Comparison of DNA topoisomerase II alpha expression in small cell and nonsmall cell carcinoma of the lung. In search of a mechanism of chemotherapeutic response

Clinical significance of topoisomerase-II expression in patients with advanced non-small cell lung cancer treated with amrubicin

Background

Amrubicin chemotherapy is a treatment option for patients with non‐small cell lung cancer (NSCLC) after third‐line treatment in Japan. Although topoisomerase‐II (Topo‐II), a target of amrubicin, has been reported to be a prognostic or predictive marker for chemosensitivity and clinical outcomes in various types of malignancies, its effects in the Japanese population remain unknown.

Methods

Data regarding 44 patients with advanced NSCLC treated with amrubicin between April 2004 and May 2014 were retrospectively analyzed. We evaluated the expression levels of Topo‐II by immunohistochemical staining of tumor specimens obtained via biopsy or surgical resection.

Results

The majority of enrolled patients were men (68%) with a median age of 67 (range, 43–78) years. The most common histological type was adenocarcinoma (70%). High Topo‐II expression was observed in 13 (30%) of the 44 patients. The median progression‐free survival and overall survival (OS) durations were 1.8 and 8.8 months, respectively. While there was no significant association between Topo‐II expression and progression‐free survival, patients with low Topo‐II expression had significantly longer OS than did those with high Topo‐II expression. Good performance status and low expression of Topo‐II were all significantly associated with a favorable OS.

Conclusion

Low expression of Topo‐II was identified as an independent prognostic factor for longer survival in patients with NSCLC receiving amrubicin, a Topo‐II inhibitor.

Key points

Discovering novel lung cancer associated antigens and the utilization of their autoantibodies in detection of lung cancer

OBJECTIVE

The identification of tumor-associated antigens (TAAs) and their corresponding autoantibodies in lung cancer (LC) may expand our vision of cancer immunity. This study aims to screen novel TAAs to distinguish LC from the healthy population.

METHODS

In our previous study, 35 genes encoding LC-associated TAAs were identified from the serological analysis of recombinant cDNA expression libraries (SEREX), and Oncomine database was further used to identify potential genes in cancer progression. Autoantibody to TAAs were tested by enzyme-linked immunosorbent assay (ELISA) in sera from 1379 participants in validation set and verification set.

FINDINGS

Based on analysis of three independent microarrays in Oncomine, ten genes were consistently dysregulated in LC. The sera level and positive frequency of the anti-TOP2A, anti-ACTR3, anti-RPS6KA5 and anti-PSIP1 from LC patients were higher than normal control in validation set. The area under curve (AUC) of anti-TOP2A, anti-ACTR3, anti-RPS6KA5 and anti-PSIP1 was respectively 0.758, 0.787, 0.707, 0.668. The sensitivity of these four autoantibodies for LC detection ranged from 26.63 % to 32.07 % with the specificity over 90 %. Data from the verification set confirmed the results. Except that, the frequency of serum autoantibody against TOP2A (43.3 %) and ACTR3 (50.0 %) was significantly higher in early stage LC than late stage (23.6 % and 22.3 %, respectively).

CONCLUSION

TOP2A, ACTR3, RPS6KA5 and PSIP1 can elicit humoral immune response in LC and their autoantibodies have relationship with the tumorigenesis of LC. Anti-TOP2A and anti-ACTR3 have the potential to serve as a serological biomarkers in early stage LC.

Carboplatin–Angelica gigas Nakai combination synergistically enhances apoptosis by suppressed Akt, Erk, and Stat3 expression in H460 human lung cancer cells

The lower potency of low dose of carboplatin often requires combination with other drugs to improve its efficacy. Newer and more potent carboplatin-based combination therapies are investigated for treatment. We investigated whether paclitaxel, carboplatin, and Angelica gigas Nakai (AGN) affect viability of H460 cells by MTT assay. Western blot analysis was used to measure the expression of various modulators, such as p-Stat3, p-Akt, and p-Erk. Paclitaxel, carboplatin, and AGN affected the viability of H460 cells. Paclitaxel, carboplatin, and AGN suppressed p-Akt, p-Erk, and p-Stat3 expression. AGN combined with carboplatin significantly decreased c-Jun, HIF-1α, and VEGF levels. AGN combined with carboplatin significantly increased p21 and p27 levels and suppressed cyclin D1 and cyclin E levels. AGN combined with carboplatin-induced apoptosis by increasing Bax and cleavage of caspase and Parp level and by suppressing Bcl-2 level. Our results clearly demonstrate that AGN combined with carboplatin could be a useful compound for treating lung cancer.

Chemotherapy Resistance in Lung Cancer

Despite a growing interest in development of non-cytotoxic targeted agents, systemic chemotherapy is still the mainstay of treatment for both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). However, chemotherapy resistance limits our ability to effectively treat advanced lung cancer. Some lung tumors are intrinsically resistant to chemotherapy, and in virtually all cases, even the initial responders rapidly develop acquired resistance. While targeting histology could result in enhanced tumor sensitivity to a particular chemotherapeutic agent, better understanding of molecular determinants of chemotherapy sensitivity/resistance would be critically important. Development of predictive biomarkers to personalize chemotherapeutic agents and combining novel agents targeting specific resistance pathways with standard chemotherapy could be some promising strategies to overcome chemotherapy resistance in lung cancer. In this chapter, we will discuss some key mechanisms of resistance for commonly used chemotherapeutic agents in lung cancer.

Predictive value of BRCA1, ERCC1, ATP7B, PKM2, TOPOI, TOPΟ-IIA, TOPOIIB and C-MYC genes in patients with small cell lung cancer (SCLC) who received first line therapy with cisplatin and etoposide

BACKGROUND

The aim of the study was to evaluate the predictive value of genes involved in the action of cisplatin-etoposide in Small Cell Lung Cancer (SCLC).

