.2013.868061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Tsavaris N, Lazaris A, Kosmas C, Gouveris P, Kavantzas N, Kopterides P, Papathomas T, Arapogiannis G, Zorzos H, Kyriakou V, Patsouris E. Topoisomerase I and IIalpha protein expression in primary colorectal cancer and recurrences following 5-fluorouracil-based adjuvant chemotherapy. Cancer Chemother Pharmacol 2008; 64:391-8. [PMID: 19083133 PMCID: PMC2688619 DOI: 10.1007/s00280-008-0886-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Accepted: 11/21/2008] [Indexed: 11/26/2022]
Abstract
Purpose Human DNA topoisomerases I and II (topo-I and -II) are essential for vital cellular processes such as DNA replication, transcription, translation, recombination, and repair. In the present study, we correlate topo-I and -II expression and outcome after chemotherapy in primary and relapsed colorectal cancer. Patients and methods Patients with colorectal cancer that had recurred, following surgery and adjuvant chemotherapy and underwent a second operation were included in the present study. All had undergone surgical resection of the primary tumor and received post-operatively 5-FU-based (5FU + Leucovorin, Mayo Clinic regimen) adjuvant chemotherapy. Tumor tissue was collected at the initial operation from the primary tumor and at the time of recurrence (during the second operation following chemotherapy). All tissue samples were analyzed for levels of expression of both topo-I and topo-IIa using standard three-step immunohistochemistry on paraffin sections. Results Forty patients were included. Levels of expression of topo-I and topo-II were higher in malignant cells from tumor recurrences compared to primary tumors (P = 0.0001 for both). There was a statistically significant positive relationship between patients age and levels of topo-I (P = 0.011) and topo-II (P = 0.011) expression. Conclusions The study results reported here underscore the role of topoisomerase expression in colorectal cancer and suggest a potential role in tumor recurrence.
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Affiliation(s)
- Nicolas Tsavaris
- Medical Oncology Unit, Department of Pathophysiology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens University School of Medicine, 11527 Athens, Greece
| | - Andreas Lazaris
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Christos Kosmas
- Second Department of Medical Oncology, “Metaxa” Cancer Hospital, Piraeus, Greece
| | - Panagiotis Gouveris
- Medical Oncology Unit, Department of Pathophysiology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens University School of Medicine, 11527 Athens, Greece
| | - Nikolaos Kavantzas
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Petros Kopterides
- Medical Oncology Unit, Department of Pathophysiology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens University School of Medicine, 11527 Athens, Greece
| | - Thomas Papathomas
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - George Arapogiannis
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Haralambos Zorzos
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Vassiliki Kyriakou
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Efstathios Patsouris
- First Department of Pathology, Medical School, “Laikon” University General Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Shamaa AA, Zyada MM, Wagner M, Awad SS, Osman MM, Abdel Azeem AA. The significance of Epstein Barr virus (EBV) & DNA topoisomerase II alpha (DNA-Topo II alpha) immunoreactivity in normal oral mucosa, oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC). Diagn Pathol 2008; 3:45. [PMID: 19021895 PMCID: PMC2611966 DOI: 10.1186/1746-1596-3-45] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 11/20/2008] [Indexed: 12/04/2022] Open
Abstract
Background Head and neck cancer including oral cancer is considered to develop by accumulated genetic alterations and the major pathway is cancerization from lesions such as intraepithelial dysplasia in oral leukoplakia and erythroplakia. The relationship of proliferation markers with the grading of dysplasia is uncertain. The involvement of EBV in oral carcinogenesis is not fully understood. Aim The present study was designed to investigate the role of EBV and DNA Topoisomerase II∝ (DNA-Topo II∝) during oral carcinogenesis and to examine the prognostic significance of these protein expressions in OSCCs. Methods Using specific antibodies for EBV and DNA-Topo II∝, we examined protein expressions in archival lesion tissues from 16 patients with oral epithelial dysplasia, 22 oral squamous cell carcinoma and 20 normal oral mucosa by immunohistochemistry. Clinical information was obtained through the computerized retrospective database from the tumor registry. Results DNA-Topo II∝ was expressed in all examined specimens. Analysis of Variance ANOVA revealed highly significant difference (P < 0.01) in young aged labial tissues and significant (P ≤ 0.05) in gingival and not significant (P > 0.05) in inferior surface of tongue and in hard palatal tissues. Significant differences were observed between OEDs and NSE (P < 0.001) and SCCs and controls (P < 0.001), also, significant differences could be observed between SCCs and OEDs. DNA-Topo II∝ expression was significantly higher in tumors of low differentiation versus tumors of moderate and high differentiation (P < 0.001), DNA-Topo II∝ expression was correlated with age, tumor size, tumor stage, node metastasis and tumor differentiation, but not with gender and tumor site. None of normal squamous epithelium (NSE) expressed EBV. Heterogenous reactivity for EBV was observed through the series of dysplasia and squamous cell carcinoma. Its expression increased progressively with lymph node metastasis and low tumor differentiation, but no significant association could be observed with other clinicopathological parameters. EBV protein expression was increased with elevated Topo II-∝ LI in OEDs and OSCCs. A tendency to positive correlation between EBV and Topo II∝ expression was observed in OEDs but not in OSCCs. Conclusion EBV and DNA Topo II-αLI expression are possible indicators in oral carcinogenesis and may be valuable diagnostic and prognostic indices in oral carcinoma.
