Lack of both androgen receptor and forkhead box A1 (FOXA1) expression is a poor prognostic factor in estrogen receptor-positive breast cancers

FOXA1 in Breast Cancer: A Luminal Marker with Promising Prognostic and Predictive Impact

The present review focuses on the function of the forkhead protein FOXA1 in breast cancer (BC) in relation to steroid hormone receptors. We explored the currently available analytic approaches for FOXA1 assessment both at gene and protein levels, comparing the differences between the available techniques used for its diagnostic assessment. In addition, we elaborated on data regarding the prognostic and predictive role of this marker in BC based on several studies that evaluated its expression in relation to the outcome and/or response to therapy. FOXA1, similar to the androgen receptor (AR), may have a dual role in BC according to hormonal status. In luminal cancers, its expression contributes to a better prognosis, while in triple-negative breast cancers (TNBC), it implies an adverse outcome. Consequently, we observed that FOXA1-positive expression in a neoadjuvant setting may predict a lack of response in luminal BC as opposed to TNBC, in which FOXA1 allegedly increases its chemosensitivity. In conclusion, considering its accessible and convenient identification by immunohistochemistry, its important impact on prognosis, and its suitability to identify patients with different responses to chemotherapy, we propose that FOXA1 could be tested in routine diagnostics as an additional prognostic and predictive marker in BC.

The importance of androgen receptors in breast cancer

Background and aim

Breast cancer (BC) is the most common malignancy among women worldwide, and one of the leading causes of cancer-related deaths in females. For the breast malignant tumors there are numerous targeted therapies, depending on the receptors expressed. Regulating the process of epithelial-mesenchyme transcription, the steroid nuclear receptors are important in invasion and progression of BC cells. Till now, it is known that androgen receptor (AR) is present in about 60-80% of BC cells but, unfortunately, there is no targeted therapy available yet.

Methods

We revised the recent literature that included the AR mechanism of action in patients diagnosed with breast cancer, the preclinical, retrospective and clinical studies and the aspects related to the prognosis of these patients, depending on the molecular subtype.

Results

A total of 12 articles were eligible for this review. AR positivity was assessed using immunohistochemistry. Herein, neither 1 nor 10% cut-points were robustly prognostic. AR was an independent prognostic marker of BC outcome, especially in triple negative BC group.

Conclusion

AR is a potential targeted pathway which can improve the prognostic of AR positive patients with BC. Further preclinical and clinical studies are necessary to clarify the mechanism of action and to establish the drugs which can be used, either alone or in combination.

Androgen receptor expression and response to chemotherapy in breast cancer patients treated in the neoadjuvant TECHNO and PREPARE trial

Background

The androgen receptor (AR) is discussed as a prognostic and/or predictive marker in breast cancer patients.

Methods

AR mRNA expression was analysed by RT-qPCR in breast cancer patients treated in the neoadjuvant TECHNO (n  =  118, HER2-positive) and PREPARE trial (n  =  321, HER2-positive and -negative). In addition, mRNA expression of the AR transcript variants 1 (AR1) and 2 (AR2) was measured.

Results

Regarding subtypes, high AR mRNA levels were frequent in HER2-positive (61.3%, 92/150) and luminal tumours (60.0%, 96/160) but almost absent in triple-negative tumours (4.3%, 3/69) (p < 0.0001). Overall, high AR mRNA levels were found to be associated with lower pathological complete remission (pCR) rates (OR 0.77 per unit, 95% CI 0.67–0.88, p  =  0.0002) but also with better prognosis in terms of longer disease-free survival (DFS) (HR 0.57, 95% CI 0.39–0.85, p  =  0.0054) and overall survival (OS) (HR 0.43, 95% CI, 0.26–0.71, p  =  0.0011). In the PREPARE trial, a survival difference for patients with high and low AR1 mRNA levels could only be seen in the standard chemotherapy arm but not in the dose-dense treatment arm (OS: HR 0.41; 95% CI 0.22–0.74 vs. HR 1.05; 95% CI 0.52–2.13; p  =  0.0459).

Conclusions

We provide evidence that AR mRNA predicts response to chemotherapy in breast cancer patients.

Analyses of an epigenetic switch involved in the activation of pioneer factor FOXA1 leading to the prognostic value of estrogen receptor and FOXA1 co-expression in breast cancer

Forkhead box protein A1 (FOXA1) is a pioneer factor of estrogen receptor α (ER)–chromatin binding and function, yet the role of FOXA1 in breast cancer and the underlying molecular mechanisms have not yet been elucidated. To evaluate gene expression alterations during breast carcinogenesis, FOXA1 expression was analyzed using the Serial Analysis of Gene Expression Genie suite, a gene expression profiling interactive analysis, and Oncomine analyses. The correlation between methylation and expression was analyzed using the MEXPRESS tool and UCSC Xena browser. Then, the expression and prognostic value of FOXA1 was validated by our own breast cancer samples using RT-PCR. We obtained the following important results. (1) The expression level of FOXA1 was significantly higher in breast cancer than normal tissues. (2) ER, PR, HEGR-2, and nodal status were positively correlated with FOXA1 expression. (3) Among patients with ER+ tumors, those with higher FOXA1 expression levels had better survival probabilities. (4) The major mutation type in FOXA1 in breast cancer samples was missense mutations. (5) FOXA1 expression was significantly higher in ER+ breast tumors than in ER− tumors or normal tissues. Our findings suggest that the aberrant DNA hypomethylation of promoter regions is one mechanism underlying the aberrant expression of FOXA1 in ER+ breast cancer, which might be a potential indicator of favorable prognosis.