METHODS

184 SCLC patients' primary tumour samples were analyzed for ERCCI, BRCA1, ATP7B, PKM2 TOPOI, TOPOIIA, TOPOIIB and C-MYC mRNA expression. All patients were treated with cisplatin-etoposide.

RESULTS

The patients' median age was 63 years and 120 (65%) had extended stage, 75 (41%) had increased LDH serum levels and 131 (71%) an ECOG performance status was 0-1. Patients with limited stage, whose tumours expressed high ERCC1 (p=0.028), PKM2 (p=0.046), TOPOI (p=0.008), TOPOIIA (p=0.002) and TOPOIIB (p<0.001) mRNA had a shorter Progression Free Survival (PFS). In limited stage patients, high expression of ERCC1 (p=0.014), PKM2 (p=0.026), TOPOIIA (p=0.021) and TOPOIIB (p=0.019) was correlated with decreased median overall survival (mOS) while in patients with extended stage, only high TOPOIIB expression had a negative impact on Os (p=0.035). The favorable expression signature expression signature (low expression of ERCC1, PKM2, TOPOIIA and TOPOIIB) was correlated with significantly better PFS and Os in both LS-SCLC (p<0.001 and p=0.007, respectively) and ES-SCLC (p=0.007 and (p=0.011, respectively) group. The unfavorable expression signature was an independent predictor for poor PFS (HR: 3.18; p=0.002 and HR: 3.14; p=0.021) and Os (HR: 4.35; p=0.001and HR: 3.32; p=0.019) in both limited and extended stage, respectively.

CONCLUSIONS

Single gene's expression analysis as well as the integrated analysis of ERCC1, PKM2, TOPOIIA and TOPOIIB may predict treatment outcome in patients with SCLC. These findings should be further validated in a prospective study.

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

While chemotherapy provides useful palliation, advanced lung cancer remains incurable since those tumors that are initially sensitive to therapy rapidly develop acquired resistance. Resistance may arise from impaired drug delivery, extracellular factors, decreased drug uptake into tumor cells, increased drug efflux, drug inactivation by detoxifying factors, decreased drug activation or binding to target, altered target, increased damage repair, tolerance of damage, decreased proapoptotic factors, increased antiapoptotic factors, or altered cell cycling or transcription factors. Factors for which there is now substantial clinical evidence of a link to small cell lung cancer (SCLC) resistance to chemotherapy include MRP (for platinum-based combination chemotherapy) and MDR1/P-gp (for non-platinum agents). SPECT MIBI and Tc-TF scanning appears to predict chemotherapy benefit in SCLC. In non-small cell lung cancer (NSCLC), the strongest clinical evidence is for taxane resistance with elevated expression or mutation of class III beta-tubulin (and possibly alpha tubulin), platinum resistance and expression of ERCC1 or BCRP, gemcitabine resistance and RRM1 expression, and resistance to several agents and COX-2 expression (although COX-2 inhibitors have had minimal impact on drug efficacy clinically). Tumors expressing high BRCA1 may have increased resistance to platinums but increased sensitivity to taxanes. Limited early clinical data suggest that chemotherapy resistance in NSCLC may also be increased with decreased expression of cyclin B1 or of Eg5, or with increased expression of ICAM, matrilysin, osteopontin, DDH, survivin, PCDGF, caveolin-1, p21WAF1/CIP1, or 14-3-3sigma, and that IGF-1R inhibitors may increase efficacy of chemotherapy, particularly in squamous cell carcinomas. Equivocal data (with some positive studies but other negative studies) suggest that NSCLC tumors with some EGFR mutations may have increased sensitivity to chemotherapy, while K-ras mutations and expression of GST-pi, RB or p27kip1 may possibly confer resistance. While limited clinical data suggest that p53 mutations are associated with resistance to platinum-based therapies in NSCLC, data on p53 IHC positivity are equivocal. To date, resistance-modulating strategies have generally not proven clinically useful in lung cancer, although small randomized trials suggest a modest benefit of verapamil and related agents in NSCLC.

Excision repair cross complementing-1 and topoisomerase IIalpha gene expression in small-cell lung cancer patients treated with platinum and etoposide: a retrospective study

HYPOTHESIS

Aim of the study was to quantify ERCC1, RRM1, and TopoIIalpha mRNA expression profile as predictive factors for response and survival in SCLC patients treated with platinum/etoposide.

METHODS

Total RNA was extracted from microdissected sections of 103 formalin-fixed, paraffin embedded biopsies. Relative quantification was performed by real-time polymerase chain reaction (PCR) using intron-spanning probes.

RESULTS

Eighty-five samples (83%) were successfully amplified. Median overall survival (OS) was 9.9 months; 45 patients had limited disease (LD) (OS = 13.1) and 40 had extensive disease (ED) (OS = 7.1). Fifty-six (65%) patients had an objective response to treatment. A gene expression was detectable in all samples and a correlation between ERCC1 and RRM1 (Rs = 0.34, p = 0.0011) was found. According to response to treatment, it was found that lower TopoIIalpha expression was associated to a better response in LD patients (p = 0.025) and, more interestingly, those who had a complete response had lower TopoIIalpha than both partial and nonresponsive patients (p = 0.015). At univariate analysis LD patients with low ERCC1 had significantly longer survival (median survival 14.9 versus 9.9, p = 0.012), whereas RRM1 and TopoIIalpha levels showed no influence on outcome. At the multivariate analysis, ERCC1 was confirmed to be an independent prognostic factor for survival in LD patients. No significant role was found for ERCC1, RRM1 and TopoIIalpha in ED patients.

