Deletion at 6q24.2-26 predicts longer survival of high-grade serous epithelial ovarian cancer patients.

Standard treatments for advanced high-grade serous ovarian carcinomas (HGSOCs) show significant side-effects and provide only short-term survival benefits due to disease recurrence. Thus, identification of novel prognostic and predictive biomarkers is urgently needed. We have used 42 paraffin-embedded HGSOCs, to evaluate the utility of DNA copy number alterations, as potential predictors of clinical outcome. Copy number-based unsupervised clustering stratified HGSOCs into two clusters of different immunohistopathological features and survival outcome (HR = 0.15, 95%CI = 0.03-0.81; Padj = 0.03). We found that loss at 6q24.2-26 was significantly associated with the cluster of longer survival independently from other confounding factors (HR = 0.06, 95%CI = 0.01-0.43, Padj = 0.005). The prognostic value of this deletion was validated in two independent series, one consisting of 36 HGSOCs analyzed by fluorescent in situ hybridization (P = 0.04) and another comprised of 411 HGSOCs from the Cancer Genome Atlas study (TCGA) (HR = 0.67, 95%CI = 0.48-0.93, Padj = 0.019). In addition, we confirmed the association of low expression of the genes from the region with longer survival in 799 HGSOCs (HR = 0.74, 95%CI = 0.61-0.90, log-rank P = 0.002) and 675 high-FIGO stage HGSOCs (HR = 0.76, 95%CI = 0.61-0.96, log-rank P = 0.02) available from the online tool KM-plotter. Finally, by integrating copy number, RNAseq and survival data of 296 HGSOCs from TCGA we propose a few candidate genes that can potentially explain the association. Altogether our findings indicate that the 6q24.2-26 deletion is an independent marker of favorable outcome in HGSOCs with potential clinical value as it can be analyzed by FISH on tumor sections and guide the selection of patients towards more conservative therapeutic strategies in order to reduce side-effects and improve quality of life.

CUL4A contributes to the biology of basal-like breast tumors through modulation of cell growth and antitumor immune response.

The CUL4A E3 ubiquitin ligase is involved in the regulation of many cellular processes and its amplification and/or overexpression has been observed in breast cancer. The 13q34 amplification, which is associated with the basal-like breast cancer subtype, has been proposed as one of the mechanism behind CUL4A up-regulation. However, the specific contribution of CUL4A to the biology of basal-like breast tumors has not yet been elucidated. In this work, by using cellular models of basal phenotype, we show the inhibitory effect of CUL4A silencing in the proliferation and growth of breast cancer cells both, in vitro and in vivo. We also demonstrate the transforming capacity of CUL4A exogenous overexpression in the 184B5 human mammary epithelial cells in vitro. Our results suggest a synergistic effect between CUL4A high levels and the activation of the RAS pathway in the tumorigenesis of basal-like breast cancer tumors. In addition, by using a proteomics approach we have defined novel candidate proteins and pathways that might mediate the oncogenic effect of CUL4A. In particular, we report a putative role of CUL4A in bypassing the immune system in breast cancer through the down-regulation of several molecules involved in the immune surveillance. These findings provide insight into the oncogenic properties of CUL4A in basal-like breast cancer and highlight the therapeutic opportunities to target CUL4A.

Analysis of DNA repair-related genes in breast cancer reveals CUL4A ubiquitin ligase as a novel biomarker of trabectedin response.

Trabectedin is more active in nucleotide excision repair (NER)-efficient and homologous recombination repair (HRR)-deficient cells. As up to 25% of sporadic breast tumors present somatic inactivation of the HRR pathway (BRCAness phenotype), we sought to characterize trabectedin effect in BRCA1-proficient and BRCA1-null breast cancer cell lines. We evaluated whether HRR and NER gene expression correlates with trabectedin sensitivity and explored the response predictive value of the CUL4A ubiquitin ligase, which ubiquitinates NER pathway members. We characterized trabectedin cytotoxicity, cell-cycle effects, and BRCA1, BRCA2, XRCC3, XPG, ERCC1, and CUL4A expression in 10 breast cancer cell lines. Gene expression and trabectedin sensitivity association were determined in cell lines. Survival assays after trabectedin treatment were conducted in CUL4A-silenced BRCA1-proficient and -deficient cells. Because of limited phase II clinical trials evaluating trabectedin efficacy in patients with breast cancer, we assessed CUL4A immunohistochemical staining in a retrospective series of 118 sarcomas from trabectedin-treated patients to validate in vivo our in vitro observations. In cell lines, greater trabectedin sensitivity was associated with higher CUL4A expression and lower BRCA1/ERCC5, BRCA1/CUL4A, and XRCC3/CUL4A expression ratios. In agreement, BRCA1-deficient CUL4A-knockdown cells presented higher cell survival after trabectedin exposure than did scramble control cells. Lack of effect in BRCA1-proficient cells suggests that HRR impairment is key in CUL4A-mediated trabectedin sensitivity. High CUL4A expression in nontranslocation-related patients with sarcoma predicted improved progression-free survival [PFS; HR, 0.37; 95% confidence interval (CI), 0.20-0.68, P = 0.001] and overall survival (OS; HR, 0.44; 95% CI, 0.21-0.93, P = 0.026). Our observations support the notion of greater trabectedin activity in tumors exhibiting BRCAness and reveal CUL4A as a potential biomarker for definition of trabectedin target patients.

Genetic anticipation is associated with telomere shortening in hereditary breast cancer.

There is increasing evidence suggesting that short telomeres and subsequent genomic instability contribute to malignant transformation. Telomere shortening has been described as a mechanism to explain genetic anticipation in dyskeratosis congenita and Li-Fraumeni syndrome. Since genetic anticipation has been observed in familial breast cancer, we aimed to study telomere length in familial breast cancer patients and hypothesized that genetic defects causing this disease would affect telomere maintenance resulting in shortened telomeres. Here, we first investigated age anticipation in mother-daughter pairs with breast cancer in 623 breast cancer families, classified as BRCA1, BRCA2, and BRCAX. Moreover, we analyzed telomere length in DNA from peripheral blood leukocytes by quantitative PCR in a set of 198 hereditary breast cancer patients, and compared them with 267 control samples and 71 sporadic breast cancer patients. Changes in telomere length in mother-daughter pairs from breast cancer families and controls were also evaluated to address differences through generations. We demonstrated that short telomeres characterize hereditary but not sporadic breast cancer. We have defined a group of BRCAX families with short telomeres, suggesting that telomere maintenance genes might be susceptibility genes for breast cancer. Significantly, we described that progressive telomere shortening is associated with earlier onset of breast cancer in successive generations of affected families. Our results provide evidence that telomere shortening is associated with earlier age of cancer onset in successive generations, suggesting that it might be a mechanism of genetic anticipation in hereditary breast cancer.