Elevations of DNA topoisomerase I in invasive carcinoma of the breast

Potential therapeutic targets shared between leishmaniasis and cancer

The association of leishmaniasis and malignancies in human and animal models has been highlighted in recent years. The misdiagnosis of coexistence of leishmaniasis and cancer and the use of common drugs in the treatment of such diseases prompt us to further survey the molecular biology of Leishmania parasites and cancer cells. The information regarding common expressed proteins, as possible therapeutic targets, in Leishmania parasites and cancer cells is scarce. Therefore, the current study reviews proteins, and investigates the regulation and functions of several key proteins in Leishmania parasites and cancer cells. The up- and down-regulations of such proteins were mostly related to survival, development, pathogenicity, metabolic pathways and vital signalling in Leishmania parasites and cancer cells. The presence of common expressed proteins in Leishmania parasites and cancer cells reveals valuable information regarding the possible shared mechanisms of pathogenicity and opportunities for therapeutic targeting in leishmaniasis and cancers in the future.

Topoisomerase 1B poisons: Over a half-century of drug leads, clinical candidates, and serendipitous discoveries

Topoisomerases are DNA processing enzymes that relieve supercoiling (torsional strain) in DNA, are necessary for normal cellular division, and act by nicking (and then religating) DNA strands. Type 1B topoisomerase (Top1) is overexpressed in certain tumors, and the enzyme has been extensively investigated as a target for cancer chemotherapy. Various chemical agents can act as "poisons" of the enzyme's religation step, leading to Top1-DNA lesions, DNA breakage, and eventual cellular death. In this review, agents that poison Top1 (and have thus been investigated for their anticancer properties) are surveyed, including natural products (such as camptothecins and indolocarbazoles), semisynthetic camptothecin and luotonin derivatives, and synthetic compounds (such as benzonaphthyridines, aromathecins, and indenoisoquinolines), as well as targeted therapies and conjugates. Top1 has also been investigated as a therapeutic target in certain viral and parasitic infections, as well as autoimmune, inflammatory, and neurological disorders, and a summary of literature describing alternative indications is also provided. This review should provide both a reference for the medicinal chemist and potentially offer clues to aid in the development of new Top1 poisons.

Change in Topoisomerase 1-Positive Circulating Tumor Cells Affects Overall Survival in Patients with Advanced Breast Cancer after Treatment with Etirinotecan Pegol

Purpose: Preplanned exploratory analyses were performed to identify biomarkers in circulating tumor cells (CTC) predictive of response to the topoisomerase 1 inhibitor etirinotecan pegol (EP).Experimental Design: The BEACON trial treated patients with metastatic breast cancer (MBC) with EP or treatment of physician's choice (TPC). Blood from 656 of 852 patients (77%) was processed with ApoStream to enrich for CTCs. A multiplex immunofluorescence assay measured expression of candidate response biomarkers [topoisomerase 1 (Top1), topoisomerase 2 (Top2), Ki67, RAD51, ABCG2, γH2AX, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)] in CTCs. Patients were classified as Top1 low (Top1Lo) or Top1 high (Top1Hi) based on median CTC Top1 expression. Correlation of CTC biomarker expression at baseline, cycle 2 day 1 (C2D1), and cycle 4 day 1 with overall survival (OS) was investigated using Cox regression and Kaplan-Meier analyses.Results: Overall, 98% of samples were successfully processed, of which 97% had detectable CTCs (median, 47-63 CTCs/mL; range, 0-2,020 CTCs/mL). Top1, Top2, and TUNEL expression was detected in 52% to 90% of samples; no significant associations with OS were observed in pretreatment samples for either group. EP-treated patients with low C2D1Top1⁺ CTCs had improved OS compared with those with higher positivity (14.1 months vs. 11.0 months, respectively; HR, 0.7; P = 0.02); this difference was not seen in TPC-treated patients (HR, 1.12; P = 0.48). Patients whose CTCs decreased from Top1Hi to Top1Lo at C2D1 had the greatest OS benefit from EP (HR, 0.57; P = 0.01).Conclusions: CTC Top1 expression following EP treatment may identify patients with MBC most likely to have an OS benefit. Clin Cancer Res; 24(14); 3348-57. ©2018 AACR.