CONCLUSIONS

ERCC1 and TopoIIalpha are candidate markers in predicting clinical outcome and response to treatment in LD SCLC patients and are worth of further investigation in a prospective study.

Upregulation of topoisomerase IIalpha expression in advanced gallbladder carcinoma: a potential chemotherapeutic target

PURPOSE

The lack of treatment options other than surgical resection results in unfavourable prognosis of advanced gallbladder carcinoma. The aim of this study was to identify cancer-specific cellular targets that would form the basis for some therapeutic approaches for this disease.

METHODS

Twelve advanced gallbladder carcinoma tissue samples and three samples of normal gallbladder epithelium were screened to identify differentially expressed genes by DNA microarray analysis. The results obtained were validated in an independent sample set by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). Among the genes picked-up, one molecule, topoisomerase IIalpha (TOPO IIalpha), was further assessed immunohistochemically as a potential chemotherapeutic target, and the growth inhibitory effects of etoposide, doxorubicin and idarubicin, representative TOPO IIalpha inhibitors, on two different gallbladder carcinoma cell lines were compared with that of gemcitabine and 5-fulorouracil.

RESULTS

Five upregulated genes were identified: four cell cycle-related genes (TOPO IIalpha, cyclin B2, CDC28 protein kinase regulatory subunit 2, ubiquitin-conjugating enzyme E2C) and a metabolism-related gene (gamma-glutamyl hydrolase). Immunohistochemically, TOPO IIalpha was expressed in gallbladder cancer cells, and 16 of 35 cases (46%) had strong TOPO IIalpha expression defined as having a labeling index of >50%. In in vitro growth inhibition assay, etoposide, as well as doxorubicin and idarubicin, was the most effective for OCUG-1 cells that had strong TOPO IIalpha expression, while gemicitabine was the most effective for NOZ cells with weak TOPO IIalpha expression. Etoposide induced apoptosis of OCUG-1 cells.

CONCLUSIONS

TOPO IIalpha might be an effective chemotherapeutic target in advanced gallbladder carcinoma, especially when it is expressed strongly.

Combined Treatment with Temozolomide and Methoxyamine: Blocking Apurininc/Pyrimidinic Site Repair Coupled with Targeting Topoisomerase IIα

PURPOSE

Methoxyamine has been shown to potentiate the cytotoxic effect of temozolomide both in vitro and in human tumor xenograft models. We postulate that the enhanced cytotoxicity is mediated by methoxyamine-bound apurininc/pyrimidinic (MX-AP) site, a key lesion formed by the combination of temozolomide and methoxyamine. When located within topoisomerase IIalpha (topo II) cleavage sites in DNA, MX-AP sites act as dual lethal targets, not only functionally disrupting the base excision repair (BER) pathway but also potentially poisoning topo II.

EXPERIMENTAL DESIGN

Using oligonucleotide substrates, in which a position-specific MX-AP site is located within topo II cleavage sites, we examined the effect of MX-AP site on both AP endonuclease- and topo II-mediated DNA cleavage in vitro.

RESULTS

MX-AP sites were refractory to the catalytic activity of AP endonuclease, indicating their ability to block BER. However, they were cleaved by either purified topo II or nuclear extracts from tumor cells expressing high levels of topo II, suggesting that MX-AP sites stimulate topo II-mediated DNA cleavages. In cells, treatment with temozolomide and methoxyamine increased the expression of topo II and enriched the formation of gammaH2AX foci, which were colocalized with up-regulated topo II, confirming that DNA double-strand breaks marked by gammaH2AX foci are associated with topo II in cells.

CONCLUSIONS

Our findings identify a molecular mechanism of cell death whereby MX-AP sites that cumulated in cells due to resistance to BER potentially convert topo II into biotoxins, resulting in enzyme-mediated DNA scission and cell death.

Tailor-made chemotherapy for non-small cell lung cancer patients

The selection of the most effective chemotherapy treatment based on evaluation of biomarkers, that is, 'tailor-made chemotherapy', can improve the clinical outcome of non-small cell lung cancer patients, including early-stage tumors with a high metastatic potential and advanced-stage tumors with a low proliferation rate. Therefore, treatment would be chosen according to which drugs would be most effective in combating specific tumors. For example: 5-fluorouracil-derived agents would be used for tumors with a low expression of thymidylate synthase; gefitinib and erlotinib for tumors with epidermal growth factor receptor (EGFR) mutations or increased EGFR gene copy numbers; cisplatin and carboplatin for tumors with a low expression of excision repair cross complementing-1; and gemcitabine for tumors with a low expression of ribonucleotide reductase. The remaining populations of non-small cell lung cancers require chemotherapy using other drugs based on an evaluation of other targeted molecules.

CD117, CK20, TTF-1, and DNA topoisomerase II-alpha antigen expression in small cell tumors

BACKGROUND

Distinguishing merkel cell carcinoma (MCC), small cell lung carcinoma (SCLC) metastatic to the skin, and atypical basal cell carcinoma (BCC) can be problematic in some cases. Significant differences in the biology of these tumors necessitate that they need to be distinguished from one another.

METHODS

We evaluated the immunophenotypic characteristics of 22 MCCs, nine SCLCs, and 19 BCCs using antibodies to cytokeratin 20 (CK20), thyroid transcription factor-1 (TTF-1), CD117, and DNA topoisomerase II-alpha (topo II).

RESULTS

Nineteen of 22 MCCs stained with the antibody to CK20, none stained with anti-TTF-1, and 13 stained with anti-CD117. No SCLC stained with anti-CK20, all stained with anti-TTF-1, and eight stained with anti-CD117. No BCC stained with any of the three markers. The proliferative index (PI), determined by the expression of topo II, was similar for SLCLs (mean 58.5 +/- 9.0%) and MCCs (mean 45.2 +/- 12.4%) and was lowest in BCCs (mean 25.0 +/- 8.7%).

