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Abstract
Introduction: Breast cancer is the most frequent cancer in which the mortality rate could be decreased by proper management. The GATA3 transcription factor is one of the most frequently mutated genes in breast cancer. Materials and Methods: We studied the immunohistochemical (IHC) expression of estrogen and progesterone receptor, human epidermal growth factor receptor 2, and GATA-3 in 166 radical/partial mastectomy specimens having different histologic grades and stages of breast carcinoma. All samples were obtained from the pathology department of Sina hospital in Tehran-Iran from 2010 to 2016. Results: There was a direct relationship between the luminal subtype carcinoma and higher GATA-3 expression (P-value: 0.001) and between triple-negative carcinoma and lower GATA-3 expression (P-value: 0.001). Moreover, there was a direct relationship between the metastasis rate and the tumor's grade with GATA-3 staining (P-value: 0.000 and 0.001, respectively). Conclusion: GATA-3 expression is related to the histopathologic and prognostic factors. GATA3 can be introduced as an important predictor in breast cancer patients.
Keywords: Breast cancer, GATA-3, prognosis
How to cite this article: Introduction 
Breast cancer is the most frequent cancer and the second leading cause of malignancy death among women.[1] However, because of its associated relevant morbidity, the use of valid biomarkers is now being discovered by researchers worldwide.[2] Even though the declining mortality rate is related to breast cancers due to the increased rate of diagnosis and application of effective treatment approaches, it is still considered a great burden on different settings of society. Hence, novel strategies are warranted to predict disease course as well as the response to the therapies. For a long time, grade and stage of a breast tumor were the main prognostic factors nevertheless, by considering immunohistochemical (IHC) markers such as progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER-2) and their considerable correlations with the treatment responses, researchers found them as appropriate alternatives. There are at least four subtypes of breast cancer concerning these biomarkers: luminal A (ER+/PR+/HER2-), luminal B (ER+/PR+/HER-2+), human epidermal growth factor receptor 2 (HER-2), overexpressing (ER-/PR-/HER-2+), and triple-negative (ER-/PR-/HER-2-).[3] Recognition of proper category for each breast cancer seems essential as they exhibit different clinical and molecular prognoses (i.e. patients with the triple-negative and ER-/PR-/HER-2 + subtypes have generally worse conditions, whereas patients with ER + breast cancers are shown to have a better prognosis and respond to hormonal therapy more efficiently).[4],[5] GATA-3 is a member of the GATA family, which are considered zinc finger transcription factors contributing to cell proliferation, development, and differentiation in various tissues and cell types such as breast epithelial cells.[6] Therefore, it could significantly act in the development of breast tumors. First, it must be noted that overexpression of GATA-3 has been observed in the luminal type of breast cancer.[7],[8] However, studies have shown that the expression of this protein reduces with increasing the tumor grade.[9],[10] Second, overexpression of GATA3 has shown to be associated with improved survival outcomes in those women with ER-positive breast cancer that are premenopausal.[11] Third, the pathogenesis of luminal breast cancers is associated with mutations in the structure of this protein.[12] Finally, “estrogen/progesterone receptor loss” metastases represent a maintained level of GATA-3 expression.[13] These findings are representative of the growing attention regarding the prognostic usefulness of GATA-3 in each type of breast cancer; nevertheless, the results are not solid and remain controversial probably due to the heterogeneous definition of GATA-3 positivity.[8],[9],[14],[15],[16] Given the present discrepancy in the role of GATA-3 in the prognosis of breast cancers, we aimed to investigate the GATA-3 status in different categories of breast cancer and its relationship with other biomarkers expression, histopathologic, and prognostic factors.
Materials and Methods Study population and setting
In the current study, we assigned 166 patients with breast cancer, which were obtained via radical/partial mastectomy between February 2010 and October 2016 from the electronic registry of the Department of Pathology, Sina Hospital affiliated to Tehran University of Medical Sciences. Each patient must have had all of the following data recorded including demographic information, tumor size, invasive type of tumor, tumor stage and grade, lymph node invasion, and formalin-fixed paraffin-embedded primary tumor samples for IHC analysis. This study was cross-sectional. Cases with incomplete information were excluded. Tumor staging was performed according to the College of American pathologists protocols 2019. In addition, tumor grading was done according to the Nottingham algorithm.[17]
Immunohistochemical analysis
The Department of Pathology of Sina hospital keeps single archival tumor blocks from each patient. Two expert pathologists evaluated H&E-stained sections from these blocks to mark areas of tumoral lesions precisely.