Topoisomerase-1 gene copy aberrations are frequent in patients with breast cancer

Topoisomerase-1 (Top1) targeting drugs have shown promising efficacy in patients with metastatic breast cancer (BC). However, these drugs are rather toxic calling for development and validation of predictive biomarkers to increase the therapeutic index. As these drugs are targeting the Top1 protein and since no validated anti-Top1 antibodies for immunohistochemistry have been reported, we raised the hypothesis that TOP1 gene amplifications may serve as a proxy for the Top1 protein and thereby a biomarker of response to treatment with Top1 inhibitors in BC. The aim was to determine the prevalence of TOP1 gene copy gain in BC. The prevalence of TOP1 gene copy gain was investigated by fluorescence in situ hybridization with a TOP1/CEN-20 probemix in normal breast tissue (N = 100) and in tissue from patients with metastatic BC in a discovery (N = 100) and a validation cohort (N = 205). As amplification of 20q including CEN-20 is common in BC a TOP1/CEN-2 probemix was applied to the validation cohort. More than 30% of the patients had gene copy numbers of ≥ 4 and ∼20% of the patients had TOP1/CEN-20 ratios ≥ 1.5. The CEN-2 probe did not add any information. Gain of the TOP1 gene appears to be common in BC making the gene a potential biomarker for response to treatment with Top1 inhibitors. As 20q amplification is a common finding in BC and as no other suitable reference gene has yet been identified, TOP1 copy number may be a more valid method of detecting gain than using a gene/centromere ratio.

A phase II study of weekly irinotecan in patients with locally advanced or metastatic HER2- negative breast cancer and increased copy numbers of the topoisomerase 1 (TOP1) gene: a study protocol

Background

About 20% of patients with primary breast cancer develop metastatic disease during the course of the disease. At this point the disease is considered incurable and thus treatment is aimed at palliation and life prolongation. As many patients will have received both an anthracycline and a taxane in the adjuvant setting, treatment options for metastatic breast cancer are limited. Furthermore response rates for the most commonly used drugs range from around 30% to 12% . Thus new treatment options are needed and preferably coupled to biomarkers predictive of response. Irinotecan is a topoisomerase 1 inhibitor used for decades for the treatment of colorectal cancer. Four studies have investigated the efficacy of irinotecan monotherapy in breast cancer and all have included non-biomarker selected patients. In these studies response rates for irinotecan ranged from 5%-23% and are thus comparable to response rates obtained with drugs commonly used in the metastatic setting. If a predictive biomarker could be identified for irinotecan, response rates might be even higher.

Methods/Design

This multi-centre phase II single arm trial was designed to investigate if patients with metastatic breast cancer and increased expression of the topoisomerase 1 gene have a high likelihood of obtaining a clinical benefit from treatment with irinotecan. Trial recruitment is two-staged as 19 patients are planned to participate in the first part. If less than 7 patients have clinical benefit the trial stops, if more than 7 patients have clinical benefit a total of 40 patients will be included.

Discussion

This ongoing trial is the first to prospectively test copy number of the topoisomerase I gene as a predictive biomarker of response to irinotecan.

Trial registration

EudraCT number 2012-002348-26.

Biomarker-guided repurposing of chemotherapeutic drugs for cancer therapy: a novel strategy in drug development

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.

Close temporal relationship between onset of cancer and scleroderma in patients with RNA polymerase I/III antibodies

OBJECTIVE

This study was undertaken to examine the temporal relationship between scleroderma development and malignancy, and to evaluate whether this differs by autoantibody status among affected patients.

METHODS

Study participants had a diagnosis of scleroderma, a diagnosis of cancer, cancer, an available serum sample, and a cancer pathology specimen. Sera were tested for autoantibodies against topoisomerase I, centromere, and RNA polymerase I/III by immunoprecipitation and/or enzyme-linked immunosorbent assay. Clinical and demographic characteristics were compared across autoantibody categories. Expression of RNA polymerases I and III was evaluated by immunohistochemistry using cancerous tissue from patients with anti-RNA polymerase antibodies.