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Affiliation(s)
- Ali A Shamaa
- Oral Biology Department, Faculty of Dentistry, Minia University, Minia, Egypt.
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Hadar T, Shvero J, Yaniv E, Shvili I, Leabu M, Koren R. Human topoisomerase II-alpha is highly expressed in sinonasal-inverted papilloma, but not in inflammatory polyp. J Cell Mol Med 2008; 12:1551-8. [PMID: 18544048 PMCID: PMC3918071 DOI: 10.1111/j.1582-4934.2008.00381.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Sinonasal-inverted papilloma is a benign tumour with a high rate of recurrence, but possible malignant transformation. Therefore, inves tigation of predisposition to malignant transformation of sinonasal-inverted papilloma gives clinicians the opportunity for adequate trea ment. Topoisomerase II-α (topoII-α) and Ki67 are markers of cell proliferation in both normal and neoplastic tissues and its level o expression could be used as a predictive parameter. Our goal was to investigate by immunochemistry the expression level of topoII-in inverted papilloma, inflammatory nasal polyp and normal sinonasal epithelium and to compare it with expression level of Ki67. TopoI α nuclear immunostaining showed a differential positivity in the investigated cases. The topoII-α index was 30.6 ± 12.8 in inverte papilloma, 10.7 ± 6.6 in the adjacent epithelium of inverted papilloma, but only 2.3 ± 2.0 in the normal sinonasal epithelium. The di ferences in topoII-α expression between inverted papilloma and normal sinonasal epithelia were statistically significant. In inflammator nasal polyp group, topoII-α index was 2.4 ± 2.1, and the difference in the topoII-α index between inverted papilloma and inflammator polyp group was also statistically significant. Nuclear immunostaining for Ki67 followed a similar variation. The Ki67 index was 50.0 ± 20. in inverted papilloma, 9.0 ± 6.6 in the adjacent epithelium of inverted papilloma and 2.4 ± 0.9 in normal sinonasal epithelium. The di ferences in Ki67 expression between inverted papilloma and either adjacent or normal sinonasal epithelia were statistically significan Significant correlation coefficients were found between topoII-α and epithelial thickness (r = 0.70, P > 0.0001), and between Ki67 inde and epithelial thickness (r = 0.71, P> 0.0001). In the inflammatory nasal polyp group Ki67 index was 5.9 ± 3.4. The difference in th Ki67 index between inverted papilloma and inflammatory nasal polyp groups was statistically significant. Significant correlation coeff cient was found between topoII-α index and Ki67 index in inverted papilloma (r = 0.42, P > 0.05). These results suggest that the inverte papilloma contains a significantly higher cell population with proliferative activity by comparison with normal sinonasal and inflamma tory polyp epithelia, showing a significant correlation between topoII-α and Ki67 expression, and indicating that topoII-α could be a independent prognostic factor for a putative malignant transformation.
