Mai Iwasa

High Expression of MicroRNA-210 is an Independent Factor Indicating a Poor Prognosis in Japanese Triple-negative Breast Cancer Patients

OBJECTIVE MicroRNAs have emerged as a new class of non-coding genes involved in regulating cell proliferation, differentiation and viability. Recent studies have identified miR-210 as one of a set of hypoxia-regulated microRNAs and demonstrated a direct regulatory role of HIF-1 alpha for its transcription. Here, we assessed miR-210 expression in Japanese triple-negative breast cancers and determined its clinical significance. METHODS TaqMan MicroRNA assays for miR-210 expression were performed on 161 samples of Japanese breast cancer tissue (58 triple-negative breast cancer and 103 estrogen receptor positive/HER2 negative). Correlations between miR-210 expression and clinicopathological factors were analyzed. The effects of several variables on survival were tested by a Cox proportional hazards regression analysis. RESULTS miR-210 expression in triple-negative breast cancers was significantly higher than in estrogen receptor-positive/HER2-negative breast cancers (P < 0.001). Patients whose triple-negative breast cancers showed low miR-210 expression experienced significantly better disease-free and overall survival than those with high miR-210 expression (P = 0.02 and P = 0.05, respectively). Although the prognosis of patients with triple-negative breast cancers is poor, Cox univariate and multivariate analyses demonstrated that a higher expression of miR-210 was an independent factor indicating a worse prognosis than for patients with a low level of miR-210. CONCLUSIONS The degree of miR-210 expression might be a clinically useful prognostic factor for decision-making regarding treatment in the adjuvant setting, especially in node-negative triple-negative breast cancer patients.

Genetic and environmental predictors, endogenous hormones and growth factors, and risk of estrogen receptor-positive breast cancer in Japanese women

The incidence of breast cancer in Japanese women has doubled in all age groups over the past two decades. We have recently shown that this marked increase is mostly due to an increase in the estrogen receptor (ER)‐positive subtype. It is necessary to establish risk factors capable of predicting the risk of ER‐positive breast cancer that will enable the efficient selection of candidates for preventive therapy. We analyzed genetic factors, including 14 single nucleotide polymorphisms (SNPs), environmental risk factors (body mass index, age at menarche, pregnancy, age at first birth, breastfeeding, family history of breast cancer, age at menopause, use of hormone replacement therapy, alcohol intake, and smoking), serum hormones and growth factors (estradiol, testosterone, prolactin, insulin‐like growth factor 1 [IGF1] and IGF binding protein 3 [IGFBP3]), and mammographic density in 913 women with breast cancer and 278 disease‐free controls. To identify important risk factors, risk prediction models for ER‐positive breast cancer in both pre‐ and postmenopausal women were created by logistic regression analysis. In premenopausal women, one SNP (CYP19A1‐rs10046), age, pregnancy, breastfeeding, alcohol intake, serum levels of prolactin, testosterone, and IGFBP3 were considered to be risk predictors. In postmenopausal women, one SNP (TP53‐rs1042522), age, body mass index, age at menopause, serum levels of testosterone, and IGF1 were identified as risk predictors. Risk factors may differ between women of different menopausal status, and inclusion of common genetic variants and serum hormone measurements as well as environmental factors might improve risk assessment models. Further validation studies will clarify appropriate risk groups for preventive therapy. (Cancer Sci 2011; 102: 2065–2072)

MiR-1290 and its potential targets are associated with characteristics of estrogen receptor α-positive breast cancer

Recent analyses have identified heterogeneity in estrogen receptor α (ERα)-positive breast cancer. Subtypes called luminal A and luminal B have been identified, and the tumor characteristics, such as response to endocrine therapy and prognosis, are different in these subtypes. However, little is known about how the biological characteristics of ER-positive breast cancer are determined. In this study, expression profiles of microRNAs (miRNAs) and mRNAs in ER-positive breast cancer tissue were compared between ER(high) Ki67(low) tumors and ER(low) Ki67(high) tumors by miRNA and mRNA microarrays. Unsupervised hierarchical clustering analyses revealed distinct expression patterns of miRNAs and mRNAs in these groups. We identified a downregulation of miR-1290 in ER(high) Ki67(low) tumors. Among 11 miRNAs that were upregulated in ER(high) Ki67(low) tumors, quantitative RT-PCR detection analysis using 64 samples of frozen breast cancer tissue identified six miRNAs (let-7a, miR-15a, miR-26a, miR-34a, miR-193b, and miR-342-3p). We picked up 11 genes that were potential target genes of the selected miRNAs and that were differentially expressed in ER(high) Ki67(low) tumors and ER(low) Ki67(high) tumors. Protein expression patterns of the selected target genes were analyzed in 256 ER-positive breast cancer samples by immunohistochemistry: miR-1290 and its putative targets, BCL2, FOXA1, MAPT, and NAT1, were identified. Transfection experiments revealed that introduction of miR-1290 into ER-positive breast cancer cells decreased expression of NAT1 and FOXA1. Our results suggest that miR-1290 and its potential targets might be associated with characteristics of ER-positive breast cancer.