CONCLUSIONS

CK20 and TTF-1 appear to be reliable in distinguishing MCC from SCLC. CD117 is expressed in both MCC and SCLC, limiting its diagnostic utility. CK20, TTF-1, and CD117 are not expressed in BCC. The high PI seen in MCCs suggests a role for topoisomerase II inhibitors in their treatment.

Human DNA topoisomerase-IIalpha expression as a prognostic factor for transitional cell carcinoma of the urinary bladder

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.

ATF is important to late S phase-dependent regulation of DNA topoisomerase IIalpha gene expression in HeLa cells

DNA topoisomerase IIalpha (Topo IIalpha) is regulated in late S phase-dependent manner. To identify late S phase-dependent cis-acting elements of Topo IIalpha gene, we have investigated the synchronized HeLa cells with chloramphenicol acetyltransferase and DNase I footprinting assays. The level of Topo IIalpha mRNA increased after release from aphidicolin block and reached a maximum in 8h (late S phase) in HeLa cells, and Topo II unknotting activity was also in parallel with the level of Topo IIalpha mRNA. The late S phase-regulatory element was found to be located in the region containing ATF-binding element between -290 and -90bp and the region was required for a maximal stimulation during late S phase. DNase I footprinting assay showed that ATF-binding element and novel cis-acting element (Topo IIalpha-specific sequence) were the principal protein-binding sites and the proteins interacting with these elements were induced during late S phase. One DNA-protein complex was formed by DNA mobility shift assay when ATF-binding site was incubated with nuclear extract prepared from late S phase cells, but no protein bound in non-S phase cells. Taken together, these results suggest that ATF may be essential transacting factor for maximal expression of Topo IIalpha gene during late S phase in HeLa cells.

Expression of topoisomerase IIalpha, Ki-67, proliferating cell nuclear antigen, p53, and argyrophilic nucleolar organizer regions in vulvar squamous lesions

OBJECTIVE

It was the aim of this study to investigate the expression of topoisomerase IIalpha (topo IIalpha), Ki-67, proliferating cell nuclear antigen (PCNA), p53, and argyrophilic nucleolar organizer region (AgNOR) staining in normal vulvar epithelia (NE, N = 10), vulvar condylomas (VC, N = 24), vulvar intraepithelial neoplasia (VIN, N = 26), as well as squamous cell carcinomas (SCC, N = 22) of the vulva.

METHODS

Formalin-fixed, paraffin-embedded archival tissue sections were immunostained with monoclonal antibodies against topo IIalpha, p53, and PCNA, as well as an affinity-isolated prediluted ready-to-use Ki-67 antibody using a standard immunohistochemical method, and stained with a colloid silver solution for AgNORs. Immunostaining was quantitated by determining the percentage of positively staining nuclei in each sample to express the labeling indices (LIs) by counting the immunoreactive nuclei in 1000 epithelial cells per case for each antibody. In each specimen 200 nuclei were examined using a x100 oil emersion lens, and the mean number of AgNORs per nucleus (AC) was calculated.

RESULTS

The LIs for topo IIalpha, Ki-67, and PCNA as well as ACs increased stepwise from NE to VCs, VIN lesions, and SCCs. In contrast to PCNA LIs and ACs, a consistent correlation in all four groups was found for Ki-67 and topo IIalpha, suggesting that the latter is a proliferation-associated marker in these tissues. p53 expression was seen 8.3% of VCs, 30.8% of VIN lesions, and 54.45% of SCCs. p53 LIs were not correlated with LIs for topo IIalpha or Ki-67 in SCCs. The LIs for topo IIalpha, Ki-67, PCNA, p53, and ACs were not related to tumor progression, FIGO stage, or tumor grade in SCCs.

CONCLUSIONS

This study presents topo IIalpha and Ki-67 as useful proliferation-associated markers of vulvar epithelia.

Topoisomerase IIalpha gene expression is regulated by the p53 tumor suppressor gene in nonsmall cell lung carcinoma patients

BACKGROUND

Topoisomerase IIalpha (Topo IIalpha) is an essential nuclear enzyme for chromosome segregation during mitosis. Previous experimental studies using cell lines reported that Topo IIalpha expression was negatively regulated by wild-type p53 through the gene's promoter region.

METHODS

Surgically resected tumor specimens from 98 nonsmall cell lung carcinoma (NSCLC) patients who were not treated with preoperative chemotherapy were studied. Quantitative reverse-transcription polymerase chain reaction analysis was done to evaluate Topo IIalpha gene expression. Polymerase chain reaction single strand conformation polymorphism following sequencing was performed to investigate mutations of p53.

RESULTS

Topo IIalpha gene expression in squamous cell carcinomas was significantly higher than in adenocarcinomas (P = 0.0007). Topo IIalpha gene expression in moderately differentiated tumors and poorly differentiated tumors was significantly higher than in well differentiated tumors (P = 0.0032 and P = 0.0005, respectively). Thirty nine tumors (40%) had mutations of p53. Topo IIalpha gene expression in tumors with mutant p53 was significantly higher than in those with wild-type p53 (P = 0.0224).

CONCLUSIONS

The current study suggests that Topo IIalpha gene expression is regulated by p53 gene status in NSCLC patients and that the overexpression of Topo IIalpha induced by mutant p53 might cause more aggressive carcinogenesis.

