Topo IIα Protein Expression Research Articles

Inhibition of topoisomerase IIα and induction of DNA damage in cholangiocarcinoma cells by altholactone and its halogenated benzoate derivatives

Topoisomerase IIα enzyme (Topo IIα) plays a critical function in DNA replication process and is considered to be a promising target of anti-cancer drugs. In the present study, we reported that the altholactone derivatives modified by adding a halogenated benzoate group showed greater inhibitory activity on Topo IIα enzyme in cell-free system concomitant with cytotoxicity against the CCA cell lines (KKU-M055 and KKU-M213) than those of the parent altholactone. However, the cytotoxic activities of four halogenated benzoate altholactone derivatives including iodo-, fluoro-, chloro-, and bromobenzoate derivatives (compound 1, 2, 3, and 4, respectively) were of equal potency. The fluorobenzoate derivative (compound 2) was chosen for investigating the underlying mechanism in CCA cells. Compound 2 arrested CCA cell cycle at sub G1 phase and induced apoptotic cell death. It markedly inhibited Topo IIα protein expression in both KKU-M055 and KKU-M213 cells, which was accompanied by DNA double-strand breaks demonstrated by an increase in phosphorylated H2A.X protein. Interestingly, KKU-M055 cells, which express higher Topo IIα mRNA compared to KKU-M213 cells, showed greater sensitivity to the compound, indicating the selectivity of the compound to Topo IIα enzyme. By computational docking analysis, the binding affinity of altholactone (-52.5 kcal/mol) and compound 2 (-56.7 kcal/mol) were similar to that of the Topo II poison salvicine (-53.7 kcal/mol). The aromatic moiety of both altholactones embedded in a hydrophobic pocket of Topo II ATPase domain. In addition, compound 2 induced the formation of linear DNA in Topo II-mediated cleavage assay. Collectively, our results demonstrate that the addition of fluorobenzoyl group to altholactone enhances potency and selectivity to inhibit type IIα topoisomerases. Atholactone and fluorobenzoate derivative act as Topo II cleavage complexes stabilizing compounds or Topo II poisons preferentially through binding at ATPase domain of Topo IIα, leading to DNA double-strand breaks and apoptosis induction. Such activity of 3-fluorobenzoate derivative of altholactone should be further explored for the development of an anti-cancer drug for CCA.

Topoisomerase IIa Protein Expression Patterns in Laryngeal Squamous Cell Carcinoma.

Topoisomerase II alpha (TopoIIa) is a critical gene associated with response to chemo-therapeutic agents, such as anthracyclines, especially in breast adenocarcinoma. The aim of this study was to investigate the role of aberrant TopoIIa protein expression in laryngeal squamous cell carcinoma (LSCC). Fifty (n=50) LSCC cases were enrolled in the study. Immunohistochemistry and a digital image analysis assay were implemented. TopoIIa protein overexpression was observed in 32/50 (64%) cases, whereas low expression rates were detected in 18/50 (36%). TopoIIa overall expression presented strong association with the grade of the examined malignant tissues and borderline association with stage. TopoIIa overexpression correlated also with Human papillomavirus (HPV) positivity. TopoIIa overexpression was observed in significant subsets of LSCCs, and correlated predominantly with the grade of differentiation. HPV persistent infection seems to be associated with increased TopoIIa protein expression. TopoIIa expression analysis appears to be critical in identifying sub-groups of patients eligible for specific chemotherapy.

Abstract P5-16-04: A randomized phase II neoadjuvant study comparing docetaxel and cyclophosphamide (TC) with 5-fluorouracil, epirubicin, and cyclophosphamide followed by docetaxel (FEC-D) for hormone receptor-negative breast cancer: The Kanagawa breast oncology group (KBOG) 1101 study

