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Background: Platinum-based chemotherapy has long been used in the treatment of a variety of cancers and functions by inducing DNA damage. ERCC1 and ERCC4 are involved in the removal of this damage and have previously been implicated in resistance to platinum compounds. The aim of the current investigation is to determine the presence, frequency and prognostic impact of ERCC1 or ERCC4 gene copy number alterations in colorectal cancer (CRC).Methods: Fluorescent in situ hybridization probes directed at ERCC1 and ERCC4 with relevant reference probes were constructed. Probes were tested in a CRC cell line panel and in tumor sections from 152 stage III CRC chemonaive patients. Relationships between biomarker status and clinical endpoints (overall survival, time to recurrence, and local recurrence in rectal cancer) were analyzed by survival statistics.Results: ERCC1-19q13 copy number alterations were observed in a single cell line metaphase (HT29). In patient material, ERCC1-19q13 copy number gains (ERCC1-19q13/CEN-2 ≥ 1.5) were detected in 27.0% of specimens, whereas ERCC1-19q13 deletions (ERCC1-19q13/CEN-2 < 0.8) were only detected in 1.3%. ERCC1-19q13 gain was significantly associated with longer survival (multivariate analysis, HR: 0.45, 95% CI: 0.20-1.00, p = 0.049) in patients with colon tumors, but not rectal tumors. No ERCC4 aberrations were detected and scoring was discontinued after 50 patients.Conclusions: ERCC1-19q13 copy number gains occur frequently in stage III CRC and influences survival in patients with colon tumors. Future studies will investigate the effect of ERCC1-19q13 aberrations in a platinum-treated patient population with the aim of developing a predictive biomarker profile for oxaliplatin sensitivity in CRC. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: A Topoisomerase 1 (Top1) poison is frequently included in the treatment regimens for metastatic colorectal cancer (mCRC). However, no predictive biomarkers for Top1 poisons are available. We here report a study on the TOP1 gene copy number in CRC patients and its association with patient prognosis and tumor cell proliferation. Experimental design: The study included TOP1 and CEN-20 fluorescence in situ hybridization (FISH) analyses on formalin fixed paraffin embedded (FFPE) tissue sections from 154 stage III CRC chemonaïve patients. The frequencies of aberration in the TOP1 gene copy number, the CEN-20 copy number and the TOP1/CEN-20 ratio were analyzed and associated with overall survival (OS), time to recurrence (TTR) and in a subgroup analysis of rectal cancer patients only with time to local recurrence (LR in RC). Moreover, the TOP1 and CEN-20 copy numbers were correlated with the tumor Ki67 proliferation index. Results: 35.7% of the tumors had an increased TOP1 copy number above 4n gene copies per cell and 28.6% and 9.7% had a TOP1/CEN-20 ratio ≥1.5 or ≥2.0, respectively. The TOP1 copy number and the TOP1/CEN-20 ratios were separately added into multivariate analyses as continuous variables, in which also age, gender, primary tumor location and Ki67 status were added as covariates. In contrast to the TOP1/CEN-20 ratio, the TOP1 copy number was significantly associated with OS (HR: 0.62; 95% CI: 0.42–0.90; p = 0.01). Neither the TOP1 copy number nor the ratio was significantly associated with TTR and only the TOP1/CEN-20 ratio was significantly associated with LR in RC (HR: 0.25; 95% CI: 0.08–0.83; p = 0.02). No significant correlation was found between the TOP1 copy number and proliferation, while a weak and inverse correlation between the CEN-20 copy number and proliferation was observed. Conclusions: This study showed that increased TOP1 gene copy numbers are frequent findings in cancer cells in stage III CRC tumors but unrelated to the proliferative status of the tumors. The association with prognosis is important to consider when planning and analyzing future studies investigating TOP1 as a potential predictive biomarker for Top1 poisons. [Copyright &y& Elsevier]

Objective. A positive relationship between topoisomerase-1 (TOP1) protein and sensitivity toward the TOP1 inhibitor irinotecan has been reported in patients with metastatic colorectal cancer (mCRC). In this study, we analyzed TOP1 gene copy number variation in tumor tissue from CRC patients and CRC cell lines with different sensitivities to the TOP1 inhibitor SN-38 and oxaliplatin. Material and methods. A TOP1 gene probe with a chromosome 20 centromere (CEN-20) reference probe was applied on normal mucosa and on tumor tissue from 50 stage III CRC patients. Additionally, associations between TOP1/CEN-20 ratio and in vitro sensitivity to SN-38 (irinotecan) and oxaliplatin were tested on 10 CRC cell lines. Results. In the malignant epithelium, 84% of the samples demonstrated an increased TOP1 gene copy number and 64% had an increased TOP1/CEN-20 ratio compared with the non-affected mucosa. Sixteen (32%) of the tumors had a ratio of ≥1.5 and 9 (18%) of these had a ratio of ≥2.0. A positive association was observed between the TOP1 gene copy number and the TOP1/CEN-20 ratio and in vitro sensitivity toward SN-38, but not toward oxaliplatin. Conclusions. A large fraction of the clinical samples demonstrated increased TOP1 gene copy number and increased TOP1/CEN-20 ratio. The cell line study suggested an association between TOP1 gene copy number or TOP1/CEN-20 ratio and sensitivity to irinotecan but not oxaliplatin. [ABSTRACT FROM AUTHOR]