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Affiliation(s)
- Tuvia Hadar
- Department of Head and Neck Surgery, Rabin Medical Center, Petah Tikva, Israel
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Gouveris P, Lazaris AC, Papathomas TG, Nonni A, Kyriakou V, Delladetsima J, Patsouris ES, Tsavaris N. Topoisomerase I protein expression in primary colorectal cancer and recurrences after 5-FU-based adjuvant chemotherapy. J Cancer Res Clin Oncol 2007; 133:1011-5. [PMID: 17605046 DOI: 10.1007/s00432-007-0253-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2006] [Accepted: 06/04/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE Our aim was to investigate whether chemotherapy with 5-FU induces an alteration in the levels of topoisomerase I (topo I) in colorectal neoplastic tissues METHODS Twenty-five colorectal cancer patients were included in our study; these had undergone surgical resection of the primary tumor, received post-operatively 5-FU-based adjuvant chemotherapy and then suffered from recurrences. In a standard three-step immunohistochemical procedure, a monoclonal antibody to topo I was applied in both specimens from each patient (one from the primary location and a second one from the recurrence). Statistical analysis was subsequently performed. RESULTS Malignant cells from the recurrences displayed a statistical significant increase, concerning the levels of topoisomerase I, by comparison with the primary tumors (P=0.01). The increase in topo I levels did not demonstrate significant correlations with Duke's stage (Fisher's Exact Test P value=0.496), differentiation grade (P value=0.661), localization (P value=0.072), patient sex (P value=0.434), nor with relapse free interval (P value=0.493). There was a statistically significant relationship between the age of patients and increase in topo I levels (P=0.011). CONCLUSIONS Topo I expression may be part of the malignant cells' phenotype in recurrent colorectal carcinomas, suggesting a potential role for Topo I in the acquisition of a metastatic phenotype. The increase of topo I immunohistochemical status is likely to be attributed to 5-FU and given the fact that high levels of topo I correlate with sensitivity to camptothecin, advanced colorectal cancer patients seem to benefit from topo I targeted anticancer drug therapy.
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Affiliation(s)
- P Gouveris
- Medical Oncology Unit, Department of Pathophysiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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Shingnapurkar D, Butcher R, Afrasiabi Z, Sinn E, Ahmed F, Sarkar F, Padhye S. Neutral dimeric copper–sparfloxacin conjugate having butterfly motif with antiproliferative effects against hormone independent BT20 breast cancer cell line. INORG CHEM COMMUN 2007. [DOI: 10.1016/j.inoche.2006.12.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Xie JJ, Xu LY, Zhang HH, Cai WJ, Mai RQ, Xie YM, Yang ZM, Niu YD, Shen ZY, Li EM. Role of fascin in the proliferation and invasiveness of esophageal carcinoma cells. Biochem Biophys Res Commun 2005; 337:355-62. [PMID: 16185662 DOI: 10.1016/j.bbrc.2005.09.055] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 09/08/2005] [Indexed: 01/12/2023]
Abstract
Fascin, an actin-bundling protein, induces membrane protrusions and increases cell motility in various transformed cells. The overexpression of fascin in esophageal squamous cell carcinoma (ESCC) has been described only recently, but the roles and mechanism still remained unclear. Here, by using RNA interference (RNAi), we have stably silenced the expression of the fascin in EC109 cells, an ESCC cell line. Down-regulation of fascin resulted in a suppression of cell proliferation and as well as a decrease in cell invasiveness. Furthermore, we revealed that fascin might have functions in regulating tumor growth in vivo. The effect of fascin on cell invasiveness correlated with the activation of matrix metalloproteases such as MMP-2 and MMP-9. We examined that fascin down-expression also led to a decrease of c-erbB-2 and beta-catenin at the protein level. These results suggested that fascin might play crucial roles in regulating neoplasm progression of ESCC.
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Affiliation(s)
- J J Xie
- Department of Biochemistry and Molecular Biology, Medical College of Shantou University, Shantou 515041, PR China
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Simon R, Atefy R, Wagner U, Forster T, Fijan A, Bruderer J, Wilber K, Mihatsch MJ, Gasser T, Sauter G. HER-2 and TOP2A coamplification in urinary bladder cancer. Int J Cancer 2004; 107:764-72. [PMID: 14566826 DOI: 10.1002/ijc.11477] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
HER-2/NEU is one of the most frequently amplified oncogenes and a potential therapeutic target in bladder cancer. In breast cancer, the adjacent TOP2A gene, the molecular target for several anticancer drugs, is frequently coamplified together with HER-2. To study the amplification and expression of TOP2A and HER-2 and associations with tumor phenotype and clinical outcome in bladder cancer, a tissue microarray containing 2,317 bladder tumor samples was analyzed by FISH and immunohistochemistry. Overall amplification frequencies were 6.3% for HER-2 and 1.5% for TOP2A. Amplifications were most frequently seen in advanced-stage (pT2-4) tumors (HER-2 13.8%, TOP2A 3.4%). Of HER-2-amplified tumors, 56% also had alterations of TOP2A, including 14.7% coamplifications, 33.3% gains and 8% deletions. Only 17.6% of TOP2A amplifications occurred independently of HER-2 alterations. Both HER-2 and TOP2A amplifications were significantly associated with advanced tumor stage (HER-2 p < 0.0001, TOP2A p = 0.0218), high grade (p < 0.0001 for both) and protein overexpression (p < 0.0001 for both). TOP2A amplification and overexpression were linked to shortened survival in muscle-invasive tumors (p = 0.0042 and 0.0077, respectively). In summary, our data suggest that HER-2 amplifications are frequently linked to alterations of the TOP2A gene in bladder cancer. The anatomy of the 17q12-q21 amplicon may be important for response to therapies targeting HER-2 or TOP2A.