Abstract Purpose: This study aimed to evaluate response to neoadjuvant chemotherapy (NAC) for patients with hormone receptor-negative (HR-negative) breast cancer (BC) to identify subtypes that require anthracycline treatment. Methods: In total, 103 patients with operable HR-negative BC were registered. They were randomely assigned to administration of 6 cycles of docetaxel (75mg/m2) and cyclophosphamide (600 mg/m2) (TC6) or 3 cycles of 5-fluorouracil (500 mg/m2), epirubicin (100mg/m2), and cyclophosphamide (500mg/m2) followed by 3 cycles of docetaxel (100mg/m2) (FEC-D). Cytokeratin (CK) 5/6 and EGFR expression were used to identify basal and non-basal triple-negative (TN) BC. The primary endpoint was pathological complete response (pCR); secondary endpoints were safety, breast-conserving surgery, disease-free survival, and overall survival. Predictive factors of pCR for each regimen were also evaluated. Results: The pCR rate was 36% for FEC-D and 25.5% for TC6, which did not differ significantly (P=0.265). When TN BC was subdivided into basal and non-basal subtypes, the pCR rate in the basal subtype was significantly lower for TC6 (13.6%) than for FEC-D (42.9%) (P=0.033), but did not significantly differ in the non-basal (TC6, 36.4%; FEC-D, 25.0%) and HER2-positive (TC6, 41.7%; FEC-D, 35.7%) cases. The relative dose intensities of epirubicin and docetaxel in FEC-D and docetaxel in TC6 were 96.3±13.0%, 93.5±14.6%, and 93.9±16.3% (mean±SD), respectively. Occurrence of grade ≥2 adverse events was significant in FEC-D-treated patients. Poor appetite (P<0.001), nausea (P<0.001), vomiting (P<0.001), dysgeusia (P=0.03), and fatigue (P=0.05) were significantly more common for FEC-D than TC6. Patients treated with FEC-D experienced significantly more febrile neutropenia and anemia (P=0.016 and 0.017, respectively). The rates of breast-conserving surgery were 68.0 and 72.3% for FEC-D and TC6, respectively (P=0.641). Patients achieved pCR had better DFS (log rank test, P = 0.287) and OS (log rank test, P = 0.069), though not significant. Patients treated with FEC-D had better DFS (log rank test, P = 0.107) and OS (log rank test, P = 0.159), though not significant. Among patients with TN BC, those treated with FEC-D had significantly better DFS (log rank test, P = 0.016) and OS (log rank test, P = 0.034) than treated with TC6. Low ALDH1 expression and high topo IIα protein expression were strongly correlated with pCR in FEC-D, with odds ratios (ORs) of 4.33 [95% CI, 1.02–18.38] and 4.08 [0.97–17.2], respectively. ALDH1 was also associated with pCR in TC, OR=3.50 [0.84–14.6]. Other factors, including age, tumor size, nodal status, tumor grade, Ki67, p53, and TOP 2A status were not associated with pCR in either regimen. Conclusions:We found that TC6 was less effective than FEC-D for treating HR-negative BC because it was insufficient for TNBC, particularly for basal BC. This suggests that anthracycline is more important than taxane for basal BC. Additionally, ALDH1 could be a marker for resistance to conventional chemotherapy. Citation Format: Narui K, Ishikawa T, Shimizu D, Tanabe M, Sasaki T, Oba MS, Morita S, Nawata S, Kida K, Mogaki M, Doi T, Tsugawa K, Ogata H, Ota T, Kosaka Y, Sengoku N, Kuranami M, Saito Y, Suzuki Y, Suto A, Arioka H, Chishima T, Ichikawa Y, Endo I, Tokuda Y. A randomized phase II neoadjuvant study comparing docetaxel and cyclophosphamide (TC) with 5-fluorouracil, epirubicin, and cyclophosphamide followed by docetaxel (FEC-D) for hormone receptor-negative breast cancer: The Kanagawa breast oncology group (KBOG) 1101 study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-04.

Expressions of HER2 and Topo IIα in breast cancer and its clinical significance

To detect the expressions of human epidermal growth factor receptor 2 (HER2) and Topo IIα in breast cancer, and to analyze the clinical significance of neoadjuvant chemotherapy for the anthracycline-based drugs. Methods: The HER2 and Topo IIα gene and protein expressions in cancer tissues from 189 patients with breast cancer were detected by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). And the objective response rate (ORR) and pathological complete rate (pCR) were analyzed. Results: The HER2 protein expression in 46 patients (24.3%) and Topo IIα protein expression in 55 patients (29.1%) was 3+ by IHC or they were 49 (25.9%) and 94 (49.0%) by FISH, respectively. The ORR and pCR in HER2 negative or positive patients were 47.4% and 20.3% or 32.7% and 16.3%, respectively, with significant differences (All P<0.05). The ORR and pCR in Topo IIα positive or negative patients were 69.1% and 36.0% or 28.4% and 2.2%, respectively, with significant differences (All P<0.05). Conclusion: FISH and IHC were consistent in the determination of HER2 expression whereas they were inconsistent in the determination of Topo IIα expression. The amplification of Topo IIα can effectively improve the effect of the adjuvant treatment effect of the anthracyclines.

