Forkhead box A1 expression in breast cancer is associated with luminal subtype and good prognosis

The role of transcription factor FOXA1/C2/M1/O3/P1/Q1 in breast cancer

Breast cancer is a common malignancy with the highest mortality rate among women worldwide. Its incidence is on the rise year after year, accounting for more than one-tenth of new cancers worldwide. Increasing evidence suggests that forkhead box (FOX) transcription factors play an important role in the occurrence and development of breast cancer. However, little is known about the relationship between the expression, prognostic value, function, and immune infiltration of FOX transcription factors in tumor microenvironment. We used bioinformatics to investigate expression and function of FOX factor in breast cancer. Our results revealed the expression levels of FOXA1 and FOXM1 were significantly higher in breast cancer tissues than in normal tissues. The high expression of mRNA in FOXA1 (P < .05), FOXM1 (P < .01), and FOXP1 (P < .05) groups was related to tumor stage. Survival analysis results showed that increased FOXP1 mRNA levels were significantly associated with overall survival (OS), recurrence-free survival (RFS), and distant metastasis-free survival (DMFS) in all patients with breast cancer (P < .05). Patients with the FOXA1 high-expression group had better RFS and DMFS than the low-expression group (P < .05), while patients with FOXM1 high-expression group had worse RFS, OS, and DMFS than the low-expression group (P < .05). Meanwhile, mutation analysis showed that genetic alterations in FOX transcription factors were significantly associated with shorter OS and progression-free survival (P < .05), but not with disease-free survival (P = .710) in patients with breast cancer. FOXP1, FOXA1, and FOXM1 may be used as potential biomarkers to predict the prognosis of patients with breast cancer. Functional enrichment indicated that FOX was mainly involved in cell division, cell senescence, cell cycle, and prolactin signaling pathway. In patients with breast cancer, FOXC2 expression was negatively correlated with the infiltration of B cells and positively correlated with the infiltration of neutrophils and dendritic cells. However, FOXM1 was negatively correlated with the infiltration of CD8 + T cells and macrophages and positively correlated with the infiltration of neutrophils and dendritic cells. These findings provided novel insights into the screening of prognostic biomarkers of the FOX family in breast cancer and laid a foundation for further research on the immune infiltration of the FOX transcription factor family members in tumors.

FOXA1 forms biomolecular condensates that unpack condensed chromatin to function as a pioneer factor

Eukaryotic DNA is packaged into chromatin in the nucleus, restricting the binding of transcription factors (TFs) to their target DNA sites. FOXA1 functions as a pioneer TF to bind condensed chromatin and initiate the opening of local chromatin for gene expression. However, the principles of FOXA1 recruitment and how it subsequently unpacks the condensed chromatin remain elusive. Here, we revealed that FOXA1 intrinsically forms submicron-sized condensates through its N- and C-terminal intrinsically disordered regions (IDRs). Notably, both IDRs enable FOXA1 to dissolve the condensed chromatin. In addition, the DNA-binding capacity of FOXA1 contributes to its ability to both form condensates and dissolve condensed chromatin. Further genome-wide investigation showed that IDRs enable FOXA1 to bind and unpack the condensed chromatin to regulate the proliferation and migration of breast cancer cells. This work provides a principle of how pioneer TFs function to initiate competent chromatin states using their IDRs.

INO80 function is required for mouse mammary gland development, but mutation alone may be insufficient for breast cancer

The aberrant function of ATP-dependent chromatin remodeler INO80 has been implicated in multiple types of cancers by altering chromatin architecture and gene expression; however, the underlying mechanism of the functional involvement of INO80 mutation in cancer etiology, especially in breast cancer, remains unclear. In the present study, we have performed a weighted gene co-expression network analysis (WCGNA) to investigate links between INO80 expression and breast cancer sub-classification and progression. Our analysis revealed that INO80 repression is associated with differential responsiveness of estrogen receptors (ERs) depending upon breast cancer subtype, ER networks, and increased risk of breast carcinogenesis. To determine whether INO80 loss induces breast tumors, a conditional INO80-knockout (INO80 cKO) mouse model was generated using the Cre-loxP system. Phenotypic characterization revealed that INO80 cKO led to reduced branching and length of the mammary ducts at all stages. However, the INO80 cKO mouse model had unaltered lumen morphology and failed to spontaneously induce tumorigenesis in mammary gland tissue. Therefore, our study suggests that the aberrant function of INO80 is potentially associated with breast cancer by modulating gene expression. INO80 mutation alone is insufficient for breast tumorigenesis.

ACBD3 Bioinformatic Analysis and Protein Expression in Breast Cancer Cells

ACBD3 overexpression has previously been found to correlate with worse prognosis for breast cancer patients and, as an incredibly diverse protein in both function and cellular localisation, ACBD3 may have a larger role in breast cancer than previously thought. This study further investigated ACBD3′s role in breast cancer. Bioinformatic databases were queried to characterise ACBD3 expression and mutation in breast cancer and to investigate how overexpression affects breast cancer patient outcomes. Immunohistochemistry was carried out to examine ACBD3 location within cells and tissue structures. ACBD3 was more highly expressed in breast cancer than in any other cancer or matched normal tissue, and expression over the median level resulted in reduced relapse-free, overall, and distant metastasis-free survival for breast cancer patients as a whole, with some differences observed between subtypes. IHC analysis found that ACBD3 levels varied based on hormone receptor status, indicating that ACBD3 could be a candidate biomarker for poor patient prognosis in breast cancer and may possibly be a biomarker for ER signal reprogramming of precancerous breast tissue.

Pioneer factors as master regulators of the epigenome and cell fate

Pioneer factors are transcription factors with the unique ability to initiate opening of closed chromatin. The stability of cell identity relies on robust mechanisms that maintain the epigenome and chromatin accessibility to transcription factors. Pioneer factors counter these mechanisms to implement new cell fates through binding of DNA target sites in closed chromatin and introduction of active-chromatin histone modifications, primarily at enhancers. As master regulators of enhancer activation, pioneers are thus crucial for the implementation of correct cell fate decisions in development, and as such, they hold tremendous potential for therapy through cellular reprogramming. The power of pioneer factors to reshape the epigenome also presents an Achilles heel, as their misexpression has major pathological consequences, such as in cancer. In this Review, we discuss the emerging mechanisms of pioneer factor functions and their roles in cell fate specification, cellular reprogramming and cancer.

Estrogen receptor-α signaling in post-natal mammary development and breast cancers

17β-estradiol controls post-natal mammary gland development and exerts its effects through Estrogen Receptor ERα, a member of the nuclear receptor family. ERα is also critical for breast cancer progression and remains a central therapeutic target for hormone-dependent breast cancers. In this review, we summarize the current understanding of the complex ERα signaling pathways that involve either classical nuclear “genomic” or membrane “non-genomic” actions and regulate in concert with other hormones the different stages of mammary development. We describe the cellular and molecular features of the luminal cell lineage expressing ERα and provide an overview of the transgenic mouse models impacting ERα signaling, highlighting the pivotal role of ERα in mammary gland morphogenesis and function and its implication in the tumorigenic processes. Finally, we describe the main features of the ERα-positive luminal breast cancers and their modeling in mice.

Transcription Factors: The Fulcrum Between Cell Development and Carcinogenesis

Higher eukaryotic development is a complex and tightly regulated process, whereby transcription factors (TFs) play a key role in controlling the gene regulatory networks. Dysregulation of these regulatory networks has also been associated with carcinogenesis. Transcription factors are key enablers of cancer stemness, which support the maintenance and function of cancer stem cells that are believed to act as seeds for cancer initiation, progression and metastasis, and treatment resistance. One key area of research is to understand how these factors interact and collaborate to define cellular fate during embryogenesis as well as during tumor development. This review focuses on understanding the role of TFs in cell development and cancer. The molecular mechanisms of cell fate decision are of key importance in efforts towards developing better protocols for directed differentiation of cells in research and medicine. We also discuss the dysregulation of TFs and their role in cancer progression and metastasis, exploring TF networks as direct or indirect targets for therapeutic intervention, as well as specific TFs' potential as biomarkers for predicting and monitoring treatment responses.