IHC staining was performed on 3-μm formalin-fixed, paraffin-embedded sections to rate the expression of several breast cancer markers including ER, PR, and HER-2. The IHC reports were conducted using the College of American Protocols 2019.
GATA-3 expression was analyzed using a mouse monoclonal anti-GATA3 antibody (1:200 dilutions, clone 7B5; Sigma, Germany). Sections were cut from each block, deparaffinized with xylene, rehydrated in a series of ethanol solutions with a decreasing concentration, and then antigen retrieval was achieved in Cell Conditioning Solution CC1 (pH 8.5, 98°C; Ventana Medical Systems) for 60 min. Finally, retrieval solutions were cooled for at least 30 min at room temperature (25°C). Afterwards, in order to inhibit endogenous peroxidase, the slides were treated for 10 min with 3% H2O2 in methanol solution. Slides were incubated with monoclonal antibodies for 120 min at room temperature and were labeled with the Envision Detection System from DAKO. The color reaction product was developed with 3,3'-diaminobenzidine, tetrahydrochloride (DAB plus; DAKO Glostrup, Denmark) as a substrate, and nuclear contrast was achieved with hematoxylin/ammoniac water counterstaining. Formalin-fixed, paraffin-embedded sections from normal breast gland were used as GATA-3 positive controls. Negative controls were performed by replacing the primary antibody with PBS/nonimmune mouse serum.
The scoring method used for GATA-3 expression appraisals was based on the percentage of staining as follows: 0 = 0% to 5% expression; 1+ = 6% to 25% expression; 2+ = 26% to 50% expression; 3+ = 51% to 75% expression; and 4+ = 76% or above [Figure 1].
Figure 1: GATA-3 staining (upper: +4, middle left: +3, middle right: +2, lower left: +1, lower right: 0)Statistical analysis
All the analysis was performed using the Statistical Package of Social Science Software (SPSS version 24; IBM Company), and a P value level of 0.05 or below was regarded as significant. The Shapiro–Wilk test and probability graphs were used to test the normality of the baseline data. Categorical variables were reported in percentage (%), whereas continuous data were represented as mean ± SD. Continuous and categorical variables were compared using an independent t-test with Levene's test for the equality of variance and the Fisher's exact test, respectively. The ethics number. IR.TUMS.REC.1394.1541 (2015 November 28).
Results The database query returned 166 patients with an average age of 50 years (22–86 years). ER staining was 123 (74.1%) positive and 43 (25.9%) negative. PR staining was 110 (66.3%) positive and 56 (33.7%) negative. HER2 staining was 91 (54.8%) positive, 48 (28.9%) equivocal, and 27 (16.3%) negative. GATA-3 staining was according to [Table 1].
In our study, 31 patients had negative ER staining, which had negative GATA-3 staining and 96 patients had positive ER staining, which had positive strong GATA-3 staining. As a result, there was a dominant relationship between the ER and the GATA-3 staining (P-value: 0.001). Moreover, 33 patients had negative PR staining, which had negative GATA-3 staining and 90 patients had positive PR staining, which had positive strong GATA-3 staining. There was a significant relationship between PR and GATA-3 staining (P-value: 0.001). A total of 19 patients had negative HER-2 staining, which had negative GATA-3 staining, and 11 patients had positive HER-2 staining, which had positive strong GATA-3 staining. There was no specific relationship between HER-2 and GATA-3 staining (P-value: 0.372). In 144 patients with luminal carcinoma, 4 patients had negative and 100 patients had positive GATA-3 staining, which indicated a direct relationship between luminal carcinoma and higher GATA-3 expression (P-value: 0.001). In 22 patients with triple-negative carcinoma, 15 patients had negative and 7 patients had positive GATA-3 staining, which showed a major relationship between triple-negative carcinoma and lower GATA-3 expression (P-value: 0.001) [Table 2].
Table 2: Relationship GATA-3 staining with other immunomarkers and carcinoma typeFurthermore, there was no significant relationship between the tumor size, local recurrence, and the number of involved lymph nodes by tumor with GATA-3 staining (P-value: 0.233, 0.101, and 0.122, respectively). However, there was a dominant relationship between the metastasis rate and the tumor's grade with GATA-3 staining (P-value: 0.000 and 0.001, respectively) [Table 3].