Abstract 10: Concordance of BAP1, PBRM1, Ki-67, and TOPOIIa protein expression in primary clear cell renal cell carcinoma tumors and patient-matched metastatic tumors

Abstract Introduction: Efforts to improve clear cell renal cell carcinoma (ccRCC) mortality have focused primarily on evaluating prognostic biomarkers in primary tumors in order to identify indicators of response to treatment and targets for novel therapies. To date little attention has been paid to the status of these biomarkers in the more therapeutically-relevant metastatic tumor. Thus, we evaluated concordance of expression of four key prognostic ccRCC biomarkers (BAP1, PBRM1, Ki-67 and TOPOIIa) in a large cohort of patient-matched primary ccRCC and metastatic tumors. Methods: We identified 114 patients treated surgically for ccRCC between 1990 and 2005 who had synchronous (M1) or metachronous (M0) metastases, underwent metastasectomy for at least one metastatic lesion and had archived tissue available from the primary and at least one metastatic tumor. We performed IHC on all primary and metastatic tumors for BAP1, PBRM1, Ki-67, and TOPOIIa using previously-published protocols. BAP1 and PBRM1 expression was categorized as positive or negative and Ki-67 and TOPOIIa was quantified as the number of positive cells per mm2. For BAP1 and PBRM1, we calculated the concordance between patient-matched primary and metastatic tumors as the percentage of pairs where the primary and metastatic tumor had the same designation (i.e., positive or negative). For TOPOIIa and Ki-67, we assessed concordance using Spearman correlation coefficient. Analysis of variance was used to evaluate if concordance between primary-metastatic tumor pairs for TOPOIIa and Ki-67 was associated with metastatic site, metastatic timing (M0/M1), metastatic tumor grade, metastatic tumor necrosis, and metastatic tumor sarcomatoid differentiation. Results: There were a total of 161 patient-matched metastatic tumors available for the 114 patients: 78 patients had only a single metastasis while 36 patients had two or more metastases. While sites of metastases varied, pulmonary metastases were the most common (44% of all metastases). Loss of BAP1 expression was observed in19% of the primary ccRCC and 98.6% of the tumor pairs had concordant BAP1 status between the paired primary and metastatic tumors. Loss of PBRM1 was observed in 56% of the primary ccRCC tumors and 89.3% of tumor pairs showed concordant PBRM1 status. By comparison, median expression of Ki-67 was 65.0mm2 in the primary ccRCC tumors and the Pearson correlation with the patient-matched metastatic tumors was 0.43. The difference in Ki-67 expression between primary-metastatic tumor pairs was associated with necrosis in the metastatic tumor (p=0.014). Median expression of TOPOIIa was 2.6mm2 in the primary ccRCC tumors and the Pearson correlation with the patient-matched metastatic tumors was 0.25. The difference in TOPOIIa expression between primary-metastatic tumor pairs was associated with metastatic site (p=0.0006) and metastases to the heart were significantly different than pulmonary metastases (p&amp;lt;0.0001). Additionally, synchronous metastases had larger differences from their patient-matched primary tumors in comparison to metachronous metastases (p=0.012), as did necrotic metastases (p=0.028). Conclusion: We observed high concordance for loss of BAP1 and PBRM1 expression between primary ccRCC and metastatic tumors in the same patient. Conversely, we noted high discordance in protein expression of Ki-67 and TOPOIIa between patient-matched primary-metastatic tumor pairs. Moreover, this discordance varied by key pathological features. Our results suggest that using the status of a biomarker in primary ccRCC as a guide for the status in metastatic tumors is not always appropriate and needs to be evaluated on a marker-by-marker basis. Citation Format: Jeanette E. Eckel-Passow, Daniel J. Serie, John C. Cheville, Thai H. Ho, Sue M. Harrington, Tracy Hilton, Christine Lohse, Amanda Shreders, Payal Kapur, James Brugarolas, R Houston Thompson, Bradley C. Leibovich, Eugene D. Kwon, Richard W. Joseph, Alexander S. Parker. Concordance of BAP1, PBRM1, Ki-67, and TOPOIIa protein expression in primary clear cell renal cell carcinoma tumors and patient-matched metastatic tumors. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Integrating Clinical Genomics and Cancer Therapy; Jun 13-16, 2015; Salt Lake City, UT. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(1_Suppl):Abstract nr 10.

