ERCC1 and telomere status in breast tumours treated with neoadjuvant chemotherapy and their association with patient prognosis

Abstract

Dysfunctional telomeres and DNA damage repair (DDR) play important roles in cancer progression. Studies have reported correlations between these factors and tumour aggressiveness and clinical outcome in breast cancer. We studied the characteristics of telomeres and expression of ERCC1, a protein involved in a number of DNA repair pathways and in telomere homeostasis, to assess their prognostic value, alone or in combination, in 90 residual breast tumours after treatment with neoadjuvant chemotherapy (NCT). ERCC1 status was investigated at different molecular levels (protein and gene expression and gene copy‐number variations) by immunohistochemistry, qRT‐PCR and quantitative multiplex fluorescent‐PCR (QMF‐PCR). A comprehensive analysis of telomere characteristics was performed using qPCR for telomere length and qRT‐PCR for telomerase (hTERT), tankyrase 1 (TNKS) and shelterin complex (TRF1, TRF2, POT1, TPP1, RAP1 and TIN2) gene expression. Short telomeres, high hTERT and TNKS expression and low ERCC1 protein expression were independently associated with worse survival outcome. Interestingly, ERCC1 gains and losses correlated with worse disease‐free (p = 0.026) and overall (p = 0.043) survival as compared to survival of patients with normal gene copy‐numbers. Unsupervised hierarchical clustering of all ERCC1 and telomere parameters identified four subgroups with distinct prognosis. In particular, a cluster combining low ERCC1, ERCC1 gene alterations, dysfunctional telomeres and high hTERT and a cluster with high TNKS and shelterin expression correlated with poor disease‐free (HR= 5.41, p= 0.0044) and overall survival (HR= 6.01, p= 0.0023) irrespective of tumour stage and grade. This comprehensive study demonstrates that telomere dysfunction and DDR can contribute synergistically to tumour progression and chemoresistance. These parameters are predictors of clinical outcome in breast cancer patients treated with NCT and could be useful clinically as prognostic biomarkers to tailor adjuvant chemotherapy post‐NCT.

Genomic profiling of metaplastic breast carcinomas reveals genetic heterogeneity and relationship to ductal carcinoma

“…We demonstrate for the first time a high frequency of hotspot TERT promoter mutations in metaplastic breast carcinomas and specifically in tumors with spindle cell and/or squamous differentiation (39%) but not matrix-producing carcinomas, which highlights the importance of telomerase activation in the former subgroups. TERT promoter mutations have been associated with poor clinical outcome in several tumor types [54,55], and TERT overexpression in breast cancer has been correlated with poor response to chemotherapy [56,57]. Whether TERT promoter mutations are prognostically significant in metaplastic carcinomas requires further study.…”

TERT promoter status and gene copy number gains: effect on TERT expression and association with prognosis in breast cancer

“…One of the hallmark features of tumor cells, it contributes to their growth advantage and survival, and upregulation of the TERT gene is the major mechanism of telomerase activation in human cancer [ 2 ]. In breast tumors, TERT overexpression was associated with tumor aggressiveness [ 3 ] and poor survival after adjuvant [ 4 ] and neoadjuvant [ 5 ] chemotherapy.…”

ADAR expression and copy number variation in patients with advanced gastric cancer

“…2). Each product was identified by its size, and the area under peak were imported into an Excel spreadsheet and the copy number of each amplicon was determined by calculating a dosage quotient (DQ) for each fragment [14,15].…”