FOXA1 Expression in Nasopharyngeal Carcinoma: Association with Clinicopathological Characteristics and EMT Markers

The forkhead box (FOXA) family of transcription factors regulates gene expression and chromatin structure during tumorigenesis and embryonic development. Until now, the relationship between FOXA1 and the nasopharyngeal carcinoma (NPC) has not yet been reported. Therefore, our purpose is to analyze the expression of FOXA1 in 56 NPC patients compared to 10 normal nasopharyngeal mucosae and to correlate the expression with the clinicopathological features. Besides, we investigated the association between FOXA1 and LMP1 gene expression, as well as the EMT markers namely the E-cadherin and Twist1. Among 56 NPC tissues, 34 (60.7%) cases were positive for FOXA1. Furthermore, we noticed that FOXA1 expression correlated with TNM (p = 0.037), and age at diagnosis (p = 0.05). Moreover, positive expression of FOXA1 is likely to be associated with prolonged disease-free survival and overall survival rates. On the other hand, we observed a positive association between the expression of E-cadherin and FOXA1 (p = 0.0051) whereas Twist1 correlated negatively with FOXA1 (p = 0.004). Furthermore, knowing that LMP1 plays a key role in the pathogenesis of NPC, we explored the association of FOXA1 with the LMP1 gene expression in both NPC cell lines and tissues. We found that, in the C666-1 which displays low levels of LMP1, the expression of FOXA1 is high, and inversely in the C15 cell line that expresses a high level of LMP1, the level of FOXA1 is low. Besides, in accordance to our results, we found that in NPC tissues there is a negative association between LMP1 and FOXA1. In conclusion, our results suggest that the overexpression of FOXA1 is associated with a nonaggressive behavior and favorable prognosis in NPC patients. FOXA1 could contribute in the EMT process through key factors as E-cadherin, Twist1, and LMP1.

High FOXA1 protein expression might predict late recurrence in patients with estrogen-positive and HER2-negative breast cancer

BACKGROUND

Multi-gene expression assays have been developed with the aim of predicting late recurrence in patients with estrogen receptor (ER)-positive breast cancer. However, establishment of alternative markers based on immunohistochemistry is also important for achieving practical use. Based on our previous study, forkhead box A1 (FOXA1) protein was tested as a potentially useful predictive marker for late recurrence.

METHODS

117 patients with ER-positive HER2-negative invasive breast cancer who developed distant metastasis following curative surgery were retrospectively investigated. We also evaluated responsiveness to endocrine therapy according to FOXA1 expression. Furthermore, publicly available mRNA microarray data were analyzed to examine patterns of metastasis according to FOXA1 mRNA expression, employing the Kaplan-Meier plotter.

RESULTS

High expression of FOXA1 was an independent factor predicting long disease-free survival (DFS), along with small tumor size (p = 0.010 and 0.016, respectively). Discrimination of DFS was improved by combining these two factors, i.e., patients with FOXA1-high small tumors had the longest DFS while those with FOXA1-low large tumors had the shortest DFS. Moreover, we revealed that risk of distant metastasis started to increase after the completion of adjuvant endocrine therapy in patients with FOXA1-high tumors.

CONCLUSION

Among patients who developed distant metastasis, those with FOXA1-high tumors had significantly longer DFS. We believe our data to raise the possibility of FOXA1 being a useful predictive marker for late recurrence and to provide new insights into the biology of FOXA1-high breast cancers.

High frequency of p16 and SOX10 coexpression but not androgen receptor expression in triple-negative breast cancers

Triple-negative breast cancers (TNBCs) represent approximately 12-17% of all breast cancers and have distinctively aggressive clinical courses. Because routine biomarkers for breast cancer do not apply for TNBCs, it is essential to find novel prognostic markers and potential targets for therapeutic agents. p16 and SOX10 are emerging biomarkers with relatively unexplored expressions in TNBCs. We present an analysis of the expression of p16 and SOX10 in combination with that of androgen receptor (AR) and cytokeratin (CK) 5/6 in TNBCs. In addition, we used tissue microarrays (TMAs) to compare frequencies of p16 and SOX10 between TNBCs and non-TNBCs. Fifty-six TNBC samples with clinical data were stained immunohistochemically with p16, SOX10, AR, and CK5/6. Fifty-four cases (96.4%) were invasive ductal carcinoma, not otherwise specified, and 46 cases (82.1%) were Nottingham histologic grade 3. The majority of TNBC cases were positive for p16 (n = 44; 78.6%) and SOX10 (n = 48; 85.7%). AR was positive in 15 cases (26.8%). CK5/6 was positive in 24 cases (42.9%), which were classified as basal-like breast cancer (BLBC) subtype. The frequencies of p16 and SOX10 expression in BLBC and non-BLBC subtypes did not reveal significant statistical difference in a separate analysis. Using archived TNBC and non-TNBC TMAs, we observed that 56% of TNBC cases were positive for p16 compared with 16% of non-TNBC cases (p-value <0.0001). SOX10 was positive in 80% of TNBC cases compared with 35% of non-TNBC cases (p-value <0.0001). A significant correlation was observed between p16 and SOX10 coexpression in TNBC cases (n = 56/80, p = 0.02) but not in non-TNBC cases (n = 23/348; p = 0.626). In conclusion, p16 and SOX10 are frequently expressed in TNBC, regardless of CK5/6 expression. Furthermore, p16 and SOX10 are often coexpressed in TNBCs compared with non-TNBCs.

Androgen receptor and FOXA1 coexpression define a "luminal-AR" subtype of feline mammary carcinomas, spontaneous models of breast cancer

Background

Invasive mammary carcinomas that spontaneously develop in female cats are associated with high mortality, and resemble the most aggressive human breast cancers, especially triple-negative breast cancer (TNBC). Transcriptome studies showed that TNBCs are a heterogeneous group that includes a potentially hormone-dependent subtype named luminal-AR. Some authors proposed an immunohistochemical definition of the luminal-AR subtype, which is not only positive for Androgen Receptor (AR), but also either positive for the transcription factor Forkhead box A1 (FOXA1), or negative for basal markers. The objectives of this study were to describe AR and FOXA1 expressions in feline mammary carcinomas (FMCs), their prognostic value, and if their coexpression could define a “luminal-AR” subtype of triple-negative mammary carcinomas in cats.

Methods

In a previously described retrospective cohort of 180 female cats with FMCs, with a 2-year follow-up post-mastectomy, we assessed AR, FOXA1, ER, PR, Ki-67, HER2, and CK14 expressions by automated immunohistochemistry.

Results

Of the 180 FMCs, 57 (32%) were luminal; i.e., ER and/or PR positive, and 123 (68%) were triple-negative (ER–, PR– and HER2–) FMCs. AR overexpression (found in 33 cases/180, 18%) and FOXA1 index ≥1% (64/180, 36%) were associated with a longer disease-free interval, overall survival, and cancer-specific survival in cats with FMC. Analysis of AR, FOXA1 and CK14 coexpression in triple-negative FMCs showed that AR+ triple-negative FMCs were heterogeneous: there existed an AR+ FOXA1+ CK14– subgroup (n = 7) associated with a better cancer-specific survival by multivariate survival analysis (HR = 0.26, 95% CI: 0.07–0.89, p = 0.03) compared to AR+ FOXA1–CK14+ triple-negative FMCs (n = 46) (HR = 1.00), independently of the pathologic tumor size and pathologic nodal stage. The non-basal-like subtype of triple-negative FMCs that coexpresses AR and FOXA1 (the AR+ FOXA1+ CK14– subgroup) could represent the equivalent of the luminal-AR subgroup of human triple-negative breast cancer.

Conclusions

We identified an AR+ FOXA1+ CK14– subgroup of triple-negative FMCs that might correspond to the luminal-AR subgroup of human triple-negative breast cancers. Cats with FMC may be interesting spontaneous animal models to investigate new strategies targeting the androgen receptor, especially in the aggressive subtype of AR+ basal-like triple-negative mammary carcinomas with loss of FOXA1 expression (the AR+ FOXA1–CK14+ subgroup).

FOXA1 Protein Expression in ER+ and ER- Breast Cancer in Relation to Parity and Breastfeeding in Black and White Women

BACKGROUND

Forkhead box protein A1 (FOXA1) promotes luminal differentiation, and hypermethylation of the gene can be a mechanism of developing estrogen receptor-negative (ER^-) breast cancer. We examined FOXA1 in breast tumor and adjacent normal tissue in relation to reproductive factors, particularly higher parity and no breastfeeding, that are associated with ER^- tumors.

METHODS

We performed IHC for FOXA1 in breast tumors (n = 1,329) and adjacent normal tissues (n = 298) in the Women's Circle of Health Study (949 Blacks and 380 Whites). Protein expression levels were summarized by histology (H) scores. Generalized linear models were used to assess FOXA1 protein expression in relation to reproductive factors by ER status.

RESULTS

ER-positive (ER⁺) versus ER^- tumors had higher FOXA1 protein expression (P < 0.001). FOXA1 expression was higher in tumor versus paired adjacent normal tissue in women with ER⁺ or non-triple-negative cancer (both P < 0.001), but not in those with ER^- or triple-negative cancer. Higher number of births (1, 2, and 3+) was associated with lower FOXA1 protein expression in ER⁺ tumors [differences in H score, or β = -8.5; 95% confidence interval (CI), -15.1 to -2.0], particularly among parous women who never breastfed (β = -10.4; 95% CI, -19.7 to -1.0), but not among those who breastfed (β = -7.5; 95% CI, -16.9 to 1.8). The associations for ER^- tumors were similar, although they were not statistically significant.