Abstract P3-06-27: BRCAness is important to identify TNBC subtype resistant to taxanes

Abstract BACKGROUND: Triple negative breast cancer (TNBC) is heterogeneous and consists of tumors associated with basal like, BRCA related and cancer stem cell (CSC) phenotypes. Although anti-cancer agents are substantial for treating TNBC, existing ones do not work in some subpopulation in TNBC at all. However, it has not been reported that subdivision of TNBC is useful for choosing ant-cancer agents. AIM: To examine whether subdividing TNBC is beneficial for tailored chemotherapy and to identify predictive factors for existing anti-cancer agents in TNBC. METHODS: Sixty-six TNBC cases from a randomized phase II trial comparing TCx6 (TC6) with FEC followed by docetaxel (FEC-D) as neoadjuvant chemotherapy for hormone receptor-negative breast cancer (Kanagawa Breast Oncology Group 1101 Study). TNBC was subdivided by 1) IHC of CK 5/6 and EGFR into basal- and non-basal subtypes, and 2) MLPA of BRCA1 into BRCA1 and non-BRCA1 subtypes. The pCR rates were examined according to each regimen and subtype. 3) The association of grade 3 pCR was examined with Ki-67, p53, aldehyde dehydrogenase (ALDH) 1 and topoisomerase 2A (topoIIα) by IHC and TOP2A by FISH for each regimen. RESULTS: 1) In basal subtype, the pCR rate was significantly higher for FEC-D (42.9%) compared with TC6 (13.6%) (p=0.033), but it was equivalent in non-basal subtype (FEC-D vs TC: 25.0% vs 36.4%, p=0.554). 2) In BRCA1 subtype, it was more significant (FEC-D vs TC: 53.8 % vs 13.3%, p=0.022). 3) An association between pCR and low ALDH1 expression was found in both FEC-D and TC6 (OR: 3.75 and 2.73). High topo IIα protein expression was associated with pCR in FEC-D (OR: 3.5). DISCUSSION: TC6 was less effective than FEC-D in basal subtype and BRCA1 subtype, showing that taxanes cannot exert their anticancer role in tumors with BRCA1 dysfunction. Although basal subtype may contain more BRCA1-defective tumors than non-basal subtype, MLPA of BRCA1 was better to identify subtype resistant to taxanes than CK5/6 and EGFR. ALDH1 predicted treatment efficacy, and could therefore represent a marker of resistance to conventional chemotherapy. Citation Format: Takashi Ishikawa, Kazutaka Narui, Kazuhiro Shimada, Kumiko Kida, Mari S Oba, Mikiko Tanabe, Yasushi Ichikawa, Sadatoshi Sugae, Itaru Endo. BRCAness is important to identify TNBC subtype resistant to taxanes [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-06-27.

Targeting The Nuclear Export Signal In Multiple Myeloma

IntroductionIn multiple myeloma (MM), de novo drug resistance to topoisomerase (topo) II poisons occurs at high cell densities due to trafficking of topo IIα from the nucleus to the cytoplasm where it is no longer in contact with the DNA and thus unable to induce cell death (Turner et al. 2009, Cancer Res, 69, 6899-905, Engel et al. 2004, Exp Cell Res, 295, 421-31). We have previously demonstrated that topo IIα is exported from the nucleus of human myeloma cells by a CRM1-dependent mechanism ( Valkov et al 2000, Br J Haematol, 108, 331-45, Engel et al. 2004, Exp Cell Res, 295, 421-31) and we have also identified the nuclear export signals (NES) for topo IIα at amino acids 1017-28 (site A) and 1054-66 (site B) ( Turner et al. 2004, J Cell Sci, 117, 3061-71). Blocking nuclear export with a CRM1 inhibitor or by siRNA has been shown to sensitize drug-resistant MM cells to topo II poisons ((Turner et al. 2009, Cancer Res, 69, 6899-905, Turner et al 2013, J. of Cancer, In press). Even though the active NES site (site A) of topo IIα conforms to the hydrophobic amino acid motif for an NES, the amino acid sequence does not occur in any other human protein. In addition, this NES is in a pocket formed by the three-dimensional structure of the topo IIα protein. This specificity of the NES could lead to the development of drugs that may exclusively block the NES of topo IIα and not affect the CRM 1-dependent export of other nuclear proteins. MethodsIn this study, our aims were to; 1) generate an atomic homology model of human topo IIα to identify lead compounds targeting the NES of topo IIα (nuclear export signal inhibitors, NESi), 2) determine if the compounds bind specifically to topo IIα and inhibit nuclear export by immunofluorescence microscopy, nuclear-cytoplasmic fractionation, immunoprecipitation, proximity ligation assay, and Biacore kinetic/affinity assay, and 3) test the anticancer activity of these compounds in multiple myeloma and normal cells with and without a topo IIα inhibitor. Results and ConclusionsWe generated an atomic homology model of human topo IIα to provide the basis for in silico molecular docking screenings of 139,735 small molecules (MW < 500) to identify lead compounds or NESi targeting the NES of topo IIα. The highest docking score NESi compounds (46 total) were assayed for their ability to induce apoptosis in drug-resistant human H929 myeloma cells when used in combination with the topo II inhibitor doxorubicin. We isolated four lead compounds that induced apoptosis (caspase 3 cleavage) when used with doxorubicin and that inhibited nuclear export of topo IIα, as shown by immuno-fluorescence microscopy and nuclear-cytoplasmic fractionation. Immunoprecipitation, proximity ligation assay and Biacore kinetic/affinity assay showed that the most potent lead compound, NCI-9138, inhibited binding of topo IIα to the export receptor CRM1. Inhibition was specific to topo IIα because p53 trafficking was unaffected and the inhibitor did not affect topo IIα protein expression or topo IIα function (decatenation). The NESi were found to sensitize drug-resistant human myeloma cells to doxorubicin but did not affect normal fibroblast cell lines (Flow2000 or WI-38) or human PBMCs. These topo IIα-specific nuclear export inhibitors may potentially lead to a new approach in circumventing drug resistance in multiple myeloma. Disclosures:No relevant conflicts of interest to declare.