Topoisomerase IIalpha and other drug resistance markers in advanced non-small cell lung cancer

Resistance to chemotherapy is common in non-small cell lung cancer. The aim of this study was to investigate the prognostic impact of in vitro established drug resistance markers on the response to chemotherapy in patients with advanced non-small cell lung cancer. Samples of 38 patients were analyzed by immunohistochemical staining, for topoisomerase IIalpha and IIbeta, Ki-67, MRP and LRP. In addition, mutation analysis of the topoisomerase IIalpha gene, the B/DNBS and the Tyr804 region, was performed. Lung tumor biopsies were taken prior for treatment with one of the following regimens; cisplatin/paclitaxel, cisplatin/VM26 or VP16, or carboplatin/VP16/ifosfamide. Seventeen patients obtained a partial response, 12 had stable disease and nine patients had progressive disease. None of the investigated markers was related with overall response rate. In one sample a point mutation in the B/DNBS region of the topo IIalpha gene was detected which substitutes IIe(510) with Val. This tumor had a partial response to four courses of cisplatin/VP16 treatment. The survival analysis showed that the patients with high topo IIalpha expressing tumors had a significantly worse survival compared with the patients with low or intermediate topo IIalpha expressing tumors. In conclusion, no relation was observed between expression of topoisomerase IIalpha, IIbeta, Ki-67, MRP or LRP and response rate. Furthermore, worse survival was seen in patients with high topoisomerase IIalpha expressing tumors. In one tumor sample, a newly described mutation in the B/DNBS region of the topo IIalpha gene was detected, which does not appear to be related to drug resistance.

Influence of cell cycle and oncogene activity upon topoisomerase IIalpha expression and drug toxicity

The cell cycle, oncogenic signaling, and topoisomerase (topo) IIalpha levels all influence sensitivity to anti-topo II drugs. Because the cell cycle and oncogenic signaling influence each other as well as topo IIalpha levels, it is difficult to assess the importance of any one of these factors independently of the others during drug treatment. Such information, however, is vital to an understanding of the cellular basis of drug toxicity. We, therefore, developed a series of analytical procedures to individually assess the role of each of these factors during treatment with the anti-topo II drug etoposide. All studies were performed with asynchronously proliferating cultures by the use of time-lapse and quantitative fluorescence staining procedures. To our surprise, we found that neither oncogene action nor the cell cycle altered topo IIalpha protein levels in actively cycling cells. Only a minor population of slowly cycling cells within these cultures responded to constitutively active oncogenes by elevating topo IIalpha production. Thus, it was possible to study the effects of the cell cycle and oncogene action on drug-treated cells while topo IIalpha levels remained constant. Toxicity analyses were performed with two consecutive time-lapse observations separated by a brief drug treatment. The cell cycle phase was determined from the first observation, and cell fate was determined from the second. Cells were most sensitive to drug treatment from mid-S phase through G(2) phase, with G(1) phase cells nearly threefold less sensitive. In addition, the presence of an oncogenic src gene or microinjected Ras protein increased drug toxicity by approximately threefold in actively cycling cells and by at least this level in the small population of slowly cycling cells. We conclude that both cell cycle phase and oncogenic signaling influence drug toxicity independently of alterations in topo IIalpha levels.

Topoisomerase II alpha: prognostic predictor and cell cycle marker in surface epithelial neoplasms of the ovary and peritoneum

Immunohistochemistry for Topoisomerase II alpha (TopoIIa), a nuclear protein important for the separation of chromosomes and deoxyribonucleic acid replication, provides insight into the molecular events in the cell cycle and the response to chemotherapeutic agents, which target TopoIIa. We test the hypothesis that the percentage of TopoIIa immunoreactive nuclei (TopoIIaI) aids in the treatment and prognostic evaluation of ovarian and primary peritoneal surface epithelial neoplasms (SENs) and correlates with established cell cycle control markers: p53, p21WAF1/CIP1 (p21), and Ki67. Paraffin sections from a retrospective surgical series of 108 SENs were immunostained with anti-TopoIIa, anti-p53, anti-p21, and anti-Ki67. The TopoIIaI, the Ki67 proliferation index (Ki67PI), and the immunoreactivity score for p53 and p21 (IMS: S1, S2, S3 < 10%, 10 to 50%, > 50% of strong staining cells, respectively) were evaluated manually. TopoIIaI and Ki67PI ranged from 5 to 84% and 4 to 88% (mean/median: 31/30 and 44/46%), respectively, and were correlated (coefficient 0.62, p < 10(-11)). IMS of 108 SENs was as follows: p53 50% + (2S1, 52S3) and p21 66% + (38S1, 12S2, 21S3). The TopoIIaI associated directly with p53 (p < 10(-5) and inversely with p21 (p < 0.005) IMS. TopoIIaI correlated with SEN architectural/nuclear grade (p < 10(-5)/10(-7)), but not histologic type. Sixty-seven patients had disease at last follow-up, 55 were dead from disease at 2 to 67 months (mean/median 24/21), and 14 were alive with disease at 31 to 230 months (mean/median 73/59). Forty-one patients were disease free at 5 to 228 months (mean/median 75/54). TopoIIaI correlated with presence of disease (p < 0.01) and poor survival (p < 1 x 10(-9), even when only 93 invasive SEN cases are considered (p < 0.005). TopoIIaI correlates with poor prognosis and other cell cycle control markers. The patients in this retrospective series of SEN were treated primarily with platinum-based chemotherapy. These data may suggest further prospective studies in which patients with SENs exhibiting high TopoIIaI are treated with chemotherapy targeted against TopoIIa (e.g., etoposide). In this retrospective series, high SEN TopoIIaI predicted poor survival when treated with platinum-based chemotherapy, which does not target TopoIIa.