CONCLUSIONS

In this tumor-based study, higher parity was associated with lower FOXA1 expression in ER⁺ tumors, and breastfeeding may ameliorate the influence.

IMPACT

These findings contribute to our understanding of FOXA1 methylation and breast cancer etiology.

Hypermethylation of FOXA1 and allelic loss of PTEN drive squamous differentiation and promote heterogeneity in bladder cancer

Intratumoral heterogeneity in bladder cancer is a barrier to accurate molecular sub-classification and treatment efficacy. However, individual cellular and mechanistic contributions to tumor heterogeneity are controversial. We examined potential mechanisms of FOXA1 and PTEN inactivation in bladder cancer and their contribution to tumor heterogeneity. These analyses were complemented with inactivation of FOXA1 and PTEN in intermediate and luminal mouse urothelium. We show inactivation and reduced expression of FOXA1 and PTEN is prevalent in human disease, where PTEN and FOXA1 are downregulated by allelic loss and site-specific DNA hypermethylation, respectively. Conditional inactivation of both Foxa1 and Pten in intermediate/luminal cells in mice results in development of bladder cancer exhibiting squamous features as well as enhanced sensitivity to a bladder-specific carcinogen. In addition, FOXA1 is hypermethylated in basal bladder cancer cell lines, and this is reversed by treatment with DNA methyltransferase inhibitors. By integrating human correlative and in vivo studies, we define a critical role for PTEN loss and epigenetic silencing of FOXA1 in heterogeneous human disease and show genetic targeting of luminal/intermediate cells in mice drives squamous differentiation.

Should Tumor Infiltrating Lymphocytes, Androgen Receptor, and FOXA1 Expression Predict the Clinical Outcome in Triple Negative Breast Cancer Patients?

Tumor-infiltrating lymphocytes (TILs) are a valuable indicator of the immune microenvironment that plays the central role in new anticancer drugs. TILs have a strong prognostic role in triple negative breast cancer (TNBC). Little is known about the interaction with the androgen receptor (AR) and forkhead box A1 (FOXA1). We analyzed the relationships between TIL levels, AR, and FOXA1 expression and their clinical significance in TNBC patients. Further, we investigated their interaction with other biomarkers like programmed cell death ligand-1 (PD-L1), breast cancer type 1 susceptibility protein (BRCA1), poly (ADP-Ribose) polymerase 1 (PARP1), and Na+/H+ exchanger regulatory factor 1 (NHERF1). The expression of the proteins was evaluated by immunohistochemistry in 124 TNBC samples. TILs were performed adhering to International TILs Working Group 2014 criteria. Cox proportional hazards models were also used to identify risk factors associated with poor prognosis. Multivariate analysis identified TILs as independent prognostic factor of disease free survival (DFS; p = 0.045). A Kaplan-Meyer analysis revealed that the patients with high TILs had a better DFS compared to patients with low TILs (p = 0.037), and the phenotypes TILs-/AR+ and TILs-/FOXA1- had a worse DFS (p = 0.032, p = 0.001 respectively). AR was associated with FOXA1 expression (p = 0.007), and the tumors FOXA1+ presented low levels of TILs (p = 0.028). A poor DFS was observed for AR+/FOXA1+ tumors compared to other TNBCs (p = 0.0117). Low TILs score was associated with poor patients' survival, and TILs level in combination with AR or FOXA1 expression affected patient's clinical outcome. In addition, AR+/FOXA1+ phenotype identified a specific subgroup of TNBC patients with poor prognosis. These data may suggest new ways of therapeutic intervention to support current treatments.

Genetic Ancestry-dependent Differences in Breast Cancer-induced Field Defects in the Tumor-adjacent Normal Breast

PURPOSE

Genetic ancestry influences evolutionary pathways of cancers. However, whether ancestry influences cancer-induced field defects is unknown. The goal of this study was to utilize ancestry-mapped true normal breast tissues as controls to identify cancer-induced field defects in normal tissue adjacent to breast tumors (NATs) in women of African American (AA) and European (EA) ancestry.

EXPERIMENTAL DESIGN

A tissue microarray comprising breast tissues of ancestry-mapped 100 age-matched healthy women from the Komen Tissue Bank (KTB) at Indiana University (Indianapolis, IN) and tumor-NAT pairs from 100 women (300 samples total) was analyzed for the levels of ZEB1, an oncogenic transcription factor that is central to cell fate, mature luminal cell-enriched estrogen receptor alpha (ERα), GATA3, FOXA1, and for immune cell composition.

RESULTS

ZEB1+ cells, which were localized surrounding the ductal structures of the normal breast, were enriched in the KTB-normal of AA compared with KTB-normal of EA women. In contrast, in EA women, both NATs and tumors compared with KTB-normal contained higher levels of ZEB1+ cells. FOXA1 levels were lower in NATs compared with KTB-normal in AA but not in EA women. We also noted variations in the levels of GATA3, CD8+ T cells, PD1+ immune cells, and PDL1+ cell but not CD68+ macrophages in NATs of AA and EA women. ERα levels did not change in any of our analyses, pointing to the specificity of ancestry-dependent variations.

CONCLUSIONS

Genetic ancestry-mapped tissues from healthy individuals are required for proper assessment and development of cancer-induced field defects as early cancer detection markers. This finding is significant in light of recent discoveries of influence of genetic ancestry on both normal biology and tumor evolution.

The prognostic relevance of FOXA1 and Nestin expression in breast cancer metastases: a retrospective study of 164 cases during a 10-year period (2004-2014)

Background

Current prognostic markers cannot adequately predict the clinical outcome of breast cancer patients. Therefore, additional biomarkers need to be included in routine immune panels. FOXA1 was a significant predictor of favorable outcome in primary breast cancer, while Nestin expression is preferentially found in triple-negative tumors with increased rate of nodal metastases, and reduced survival. No studies have investigated the prognostic value of FOXA1 and Nestin expression in breast cancer metastases.

Methods

Breast cancer metastases (n = 164) from various anatomical sites were retrospectively analyzed by immunohistochemistry for FOXA1, Nestin and GATA3 expression. Cox regression analysis assessed the prognostic value of FOXA1 and Nestin expression.

Results

In breast cancer metastases, FOXA1 expression was associated with Nestin-negativity, GATA3-positivity, ER-positivity, HER2-positivity and non-triple-negative status (P < 0.05). In contrast, Nestin expression was associated with FOXA1-negative, GATA3-negative, ER-negative, and triple-negative metastases (P < 0.05). Univariate Cox regression analysis showed FOXA1 expression was predictive of overall survival (OS, P = 0.00048) and metastasis-free survival (DMFS, P = 0.0011), as well as, distant metastasis-free survival in ER-positive patients (P = 0.036) and overall survival in ER-negative patients (P = 0.024). Multivariate analysis confirmed the significance of FOXA1 for both survival endpoints in metastatic breast cancer patients (OS, P = 0.0033; DMFS, P = 0.015).

Conclusions

In our study, FOXA1 was expressed mostly in ER-positive breast cancer metastases. Expression of Nestin was related to triple-negative metastases, where brain was the most frequent metastatic site. These findings highlight the clinical utility of FOXA1 and Nestin expression and warrant their inclusion in routine immunohistochemical panels for breast carcinoma.

The high expression of FOXA1 is correlated with a favourable prognosis in salivary duct carcinomas: a study of 142 cases

AIMS

Salivary duct carcinoma (SDC) is an uncommon, aggressive tumour that, histologically, resembles high-grade mammary ductal carcinoma, and is characterised by the expression of androgen receptor (AR). The androgen signalling pathway, a potential therapeutic target, can be regulated by FOXA1. This study aimed to evaluate the clinicopathological implications of FOXA1 in SDC.

METHODS AND RESULTS

We examined the relationship between the immunoexpression of FOXA1 and FOXA1 mutations and clinicopathological factors, including the biomarker status and clinical outcome, in 142 SDCs. FOXA1 was expressed in 128 SDCs (90.1%); the immunoexpression was heterogeneous. SDCs with a higher FOXA1 labelling index (LI) (≥20%) more frequently showed less advanced tumors on T classification (P = 0.002). FOXA1 LI was correlated positively with the AR expression value (r = 0.430, P < 0.001). PI3K and p-mTOR positivity, and intact-PTEN, were associated with a higher FOXA1 LI. Twenty-two of 121 SDCs (18.2%) harboured FOXA1 gene mutations at the flanking regions in and around the forkhead DNA binding domain; however, the given gene mutation and the expression of FOXA1 were not significantly correlated. A multivariate analysis revealed that SDCs with a higher FOXA1 LI were associated with longer overall survival and progression-free survival (P = 0.029 and 0.016, respectively).