Topoisomerase II alpha gene amplification is a favorable prognostic factor in patients with HER2-positive metastatic breast cancer treated with trastuzumab

BackgroundThe vast majority of patients with HER2-positive metastatic breast cancer (MBC) treated with trastuzumab eventually develop resistance to this agent. There is an unmet need therefore, for identifying biological markers with possible prognostic/predictive value in such patients. The aim of this study was to investigate the prognostic role of topoisomerase II alpha gene (TOP2A) amplification and protein (TopoIIa) expression in patients treated with trastuzumab-containing regimens.MethodsFormalin-fixed paraffin-embedded tumor tissue samples were retrospectively collected from 225 eligible patients treated with trastuzumab. Protein expression of ER, PgR, Ki67, PTEN, HER2 and TopoIIa were centrally assessed by immunohistochemistry. HER2 and TOP2A gene amplification was evaluated by fluorescence in situ hybridization. PIK3CA mutations were identified by single nucleotide polymorphism genotyping. Survival was evaluated from the initiation of trastuzumab as 1st line treatment to the date of last follow-up or death.ResultsAmong the 225 samples analyzed, only 137 (61%) were found to be HER2-positive. TOP2A was amplified in 41% and deleted in 16% of such tumors. TOP2A gene amplification was more frequent in ER-negative tumors. TopoIIa protein expression was observed in the majority (65%) of the samples and was associated with ER-positive status, high Ki67 expression, presence of PTEN protein and PIK3CA mutations. Median follow-up for patients treated in the 1st line was 51 months. Survival was more prolonged with trastuzumab-containing treatment in HER2-positive patients (50 months, log-rank, p=0.007). TOP2A non-amplified or deleted tumors were associated with increased risk for death compared to TOP2A amplified tumors (HR=2.16, Wald’s p=0.010 and HR=2.67, p=0.009, respectively). In multivariate analysis, a significant interaction of TOP2A with anthracycline treatment (either in the adjuvant or the 1st line setting) was observed for survival (Wald’s p=0.015). Among the TOP2A amplified subgroup, anthracycline-treated patients were associated with decreased risk for death.ConclusionsTOP2A gene amplification was shown to be a favorable prognostic marker in HER2-positive MBC patients treated with trastuzumab, such an effect however, appears to rather be related to treatment with anthracyclines (predictive marker for benefit from anthracyclines). The results of the present retrospective study warrant validation in larger cohorts of patients treated in the context of randomized trials.

Correlations of TOP2A gene aberrations and expression of topoisomerase IIα protein and TOP2A mRNA expression in primary breast cancer: A retrospective study of 86 cases using fluorescence in situ hybridization and immunohistochemistry

Our aim in this study was to assess the status of TOP2A gene aberrations (no change/amplification or deletion) and its correlations with topoisomerase IIα (Topo IIα) protein and TOP2A mRNA expression, respectively. TOP2A amplification, Topo IIα protein expression and TOP2A mRNA expression were assessed using samples of 86 cases of breast cancer by fluorescence in fluorescence in situ hybridization, quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Twenty two (22.57%) had amplification/deletion of TOP2A gene. Twenty eight (32.56%) tumor samples were 17q polysomy or monosomy. Topo IIα protein was expressed in 57 cases (66.27%, 57/86): 22 cases (38.62%, 22/57) and 35 cases (61.40%, 35/57) had amplification/deletion and no change of TOP2A gene, respectively. These three groups showed significant differences by one-way analysis of variance (P < 0.001). The average Ct values of TOP2A mRNA expression in the tumors with deletion, amplification and no change of TOP2A gene were 27.00, 27.33 and 31.66, respectively. We demonstrated that the TOP2A gene was amplified or deleted in breast cancer, with a significant correlation with high expressions of Topo IIα protein and TOP2A mRNA expression. Ki-67 expression index (mean = 14.9) decreased significantly in cases wherein TOP2A gene had no change and Her2/neu protein expression was weakly positive (0-1+, P < 0.001).