RESULTS

Twenty-three patients were enrolled. Six patients tested positive for anti-RNA polymerase I/III, 5 for anti-topoisomerase I, and 8 for anticentromere, and 4 were not positive for any of these antigens. The median duration of scleroderma at cancer diagnosis differed significantly between groups (-1.2 years in the anti-RNA polymerase I/III group, +13.4 years in the anti-topoisomerase I group, +11.1 years in the anticentromere group, and +2.3 years in the group that was negative for all antigens tested) (P = 0.027). RNA polymerase III demonstrated a robust nucleolar staining pattern in 4 of 5 available tumors from patients with antibodies to RNA polymerase I/III. In contrast, nucleolar RNA polymerase III staining was not detected in any of 4 examined tumors from the RNA polymerase antibody-negative group (P = 0.048).

CONCLUSION

Our findings indicate that there is a close temporal relationship between the onset of cancer and scleroderma in patients with antibodies to RNA polymerase I/III, which is distinct from scleroderma patients with other autoantibody specificities. In this study, autoantibody response and tumor antigen expression are associated. We propose that malignancy may initiate the scleroderma-specific immune response and drive disease in a subset of scleroderma patients.

Epidermal growth factor-induced heparanase nucleolar localization augments DNA topoisomerase I activity in brain metastatic breast cancer

Identification of molecular mechanisms responsible for brain metastatic breast cancer (BMBC) is imperative to develop novel therapies. However, current understanding of the molecular circuitry that governs BMBC dissemination remains fragmentary. Heparanase (HPSE) is the only functional mammalian endoglycosidase whose activity correlates with cancer metastasis, angiogenesis, and the reduced postoperative survival of cancer patients, making it an active target for anticancer therapeutics. We hypothesized that human epidermal growth factor receptor 2 (HER2)/epidermal growth factor receptor (EGFR) activation promotes HPSE function in human BMBC. To address this, we examined HPSE content, activity, and intracellular trafficking in a HER2/EGFR-expressing BMBC model system and show that HPSE is present, functional, and correlates with HER2 status. Further, we showed that EGF induced nucleolar translocation of HPSE in these cells in a dose- and time-dependent manner upon activation of HER2/EGFR. Knockdowns of HER2/EGFR by small interference RNA abolished EGF-induced HPSE nucleolar translocalization. It was also noted that nucleolar HPSE modulates DNA topoisomerase I (Topo I), an enzyme that is highly present in nucleoli, essential for DNA replication and transcription in a variety of tumors, and inhibited by heparan sulfate. Evidence is provided that HPSE can regulate Topo I activity, which subsequently affects BMBC cell proliferation. Finally, we showed that the nucleolar presence of HPSE with Topo I colocalization is detected only in HER2-overexpressing BMBC patient specimens. Altogether, these findings support the notion that HPSE is a critical downstream target of HER2 mechanisms driving BMBC and is potentially relevant for BMBC therapeutic interventions.

Topoisomerase I and IIalpha protein expression in primary colorectal cancer and recurrences following 5-fluorouracil-based adjuvant chemotherapy

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.

Topoisomerase I protein expression in primary colorectal cancer and recurrences after 5-FU-based adjuvant chemotherapy

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.

RNA expression of MDR1/P-glycoprotein, DNA-topoisomerase I, and MRP2 in ovarian carcinoma patients: correlation with chemotherapeutic response

OBJECTIVE

Clinical drug resistance is the major obstacle in the successful treatment of ovarian cancer. Besides elevated expression of adenosine triphosphate binding cassette (ABC) transporters, such as MDR1/P-gp or MRP2/cMOAT/ABCC2, alterations in the expression of DNA topoisomerase I (TOP1) are associated with drug-resistant phenotypes in various model systems.

METHODS

In ovarian specimens of 61 patients, the mRNA expression levels of MDR1/P-gp, MRP2, and TOP1 were determined using a competitive quantitative RT-PCR protocol with internal standards. The mRNA expression levels were correlated with the clinical outcome and histopathological criteria. The tumor specimens included 11/61 (18%) benign ovarian tumors, including 2 LMP tumors, and 50/61 (82%) ovarian carcinomas, including 34 primary and 16 recurrent cancers. Moreover, 20/61 (33%) ovarian specimens showed low or no MDR1/P-gp expression.