CONCLUSIONS

In SDC, FOXA1, which may biologically interact with the AR and PI3K signalling pathways, is a putative biomarker that may be associated with a favourable prognosis. Further studies are needed to apply the findings to the development of targeted personalised therapy for patients with SDC.

FOXA1 and AR in invasive breast cancer: new findings on their co-expression and impact on prognosis in ER-positive patients

Background

The role of forkhead-box A1 (FOXA1) and Androgen receptor (AR) in breast cancer (BC) has been extensively studied. However, the prognostic role of their co-expression in Estrogen receptor positive (ER+) BC has not been investigated so far. The aim of the present study was thus to assess the co-expression (protein and mRNA) of FOXA1 and AR in BC patients, in order to evaluate their prognostic impact according to ER status.

Methods

Immunohistochemical expression of AR and FOXA1 was evaluated on 479 consecutive BC, with complete clinical-pathological and follow up data. Fresh-frozen tissues from 65 cases were available. The expression of AR and FOXA1 with ER was validated using mRNA analyses. Survival and Cox proportional hazard analyses were used to evaluate the relationship between FOXA1, AR and prognosis.

Results

Expression of ER, AR and FOXA1 was observed in 78, 60 and 85% of cases respectively. Most AR+ cases (97%) were also FOXA1+. The level of FOXA1 mRNA positively correlated with level of both AR mRNA (r = 0.8975; P < 0.001) and ER mRNA (r = 0.7326; P < 0.001). In ER+ BC, FOXA1 was associated with a good prognosis independently of AR expression in the three subgroups analyzed (FOXA1+/AR+; FOXA1+/AR-; FOXA1−/AR-). Multivariate analyses confirmed that FOXA1 may provide more information than AR in Disease-Free Interval (DFI) of ER+ BC patients.

Conclusion

Our results suggest that in BC the expression of FOXA1 is directly related to the expression of AR. Despite that, FOXA1 is found as superior predicting marker of recurrences compared to AR in ER+ BC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4624-y) contains supplementary material, which is available to authorized users.

Microenvironmental control of breast cancer subtype elicited through paracrine platelet-derived growth factor-CC signaling

Breast tumors of the basal-like, hormone receptor-negative, subtype remain an unmet clinical challenge, as patients exhibit a high rate of recurrence and poor survival. Co-evolution of the malignant mammary epithelium and its underlying stroma instigates cancer-associated fibroblasts (CAFs) to endorse most, if not all, hallmarks of cancer progression. Here, we delineate a previously unappreciated role for CAFs as determinants of the molecular subtype of breast cancer. We identified a paracrine cross-talk between cancer cells expressing platelet-derived growth factor (PDGF)-CC and CAFs expressing the cognate receptors in human basal-like mammary carcinomas. Genetic or pharmacological intervention with PDGF-CC activity in mouse models of cancer resulted in conversion of basal-like breast cancers into a hormone receptor-positive state that conferred sensitivity to endocrine therapy in previously impervious tumors. We conclude that specification of the basal-like subtype of breast cancer is under microenvironmental control and therapeutically actionable in order to achieve sensitivity to endocrine therapy.

Pioneer transcription factors shape the epigenetic landscape

Pioneer transcription factors have the unique and important role of unmasking chromatin domains during development to allow the implementation of new cellular programs. Compared with those of other transcription factors, this activity implies that pioneer factors can recognize their target DNA sequences in so-called compacted or "closed" heterochromatin and can trigger remodeling of the adjoining chromatin landscape to provide accessibility to nonpioneer transcription factors. Recent studies identified several steps of pioneer action, namely rapid but weak initial binding to heterochromatin and stabilization of binding followed by chromatin opening and loss of cytosine-phosphate-guanine (CpG) methylation that provides epigenetic memory. Whereas CpG demethylation depends on replication, chromatin opening does not. In this Minireview, we highlight the unique properties of this transcription factor class and the challenges of understanding their mechanism of action.

Decreased expression of FOXF2 as new predictor of poor prognosis in stage I non-small cell lung cancer

Background

Forkhead box F2 (FOXF2) is relatively limited to the adult lung, but its contribution to non-small cell lung cancer (NSCLC) prognosis is unclear.

Results

FOXF2 mRNA levels in NSCLC were lower than that in paired normal lung tissues (P = 0.012). The FOXF2_low patients had shorter survival time than the FOXF2_high patients (P = 0.024) especially in stage I (P = 0.002), chemotherapy (P = 0.018) and < 60 age groups (P = 0.002). Lower FOXF2 mRNA levels could independently predict poorer survival for patients with NSCLC (HR = 2.384, 95% CI = 1.241–4.577; P = 0.009), especially in stage I (HR =4.367, 95% CI =1.599–11.925; P = 0.004). The two independent datasets confirmed our findings.

Methods

We examined FOXF2 mRNA levels in 84 primary NSCLC and 8 normal lung tissues using qRT-PCR. Rank-sum tests and chi-square tests were used to assess the differences among groups with various clinicopathological factors. Kaplan-Meier tests were used to compare survival status in patients with different FOXF2 mRNA levels. Cox proportional hazards regression model was used to evaluate the predictive value of FOXF2 mRNA level in NSCLC patients. Independent validation was performed using an independent dataset (98 samples) and an online survival analysis software Kaplan-Meier plotter (1928 samples).

Conclusions

Our results demonstrated that decreased FOXF2 expression is an independent predictive factor for poor prognosis of patients with NSCLC, especially in stage I NSCLC.

Clinical significance and prognostic value of Forkhead box A1 expression in human epithelial ovarian cancer

Forkhead box (FOX) A1 is a member of the FOX family of transcription factors, which serve a function in numerous types of tumor. The present study assessed the potential role of FOXA1 in human epithelial ovarian carcinoma (EOC). Total RNA was isolated from 16 fresh-frozen EOC tumors with paired corresponding non-malignant ovarian epithelium tissues, and FOXA1 expression was analyzed using reverse transcription-quantitative polymerase chain reaction. Immunohistochemical analysis was performed to evaluate FOXA1 expression in 110 epithelial ovarian carcinoma tissue specimens (including 80 serous papillary adenocarcinoma, 9 clear cell carcinoma, 12 endometrioid adenocarcinoma, 5 mucinous carcinoma and 4 transitional cell carcinoma specimens), 24 benign ovarian tumor surface epithelium tissues and 10 normal ovarian tissue samples. The present study analyzed the association between FOXA1 expression and clinical characteristics in patients with EOC. The Kaplan-Meier method was used for survival analysis. The results of the present study revealed that FOXA1 mRNA expression was significantly increased in EOC tissues compared with paired normal ovarian samples (P=0.014). The immunohistochemical expression of FOXA1 in EOC tissues was associated with the FIGO grade, differentiation status and overall survival time (all P<0.05). Finally, the significance of FOXA1 expression in the prognosis of the patients was evaluated. The results of Kaplan-Meier survival curve revealed that high FOXA1 expression was associated with decreased overall survival time in the patients, relative to low FOXA1 expression (P=0.0132). In conclusion, FOXA1 is overexpressed in EOC and associated with clinicopathological features, including overall survival time. FOXA1 potentially represents a novel biomarker and therapeutic target for EOC.

Recurrent and functional regulatory mutations in breast cancer

Genomic analysis of tumours has led to the identification of hundreds of cancer genes on the basis of the presence of mutations in protein-coding regions. By contrast, much less is known about cancer-causing mutations in non-coding regions. Here we perform deep sequencing in 360 primary breast cancers and develop computational methods to identify significantly mutated promoters. Clear signals are found in the promoters of three genes. FOXA1, a known driver of hormone-receptor positive breast cancer, harbours a mutational hotspot in its promoter leading to overexpression through increased E2F binding. RMRP and NEAT1, two non-coding RNA genes, carry mutations that affect protein binding to their promoters and alter expression levels. Our study shows that promoter regions harbour recurrent mutations in cancer with functional consequences and that the mutations occur at similar frequencies as in coding regions. Power analyses indicate that more such regions remain to be discovered through deep sequencing of adequately sized cohorts of patients.