Myoepithelial Carcinoma of the Breast Treated with Surgery and Chemotherapy

Myoepithelial carcinoma (malignant myoepithelioma) of the breast is a rare tumor, for which only a limited number of reports have been published. Most of the reports emphasized diagnosis and pathology but not biological behavior and treatment. We report a 61-year-old patient with breast myoepithelial carcinoma who developed locoregional and distant metastases and received many chemotherapy regimens. She presented with an elastic hard mass of the left breast. Breast conserving surgery was performed as part of both diagnosis and treatment. From the results of histological and immunohistochemical examinations, this case was considered to be a myoepithelial carcinoma. Fifteen months after the completion of adjuvant radiotherapy, distant metastasis of the left parasternal lymph node metastasis developed. She was treated by further excision and received a total of four regimens of chemotherapy including a combination of doxorubicin and cyclophosphamide. She received chemotherapy for 20 months after the diagnosis of metastasis.

Abstract P4-12-06: A mammographic density prediction model using environmental factors, endogenous hormones and growth factors in Japanese women

The incidence of breast cancer in Japanese women has doubled in all age groups over the past two decades, making it important to evaluate breast cancer risk factors in Japanese women. It is well known that mammographic density is positively associated with breast cancer risk in Western countries, and mammographic density is known to be affected by some environmental factors, serum hormones, and growth factors. We performed stepwise variable selection in a multiple regression model with fifteen independent variables as described below, based on the Akaike information criteria (AIC) to build a mammographic density prediction model using a dataset of 1191 women (913 women with breast cancer and 278 disease-free controls). The variables included were: environmental risk factors (body-mass index (BMI), age at menarche, pregnancy, age at first birth, breastfeeding, family history of breast cancer, age at menopause, use of hormone replacement therapy, alcohol intake and smoking), serum hormones and growth factors (estradiol, testosterone, prolactin, insulin-like growth factor 1 (IGF1) and IGF binding protein 3 (IGFBP3)) and mammographic density. The resulting prediction model is: Mammographic density = + 0.000476 (IGF1) −0.0605 (testosterone) − 0.0508 (IGFBP3) − 0.00683 (age) − 0.0175 (BMI) + 0.00883 (age at menarche) − 0.0153 (breast feeding), (R 2 = 0.336). In this model, IGF1, testosterone, IGFBP3, age, BMI, age at menarche, and breastfeeding were considered to be important factors. IGF1 and age at menarche were positively associated with mammographic density, while on the other hand testosterone, IGFBP3, age, BMI, and breast feeding were negatively associated with mammographic density. Further studies are required to build a modified model incorporating serial measurements of serum hormones and growth factors to take into account time-dependent changes of serum hormones and growth factors, and to assess its accuracy. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-12-06.