RESULTS

None of the benign tumors showed MRP2 expression, whereas 15/50 (30%) ovarian carcinomas expressed MRP2. In 61/61 (100%) of the samples, expression of TOP1 could be measured. In patients with recurrent ovarian cancer, no differences in expression of any of the factors could be observed. In patients with primary FIGO III carcinomas (n = 18), the overall-survival time (OST) was significantly prolonged with low MDR1/P-gp expression level (P = 0.015). Expression levels of MRP2 and TOP1 did not correlate with OST. Moreover, the progression-free survival (PFS) in FIGO III patients showed a clear tendency to be associated with low MDR1/P-gp (P = 0.218) and TOP1 expression (P = 0.466), and negativity for MRP2 (P = 0.244).

CONCLUSION

MDR1/P-gp and MRP2 might have some additional predictive value for the clinical outcome of patients with advanced ovarian carcinoma.

Large-scale analysis of HLA peptides presented by HLA-Cw4

A large number of HLA-Cw4 (Cw *0402) peptides were purified, sequenced, and identified from breast and ovarian carcinoma cell lines. HLA-Cw4 molecules were expressed in these cells as soluble, secreted HLA (sHLA) and recovered from the growth medium. The peptides were separated by capillary reversed-phase HPLC and analyzed by tandem mass-spectrometry. The resulting peptides fit to some extent, but not completely, the known consensus of the Cw4 peptide-binding motif. Among the identified peptides, there are a few that originate from proteins of possible interest for cancer immunotherapy or diagnostics, including mucin-5B, ART-1, fatty acid synthase, putative prostate cancer tumor suppressor, DNA topoisomerase-1, and Rac1. This work demonstrates that large-scale identification of HLA peptides recovered from sHLA is an advantageous approach for establishing the HLA peptide consensus of different haplotypes and the identification of useful peptides for treatment of diseases such as cancer, viral, and autoimmune diseases.

Topoisomerase I interactive agents

Increased insight into the mechanism of interaction of topoisomerase I interactive agents will maximize the therapeutic index and enhance the development of additional agents. Preclinical studies designed to elucidate mechanisms by which the topoisomerase I interactive agents induce cell death will be essential. The role of ABC transporters in resistance to topoisomerase I interactive agents has been recently appreciated and future studies should be directed at circumventing this resistance. The results of preclinical studies must be translated into the design of clinical trials so that these agents can be used rationally. In this regard results of preclinical studies have clearly pointed to the enhanced antitumor activity from protracted dosing of topoisomerase I interactive agents and results of clinical trials are now supporting these preclinical findings. Finally, investigators are trying to understand better the mechanism(s) of the dose-limiting toxicities observed with the currently available topoisomerase I interactive agents in an effort to enable the optimal dosing of these agents. Even though the first priority must be to determine the therapeutic potential of the currently available agents, it is reassuring to know that other topoisomerase I interactive agents are currently under development.

Irinotecan: mechanisms of tumor resistance and novel strategies for modulating its activity

Camptothecins are broad-spectrum anticancer drugs that specifically target DNA topoisomerase I (Topo I). The formation of a cleavable drug-Topo I-DNA complex results in lethal double-strand DNA breakage and cell death. However, de novo or acquired clinical resistance to camptothecins is common. Studies of the camptothecin analog irinotecan suggest the following general mechanisms of resistance: (i) variable levels of the enzymes involved in the conversion of irinotecan; (ii) reduced cellular accumulation from active drug efflux; (iii) reduced levels of Topo I expression; (iv) alterations in the structure of Topo I from different mutations; (v) alterations in the cellular response to camptothecin-Topo I-DNA complex formation, which involves proteasome degradation of Topo I and/or enhanced DNA repair; and (vi) activation of the transcription factor nuclear factor kappa B by DNA damage and subsequent suppression of apoptosis. Multiple approaches using pharmacological and biological modulation to circumvent the above mechanisms of resistance have been incorporated into ongoing clinical trials and are expected to enhance the antitumor activity of irinotecan and reduce its systemic toxicity.

Topoisomerase I protein expression in primary colorectal cancer and lymph node metastases

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.