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Affiliation(s)
- Ronald Simon
- Institute for Pathology and Urologic Clinics, University of Basel, Basel, Switzerland.
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Koren R, Kugel V, Dekel Y, Weissman Y, Livne PM, Gal R. Human DNA topoisomerase-IIalpha expression as a prognostic factor for transitional cell carcinoma of the urinary bladder. BJU Int 2003; 91:489-92. [PMID: 12656900 DOI: 10.1046/j.1464-410x.2003.04118.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the immunohistochemical expression of topoisomerase II-alpha (TII-alpha, a nuclear enzyme, the expression of which increases rapidly at the end of the S to G2/M phase and declines when mitosis ends) in bladder urothelial neoplasms (transitional cell carcinoma), and its correlation with grade, stage and survival. PATIENTS AND METHODS Histological sections from 57 urothelial neoplasms were stained immunohistochemically for TII-alpha expression; the percentage of positive cells in the area of greatest staining was recorded as the TII-alpha index. RESULTS TII-alpha nuclear staining was positive in all the samples except one. The mean (sd) TII-alpha index was 10.7 (5.9) in urothelial neoplasms of low malignant potential (grade 1), 15.5 (5.0) in low-grade (grade 2) and 42.1 (13.4) in high-grade urothelial carcinoma (grade 3). The mean TII-alpha index was 10.7 (5.9), 26.3 (14.8) and 44 (19) in stages pTa, pT1 and pT2, respectively. The TII-alpha index was significant for predicting death from cancer, independently of the stage or grade of the disease (P = 0.019, hazard ratio 1.1). CONCLUSIONS A higher TII-alpha index indicates a greater probability of recurrence of disease and lower overall survival. Therefore TII-alpha expression has prognostic value in bladder carcinoma.
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Affiliation(s)
- R Koren
- Department of Pathology, Hasharon Hospital, Rabin Medical Center, Petah Tikva, Israel.
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Abstract
It is thought that when tumor cells are treated with anticancer drugs, they die through the apoptotic pathway and that cell resistance to cancer chemotherapy is mainly a resistance to apoptosis commitment. p53 is not functional in nearly half of the tumors examined and because of its involvement (directly or through its target genes) in the apoptotic pathway, drug resistance to chemotherapy has been largely attributed to the status of this "tumor suppressor protein". Topoisomerase II (topo II) inhibitors are widely used not only as single agents, but also in the majority of combination treatment protocols for hematologic malignancies and solid tumors. The relationship between p53 and topo II raises many questions about basic regulatory, biochemical, structural and functional characteristics that could be different in cells in different tissues, and most importantly, between different tumor cell types and their normal tissue counterpart. Understanding these relationships may lead to strategies for chemotherapy optimization and further precision targeting of tumor cells in order to avoid drug resistance and thereby chemotherapy failure.