The Role of MicroRNAs in Estrogen Receptor α-Positive Human Breast Cancer

MicroRNAs (miRNAs) are a class naturally occurring small non-coding RNAs that control gene expression by targeting mRNAs for translational repression or cleavage (Krol et al., 2010). Recent evidence has shown that miRNA mutations or mis-expression correlate with various human cancers, and that lossor gain-of function of specific miRNAs contributes to breast epithelial cellular transformation and tumorigenesis (Esquela-Kerscher et al., 2006). miRNA expression profiling also revealed that miRNAs are differently expressed among molecular subtypes in breast cancer (Blenkiron et al., 2007; Iorio et al., 2005). There are large-scale molecular differences between estrogen receptor (ER) ┙-positive and ER┙-negative breast cancers (Perou et al., 2000; Sorlie et al., 2003). Endocrine therapy has become the most important treatment option for women with ER┙-positive breast cancer, and approximately 70% of primary breast cancers express ER┙. ER┙ is essential for estrogen-dependent growth, and its level of expression is a crucial determinant of response to endocrine therapy and prognosis in ER┙-positive breast cancer (Dowsett et al., 2008; Harvey et al., 1999; Yamashita et al., 2006). Multiple mechanisms involved in altering ER┙ gene expression in breast cancer have been proposed, including ER┙ gene amplification (Holst et al., 2007) as well as transcriptional silencing by DNA methylation of CpG islands within the ER┙ promoter (Giacinti et al., 2006) and mutations within the open reading frame of ER┙ (Herynk et al., 2004). However, expression levels of ER┙ in breast cancer tissues differ widely among patients (Yamashita et al., 2011), and frequently change during disease progression and in response to systemic therapies (Yamashita et al., 2009). It was reported that the microRNA miR-206 decreases endogenous ER┙ mRNA and protein levels in human MCF-7 breast cancer cells via two specific target sites within the 3’-untranslated region (UTR) of the human ER┙ transcript (Adams et al., 2007). We found that the expression levels of miR-206 were gradually decreased as ER┙ protein expression increased in breast cancer tissues, suggesting that miR-206 is a key factor for the regulation of ER┙ expression in human breast cancer (Kondo et al., 2008). Moreover, recent studies have shown that ER┙regulating miRNAs, miR-18a, miR-18b, miR-22, miR-193b, miR-302c, and miR-221/222, as well as miR-206, directly targeted ER┙ in 3’UTR reporter assays, and suggested that several miRNAs regulate ER┙ expression.

P4-10-11: Genetic and Environmental Predictors, Endogenous Hormones and Growth Factors and Risk of Estrogen Receptor-Positive Breast Cancer in Japanese Women.

The incidence of breast cancer in Japanese women has doubled in all age groups over the past two decades. We have recently demonstrated that this marked increase is mostly due to an increase in the estrogen receptor (ER)-positive subtype. It is necessary to establish risk factors capable of predicting the risk of ER-positive breast cancer which will enable the efficient selection of candidates for preventive chemotherapy. We analyzed genetic factors, including 14 single nucleotide polymorphisms (SNPs), environmental risk factors (body-mass index (BMI), age at menarche, pregnancy, age at first birth, breastfeeding, family history of breast cancer, age at menopause, use of hormone replacement therapy, alcohol intake and smoking), serum hormones and growth factors (estradiol, testosterone, prolactin, insulin-like growth factor 1 (IGF1) and IGF binding protein 3 (IGFBP3)) and mammographic density in 913 women with breast cancer and 278 disease-free controls. To identify important risk factors, risk prediction models for ER-positive breast cancer in both pre- and postmenopausal women were created by logistic regression analysis. In premenopausal women, 1 SNP (CYP19A1-rs10046), age, pregnancy, breastfeeding, alcohol intake, serum levels of prolactin, testosterone and IGFBP3 were considered to be risk predictors. In postmenopausal women, 1 SNP (TP53-rs1042522), age, BMI, age at menopause, serum levels of testosterone and IGF1 were identified as risk predictors. Risk factors may differ between women of different menopausal status, and inclusion of common genetic variants and serum hormone measurements as well as environmental factors might improve risk assessment models. Further validation studies will clarify appropriate risk groups for preventive chemotherapy. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-10-11.

P3-03-01: Low Expression of microRNA-210 Is an Independent Good Prognostic Factor in Japanese Triple-Negative Breast Cancer Patients.

Background: microRNAs (miRNAs) have emerged as a new class of non-coding genes involved in regulating cell proliferation, differentiation, and viability. Recent studies have identified miR-210 among a set of hypoxia-regulated miRNAs and demonstrated a direct regulatory role of hypoxia-inducible factor-1 alpha (HIF-1 a) in its transcription. High expression of miR-210 has been reported to be a poor prognostic factor in several types of cancers including breast. Materials and Methods: TaqMan MicroRNA assays for miR-210 expression were performed in 219 breast cancers (58 triple-negative (TNBCs), and 161 ER-positive and HER2−negative). Correlations between miR-210 expression and clinicopathological factors were analyzed. The effects of several variables on survival were tested by Cox proportional hazards regression analysis. Results: miR-210 expression in TNBCs was significantly higher than in ER-positive and HER2−negative breast cancers (p Discussion: Although prognosis of patients with TNBCs is poor, those whose tumors expressed low levels of miR-210 had a more favorable prognosis. Thus, the degree of miR-210 expression might be a clinically useful prognostic factor for decision-making regarding treatment in the adjuvant setting, especially in node-negative TNBC patients. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-03-01.