HER2 and TOP2A in high-risk early breast cancer patients treated with adjuvant epirubicin-based dose-dense sequential chemotherapy

BackgroundHER2 and TOP2A parameters (gene status, mRNA and protein expression) have individually been associated with the outcome of patients treated with anthracyclines. The aim of this study was to comprehensively evaluate the prognostic/predictive significance of the above parameters in early, high-risk breast cancer patients treated with epirubicin-based, dose-dense sequential adjuvant chemotherapy.MethodsIn a series of 352 breast carcinoma tissues from patients that had been post-operatively treated with epirubicin-CMF with or without paclitaxel, we assessed HER2 and TOP2A gene status (chromogenic in situ hybridization), mRNA expression (quantitative reverse transcription PCR), as well as HER2 and TopoIIa protein expression (immunohistochemistry).ResultsHER2 and TOP2A amplification did not share the same effects on their downstream molecules, with consistent patterns observed in HER2 mRNA and protein expression according to HER2 amplification (all parameters strongly inter-related, p values < 0.001), but inconsistent patterns in the case of TOP2A. TOP2A gene amplification (7% of all cases) was not related to TOP2A mRNA and TopoIIa protein expression, while TOP2A mRNA and TopoIIa protein were strongly related to each other (p < 0.001). Hence, TOP2A amplified tumors did not correspond to tumors with high TOP2A mRNA or TopoIIa protein expression, while the latter were characterized by high Ki67 scores (p = 0.003 and p < 0.001, respectively). Multivariate analysis adjusted for nodal involvement, hormone receptor status, Ki67 score and HER2/TOP2A parameters revealed HER2/TOP2A co-amplification (21.2% of HER2 amplified tumors) as an independent favorable prognostic factor for DFS (HR = 0.13, 95% CI: 0.02-0.96, p = 0.046); in contrast, increased HER2/TOP2A mRNA co-expression was identified as an independent adverse prognostic factor for both DFS (HR = 2.41, 95% CI: 1.31-4.42, p = 0.005) and OS (HR = 2.83, 95% CI: 1.42-5.63, p = 0.003), while high TOP2A mRNA expression was an independent adverse prognostic factor for OS (HR = 2.06, 95% CI: 1.23-3.46, p = 0.006). None of the parameters tested was associated with response to paclitaxel.ConclusionsThis study confirms the favorable prognostic value of HER2/TOP2A co-amplification and the adverse prognostic value of high TOP2A mRNA expression extending it to the adjuvant treatment setting in early high-risk breast cancer. The strong adverse prognostic impact of high HER2/TOP2A mRNA co-expression needs further validation in studies designed to evaluate markers predictive for anthracyclines.Trial registrationAustralian New Zealand Clinical Trials Registry ACTRN12611000506998.

Etoposide-mediated glioblastoma cell death: dependent or independent on the expression of its target, topoisomerase II alpha?

Treatments which significantly improve progression-free and overall survival for patients with relapsed glioblastoma (GBM) after the standard therapy are lacking. The Topoisomerase II (TopoII) enzyme is a key target of anticancer agents because of the important role it plays in transcription regulation and chromatin remodeling. A drug with strong topoisomerase-mediated anticancer activity is etoposide that is used in combination with carboplatin in patients with relapsed GBM. We hypothesized that tumors harboring high expression of TopoII alpha (TopoIIa) would be more sensitive to etoposide treatment. The relative expression levels of TopoIIa protein were measured in a panel of GBM cell lines using Western blot analysis and in a cohort of GBM using immunohistochemistry. Expression levels of TopoIIa in the cell lines were correlated with relative sensitivity to treatment with etoposide. To ascertain the role TopoIIa plays in mediating response to etoposide, expression was reduced with a siRNA targeted to TopoIIa. Protein expression of TopoIIa, although high in the cell lines, was very low in patient specimens. Correlations between TopoIIa protein expression and sensitivity to etoposide were evident. The IC(50) for the low-TopoIIa-expressing cell line, T98G, was almost 50 times higher than M059K (high TopoIIa). Inhibition of TopoIIa in MO59K cells with siRNA significantly altered the IC(50), increasing the resistance to etoposide. Interestingly, the expression of TopoIIa was not decreased after treatment with etoposide, indicating other mechanisms underplay treatment response. In vitro, the levels of TopoIIa protein expression correlate with response to etoposide but also multiple molecular events namely DNA-PK and MDR also play a role in cell sensitivity to etoposide. That we did not find a high expression of TopoIIa in clinical specimens further suggests the mechanisms underlying treatment response are complex.