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Affiliation(s)
- Nikola I Valkov
- Department of Interdisciplinary Oncology, H Lee Moffitt Cancer Center and Research Institute, University of South Florida, 12902 Magnolia Drive, Tampa, FL 33612, USA
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16
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Boonsong A, Curran S, McKay JA, Cassidy J, Murray GI, McLeod HL. Topoisomerase I protein expression in primary colorectal cancer and lymph node metastases. Hum Pathol 2002; 33:1114-9. [PMID: 12454816 DOI: 10.1053/hupa.2002.129202] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Topoisomerase I (topo I) is an important target for the treatment of malignant disease, especially colorectal cancer. Because there is little information on the expression of topo I in colorectal tumors, this study evaluated and characterized topo I protein expression in primary colorectal cancer and lymph node metastases and studied the association between topo I protein expression and clinicopathologic data, p53 status, and proliferating cell nuclear antigen (PCNA) status. Immunohistochemistry assay was performed for topo I protein expression in 249 primary human colorectal cancer and 42 paired lymph node metastasis samples. Topo I expression was described as the percentage of cells staining positive for topo I, along with the intensity and localization of the staining. Clinicopathologic data (sex, age, Dukes' stage, differentiation grade, survival status), p53 status, and PCNA status were statistically analyzed for association with topo I protein expression. Topo I expression in paired primary lymph node metastases were studied for concordance. Topo I protein expression was detected in 127 (51%) samples, including 24.4% with >50% positive tumor cells. The majority had nuclear (70.1%) or nuclear and cytoplasmic staining (17.3%). A higher percentage of cells expressing topo I in primary colorectal cancer was significantly associated with advanced age (P =.040). Patients with rectal cancer had greater topo I expression than those with colon tumors (P =.029). No significant correlation was found between topo I protein expression and sex, Dukes' stage, differentiation grade, survival status, p53 status, and PCNA status. Concordance in topo I staining between primary and lymph node metastases was observed in 33 of 42 cases (P =.029). This suggests that the activity of topo I inhibitors will not differ across various tumor stages, pathology, and patient gender. p53 and PCNA status do not appear to influence topo I expression, and topo I has no apparent association with the acquisition of a metastatic phenotype. Topo I expression now needs to be evaluated in patients undergoing topo I-inhibitor therapy, to better define the role of this protein as a predictive marker.
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Affiliation(s)
- Attasit Boonsong
- Department of Medicine & Therapeutics and Pathology, University of Aberdeen Institute of Medical Sciences, Aberdeen, Scotland, UK
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17
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Berney DM, Shamash J, Gaffney J, Jordan S, Oliver RTD. DNA topoisomerase I and II expression in drug resistant germ cell tumours. Br J Cancer 2002; 87:624-9. [PMID: 12237772 PMCID: PMC2364243 DOI: 10.1038/sj.bjc.6600472] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2002] [Revised: 05/21/2002] [Accepted: 05/23/2002] [Indexed: 12/02/2022] Open
Abstract
A small number of testicular germ cell tumours are refractory to current chemotherapy regimens. DNA topoisomerase I is the target for several new drugs and a potential candidate treatment for chemorefractory germ cell tumours. DNA topoisomerase II alpha is the target for etoposide, which is currently used regularly in germ cell tumour treatment. The expression of DNA topoisomerase I and II alpha were therefore assessed immunohistochemically in a range of testicular tumours, especially those with persistent malignant elements on retroperitoneal lymph node dissection. Pre-chemotherapy orchidectomy specimens were matched with post-chemotherapy retroperitoneal lymph node dissections to examine changes in expression. There was considerable variation in the expression of topoisomerase I in different tumour types. Both yolk sac tumours and teratoma, mature showed universal expression of topoisomerase I, while 38% of seminomas and 30% of embryonal carcinomas were positive. Strong topoisomerase II alpha expression was found in embryonal carcinoma. There was a negative correlation between topoisomerase I and II alpha expression (P=0.004) and downregulation of topoisomerase II alpha after chemotherapy (P=0.02). Topoisomerase I expression appears to increase in those cases with residual teratoma, mature, but is largely unchanged in those cases remaining as embryonal carcinoma. These results suggest that topoisomerase I inhibitors may be useful in chemorefractory germ cell tumours, especially yolk sac tumours and where there are unresectable residual teratoma, mature deposits.
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Affiliation(s)
- D M Berney
- Department of Histopathology and Morbid Anatomy, St Bartholomew's Hospital, Queen Mary's School of Medicine and Dentistry, London EC1 7BE, UK.