Simultaneous quantitation of topoisomerase II alpha and beta isoform mRNAs in lung tumor cells and normal and malignant lung tissue

Certain drugs used in the treatment of lung cancer and other human malignancies are cytotoxic because of their ability to interact with the two isoforms of topoisomerase II (topo II), topo IIalpha and topo IIbeta. As part of an effort to evaluate the contribution of topo II alterations to drug sensitivity and resistance in lung cancer, we have developed a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay to measure levels of topo II alpha and beta mRNAs simultaneously using a single pair of primers with sequences common to both isoforms. The PCR products derived from the topo II alpha and beta mRNAs are both 446 bp but have different electrophoretic mobilities in a nondenaturing polyacrylamide gel, allowing sensitive, rapid quantitation when the products are radiolabeled with [35S]-dATP. Using this RT-PCR method, poly(A+) RNA from 13 non-small cell lung cancer (NSCLC) cell lines was analyzed. The results obtained indicated that the cell lines express a wide range of topo II alpha mRNA levels (12-fold) and topo IIbeta mRNA levels (5.5-fold). Tumor and normal lung tissues from 25 patients with NSCLC were also examined. In the tumor samples, the levels of the topo II alpha and beta mRNAs were similar. However, mean topo IIalpha mRNA levels in the tumors were approximately 7-fold higher than those of the paired normal lung tissues. In contrast, topo IIbeta mRNA levels were similar in both tumor and normal lung. Topo II alpha and beta mRNA levels were both significantly lower in the squamous cell tumors than in the adenocarcinoma samples. Topo IIbeta mRNA levels in the squamous cell tumors were also significantly lower than those in paired normal lung tissue. The RT-PCR method described is reliable and convenient, and for the first time, makes the rapid simultaneous direct comparison of topo IIalpha and topo IIbeta mRNA levels feasible in large numbers of clinical samples.

Immunohistochemical staining for DNA topoisomerase II-alpha in benign, premalignant, and malignant lesions of the prostate

BACKGROUND

The DNA topoisomerase II-alpha (topo II-alpha)-targeting drug etoposide was recently shown to be an active agent in the combined chemotherapy of hormone-insensitive prostatic carcinoma. Aside from being the molecular target of etoposide, topo II-alpha is also a cell proliferation marker. Much experimental data indicate that cells sensitive to topo II-targeting chemotherapeutic drugs are rapidly proliferating and show elevated topo II expression. There is little information concerning topo II expression in lesions of the prostate.

METHODS

Paraffin blocks from cases of invasive prostatic carcinoma, prostatic intraepithelial neoplasia, and prostatic nodular hyperplasia were retrieved from the surgical pathology files at the University of Utah Health Sciences Center. Using a new immunohistochemical stain, specific for the alpha isoform of DNA topo II, enzyme expression was evaluated in 54 prostatic adenocarcinomas, 22 lesions of high-grade prostatic intraepithelial neoplasia (PIN), and 10 cases of benign prostatic nodular hyperplasia. Results were semiquantitated by determining for each case a topo II-alpha index, which represented the percent of positively staining cells.

RESULTS

The average topo II-alpha index for well-differentiated prostatic adenocarcinomas (Gleason scores 2-4) was 1.5 +/- 0.9; for moderately differentiated tumors (Gleason scores 5-7), 3.1 +/- 2.4; and for poorly differentiated tumors (Gleason scores 8-10), 6.7 +/- 5.5. The average topo II-alpha index for all invasive prostatic adenocarcinomas was 4.0 (range, 0-19.0). Benign prostatic nodular hyperplasia had the lowest average topo II-alpha index, of 0.54 (range, 0.2-1.0). The average topo II-alpha index of 2.3 (range, 0-8.6) for high-grade prostatic intraepithelial neoplasia was intermediate between the invasive tumors and benign prostate.

CONCLUSIONS

Topo II-alpha expression in carcinoma of the prostate correlates with Gleason score. The carcinomas with the highest expression of enzyme are more poorly differentiated and have the highest Gleason scores. Prostatic nodular hyperplasia shows little expression of topo II-alpha. Prostatic intraepithelial neoplasia has an average topo II-alpha index intermediate between nodular hyperplasia and carcinoma.

Expression of DNA topoisomerase I in neoplasms of the kidney: correlation with histological grade, proliferation, and patient survival

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.

Proliferation, C-myc, and cyclin D1 expression in diffuse alveolar damage: potential roles in pathogenesis and implications for prognosis

In this study we compared expression of DNA topoisomerase IIalpha, a marker of cellular proliferation, c-myc, and cyclin D1 in lung biopsy specimens showing diffuse alveolar damage (DAD) with control lung tissues. We subsequently correlated DNA topoisomerase IIalpha, c-myc, and cyclin D1 expression with survival. We hypothesized that poor outcome may correlate with a higher proliferation index, and that c-myc and cyclin D1 activation are potentially important regulators of both proliferation and apoptosis in DAD. Immnuohistochemical stains for c-myc, cyclin D1, and DNA topoisomerase IIalpha were performed on 10 cases of DAD (15 cases for DNA topoisomerase IIalpha) and 10 control lungs. A proliferation index for each case was calculated by dividing the number of nuclei expressing DNA topoisomerase IIalpha by the total number of nuclei counted. The percentages of alveolar pneumocytes and interstitial cells staining positively for c-myc and cyclin D1 were estimated. The average proliferation index (DNA topoisomerase IIalpha index) in DAD (0.16 +/- 0.06, n = 15) was significantly greater than in control lungs (0.00 +/- 0.01, n = 10) (P < .0001). The average proliferation index of patients with DAD who died of respiratory failure (0.18 +/- 0.05, n = 9) was significantly greater than the average proliferation index of patients whose respiratory disease resolved or stabilized (0.11 +/- 0.05, n = 5) (P < .03). Expression of c-myc in alveolar pneumocytes and interstitial cells was more intense and slightly more widespread in cases of DAD compared with control lungs. In 9 of 10 cases of DAD, cyclin D1 expression was present in up to 30% of alveolar pneumocytes and up to 10% of interstitial cells. No staining for cyclin D1 was present in control lungs. These results show that the proliferation index in DAD potentially correlates with patient survival. Furthermore, enhanced expression of c-myc and cyclin D1 may contribute to dysregulation of cellular proliferation and apoptosis observed in DAD.