Topo IIα gene alterations correlated with survival in patients with diffuse large B-cell lymphoma

Topoisomerase IIα (topo IIα) protein expression has prognostic significance in many cancers. However, it is still unclear whether topo IIα protein expression and gene alterations play roles as prognostic factors in diffuse large B-cell lymphoma (DLBCL). We selected 102 patients with DLBCL who were homogeneously treated with CHOP chemotherapy and followed up. Using tissue microarray technology, all of the cases, consisting of 25 germinal centre B-cell-like (GCB) and 77 nongerminal centre B-cell-like (non-GCB) types, were studied. Topo IIα protein expression was detected by immunohistochemistry. Gene copy number of topo IIα was analysed by chromogenic in situ hybridization. Cox regression, chi-square test and Kaplan-Meier statistics were performed using SPSS 15·0. Topo IIα protein overexpression was found in 91 (91/102, 89·2%) cases, while topo IIα gene amplification was absent in all cases. Chromosome 17 deletion was identified in 3 (3/102, 2·9%) cases, diploid in 66 (66/102, 64·7%) cases and aneuploidy in 33 (33/102, 32·4%) cases. By multivariate analysis, no significant differences in progression-free survival (PFS) and overall survival (OS) were observed in patients with topo IIα protein overexpression (P > 0·05), while chromosome 17 aneuploidy predicted worse PFS and OS (P < 0·001). These results suggested that chromosome 17 aneuploidy, but not topo IIα protein expression, could predict worse survival in patients with DLBCL.

Molecular and genomic predictors of response to single-agent doxorubicin (ADR) versus single-agent docetaxel (DOC) in primary breast cancer (PBC).

502 Background: ADR and DOC improve disease-free survival (DFS) of PBC, but patients (pts) who actually obtain a benefit with either of these agents cannot be identified. Predictors of response to ADM and DOC are necessary. Methods: ER, PR, Ki-67, topoIisomerase IIα protein (topoII), tau and p27 proteins, bcl-2, EGFR, and CK 5/6 (all determined by IHC), topoIIα and her2 gen alterations (by FISH) and a genomic profiling (PAM50/claudin low classifier, using Agilent 44K microarrays) were studied as predictors of response to ADR (75mg/m2 × 4 cy) vs DOC (100mg/m2 × 4 cy) q3w in a neoadjuvant phase II study in pts with PBC (www.ClinTrials.gov, NCT 00123929). Pathological responses (PatRes) and residual cancer burden (RCB) were estimated according to Symmans et al. (J Clin Oncol 25:4414,2007). PCR+class I were considered good PatRes. Multivariable logistic regression analysis was used to determine the odds ratio to response. Results: 204 pts (104 ADR, 100 DOC) were analyzed. PatRes were 19% (ADR) vs 20% (DOC), p=1.0. In multivariate analysis, high topoII expression (but not topoII gene alterations) and ER+ status (for ADM) and ER+ status and tumor size (T) >5cm (for DOC) were associated with poorer PatRes. The odd ratios of PatRes for ADR were 10.4 (95% CI 2.0-55.1) for normal vs high topoII (p=0.006) and 4.6 (95% CI 1.4-15.3) for ER—; vs ER+ tumors (p=0.012); and for DOC 8.3 (2.25-30.73) for ER— vs ER+ tumors (p=0.001) and 13.9 (3.4-56.3) for T≤5 cm vs >5cm (p<0.001). Genomic profiles were possible in 94 pts. Basal-like tumors were selectively sensitive to DOC and resistant to ADR; no differences were seen in other subtypes. Conclusions: Normal topoIIα protein expression and ER-negative status were predictive of response to ADR, while ER-negative status and T≤5cm were predictive of response to DOC. Basal-like tumors are sensitive to DOC and resistant to ADR. Good PatRes (PCR+I) RCB (mean) Genomic subtype ADR DOC P* ADR DOC P* Luminal A 1/12 (8%) 0/5 (0%) NS 3.386 2.839 NS Luminal B 2/14 (14%) 0/11 (0%) NS 2.378 2.806 NS HER2-enriched 1/5 (20%) 2/5 (40%) NS 2.822 1.670 NS Basal 0/7 (0%) 5/9 (56%) 0.034 3.245 1.626 0.039 Claudin low 3/12 (25%) 1/5 (20%) NS 2.626 2.538 NS Normal 1/4 (25%) 2/5 (40%) NS 2.183 2.821 NS Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration University Genomics