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18
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Coleman LW, Rohr LR, Bronstein IB, Holden JA. Human DNA topoisomerase I: An anticancer drug target present in human sarcomas. Hum Pathol 2002; 33:599-607. [PMID: 12152158 DOI: 10.1053/hupa.2002.124911] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
New anticancer drugs targeting DNA topoisomerase I (topo I) are showing activity against human sarcomas. Laboratory studies have indicated that cells responsive to topo I-targeted drugs have elevated levels of topo I, require active DNA replication, and may require a functional apoptotic pathway. In this study, we evaluated these potential markers of topo I-targeted drug sensitivity in 55 cases of human sarcoma (42 high grade, 4 intermediate grade, and 9 low grade). By immunohistochemical staining, we observed elevated topo I expression in 20 of 55 neoplasms (36%). Immunohistochemical staining for the proliferation marker DNA topoisomerase II-alpha (topo II-alpha), showed that 15 of 55 neoplasms (27%) had topo II-alpha indices >50, indicating a large number of actively cycling tumor cells. Abnormal p53 expression was observed in 19 of the 55 cases (35%). None of the cases were interpreted as positive for ALK-1. To complement our immunohistochemical staining of topo I, we isolated functionally active topo I from extracts of a human sarcoma. These isolates demonstrated that sarcoma topo I is sensitive to topo I-targeted anticancer drugs. Of the 55 cases of human sarcoma, 7 (13%) had high levels of topo I, a large number of cycling tumor cells, and normal p53 expression. These are the molecular parameters that might suggest responsiveness to drugs targeting topo I.
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Affiliation(s)
- Landon W Coleman
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City 84132, USA
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Gupta D, Shidham V, Holden J, Layfield L. Value of topoisomerase II alpha, MIB-1, p53, E-cadherin, retinoblastoma gene protein product, and HER-2/neu immunohistochemical expression for the prediction of biologic behavior in adrenocortical neoplasms. Appl Immunohistochem Mol Morphol 2001; 9:215-21. [PMID: 11556748 DOI: 10.1097/00129039-200109000-00004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Prediction of biologic behavior in adrenocortical neoplasms is difficult because of the lack of availability of reliable clinical, biochemical, and pathologic prognostic markers. Reliable objective markers predictive of clinical outcome in adrenocortical neoplasms are needed to assign optimal treatment of potentially malignant tumors. In the current article, the authors evaluated a set of molecular markers (topoisomerase II alpha (Topo II alpha), MIB-1, p53, human epithelial cadherin (E-cadherin), retinoblastoma gene protein product, and HER-2/neu) and correlated their expression with histologic diagnosis and clinical outcome. Paraffin-embedded, formalin-fixed tissue blocks from 30 cases of adrenocortical neoplasms (15 benign and 15 malignant) were obtained from the surgical pathology archives at the University of Utah Health Sciences Center (Salt Lake City, UT) and the Medical College of Wisconsin (Milwaukee, WI). Age, gender, recurrence, tumor size and weight, hemorrhage, necrosis, pleomorphism, mitotic count, capsular and lymphovascular invasion, hyaline globules, intranuclear inclusions, and immunohistochemical expression of Topo II alpha, p53, MIB-1, E-cadherin, retinoblastoma gene protein product, and HER-2/neu were studied. Clinical data were obtained from the clinical charts, or communication with the treating physician, or both. Adrenocortical neoplasms with hemorrhage, necrosis, large size (>5 cm), weight more than 100 g, nuclear pleomorphism, lymphovascular invasion, and brisk mitotic rate (more than 5 per 30 high-power fields) were more likely to behave in a malignant fashion (P approximately 0.001-0.009). The difference in proliferation indices in benign and malignant neoplasms was statistically significant (P < 0.001). The difference in p53 staining in benign and malignant neoplasms also was statistically significant (P < 0.001). Higher p53 labeling index (>20%) was present in 73% (11/15) of malignant lesions but was found in only 1 of 15 (6.6%) benign lesions. The difference in retinoblastoma staining between benign and malignant neoplasms was statistically significant (P = 0.004). There was no significant difference in staining pattern of E-cadherin expression between benign and malignant lesions. HER-2/neu overexpression was not observed in any of the benign or malignant adrenocortical neoplasms.
