Physical activity and breast cancer survival: an epigenetic link through reduced methylation of a tumor suppressor gene L3MBTL1.

The study was conducted to determine the effect of physical activity on DNA methylation and to predict the consequence of this effect concerning gene expression and breast cancer survival. Blood samples, collected from 12 breast cancer patients who participated in a randomized clinical trial of exercise, were examined for exercise-related changes in DNA methylation using a methylation microarray. Tumor samples of 348 breast cancer patients were analyzed with qRT-PCR and qMSP to determine gene expression and methylation identified in the microarray analysis. Cox regression models were developed to predict survival outcomes in association with gene expression and methylation. After 6 months of moderate-intensity aerobic exercise, changes in DNA methylation (P < 5 × 10(-5)) in peripheral blood leukocytes were detected in 43 genes from a panel of 14 495. Based on the list, we analyzed gene expression in association with overall survival in breast tumors and found three genes whose methylation was reduced after exercise were favorably in association with overall survival, i.e., higher expression associated with better survival. Of the three genes, L3MBTL1 was a putative tumor suppressor gene with known function to repress chromatin for transcription, which is activated mainly in germline stem cells. Further analyses of tumor features among patients indicated that high expression of L3MBTL1 was associated with low grade and hormone receptor-positive tumors, as well as low risk of disease recurrence and breast cancer death. In conclusion, the study suggests that increasing physical activity after a breast cancer diagnosis may affect epigenetic regulation of tumor suppressor genes, which have favorable impacts on survival outcomes of breast cancer patients.

Favorable outcome associated with an IGF-1 ligand signature in breast cancer.

The insulin-like growth factor (IGF) axis is fundamentally important in cell growth, development and cancer. We used genomic technologies to better characterize the activity of the IGF axis in human breast cancer and to identify predictors of response to IGF targeted therapies. Analysis of the gene expression patterns and pathway analysis in 204 clinically annotated primary breast cancers were performed and compared to levels of mRNA for IGF ligands and receptors. Pathway activation scores were calculated by Pearson correlation (+1, -1). Network analysis was performed using Ingenuity software. IGF-1 ligand levels were strongly negatively correlated (P < 10⁻6) with a published IGF-IR activation signature.A signature of high IGF-1 ligand was associated with better prognosis (P = 0.025-1.5 x 10⁻8) in several public datasets. Pathway analysis revealed upregulation of pathways associated with breast differentiation (adipocyte growth factors, PPAR-gamma) and down-regulation of proliferation pathways (AKT/MAPK) in the IGF-1 ligand high group. Of note, the IGF-1 ligand signature was anti-correlated with IGFIR receptor levels (P = 0.07). In conclusion, a breast tumor-derived signature of high IGF-1 ligand is associated with favorable outcome, in contrast to a previously reported IGF-IR activation signature. The prognostic value of the IGF-I ligand signature is validated in three independent datasets. These signatures should be applied in study of IGF1-R targeted therapy.

Association between miR-200c and the survival of patients with stage I epithelial ovarian cancer: a retrospective study of two independent tumour tissue collections.

BACKGROUND: International Federation of Gynecology and Obstetrics stage I epithelial ovarian cancer (EOC) has a significantly better prognosis than stage III/IV EOC, with about 80% of patients surviving at 5 years (compared with about 20% of those with stage III/IV EOC). However, 20% of patients with stage I EOC relapse within 5 years. It is therefore crucial that the biological properties of stage I EOCs are further elucidated. MicroRNAs (miRNAs) have shown diagnostic and prognostic potential in stage III and IV EOCs, but the small number of patients diagnosed with stage I EOC has so far prevented an investigation of its molecular features. We profiled miRNA expression in stage I EOC tumours to assess whether there is a miRNA signature associated with overall and progression-free survival (PFS) in stage I EOC. METHODS: We analysed tumour samples from 144 patients (29 of whom relapsed) with stage I EOC gathered from two independent tumour tissue collections (A and B), both with a median follow-up of 9 years. 89 samples from tumour tissue collection A were stratified into a training set (51 samples, 15 of which were from patients who relapsed) for miRNA signature generation, and into a validation set (38 samples, seven of which were from patients who relapsed) for signature validation. Tumour tissue collection B (55 samples, seven of which were from patients who relapsed) was used as an independent test set. The Cox proportional hazards model and the log-rank test were used to assess the correlation of quantitative reverse transcription PCR (qRT-PCR)-validated miRNAs with overall survival and PFS. FINDINGS: A signature of 34 miRNAs associated with survival was generated by microarray analysis in the training set. In both the training set and validation set, qRT-PCR analysis confirmed that 11 miRNAs (miR-214, miR-199a-3p, miR-199a-5p, miR-145, miR-200b, miR-30a, miR-30a*, miR-30d, miR-200c, miR-20a, and miR-143) were expressed differently in relapsers compared with non-relapsers. Three of these miRNAs (miR-200c, miR-199a-3p, miR-199a-5p) were associated with PFS, overall survival, or both in multivariate analysis. qRT-PCR analysis in the test set confirmed the downregulation of miR-200c in relapsers compared with non-relapsers, but not the upregulation of miR-199a-3p and miR-199a-5p. Multivariate analysis confirmed that downregulation of miR-200c in the test set was associated with overall survival (HR 0·094, 95% CI 0·012-0·766, p=0·0272) and PFS (0·035, 0·004-0·311; p=0·0026), independent of clinical covariates. INTERPRETATION: miR-200c has potential as a predictor of survival, and is a biomarker of relapse, in stage I EOC. FUNDING: Nerina and Mario Mattioli Foundation, Cariplo Foundation (Grant Number 2010-0744), and the Italian Association for Cancer Research.