Abstract 317: p38γ MAPK regulates topoisomerase IIα activity by phosphorylation

Abstract DNA topoisomerase IIα (Topo IIα) is a critical target for cancer therapy and its protein expression, however, is frequently depleted by its inhibitors and strategies to maintain Topo IIα expression and thereby to sustain the Topo II drug sensitivity are still lacking. Here we show that p38γ MAPK is specifically activated by Topo II inhibitors and activated p38γ in turn phosphorylates Topo IIα, leading to increased Topo IIα protein expression through attenuating its proteasome-dependent degradation. The sensitivity of a panel of human breast cancer cell lines to Topo II inhibitors was found not to correlate with the intrinsic but with inducible Topo IIα protein expression and with endogenous protein expression of p38γ MAPK that is specifically phosphorylated in response to Topo II toxins. p38γ activation and inhibition alone were shown to increase and decrease Topo IIα expression and Topo drug toxicities. Mechanistically, p38γ MAPK phosphorylates Topo IIα at Ser 1524, leading to a decreased proteasome-dependent Topo IIα degradation. These results reveal a novel mechanism by which p38γ MAPK specifically confers Topo II drug toxicity in breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 317.

Simultaneous detection of TOP2A and HER2 gene amplification by multiplex ligation-dependent probe amplification in breast cancer

HER-2/neu gene amplification, found in certain subtypes of (breast-) cancers, is an independent prognostic factor of poor outcome and determines eligibility for systemic treatment with trastuzumab. TopoIIα (TOP2A) gene amplification seems to be predictive of response to a class of cytostatic agents called TopoII inhibitors, which include the anthracyclines. The observed increased efficacy of anthracyclines in HER2-positive tumors is thought to arise from the close proximity of both genes on chromosome 17, where the TopoII amplification status will determine the anthracycline sensitivity. This study aimed to validate a new polymerase chain reaction-based test, called multiplex ligation-dependent probe amplification (MLPA), as a simple and quick method to simultaneously assess HER-2/neu and TopoIIα gene amplification status in paraffin-embedded breast cancer samples. To this end, MLPA results were compared with TopoIIα, HER2 chromogenic in situ hybridization (CISH). We also assessed TopoIIα protein expression by immunohistochemistry. Of 353 patients, 9% showed TopoIIα amplification by MLPA and 13% of patients were HER2 amplified. TopoIIα amplification was seen in 42% of HER2-amplified cases and showed no high level amplification without HER2 amplification. Eleven patients displayed TopoIIα loss (3%). Concordance between MLPA and CISH was 91% for TopoIIα and 96% for HER2. Correlation between amplification and overexpression of TopoIIα was significant (P=0.035), but amplification did not always predict protein overexpression. Loss of the TopoIIα gene was almost never associated with loss of its protein. In conclusion, MLPA is an easy and accurate method to simultaneously detect breast cancer HER-2/neu and TopoIIα copy number status in paraffin-embedded tissue, and thus an attractive supplement or alternative to CISH.

Proteasomal inhibition stabilizes topoisomerase IIα protein and reverses resistance to the topoisomerase II poison ethonafide (AMP-53, 6-ethoxyazonafide)

Multiple myeloma (MM) is an incurable malignancy of plasma cells. Although multiple myeloma patients often respond to initial therapy, the majority of patients will relapse with disease that is refractory to further drug treatment. Thus, new therapeutic strategies are needed. One common mechanism of acquired drug resistance involves a reduction in the expression or function of the drug target. We hypothesized that the cytotoxic activity of topoisomerase II (topo II) poisons could be enhanced, and drug resistance overcome, by increasing the expression and activity of the drug target, topo II in myeloma cells. To test this hypothesis, we evaluated the cytotoxicity of the anthracene-containing topo II poison, ethonafide (AMP-53/6-ethoxyazonafide), in combination with the proteasome inhibitor bortezomib (PS-341/Velcade). Combination drug activity studies were done in 8226/S myeloma cells and its drug resistant subclone, 8226/Dox1V. We found that a 24-h treatment of cells with bortezomib maximally increased topo IIα protein expression and activity, and consistently increased the cytotoxicity of ethonafide in the 8226/S and 8226/Dox1V cell lines. This increase in cytotoxicity corresponded to an increase in DNA double-strand breaks, as measured by the neutral comet assay. Therefore, increasing topo IIα expression through inhibition of proteasomal degradation increased DNA double-strand breaks and enhanced the cytotoxicity of the topo II poison ethonafide. These data suggest that bortezomib-mediated stabilization of topo IIα expression may potentiate the cytotoxic activity of topo II poisons and thereby, provide a strategy to circumvent drug resistance.