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Affiliation(s)
- D Gupta
- Magee Women's Hospital and University of Pittsburgh, Pennsylvania, USA
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Nakopoulou L, Zervas A, Lazaris AC, Constantinides C, Stravodimos C, Davaris P, Dimopoulos C. Predictive value of topoisomerase II alpha immunostaining in urothelial bladder carcinoma. J Clin Pathol 2001; 54:309-13. [PMID: 11304849 PMCID: PMC1731402 DOI: 10.1136/jcp.54.4.309] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
AIMS The nuclear enzyme DNA topoisomerase II has been shown to be required for chromatin condensation and chromosomal segregation during mitosis; its isoform topo II alpha is linked with active cell proliferation in mammalian cells. The aim of this study was to examine the relation of the expression of topo II alpha to the biological behaviour of conventional urinary bladder cancer. METHODS Formalin fixed, paraffin wax embedded tissue from 94 specimens of bladder urothelial cancer were immuno-histochemically stained for topo II alpha. For each case, a topo II alpha index was determined. A similar index had been determined for Ki-67, a known cell proliferation marker. Each case had also been graded, staged, and evaluated for DNA ploidy as well as for p53 and bcl-2 immunoreactivity. RESULTS Raised topo II alpha expression (in > or = 10% of malignant nuclei) correlated with two adverse prognosticators--high grade (p = 0.027) and invasion of the muscularis propria (p = 0.013), but with no other evaluated parameter. By multivariate survival analysis using Cox's proportional hazard model, high expression of topo II alpha was found to be predictive for worse survival (p = 0.0047). Patients' age, tumour stage, and grade were also retained as independent prognostic factors (p = 0.0349, p = 0.00005, and p = 0.0130, respectively). The negative influence of increased topo II alpha immunopositivity on patients' survival was also seen in the subgroup of patients with non-muscle invasive carcinomas (p = 0.0004), in patients with a bcl-2 negative phenotype (p = 0.0330), and in those with low Ki-67 indices (p = 0.0341). CONCLUSIONS Because topo II alpha and Ki-67 failed to demonstrate a significant interrelation, they appear to be different molecules that both function at separate phases in the complex process of cellular proliferation. The assessment of increased topo II alpha immunoreactivity in specimens from urothelial carcinomas might help to select patients (particularly among those with superficial tumours) in the worse prognostic categories for new therapeutic strategies.
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Affiliation(s)
- L Nakopoulou
- Department of Pathology, Athens National University School of Medicine, 75 Mikras Asias Str., Goudi, GR-115 27 Athens, Greece.
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Prognostic value of immunohistochemical expression of topoisomerase alpha II, MIB-1, p53, E-cadherin, retinoblastoma gene protein product, and HER-2/neu in adrenal and extra-adrenal pheochromocytomas. Appl Immunohistochem Mol Morphol 2001. [PMID: 11127918 DOI: 10.1097/00022744-200012000-00003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
No reliable pathologic criteria have been identified that predict clinical behavior in adrenal and extra-adrenal pheochromocytomas (PHEOs). Reliable prognostic markers for the prediction of clinical outcome are needed to assign optimal treatment for potentially malignant tumors. In this report, we evaluated several molecular markers (topoisomerase II alpha, E-cadherin, HER-2/neu, and retinoblastoma (RB) gene protein) that have not been previously studied in PHEOs. Paraffin-embedded, formalin-fixed tissue blocks from 50 cases of PHEO (30 benign and 20 malignant, 31 adrenal and 19 extra-adrenal) were obtained from University of Utah Health Sciences Center, Salt Lake City, and the Medical College of Wisconsin, Milwaukee. Gross (tumor size, weight, local extension, cyst formation, hemorrhage, necrosis), microscopic (pleomorphism, hyaline globules, intranuclear inclusion, mitotic count, capsular and vascular invasion, ganglionic/neuronal differentiation), and immunohistochemical features (topoisomerase II alpha, p53, MIB-1, E-cadherin, RB, and HER-2/neu) were studied. With the exception of vascular invasion (P = 0.025), there were no unequivocal gross or microscopic characteristics that distinguished benign from malignant lesions (P approximately = 0.11-0.71). Topoisomerase III and MIB-1 indices in malignant lesions were significantly higher than those observed in benign lesions (P = 0.012 and 0.019). Differences in p53 expression were not statistically significant (P = 0.082). Loss in RB protein product expression was significantly more common in malignant lesions (P = 0.001), E-cadherin loss and HER-2/-neu overexpression were not observed in any of the benign or malignant lesions. We studied the immunohistochemical expression of topoisomerase II alpha, MIB-1, p53, RB gene protein product, E-cadherin, and HER-2/neu in a series of adrenal and extra-adrenal PHEOs. Overexpression of topoisomerase II alpha and MIB-1 and loss of RB protein product were more common in malignant lesions, whereas p53, E-cadherin, and HER-2/neu do not seem to have diagnostic utility in the prediction of biologic behavior in these neoplasms.