A novel FOXA1/ESR1 interacting pathway: A study of Oncomine™ breast cancer microarrays

Forkhead box protein A1 (FOXA1) is essential for the growth and differentiation of breast epithelium, and has a favorable outcome in breast cancer (BC). Elevated FOXA1 expression in BC also facilitates hormone responsiveness in estrogen receptor (ESR)-positive BC. However, the interaction between these two pathways is not fully understood. FOXA1 and GATA binding protein 3 (GATA3) along with ESR1 expression are responsible for maintaining a luminal phenotype, thus suggesting the existence of a strong association between them. The present study utilized the Oncomine™ microarray database to identify FOXA1:ESR1 and FOXA1:ESR1:GATA3 co-expression co-regulated genes. Oncomine™ analysis revealed 115 and 79 overlapping genes clusters in FOXA1:ESR1 and FOXA1:ESR1:GATA3 microarrays, respectively. Five ESR1 direct target genes [trefoil factor 1 (TFF1/PS2), B-cell lymphoma 2 (BCL2), seven in absentia homolog 2 (SIAH2), cellular myeloblastosis viral oncogene homolog (CMYB) and progesterone receptor (PGR)] were detected in the co-expression clusters. To further investigate the role of FOXA1 in ESR1-positive cells, MCF7 cells were transfected with a FOXA1 expression plasmid, and it was observed that the direct target genes of ESR1 (PS2, BCL2, SIAH2 and PGR) were significantly regulated upon transfection. Analysis of one of these target genes, PS2, revealed the presence of two FOXA1 binding sites in the vicinity of the estrogen response element (ERE), which was confirmed by binding assays. Under estrogen stimulation, FOXA1 protein was recruited to the FOXA1 site and could also bind to the ERE site (although in minimal amounts) in the PS2 promoter. Co-transfection of FOXA1/ESR1 expression plasmids demonstrated a significantly regulation of the target genes identified in the FOXA1/ESR1 multi-arrays compared with only FOXA1 transfection, which was suggestive of a synergistic effect of ESR1 and FOXA1 on the target genes. In summary, the present study identified novel FOXA1, ESR1 and GATA3 co-expressed genes that may be involved in breast tumorigenesis.

Twist1 promotes breast cancer invasion and metastasis by silencing Foxa1 expression

The heterogeneous breast cancers can be classified into different subtypes according to their histopathological characteristics and molecular signatures. Foxa1 expression is linked with luminal breast cancer (LBC) with good prognosis, whereas Twist1 expression is associated with basal-like breast cancer (BLBC) with poor prognosis owing to its role in promoting epithelial-to-mesenchymal transition (EMT), invasiveness and metastasis. However, the regulatory and functional relationships between Twist1 and Foxa1 in breast cancer progression are unknown. In this study, we demonstrate that in the estrogen receptor (ERα)-positive LBC cells Twist1 silences Foxa1 expression, which has an essential role in relieving Foxa1-arrested migration, invasion and metastasis of breast cancer cells. Mechanistically, Twist1 binds to Foxa1 proximal promoter and recruits the NuRD transcriptional repressor complex to de-acetylate H3K9 and repress RNA polymerase II recruitment. Twist1 also silences Foxa1 promoter by inhibiting AP-1 recruitment. Twist1 expression in MCF7 cells silenced Foxa1 expression, which was concurrent with the induction of EMT, migration, invasion and metastasis of these cells. Importantly, restored Foxa1 expression in these cells largely inhibited Twist1-promoted migration, invasion and metastasis. Restored Foxa1 expression did not change the Twist1-induced mesenchymal cellular morphology and the expression of Twist1-regulated E-cadherin, β-catenin, vimentin and Slug, but it partially rescued Twist1-silenced ERα and cytokeratin 8 expression and reduced Twist1-induced integrin α5, integrin β1 and MMP9 expression. In a xenografted mouse model, restored Foxa1 also increased Twist1-repressed LBC markers and decreased Twist1-induced BLBC markers. Furthermore, Twist1 expression is negatively correlated with Foxa1 in the human breast tumors. The tumors with high Twist1 and low Foxa1 expressions are associated with poor distant metastasis-free survival. These results demonstrate that Twist1's silencing effect on Foxa1 expression is largely responsible for Twist1-induced migration, invasion and metastasis, but less responsible for Twist1-induced mesenchymal morphogenesis and expression of certain EMT markers.

Coexpression of androgen receptor and FOXA1 in nonmetastatic triple-negative breast cancer: ancillary study from PACS08 trial

AIM

Microarray studies identified a subgroup of molecular apocrine tumors (estrogen receptor [ER] negative/androgen receptor [AR] positive) that express luminal genes including FOXA1. FOXA1 may direct AR to sites normally occupied by ER in luminal tumors, inducing an estrogen-like gene program that stimulated proliferation.

MATERIALS & METHODS

Expression of AR and FOXA1 was evaluated by immunohistochemistry in 592 patients with nonmetastatic triple-negative breast cancer (TNBC).

RESULTS

Coexpression of AR and FOXA1 was found in 15.2% of patients. These tumors were more frequently lobular, found in older patients and exhibited a lower nuclear grade and a greater degree of node involvement. They less often exhibited lymphocytic infiltrate, pushing margins, syncytial architecture, central fibrosis or necrosis.

CONCLUSION

TNBC with coexpression of AR and FOXA1 seems to behave like luminal tumors with a morphological profile distinct from other TNBC. These biomarkers could be useful to identify a subgroup of TNBC and could have future therapeutic implications.

Comparative Cistromics Reveals Genomic Cross-talk between FOXA1 and ERα in Tamoxifen-Associated Endometrial Carcinomas

Tamoxifen, a small-molecule antagonist of the transcription factor estrogen receptor alpha (ERα) used to treat breast cancer, increases risks of endometrial cancer. However, no parallels of ERα transcriptional action in breast and endometrial tumors have been found that might explain this effect. In this study, we addressed this issue with a genome-wide assessment of ERα-chromatin interactions in surgical specimens obtained from patients with tamoxifen-associated endometrial cancer. ERα was found at active enhancers in endometrial cancer cells as marked by the presence of RNA polymerase II and the histone marker H3K27Ac. These ERα binding sites were highly conserved between breast and endometrial cancer and enriched in binding motifs for the transcription factor FOXA1, which displayed substantial overlap with ERα binding sites proximal to genes involved in classical ERα target genes. Multifactorial ChIP-seq data integration from the endometrial cancer cell line Ishikawa illustrated a functional genomic network involving ERα and FOXA1 together with the enhancer-enriched transcriptional regulators p300, FOXM1, TEAD4, FNFIC, CEBP8, and TCF12. Immunohistochemical analysis of 230 primary endometrial tumor specimens showed that lack of FOXA1 and ERα expression was associated with a longer interval between breast cancer and the emergence of endometrial cancer, exclusively in tamoxifen-treated patients. Our results define conserved sites for a genomic interplay between FOXA1 and ERα in breast cancer and tamoxifen-associated endometrial cancer. In addition, FOXA1 and ERα are associated with the interval time between breast cancer and endometrial cancer only in tamoxifen-treated breast cancer patients. Cancer Res; 76(13); 3773-84. ©2016 AACR.

Clinicopathological significance of forkhead box protein A1 in breast cancer: A meta-analysis

The aim of the present study was to investigate the associations between the expression of forkhead box protein A1 (FOXA1) and differential clinicopathological characteristics in breast cancer using a meta-analysis method. Eligible studies that investigated the correlation between FOXA1 expression and the clinical characteristics of breast cancer were collected through searching numerous databases, including PubMed, EMBASE, the Chinese National Knowledge Infrastructure and the VIP database. In total, eight studies were included in the meta-analysis. Following a systematic analysis, the expression of FOXA1 was found to be significantly associated with the estrogen receptor α status, the progesterone receptor status, lymph node metastasis and the histological grade in breast cancer. However, no statistically significant association was observed between FOXA1 expression and the human epidermal growth factor receptor-2 status in breast cancer patients.

FoxA and LIPG endothelial lipase control the uptake of extracellular lipids for breast cancer growth

The mechanisms that allow breast cancer (BCa) cells to metabolically sustain rapid growth are poorly understood. Here we report that BCa cells are dependent on a mechanism to supply precursors for intracellular lipid production derived from extracellular sources and that the endothelial lipase (LIPG) fulfils this function. LIPG expression allows the import of lipid precursors, thereby contributing to BCa proliferation. LIPG stands out as an essential component of the lipid metabolic adaptations that BCa cells, and not normal tissue, must undergo to support high proliferation rates. LIPG is ubiquitously and highly expressed under the control of FoxA1 or FoxA2 in all BCa subtypes. The downregulation of either LIPG or FoxA in transformed cells results in decreased proliferation and impaired synthesis of intracellular lipids.

Deregulation of lipid metabolism in cancer cells is critical to the maintenance of certain malignant features. Here, the authors show that the proliferation of breast cancer cells depends upon the extracellular activity of the endothelial lipase enzyme LIPG whose expression is regulated by the FoxA family of transcription factors.

Prognostic value of FOXA1 in breast cancer: A systematic review and meta-analysis

BACKGROUND

Despite some published papers analyzing the prognostic role of forkhead-box A1 (FOXA1) in breast cancer, it has not yet been considered as an established prognostic factor in clinical practice. The present meta-analysis evaluated the prognostic value of FOXA1 in breast cancer.