Integrative analyses of triple negative dysregulated transcripts compared with non-triple negative tumors and their functional and molecular interactions

Triple-negative (TN) tumors are a subtype of breast cancer with aggressive behaviors and limited targeted therapies. Microarray studies were not concerned with interactions and functional relations of dysregulated transcripts. Here, we aimed to conduct integrative strategy to analyze gene and miRNA available microarray data as well as bioinformatic analyses to catch a more inclusive picture of pivotal dysregulated transcripts and their interactions in TN tumors. Several online datasets and offline bioinformatic tools were used to detect differentially expressed (DE) transcripts, both protein and nonprotein coding, in TN compared with non-TN tumors and their functional and molecular interactions. Sixteen upregulated and 58 downregulated genes with a log fold change higher or equal to | 2 | were identified, including nine transcription factors. Coexpression network revealed EN1 as a hub gene, moreover Kaplan-Meier plotter survival analysis indicated that it was an appropriate prognostic marker for TN patients with breast cancer. Functional annotation analysis of protein-protein interaction network showed FOXM1 as an upexpressed and ESR1 as a downexpressed hub genes are suitable targets as far as antitumor protein therapy is concerned in TN breast cancers. The consensus analysis of two microRNA datasets revealed seven DE miRNAs. The gene-transcriptional factor (TF)-miRNA network revealed mir-135b and mir-29b are the hub nodes and involved in feedback loops with GATA3. This study suggests that dysregulated TFs and miRNAs have pivotal roles in regulation of TN oncotranscriptomic profile and might become both biomarkers and therapeutic targets.

Forkhead‑box A1 regulates tumor cell growth and predicts prognosis in colorectal cancer

Forkhead box A1 (FOXA1) functions as a tumor suppressor gene or an oncogene in various types of cancer; however, the distinct function of FOXA1 in colorectal cancer is unclear. The present study aimed to evaluate whether FOXA1 affects the oncogenic behavior of colorectal cancer cells, and to investigate its prognostic value in colorectal cancer. The impact of FOXA1 on tumor cell behavior was investigated using small interfering RNA and the pcDNA6‑myc vector in human colorectal cancer cell lines. To investigate the role of FOXA1 in the progression of human colorectal cancer, an immunohistochemical technique was used to localize FOXA1 protein in paraffin‑embedded tissue blocks obtained from 403 patients with colorectal cancer. Tumor cell apoptosis and proliferation were evaluated using a terminal deoxynucleotidyl transferase‑mediated dUTP nick‑end labeling assay and Ki‑67 immunohistochemical staining, respectively. FOXA1 knockdown inhibited tumor cell invasion in colorectal cancer cells, and induced apoptosis and cell cycle arrest. FOXA1 knockdown activated cleaved caspase‑poly (ADP‑ribose) polymerase, upregulated the expression of p53 upregulated modulator of apoptosis, and downregulated BH3 interacting domain death agonist and myeloid cell leukemia‑1, leading to the induction of apoptosis. FOXA1 knockdown increased the phosphorylation level of signal transducer and activator of tran-scription‑3. By contrast, these results were reversed following the overexpression of FOXA1. The overexpression of FOXA1 was associated with differentiation, lymphovascular invasion, advanced tumor stage, depth of invasion, lymph node metastasis and poor survival rate. The mean Ki‑67 labeling index value of FOXA1‑positive tumors was significantly higher than that of FOXA1‑negative tumors. However, no significant association was observed between the expression of FOXA1 and the mean apoptotic index value. These results indicate that FOXA1 is associated with tumor progression via the modulation of tumor cell survival in human colorectal cancer.

MicroRNAs and Androgen Receptor: Emerging Players in Breast Cancer

Breast cancer (BC) is the most common cause of cancer among women, with a high incidence rate occurrence every year worldwide despite advances in its management. BC is characterized by a spectrum of subtypes which respond differently to treatments due to their biological features, representing the main issue in the control of this type of malignancy. Androgen receptor (AR) is emerging as a target to investigate among hormone receptors, since it seems to play a role at various stages of development of specific BC subsets. For this reason, in recent years AR has become very important in the clinical practice, although its role remains controversial. A number of studies have proposed a correlation between microRNAs (miRNAs), a class of gene expression modulators, and AR in prostate cancer (PC), but there are still few evidences about the relationship between miRNAs and AR in BC. The purpose of this review is to present a state of the art scenario with consideration to the most recent discoveries about miRNAs involved in the AR associated pathogenesis of BC, in order to provide new insights into the role of miRNAs as key drivers in the modulation of AR, and possible actors in the development and progression of BC. Moreover, we consider findings about involvement of AR signaling in all stages of BC, highlighting its association with different subsets of breast carcinomas and with pre- and postmenopausal state of patients.