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Prognostic Value of Immunohistochemical Expression of Topoisomerase Alpha II, MIB-1, p53, E-Cadherin, Retinoblastoma Gene Protein Product, and HER-2/neu in Adrenal and Extra-adrenal Pheochromocytomas. Appl Immunohistochem Mol Morphol 2000. [DOI: 10.1097/00129039-200012000-00003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Gupta D, Bronstein IB, Holden JA. Expression of DNA topoisomerase I in neoplasms of the kidney: correlation with histological grade, proliferation, and patient survival. Hum Pathol 2000; 31:214-9. [PMID: 10685636 DOI: 10.1016/s0046-8177(00)80222-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Renal cell carcinoma is an inherently chemotherapeutically resistant neoplasm. Because of this, new drugs targeting this tumor are needed. One class of new anticancer drug targets the enzyme DNA topoisomerase I. Laboratory data indicate that cells sensitive to topo I targeting drugs contain high topo I levels. To determine whether some renal cell carcinomas contain elevated topo I and might therefore be targets of topo I active antitumor agents, we used a new immunohistochemical stain for topo I to determine the expression of the enzyme in 51 tumors of the kidney. Increased topo I expression was found in 4 of 11 (36%) grade 3 renal cell carcinomas and in 8 of 8 (100%) grade 4 renal cell carcinomas. Normal topo I expression was observed in all adenomas, oncocytomas, and grade 1 and grade 2 renal cell carcinomas. Because topo I targeted anticancer drugs are S-phase specific, topo II-alpha and MIB-1 proliferation indices also were performed. Topo II-alpha correlates well with MIB-1 (correlation coefficient = 0.96). Of the 12 tumors with elevated topo I, only 3 had topo II-alpha proliferation indices greater than 40, indicating a tumor with elevated topo I expression and a large growth fraction. We hypothesize that these tumors might be susceptible to topo I anticancer drug therapy. In addition, we found that the average topo II-alpha proliferation index of tumors from patients who died of disease was 27.4 +/- 19.8, which was statistically different from the average topo II-alpha index of 5.8 +/- 6.5 observed in tumors from patients who remained alive during our follow-up.
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Affiliation(s)
- D Gupta
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City 84132, USA
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Holden JA, Wall ME, Wani MC, Manikumar G. Human DNA topoisomerase I: quantitative analysis of the effects of camptothecin analogs and the benzophenanthridine alkaloids nitidine and 6-ethoxydihydronitidine on DNA topoisomerase I-induced DNA strand breakage. Arch Biochem Biophys 1999; 370:66-76. [PMID: 10496978 DOI: 10.1006/abbi.1999.1355] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human DNA topoisomerase I (topo I) has been purified from normal placenta and from a recombinant baculovirus expression system. A new radiolabeled plasmid DNA assay has been used to quantitate the activity of the purified enzymes and to compare the ability of several types of topo I-targeted drugs to induce topo I-mediated DNA strand breaks. The 100-kDa recombinant enzyme form isolated from the baculovirus expression system is able to relax 2564 ng of supercoiled M-13 mp19 plasmid per minute per nanogram of enzyme. The addition of camptothecin (1 microM) to the reaction lowers the rate to 1282 ng per minute per nanogram of enzyme. The 100-kDa topo I from human placenta is able to relax 1092 ng of supercoiled plasmid per minute per nanogram of enzyme and the 68-kDa topo I form from placenta is able to relax 2069 ng of supercoiled plasmid per minute per nanogram of enzyme. Camptothecin (1 microM) decreases the relaxation rate of the placental enzymes about 50%. In the presence of several different types of topo I-targeted drugs, both the recombinant and placental enzymes are induced to cleave plasmid DNA. Quantitative DNA cleavage assays with radioactive plasmid DNA and 9-aminocamptothecin, topotecan, SN-38, 10, 11-methylenedioxycamptothecin, 7-ethyl-10, 11-methylenedioxycamptothecin, 7-chloromethyl-10, 11-methylenedioxycamptothecin, nitidine, and 6-ethoxy-5, 6-dihydronitidine indicate that the order of potency in inducing topo I-mediated DNA breakage is methylenedioxycamptothecin analogs > SN-38 > 9-aminocamptothecin > topotecan and camptothecin > nitidine compounds. The order of potency correlates with the half-lives of the topo I-DNA drug complex determined with radiolabeled DNA in 0.45 M NaCl at 30 degrees C. The half-life of the complex formed with 7-chloromethyl-10,11-methylenedioxycamptothecin is greater than 90 min whereas the half-life of the topo I-DNA complex with 6-ethoxy-5, 6-dihydronitidine is less than 15 s. The other drugs tested were found to have drug complex half-lives which fall between these two extremes.
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Affiliation(s)
- J A Holden
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah, 84132, USA
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