METHODS

PubMed, Web of Science and Embase databases were searched for relevant published literature that evaluated the correlation between FOXA1 and breast cancer. Either a fixed or random effect model was applied to estimate the pooled hazard ratio (HR) for FOXA1 prognosis in breast cancer.

RESULT

A total of nine articles comprising 6386 breast cancer patients met the inclusion criteria. Among these nine studies, five studies and four studies investigated the prognostic association with disease-free survival (DFS), and overall survival (OS), respectively. Meta-analysis results suggested that high FOXA1 expression was positively associated with DFS (pooled HR: 0.43, 95% CI: 0.23-0.81; P < 0.05) and OS (pooled HR: 0.39, 95% CI: 0.26-0.60; P < 0.05) in breast cancer patients. No publication bias was discovered by Begg's test in this meta-analysis.

CONCLUSION

The results from this meta-analysis indicated that elevated FOXA1 expression level was associated with better outcome in breast cancer.

FOXA2 mRNA expression is associated with relapse in patients with Triple-Negative/Basal-like breast carcinoma

The FOXA family of transcription factors regulates chromatin structure and gene expression especially during embryonic development. In normal breast tissue FOXA1 acts throughout mammary development; whereas in breast carcinoma its expression promotes luminal phenotype and correlates with good prognosis. However, the role of FOXA2 has not been previously studied in breast cancer. Our purpose was to analyze the expression of FOXA2 in breast cancer cells, to explore its role in breast cancer stem cells, and to correlate its mRNA expression with clinicopathological features and outcome in a series of patients diagnosed with breast carcinoma. We analyzed FOXA2 mRNA expression in a retrospective cohort of 230 breast cancer patients and in cell lines. We also knocked down FOXA2 mRNA expression by siRNA to determine the impact on cell proliferation and mammospheres formation using a cancer stem cells culture assay. In vitro studies demonstrated higher FOXA2 mRNA expression in Triple-Negative/Basal-like cells. Further, when it was knocked down, cells decreased proliferation and its capability of forming mammospheres. Similarly, FOXA2 mRNA expression was detected in 10% (23/230) of the tumors, especially in Triple-Negative/Basal-like phenotype (p < 0.001, Fisher's test). Patients whose tumors expressed FOXA2 had increased relapses (59 vs. 79%, p = 0.024, log-rank test) that revealed an independent prognostic value (HR = 3.29, C.I.95% = 1.45-7.45, p = 0.004, Cox regression). Our results suggest that FOXA2 promotes cell proliferation, maintains cancer stem cells, favors the development of Triple-Negative/Basal-like tumors, and is associated with increase relapses.

TFAP2C expression in breast cancer: correlation with overall survival beyond 10 years of initial diagnosis

Recurrence and death in a significant number of patients with ERα-positive breast cancer occurs 10-20 years after diagnosis. Prognostic markers for late events have been more elusive. TFAP2C (AP2γ) regulates the expression of ERα, the ERα pioneer factors FOXA1 and GATA3, and controls ERα-dependent transcription. The purpose of this investigation is to determine the long-term prognostic value of TFAP2C. A tissue microarray (TMA) consisting of breast tumors from 451 patients with median follow-up time of 10.3 years was created and tested for the expression of TFAP2C by immunohistochemistry. Wilcoxon Rank-Sum and Kruskal-Wallis tests were used to determine if TFAP2C H-scores correlate with other tumor markers. Cox proportional hazards regression models were used to determine whether TFAP2C H-scores and other tumor markers were related to overall and disease-free survival in univariate and multivariable models. TFPAC2 overexpression did not impact overall survival during the first 10 years after diagnosis, but was associated with a shorter survival after 10 years (HR 3.40, 95 % CI 1.58, 7.30; p value = 0.002). This late divergence persisted in ER-positive (HR 2.86, 95 % CI 1.29, 6.36; p value = 0.01) and endocrine therapy-positive subgroups (HR 4.19, 95 % CI 1.72, 10.23; p value = 0.002). For the ER+ and endocrine therapy subgroup, the HR was 3.82 (95 % CI 1.53, 9.50; p value = 0.004). TFAP2C H-scores were not correlated with other tumor markers or related to disease-free survival. In this hypothesis-generating study, we show that higher TFAP2C scores correlate with poor overall survival after 10 years of diagnosis in ERα-positive and endocrine therapy-treated subgroups.

Co-modulation analysis of gene regulation in breast cancer reveals complex interplay between ESR1 and ERBB2 genes

BACKGROUND

Gene regulation is dynamic across cellular conditions and disease subtypes. From the aspect of regulation under modulation, regulation strength between a pair of genes can be modulated by (dependent on) expression abundance of another gene (modulator gene). Previous studies have demonstrated the involvement of genes modulated by single modulator genes in cancers, including breast cancer. However, analysis of multi-modulator co-modulation that can further delineate the landscape of complex gene regulation is, to our knowledge, unexplored previously. In the present study we aim to explore the joint effects of multiple modulator genes in modulating global gene regulation and dissect the biological functions in breast cancer.

RESULTS

To carry out the analysis, we proposed the Covariability-based Multiple Regression (CoMRe) method. The method is mainly built on a multiple regression model that takes expression levels of multiple modulators as inputs and regulation strength between genes as output. Pairs of genes were divided into groups based on their co-modulation patterns. Analyzing gene expression profiles from 286 breast cancer patients, CoMRe investigated ten candidate modulator genes that interacted and jointly determined global gene regulation. Among the candidate modulators, ESR1, ERBB2, and ADAM12 were found modulating the most numbers of gene pairs. The largest group of gene pairs was composed of ones that were modulated by merely ESR1. Functional annotation revealed that the group was significantly related to tumorigenesis and estrogen signaling in breast cancer. ESR1-ERBB2 co-modulation was the largest group modulated by more than one modulators. Similarly, the group was functionally associated with hormone stimulus, suggesting that functions of the two modulators are performed, at least partially, through modulation. The findings were validated in majorities of patients (> 99%) of two independent breast cancer datasets.

CONCLUSIONS

We have showed CoMRe is a robust method to discover critical modulators in gene regulatory networks, and it is capable of achieving reproducible and biologically meaningful results. Our data reveal that gene regulatory networks modulated by single modulator or co-modulated by multiple modulators play important roles in breast cancer. Findings of this report illuminate complex and dynamic gene regulation under modulation and its involvement in breast cancer.

FOXA1 Expression Significantly Predict Response to Chemotherapy in Estrogen Receptor-Positive Breast Cancer Patients

PURPOSE

Most estrogen receptor (ER)-positive breast cancer responds poorly to chemotherapy and no single cost-effective biomarker capable of selecting chemosensitive ones has been found yet. We investigated FOXA1 for its role in predicting chemosensitivity of this subgroup in neoadjuvant chemotherapy settings.

METHODS

We reviewed pathologic slides of 123 patients who were diagnosed with ER-positive breast cancer on core needle biopsy and underwent neoadjuvant chemotherapy at our institution between 2002 and 2012. FOXA1 expression and pathologic response were evaluated. We then statistically analyzed FOXA1 expression and its relationship with chemosensitivity.

RESULTS

FOXA1 expression before NAC was correlated with poor chemoresponse in ER-positive as well as luminal A and luminal B breast cancer patients (p = 0.002, 0.001, and 0.049 respectively). Significant association between change of FOXA1 staining position after NAC and chemosensitivity also was observed (p = 0.024). Multivariate analysis identified FOXA1 expression before NAC as an independent predictor of chemosensitivity in ER-positive and luminal A breast cancer patients [p = 0.002; relative risk (RR) 0.163; 95 % confidence interval (CI) 0.053-0.500, and p = 0.002; RR 0.055; 95 % CI 0.008-0.353, respectively]. Additionally, change of FOXA1 staining position after NAC was shown to be an independent predictor of chemoresponse in luminal B subtype breast cancer patients (p = 0.012; RR 0.153; 95 % CI 0.035-0.665).

CONCLUSIONS

FOXA1 expression can independently predict chemosensitivity of ER-positive breast cancer patients.

Low FOXA1 expression predicts good response to neo-adjuvant chemotherapy resulting in good outcomes for luminal HER2-negative breast cancer cases

Background:

FOXA1 expression is a good prognostic marker for endocrine therapy in hormone-positive breast cancer. We retrospectively examined breast cancer patients with luminal human epidermal growth factor receptor 2 (HER2)-negative tumours, as defined by immunohistochemistry, who received neo-adjuvant chemotherapy (NAC) and investigated the relationship between treatment effects and FOXA1 expression.

Methods:

Biopsy specimens from 103 luminal HER2-negative tumours were immunohistochemically examined. FOXA1 effects on chemo-sensitivity were also investigated employing in vitro experiments.

Results:

FOXA1 and Ki67 expressions independently predicted a pathological complete response (pCR). Knockdown of FOXA1 by siRNA boosted the chemo-effect in oestrogen receptor-positive cells. The Cox hazards model revealed a pCR to be the strongest factor predicting a good patient outcome.