DNA Topoisomerase II-alpha as a marker of cell proliferation in endocrine and other neoplasms

DNA topoisomerases are enzymes that are able to link and unlink DNA strands. They are classified as type I or type II topoisomerase if they catalyze transient single-strand (topo I) or double-strand (topo II) DNA breaks. Topo II-alpha has been used as a proliferation marker and it can also serve as a molecular target for a variety of anticancer drugs that are used clinically.Topo II-alpha expression is similar to MIB1 immunoreactivity in breast, ovarian, cervix, gastric, endometrial, adrenocortical, and hematological malignancies. In a study of adrenocortical tumors with metastases topo II was significantly higher than in tumors without metastases.Studies of topo II-alpha expression may provide information about the biological behavior of specific tumors and may also provide insights into the role that this enzyme plays in the response of human cancers to topo II-targeted anticancer drugs.

Elevations of DNA topoisomerase I in transitional cell carcinoma of the urinary bladder: correlation with DNA topoisomerase II-alpha and p53 expression

DNA topoisomerase I (topo I) is the molecular target of the camptothecin group of antitumor drugs. Laboratory studies have indicated that cells sensitive to these drugs contain elevated levels of topo I. In this study, we immunostained 49 cases of transitional cell carcinoma from the urinary bladder with a monoclonal antibody directed against human topo I. We found elevated expression of the enzyme in 77% (38 of 49). This included three of six grade I tumors (50%), 9 of 15 grade II tumors (60%), 14 of 15 grade III tumors (93%) and 12 of 13 grade IV tumors (92%). Because the number of cycling cells in a tumor also may be an important determinant of topo I drug response, a proliferation index (topo II-alpha) also was performed for each case. The average topo II-alpha index of grade I tumors was 7.5 x 3.8; for grade II tumors, 20.1+/-10.5; for grade III tumors, 40.3 x 8.2; and for grade IV tumors, 50.5+/-13.0. Because a functional p53 tumor suppressor gene may be necessary for anticancer drug response, we also evaluated our cases for alteration in p53 function. Mutations in the p53 tumor suppressor gene, estimated by immunohistochemical staining, were common, occurring in 23 of 49 cases (47%). The number of cases with elevated topo I, a large growth fraction, and a functional p53 tumor suppressor gene was 4 of 49 (8%). Our results suggest that a small population of patients with transitional cell carcinoma of the urinary bladder may have tumors with molecular features suggesting responsiveness to the new anticancer drugs targeting topo I.

Clinical resistance to topoisomerase-targeted drugs

This review describes topoisomerase (topo)-mediated drug resistance and topo expression in human tissues and cancers. In some in vitro studies a relation has been observed between topo I, IIalpha or IIbeta expression and sensitivity to topo inhibitors. Drug resistance to topo inhibitors may, however, be multifactorial. Several topo inhibitors are substrates for drug membrane transporters. As most topo inhibitors are cell cycle specific, disturbances in cell cycle regulation can also confer resistance, and downstream events following DNA damage induced by topo inhibitors may be involved in regulating cell death or survival. Several studies in patient specimens have shown a relation between topo IIalpha expression and the proliferative state of the tumor, higher topo IIalpha levels being seen in more highly proliferating tumor types. In contrast, topo IIbeta appears to be expressed in both proliferating and quiescent cells. Furthermore, higher topo I levels were observed in some tumors when compared to their normal counterparts. In some studies a reduced topo IIalpha level was seen in samples taken after chemotherapy treatment, as compared with specimens prior to treatment. No unequivocal relation was observed, however, between expression or activity of the topo genes and response to chemotherapy; nonetheless only a few studies have properly addressed this question. This review summarizes the results of the clinical studies performed so far, and analyzes the critical issues in performing studies on patient material.

Differential expression of DNA topoisomerase II alpha and II beta genes between small cell and non-small cell lung cancer

DNA topoisomerase II (Topo II) inhibitors are widely used in lung cancer chemotherapy, but small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) show different sensitivity to them. In this study, we examined the gene expression levels of both isoforms of Topo II (II alpha and II beta) in lung cancer specimens to investigate the differential expression between SCLC and NSCLC. The expression levels of the Topo II alpha and Topo II beta genes were assessed in 80 autopsy samples (40 primary tumors and 40 corresponding normal lung tissues) by using the reverse transcription polymerase chain reaction. We found that the expression levels of the Topo II alpha gene in tumors were significantly higher than those in normal lung tissues, and that those in SCLC were significantly higher than those in NSCLC. There were no significant differences in Topo II beta gene expression between tumors and normal lung tissues and between SCLC and NSCLC. Further-more, correlation analysis revealed that Topo II alpha expression was correlated with Topo II beta expression in both tumor and normal lung tissues. These results indicate that a difference exists in the regulation of the Topo II gene between lung tumors and normal lung tissues. Our finding of differential expression of Topo II alpha between SCLC and NSCLC also suggests that the Topo II alpha expression level is associated with sensitivity to Topo II inhibitors.