Discussion A current challenge for cancer biologists is to investigate the emerging genomic data in a mechanistic context, establishing the relationship between specific mutations and tumor biology, and informing on clinical parameters including aggressiveness, response to therapy, and potential for metastasis.[18] ER, PR, and HER-2 for breast cancer are known very well, but we assessed a new marker, GATA-3, in which the expression is required for normal development of the mammary gland where it is estimated to be the most abundant transcription factor in luminal epithelial cells.[19] GATA-3 and ER are involved in a cross-regulatory loop and are frequently co-expressed in breast carcinomas; however, several studies have demonstrated that subsets of triple-negative breast carcinomas stain positively for GATA-3.[20] Many studies have examined the prognostic significance of GATA-3 expression in breast carcinoma, and some studies discovered potential clinical usefulness of GATA-3 as a prognostic biomarker, whereas other studies have failed to demonstrate such independent prognostic association.[21] The impairment of this gene set likely contributes to the aggressive phenotype and the poor outcome of tumors.[22] In our study, we considered a prognostic role for GATA-3 expression. We established GATA-3 expression related to tumor grade and metastasis rate (P-value: 0.001 and 0.000, respectively). However, the clinical and molecular outcomes of GATA-3 mutations are poorly understood because there are very few studies describing the functions of mutant GATA-3.[23] In Nam K Yoon et al. study,[9] low GATA3 expression correlated with increased tumor size, and ER and PR negativity were studied. In some studies, GATA-3 expression has been found to correlate with tumor grade and with ER and PR status.[24] Thus, GATA-3 expression is associated with breast carcinomas of luminal subtype and low histological grade.[25] In our study, GATA-3 expression related to luminal carcinoma (P-value: 0.001), which was similar to the other studies and GATA3 mutations appear to occur mainly in patients with luminal subtype breast cancer and are associated with a favorable prognosis.[26] Almost large-scale studies have evaluated GATA-3 expression in ductal carcinoma, and little is known on GATA3 expression in other various subtypes of breast carcinoma. Therefore, we only evaluated ductal carcinoma.[27] In addition, GATA-3 is a useful immunohistochemistry marker in the diagnosis of both primary and metastatic disease. GATA-3 can be particularly useful as a marker for metastatic breast carcinoma, especially triple-negative, which has a lack of specific markers of mammary origin.[13] GATA-3 was associated with good disease-free survival and overall survival (P = 0.001 and P = 0.0009) in some studies and was an independent prognostic factor for overall survival.[28] These findings are supported by Lin H-Y et al.[29] who reported that GATA-3 is connected to a less aggressive, PR-positive, HER2-negative phenotype, and therefore with a favorable survival outcome in breast cancer patients, which was similar to our findings. On the other hand, low GATA-3 expression is strongly associated with the higher histologic grade, poor differentiation, positive lymph nodes, ER and PR negative status, and HER2 overexpression, all indicators of poor prognosis.[30] Our data provide a link of the loss of function of GATA-3 to breast cancer progression.[31] In a study performed by Ciocca et al.,[32] no statistically significant differences in recurrence or survival rates between GATA-3 positive and GATA-3 negative tumors were found, which was in opposition to other studies and our findings. Biomarker analysis is playing an essential role in cancer diagnosis, prognosis, and recurrence prediction. GATA-3 drives invasive breast cancer cells to undergo the reversal of epithelial-mesenchymal transition, leading to the suppression of cancer metastasis.[33] Moreover, determining the indications for adjuvant chemotherapy in patients with hormone receptor-positive/HER2-negative breast cancer is difficult.[34] In another study, Larsen V et al.[35] provided some evidence for the predictive value of GATA-3 genotypes for breast cancer adjuvant therapies. Thus, GATA-3 is crucial for the hormone response phenotype of breast cancer. Based on these findings, the expression assessment of GATA-3 in breast cancer patients can provide important clinical information not only regarding the favorable prognostic nature and tumor behavior but it can also constitute an important tool to hormone response assessment in breast cancer.[36] Therefore, GATA-3 expression may be potentially used in assisting clinical decision-making. In the present study, we provided an immunohistochemical approach studying GATA-3 expression in order to predict the tumor behavior of breast cancer patients. For diagnostic purposes, an increased clinical sensitivity must be required; thus, the clone with higher sensitivity was chosen.[37] Further investigation of GATA3-related pathways will be crucial to our understanding of breast cancer dissemination and may also provide novel therapeutic targets.[14]
Conclusion GATA3 expression is useful as a prognostic indicator in breast cancer, and it is related to other hormonal receptors. We recommend that GATA3 be routinely included in the panel of immunohistochemical markers on surgical specimens.
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Conflicts of interest
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References 
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CheckDOI: 10.4103/ijpm.ijpm_453_21
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