Conclusions:

Our present study showed low FOXA1 expression to be associated with a good response to NAC in luminal HER2-negative breast cancer. Improved outcomes of these patients suggest that NAC should be recommended to patients with low FOXA1 tumours.

FOXA1: a promising prognostic marker in breast cancer

Accurate diagnosis and proper monitoring of cancer patients remain important obstacles for successful cancer treatment. The search for cancer biomarkers can aid in more accurate prediction of clinical outcome and may also reveal novel predictive factors and therapeutic targets. One such prognostic marker seems to be FOXA1. Many studies have shown that FOXA1 is strongly expressed in a vast majority of cancers, including breast cancer, in which high expression is associated with a good prognosis. In this review, we summarize the role of this transcription factor in the development and prognosis of breast cancer in the hope of providing insights into utility of FOXA1 as a novel biomarker.

Decreased FOXF2 mRNA expression indicates early-onset metastasis and poor prognosis for breast cancer patients with histological grade II tumor

The transcription factor, FOXF2, plays an important role in tissue development, extracellular matrix synthesis, and epithelial-mesenchymal interactions, implying that it may be associated with the metastatic capabilities of cancer cells. However, the relationship between FOXF2 expression and breast cancer progression, metastasis, and prognosis, remains to be elucidated. In this study, FOXF2 mRNA levels in 305 primary breast cancer tissues were examined using RT-QPCR. Results showed that FOXF2 mRNA levels in primary breast cancer were negatively associated with tumor progression, including tumor size, number of metastatic lymph nodes, and clinical stage. Patients with low FOXF2 mRNA levels had a high risk of relapse and metastasis within three years. Low FOXF2 mRNA levels could predict shorter disease-free survival for those patients with histological grade II and triple-negative breast cancer. Taken together, we conclude that decreased FOXF2 expression indicates the early-onset metastasis and poor prognosis for patients with histological grade II and triple-negative breast cancer.

Tamoxifen resistance: from bench to bedside

Although tamoxifen is a classical example of a targeted drug, a substantial proportion of estrogen receptor alpha positive breast cancer patients does not benefit from the drug. Over the last few decades, many potential biomarkers have been discovered in cell biological studies that may aid in the prediction of tamoxifen sensitivity and guide in treatment selection. Nonetheless, the transition of such a biomarker from the scientific community towards a diagnostic test that can be used in daily clinical practice has been far from ideal, and such markers seldom face clinical introduction. From a large number of potential predictive biomarkers as described in cell biological literature, the clinical (translational) scientist has to make a decision which of these biomarkers should be tested in clinical material to determine their clinical validity. This problem is not trivial, since patient samples with clinical follow-up are a valuable asset that should therefore be cherished. In this review, we will describe a number of 'cell biological biomarkers' for tamoxifen resistance and their possible clinical implications. This may guide the clinical scientist in choosing what potential biomarkers to test on tumour samples, which may catalyse the translation of scientific discoveries into daily clinical practice of breast cancer medicine.

A simple immunohistochemical panel comprising 2 conventional markers, Ki67 and p53, is a powerful tool for predicting patient outcome in luminal-type breast cancer

BACKGROUND

Ki67 is widely used in order to distinguish the "A" and "B" subtypes of luminal-type breast cancer. This study aimed to validate the prognostic value of adding p53 to Ki67 for characterizing luminal-type breast cancer.

METHODS

Immunostaining for Ki67, p53, and the molecular markers HER2, CK5/6, CK14, EGFR, FOXA1, GATA3, and P-cadherin was examined hormone receptor (HR)-positive cancer tissues from 150 patients. The prognostic value of an immunohistochemical panel comprising Ki67 and p53 was compared with that of the single Ki67 labeling index (LI), and uni- and multivariate analyses were performed.

RESULTS

Division of the patients based on the immunohistochemistry results into favorable- (low Ki67 LI, p53-negative) and unfavorable- (high Ki67 LI and/or p53-positive) phenotype groups yielded distinctly different Kaplan-Meier's curves of both disease-free (P<0.0001) and overall survival (P=0.0007). These differences were much more distinct than those between the corresponding low Ki67 LI vs. high Ki67LI curves. While the prognostic values of the other molecular markers were not significant, combined Ki67-p53 status was an independent prognostic factor by multivariate analysis.

CONCLUSION

These data indicate that an immunohistochemical panel comprising Ki67 and p53 is a practical tool for management of patients with HR-positive breast cancer.

FOXA1 represses the molecular phenotype of basal breast cancer cells

Breast cancer is a heterogeneous disease that comprises multiple subtypes. Luminal subtype tumors confer a more favorable patient prognosis, which is, in part, attributed to estrogen receptor (ER)-α positivity and antihormone responsiveness. Expression of the forkhead box transcription factor, FOXA1, similarly correlates with the luminal subtype and patient survival, but is also present in a subset of ER-negative tumors. FOXA1 is also consistently expressed in luminal breast cancer cell lines even in the absence of ER. In contrast, breast cancer cell lines representing the basal subtype do not express FOXA1. To delineate an ER-independent role for FOXA1 in maintaining the luminal phenotype, and hence a more favorable prognosis, we performed expression microarray analyses on FOXA1-positive and ER-positive (MCF7, T47D), or FOXA1-positive and ER-negative (MDA-MB-453, SKBR3) luminal cell lines in the presence or absence of transient FOXA1 silencing. This resulted in three FOXA1 transcriptomes: (1) a luminal signature (consistent across cell lines), (2) an ER-positive signature (restricted to MCF7 and T47D) and (3) an ER-negative signature (restricted to MDA-MB-453 and SKBR3). Gene set enrichment analyses revealed FOXA1 silencing causes a partial transcriptome shift from luminal to basal gene expression signatures. FOXA1 binds to a subset of both luminal and basal genes within luminal breast cancer cells, and loss of FOXA1 increases enhancer RNA transcription for a representative basal gene (CD58). These data suggest FOXA1 directly represses a subset of basal signature genes. Functionally, FOXA1 silencing increases migration and invasion of luminal cancer cells, both of which are characteristics of basal subtype cells. We conclude FOXA1 controls plasticity between basal and luminal breast cancer cells, not only by inducing luminal genes but also by repressing the basal phenotype, and thus aggressiveness. Although it has been proposed that FOXA1-targeting agents may be useful for treating luminal tumors, these data suggest that this approach may promote transitions toward more aggressive cancers.

FOXP1 and estrogen signaling in breast cancer

Breast cancers are considered to be primarily regulated by estrogen signaling pathways because estrogen-dependent proliferation is observed in the majority of breast cancer cases. Thus, hormone therapy using antiestrogen drugs such as tamoxifen is effective for breast cancers expressing estrogen receptor α (ERα). However, acquired resistance during the endocrine therapy is a critical unresolved problem in breast cancer. Recently, a forkhead transcription factor FOXA1 has been reported to play an important role in the regulation of ERα-mediated transcription and proliferation of breast cancer. Interestingly, immunohistochemical analysis of breast cancer specimens has revealed that nuclear immunoreactivities of FOXP1 as well as those of FOXA1 are positively correlated with hormone receptor status, including ERα and progesterone receptor. In particular, the double-positive immunoreactivities of FOXP1 and FOXA1 are significantly associated with a favorable prognosis for survival of breast cancer patients receiving adjuvant tamoxifen therapy. The functions of FOXP1 and FOXA1 have been characterized in cultured cells; further, similar to FOXA1, FOXP1 is assumed to be a critical transcription factor for ERα signaling, and both forkhead transcription factors can serve as predictive factors for acquired endocrine resistance in breast cancer.

