SIP1/NHERF2 enhances estrogen receptor alpha transactivation in breast cancer cells

The estrogen receptor alpha (ERα) is a ligand-activated transcription factor that possesses two activating domains designated AF-1 and AF-2 that mediate its transcriptional activity. The role of AF-2 is to recruit coregulator protein complexes capable of modifying chromatin condensation status. In contrast, the mechanism responsible for the ligand-independent AF-1 activity and for its synergistic functional interaction with AF-2 is unclear. In this study, we have identified the protein Na+/H+ Exchanger RegulatoryFactor 2 (NHERF2) as an ERα-associated coactivator that interacts predominantly with the AF-1 domain of the nuclear receptor. Overexpression of NHERF2 in breast cancer MCF7 cells produced an increase in ERα transactivation. Interestingly, the presence of SRC-1 in NHERF2 stably overexpressing MCF7 cells produced a synergistic increase in ERα activity. We show further that NHERF2 interacts with ERα and SRC-1 in the promoter region of ERα target genes. The binding of NHERF2 to ERα in MCF7 cells increased cell proliferation and the ability of MCF7 cells to form tumors in a mouse model. We analyzed the expression of NHERF2 in breast cancer tumors finding a 2- to 17-fold increase in its mRNA levels in 50% of the tumor samples compared to normal breast tissue. These results indicate that NHERF2 is a coactivator of ERα that may participate in the development of estrogen-dependent breast cancer tumors.

[Evaluation of breast cancer treatment at a tertiary-level institution with Popular Health Insurance in Mexico]

BACKGROUND

In our country breast cancer represents a major health problem. Only 45% of all population has access to health services, the consequence is delay in diagnosis and treatment. In Mexico, 66% of all new cases of breast cancer are diagnosed in locally advanced stages. From May 2007 the Health System Protection Against Catastrophic Expenses, called Seguro Popular (SP), breast cancer was included in covering the treatment of this neoplasm in any patient without access to social security.

OBJECTIVE

To evaluate the results and impact of SP in the adjuvant and neoadjuvant treatment of a group of patients diagnosed with breast cancer at an institution of national reference.

MATERIAL AND METHODS

We analyzed a group of 259 patients in stages (I-IIIC). The clinical stages I and II (55 patients) were treated with adjuvant chemotherapy FAC -T (fluorouracil 500 mg/m2, adriamycin 50 mg/m2 and cyclophosphamide 500 mg/m2 (FAC) followed by 12 weeks of paclitaxel 80 mg/m2 +/- trastuzumab loading dose of 4 mg/kg followed by 2 mg/kg); 204 patients in locally advanced stages (IIB-IIIC) received FAC-T +/- trastuzumab followed by surgery. Adjuvant treatment consisted of endocrine therapy for hormone-sensitive patients and radiotherapy 50 cGy according to international standards.

RESULTS

The age at diagnosis was 47 years (range 23-68). 80% of them were locally advanced stages (IIB-IIIC) and were treated in a neoadjuvant setting, 20% was in early stages, treated with surgery and adjuvant chemotherapy The disease-free survival and overall survival at 30 months was 85.7 and 90% respectively. Overall pathologic complete response was obtained in 15% of cases. In the subgroup analysis showed that 41% of patients HER2 (+), 29% of triple-negative patients and 9% of hormone-sensitive tumors achieved complete pathological response (p = 0.0001).

CONCLUSION

This is the first analysis of efficacy of adjuvant and neoadjuvant treatment in breast cancer since the introduction of popular secure non-entitled population. It is clear that treatment efficacy is similar to that reported in the literature, with 15% of pRC and survival to 30 months in 94-80%. The coverage of health expenditures treats a larger number of patients optimally. Along with this, efforts should be made to reduce the high frequency of diagnosis at advanced stage.

Triple-negative breast cancer in Hispanic patients: high prevalence, poor prognosis, and association with menopausal status, body mass index, and parity

BACKGROUND

Triple-negative breast cancer (TNBC) is defined as breast cancer that is negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. TNBC represents 15% of all invasive breast cancers, but some studies have suggested that its prevalence differs between races. To the authors' knowledge, no previous studies have determined the prevalence of TNBC and its risk factors among Hispanic women.

METHODS

The authors identified 2074 Hispanic women with breast cancer who attended the National Cancer Institute in Mexico City from 1998 to 2008. All histopathologic and immunohistochemical diagnoses were rereviewed by a breast cancer pathologist. The prevalence of TNBC, its association with clinicopathologic characteristics, and its prognostic impact were determined.

RESULTS

The median patient age at diagnosis (±standard deviation) was 50 ± 12 years. The overall prevalence of TNBC was 23.1%. Younger age (P < .001), premenopausal status (P = .002), increased parity (P = .029), hormonal contraceptive use (P = .04) high histologic grade (P < .001), and advanced disease (P < .001) were associated independently with TNBC. Postmenopausal patients who had a body mass index (BMI) <25 kg/m(2) (P = .027) or <30 kg/m(2) (P < .001) were more likely to have TNBC. In multivariate analysis, patients with TNBC had a higher risk of locoregional recurrence (LRR), lower disease-free survival (DFS) (hazard ratio, 1.62; 95% confidence interval, 1.13-2.32; P = .009), and a lower cancer-specific survival (CSS) rate (hazard ratio, 1.66; 95% confidence interval, 1.20-2.30; P = .002) than patients with non-TNBC.

CONCLUSIONS

The median age at diagnosis of Hispanic women with breast cancer was 11 years younger than the average age reported in the United States. The prevalence of TNBC in this study population was higher than that reported in white women with breast cancer. TNBC was associated with a higher risk of LRR and with lower DFS and CSS than those in patients with non-TNBC.