Immunohistochemical detection of DNA topoisomerase IIalpha, P-glycoprotein and multidrug resistance protein (MRP) in small-cell and non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) differ significantly in their clinical response to topoisomerase IIalpha (topo-IIalpha)-directed drugs, such as etoposide and teniposide, as NSCLC is virtually insensitive to single-agent therapy, while SCLC responds in two-thirds of cases. Preclinical studies have indicated that resistance to topo-IIalpha drugs depends on topo-IIalpha content and/or activity, the altered-topo-II multidrug resistance phenotype (at-MDR) and/or one of two different drug efflux pumps, P-glycoprotein (P-gp) and the multidrug resistance protein (MRP). Immunohistochemical analysis on paraffin-embedded tissue from 27 cases of untreated NSCLC and 29 cases of untreated SCLC (of which additional tumour biopsies after treatment with topo-IIalpha-directed drugs were available in ten cases) yielded the following results: NSCLC had significantly less topo-IIalpha than SCLC (P < 0.0001), as only 5 out of 27 NSCLC cases had > 5% positive cells compared with 28 out of 29 SCLC, and 0 out of 27 NSCLC had > 25% positive cells compared with 26 out of 29 SCLC. P-gp was detected in > 5% of cells in only 3 out of 27 NSCLC and in 6 out of 29 SCLC, and MRP in 5 out of 27 of NSCLC and 9 out of 29 SCLC. After treatment of patients with SCLC with either etoposide or teniposide, which are topo-IIalpha-directed drugs, there was an increase in MRP (P < 0.1) and P-gp (P < 0.05) positivity, while topo-IIalpha decreased (P < 0.05). In conclusion, the major difference between untreated NSCLC and SCLC was in topo-IIalpha content. In the small series of ten patients treated for SCLC, all three MDR phenotypes appeared to increase.

Immunohistochemical p53 protein status in nonsmall cell lung cancer is a promising indicator in determining in vitro chemosensitivity to some anticancer drugs

BACKGROUND AND OBJECTIVES

The tumor suppressor oncogene p53 abnormalities have been closely associated with resistance or sensitivity of cancer cells to some chemotherapeutic agents. We examined the association between p53 protein status in nonsmall cell lung cancer (NSCLC) and in vitro chemosensitivity to several chemotherapeutic agents.

METHODS

Using 146 surgically resected specimens of NSCLC, p53 status was immunohistochemically evaluated, and in vitro chemosensitivity to 5-fluorouracil (5-Fu), cisplatin (CDDP), mitomycin C (MMC), etoposide (VP-16), doxorubicin hydrochloride (ADM), and vindesine sulfate (VDS) was examined by a collagen gel-droplet embedded culture drug sensitivity test (CD-DST, Int J Oncol, 1997;11:449).

RESULTS

Sixty-five of 146 materials (45%) showed immunohistochemically abnormal p53 protein accumulation in >10% of cancer cells within the tumor tissue, being regarded as p53+, whereas 81 (55%) were to p53-, in which no or less than 10% positive immunostaining cancer cells were detected. By CD-DST, the incidence of chemosensitive, borderline, and resistant p53- materials (N=81) to 5-Fu was 37%(N=30), 14%(N=11), and 49%(N=40), whereas that of p53+ materials (N=65) was 20%(N=13), 6%(N=4), and 74%(N=48), respectively, showing that p53- materials were significantly more sensitive to 5-Fu than p53+ materials (P=0.011), especially in the adenocarcinoma type. As similar borderline association between p53 protein status and in vitro chemosensitivity was also shown in ADM (P=0.078), but not in other chemoagents.

CONCLUSIONS

Immunohistochemically detected p53 protein status in NSCLC patients may be a promising indicator in determining in vitro chemosensitivity to some anticancer drugs, especially 5-Fu and ADM.

Drug resistance to topoisomerase II inhibitors

We describe in this review the mechanisms of resistance to topoisomerase II inhibitors that have been identified in cell lines rendered resistant to drugs. They concern especially both quantitative and qualitative alterations of topoisomerase II, leading to drug insensitivity of the cells. Expression and activity of topoisomerase II have also been studied in a number of tumor specimens originating from patients, but the role of topoisomerase II alterations in drug resistance in the clinical setting has not yet been firmly established. It would be worthwhile, however, to develop predictive assays for drug activity in human cancers, based upon the topoisomerase II status of tumor samples.

Human DNA topoisomerase II-alpha: a new marker of cell proliferation in invasive breast cancer

DNA topoisomerase II-alpha is the molecular target of doxorubicin, an active drug used in the therapy of breast cancer. From many in vitro studies, it is known that high levels of topo II-alpha expression correlate with drug sensitivity, and low levels of topo II-alpha correlate with drug resistance. In addition, the enzyme is known to be a marker of cell proliferation in normal tissues. Because the number of proliferating cells in a breast cancer has been shown to be prognostically important, and because doxorubicin is used in the treatment of breast cancer, we hypothesized that the measurement of topo II-alpha in breast cancer may not only give drug sensitivity information but also may yield important data on cell proliferation. In this study, formalin-fixed, paraffin-embedded tissue from 30 specimens of invasive breast cancer from 20 patients were immunohistochemically stained for topo II-alpha with a mouse monoclonal antibody. For each case, a topo II-alpha index was determined that represents the number of positive-staining tumor cells divided by the total number of tumor cells counted times 100. A similar index was determined for MIB1, a known cell proliferation marker. Each case was also graded according to the modified Bloom-Richardson criteria and evaluated for c-erbB-2 amplification, hormonal status, S-phase fraction, and mitotic index. The topo II-alpha index correlates better with the MIB1 index than with the S-phase fraction or mitotic index. The topo II-alpha expression in breast cancer ranges from low (topo II-alpha index <1) to high (topo II-alpha index = 86). Amplification of c-erbB-2 was observed in 4 of 28 cases (14%) but did not correlate with high topo II-alpha indices. We conclude that measurement of topo II-alpha in invasive breast cancer can be readily performed by immunohistochemical staining, and it gives information on the number of cycling tumor cells. In addition, because the enzyme is the molecular target of doxorubicin, the expression of the enzyme may relate also to the sensitivity or resistance of the tumor to doxorubicin-based chemotherapeutic protocols.