Cancer genetics and genomics of human FOX family genes

Forkhead-box (FOX) family proteins, involved in cell growth and differentiation as well as embryogenesis and longevity, are DNA-binding proteins regulating transcription and DNA repair. The focus of this review is on the mechanisms of FOX-related human carcinogenesis. FOXA1 is overexpressed as a result of gene amplification in lung cancer, esophageal cancer, ER-positive breast cancer and anaplastic thyroid cancer and is point-mutated in prostate cancer. FOXA1 overexpression in breast cancer and prostate cancer is associated with good or poor prognosis, respectively. Single nucleotide polymorphism (SNP) within the 5'-UTR of the FOXE1 (TTF2) gene is associated with thyroid cancer risk. FOXF1 overexpression in breast cancer is associated with epithelial-to-mesenchymal transition (EMT). FOXM1 is overexpressed owing to gene amplification in basal-type breast cancer and diffuse large B-cell lymphoma (DLBCL), and it is transcriptionally upregulated owing to Hedgehog-GLI, hypoxia-HIF1α or YAP-TEAD signaling activation. FOXM1 overexpression leads to malignant phenotypes by directly upregulating CCNB1, AURKB, MYC and SKP2 and indirectly upregulating ZEB1 and ZEB2 via miR-200b downregulation. Tumor suppressor functions of FOXO transcription factors are lost in cancer cells as a result of chromosomal translocation, deletion, miRNA-mediated repression, AKT-mediated cytoplasmic sequestration or ubiquitination-mediated proteasomal degradation. FOXP1 is upregulated as a result of gene fusion or amplification in DLBCL and MALT lymphoma and also repression of miRNAs, such as miR-1, miR-34a and miR-504. FOXP1 overexpression is associated with poor prognosis in DLBCL, gastric MALT lymphoma and hepatocellular carcinoma but with good prognosis in breast cancer. In neuroblastoma, the entire coding region of the FOXR1 (FOXN5) gene is fused to the MLL or the PAFAH1B gene owing to interstitial deletions. FOXR1 fusion genes function as oncogenes that repress transcription of FOXO target genes. Whole-genome sequencing data from tens of thousands of human cancers will uncover the mutational landscape of FOX family genes themselves as well as FOX-binding sites, which will be ultimately applied for cancer diagnostics, prognostics, and therapeutics.

FOXA1 promotes tumor progression in prostate cancer via the insulin-like growth factor binding protein 3 pathway

Fork-head box protein A1 (FOXA1) is a "pioneer factor" that is known to bind to the androgen receptor (AR) and regulate the transcription of AR-specific genes. However, the precise role of FOXA1 in prostate cancer (PC) remains unknown. In this study, we report that FOXA1 plays a critical role in PC cell proliferation. The expression of FOXA1 was higher in PC than in normal prostate tissues (P = 0.0002), and, using immunohistochemical analysis, we found that FOXA1 was localized in the nucleus. FOXA1 expression levels were significantly correlated with both PSA and Gleason scores (P = 0.016 and P = 0.031, respectively). Moreover, FOXA1 up-regulation was a significant factor in PSA failure (P = 0.011). Depletion of FOXA1 in a prostate cancer cell line (LNCaP) using small interfering RNA (siRNA) significantly inhibited AR activity, led to cell-growth suppression, and induced G0/G1 arrest. The anti-proliferative effect of FOXA1 siRNA was mediated through insulin-like growth factor binding protein 3 (IGFBP-3). An increase in IGFBP-3, mediated by depletion of FOXA1, inhibited phosphorylation of MAPK and Akt, and increased expression of the cell cycle regulators p21 and p27. We also found that the anti-proliferative effect of FOXA1 depletion was significantly reversed by simultaneous siRNA depletion of IGFBP-3. These findings provide direct physiological and molecular evidence for a role of FOXA1 in controlling cell proliferation through the regulation of IGFBP-3 expression in PC.

Association of double-positive FOXA1 and FOXP1 immunoreactivities with favorable prognosis of tamoxifen-treated breast cancer patients

Breast cancer is primarily a hormone-dependent tumor that can be regulated by the status of the steroid hormones estrogen and progesterone. Forkhead box A1 (FOXA1) is a member of the forkhead box transcription factor family and functions as a pioneer factor of the estrogen receptor (ER) in breast cancer. In the present study, we demonstrate that FOXA1 mRNA was upregulated by estrogen and that estrogen receptor-α (ERα) recruitment to ER-binding sites in the vicinity of the FOXA1 gene was increased by estrogen in ERα-positive MCF-7 breast cancer cells. The estrogen-induced FOXA1 upregulation was repressed by 4-hydroxytamoxifen treatment. We also demonstrated that the proliferation and the migration of MCF-7 cells were decreased by FOXA1-specific small interfering RNA (siRNA; siFOXA1). Furthermore, siFOXA1 decreased the estrogen response element-driven transcription and the estrogen-dependent upregulation of ERα target genes in MCF-7 cells. Next, the immunohistochemical analyses of FOXA1 were performed using two groups of breast cancer specimens. The nuclear immunoreactivity of FOXA1 was detected in 80 (74%) of 108 human invasive breast cancers and was negatively correlated with tumor grade and positively correlated with hormone receptor status, including ERα and progesterone receptor, pathological tumor size, and immunoreactivity of FOXP1, another FOX family transcription factor. FOXA1 immunoreactivity was significantly elevated in the relapse-free breast cancer patients treated with tamoxifen. Notably, the double-positive immunoreactivities of FOXA1 and FOXP1 were significantly associated with a favorable prognosis for the relapse-free and overall survival of patients with tamoxifen-treated breast cancer, with lower P values compared with FOXA1 or FOXP1 immunoreactivity alone. These results suggest that FOXA1 plays an important role in the proliferation and migration of breast cancer cells by modulating estrogen signaling and that the double-positive immunoreactivities of FOXA1 and FOXP1 are associated with a favorable prognosis of tamoxifen-treated breast cancer.

Cross-regulation between FOXA1 and ErbB2 signaling in estrogen receptor-negative breast cancer

Molecular apocrine is a subtype of estrogen receptor-negative (ER.) breast cancer, which is characterized by a steroid-response gene signature that includes androgen receptor, FOXA1, and a high frequency of ErbB2 overexpression. In this study, we demonstrate that there is a strong association between the overexpression of FOXA1 and ErbB2 in ER- breast tumors. This has led us to identify a cross-regulation network between FOXA1 and ErbB2 signaling in ER- breast cancer. We present two mechanisms to explain the association between FOXA1 and ErbB2 overexpression in molecular apocrine cells. In one process, ErbB2 signaling genes CREB1 and c-Fos regulate FOXA1 transcription, and in another process, AP2α regulates the expression of both FOXA1 and ErbB2. Moreover, we demonstrate that FOXA1, in turn, regulates the transcription of ErbB2 signaling genes. This includes a core gene signature that is shared across two molecular apocrine cell lines. Importantly, the most upregulated (RELB) and downregulated (PAK1) genes in this signature are direct FOXA1 targets. Our data suggest that FOXA1 acts as a dual-function transcription factor and the repressive function of FOXA1 on RELB can be explained by the recruitment of its binding partner corepressor TLE3. It is notable that a group of FOXA1-regulated genes vary across molecular apocrine cell lines leading to the differences in the functional effects of FOXA1 on extracellular signal-regulated kinase phosphorylation and cell viability between these lines. This study demonstrates that there is a cross-regulation network between FOXA1 and ErbB2 signaling that connects FOXA1 to some of the key signaling pathways in ER-breast cancer.

FOXA1: a transcription factor with parallel functions in development and cancer

When aberrant, factors critical for organ morphogenesis are also commonly involved in disease progression. FOXA1 (forkhead box A1), also known as HNF3α (hepatocyte nuclear factor 3α), is required for postnatal survival due to its essential role in controlling pancreatic and renal function. In addition to regulating a variety of tissues during embryogenesis and early life, rescue experiments have revealed a specific role for FOXA1 in the postnatal development of the mammary gland and prostate. Activity of the nuclear hormone receptors ERα (oestrogen receptor α) and AR (androgen receptor) is also required for proper development of the mammary gland and prostate respectively. FOXA1 modulates ER and AR function in breast and prostate cancer cells, supporting the postulate that FOXA1 is involved in ER and AR signalling under normal conditions, and that some carcinogenic processes in these tissues stem from hormonally regulated developmental pathways gone awry. In addition to broadly reviewing the function of FOXA1 in various aspects of development and cancer, this review focuses on the interplay of FOXA1/ER and FOXA1/AR, in normal and cancerous mammary and prostate epithelial cells. Given the hormone dependency of both breast and prostate cancer, a thorough understanding of FOXA1's role in both cancer types is critical for battling hormone receptor-positive disease and acquired anti-hormone resistance.

Forkhead box transcription factor, forkhead box A1, shows negative association with lymph node status in endometrial cancer, and represses cell proliferation and migration of endometrial cancer cells

Endometrial cancer is the most common malignancy of the female genital tract and is associated with poor prognosis. It is primarily a hormone-dependent cancer that is regulated by steroid hormones, including estrogen and progesterone. Forkhead box A1 (FOXA1) is a member of the forkhead box transcription factor family and functions as a pioneer factor in estrogen receptor (ER)-positive breast cancer. In the present study, we investigated the expression of FOXA1 in endometrial cancers by immunohistochemical analysis. Nuclear immunoreactivity for FOXA1 was detected in 40 of 109 cases (37%), and was found to be negatively associated with lymph node status (P = 0.033). In ER-positive Ishikawa endometrial cancer cells, small interfering RNA-mediated downregulation of FOXA1 promoted cell proliferation and migration. Furthermore, exogenously introduced FOXA1 suppressed both proliferation and migration of Ishikawa cells. These results suggest that FOXA1 functions as a tumor suppressor through modulation of proliferation and migration of endometrial cancer cells.