MicroRNA let-7a: a potential marker for selection of paclitaxel in ovarian cancer management.

OBJECTIVES: Let-7 is a family of small non-coding RNAs regulating the expression of many genes that control important cellular activities. Let-7 is shown in vitro to sensitize cancer cells to platinum, but induce ovarian cancer resistance to paclitaxel. This study aims to investigate the effect of let-7a expression on survival outcomes of epithelial ovarian cancer (EOC) patients treated with different chemotherapy. METHODS: Let-7a expression was measured with qRT-PCR in ovarian tumors of 178 EOC patients who received platinum-based chemotherapy with and without paclitaxel after surgery. Survival analysis was performed to assess the effects of let-7a and chemotherapy on disease outcomes. RESULTS: Let-7a expression was detectable in the EOC samples, but the expression was not associated with disease stage, tumor grade, histology and debulking results. Patients who responded to platinum with paclitaxel had significantly lower let-7a than those who did not. Survival analyses showed that patients with high let-7a had better survival compared to those with low let-7a when they were treated with platinum without paclitaxel. The hazards ratios (HRs) for death and disease progression were 0.52 (95% CI: 0.29-0.96) and 0.48 (0.26-0.89) for high let-7a when compared to low let-7a, respectively. However, when patients were treated with platinum and paclitaxel, high let-7a was associated with worse progression-free and overall survival. The HRs for death and disease progression were 3.87 (95% CI: 1.28-11.66) and 3.48 (95% CI: 1.25-9.67) for high let-7a when compared to low let-7a, respectively. Further studies showed that among patients with low let-7a, those treated with paclitaxel in addition to platinum survived better than those treated without paclitaxel [adjusted-HRs were 0.31 (95% CI: 0.15-0.66) for death and 0.40 (95% CI: 0.22-0.75) for disease], while among those with high let-7a, the two types of treatment made no difference in patient survival. CONCLUSIONS: The study suggests that the beneficial impact of the addition of paclitaxel on EOC survival was significantly linked to let-7a levels, and that miRNAs such as let-7a may be a useful marker for selection of chemotherapeutic agents in EOC management.

Surgical and medical treatment of clear cell ovarian cancer: results from the multicenter Italian Trials in Ovarian Cancer (MITO) 9 retrospective study.

OBJECTIVE: Clear cell ovarian carcinoma has a poorer prognosis compared with other histological subtypes. MATERIALS AND METHODS: The Multicenter Italian Trials in Ovarian Cancer (MITO) 9 study retrospectively assessed an Italian cohort of patients with clear cell ovarian cancer observed in the years 1991-2007 in 20 Italian centers. RESULTS: A total of 240 patients with ovarian cancer were analyzed. Forty-five percent of the patients had stage I disease. In 62.9%, clear cell histology was pure, whereas in the other cases, a mixed population was evident. Most of the cases underwent standard surgery, whereas in 7.1% of the patients, a fertility-sparing surgery was given. Lymphadenectomy was performed in 47.9% (115/240) of the patients (54.3% in stages I and II; 39.2% in advanced stage). Most of the patients were treated with platinum-based chemotherapy including paclitaxel in 52.9%. Disease-free survival was longer in patients undergoing lymphadenectomy at surgery (P = 0.0001), both in early stages (P = 0.0258) and in stage III and IV diseases (P = 0.0037). The impact of lymphadenectomy was also evident on overall survival in patients with advanced-stage disease. At multivariate analysis, lymphadenectomy (done vs not done) and stage (I and II vs III and IV) were independently associated with longer disease-free and overall survival, whereas front-line chemotherapy (with vs without taxanes) was not significant. CONCLUSION: This analysis suggests that lymphadenectomy has a strong prognostic role for clear cell ovarian cancer influencing disease-free survival and overall survival. The addition of paclitaxel to platinum-based chemotherapy does not affect the outcome.