Immunohistochemical Expression of Gata3 Gene in Patients with Breast Cancer

Breast cancer (BC) is one of the most common cancers in the world. In numerous tissues, including the breast, GATA3 plays an important role in stimulating proliferation and differentiation. The main aims of this study is determining the types of BC (IDC and ILC) then the estimation of the role of GATA3 protein expression by immunohistochemical staining method (IHC) in BC patients and control groups as a biomarker. The present study was done during the period from October 2020 to April 2021. Sixty seven tissue samples block embedded in wax taken from BC female patients and thirty four of normal non-tumoral breast tissue as a control group collected randomly with their data from three private pathological clinics, these blocks have been prepared between (2014 – 2021), three pathologists re-evaluate each pathologic material. Regarding to IHC GATA3 protein expression, after histological re-evaluation of slides, the rate of IDC was 80.6% (54 patients) and of ILC was (19.4%) (13 patients).The scoring system +1 (37.3%) and +2(19.4%) increased significantly in BC patients than control (P=0.001), in addition to, the nuclear positive expression of GATA3 decrease significantly in BC patients than control (Odd ratio 2.55, 95% CI 1.45-2.37, P=0.0001), On the other hand, the positivity of GATA3 protein increased significantly in patients with invasive ductal carcinoma (IDC) (P=0.001). Keyword: GATA3, Breast Cancer, Immunohistochemical Expression.

Cathepsin V suppresses GATA3 protein expression in luminal A breast cancer

Background Lysosomal cysteine protease cathepsin V has previously been shown to exhibit elevated expression in breast cancer tissue and be associated with distant metastasis. Research has also identified that cathepsin V expression is elevated in tumour tissues from numerous other malignancies, but despite this, there has been limited examination of the function of this protease in cancer. Here we investigate the role of cathepsin V in breast cancer in order to delineate the molecular mechanisms by which this protease contributes to tumourigenesis. Methods Lentiviral transductions were used to generate shRNA cell line models, with cell line validation undertaken using RQ-PCR and Western blotting. Phenotypic changes of tumour cell biology were examined using clonogenic and invasion assays. The relationship between GATA3 expression and cathepsin V was primarily analysed using Western blotting. Site-directed mutagenesis was used to generate catalytic mutant and shRNA-resistant constructs to confirm the role of cathepsin V in regulating GATA3 expression. Results We have identified that elevated cathepsin V expression is associated with reduced survival in ER-positive breast cancers. Cathepsin V regulates the expression of GATA3 in ER-positive breast cancers, through promoting its degradation via the proteasome. We have determined that depletion of cathepsin V results in elevated pAkt-1 and reduced GSK-3β expression, which rescues GATA3 from proteasomal degradation. Conclusions In this study, we have identified that cysteine protease cathepsin V can suppress GATA3 expression in ER-positive breast cancers by facilitating its turnover via the proteasome. Therefore, targeting cathepsin V may represent a potential therapeutic strategy in ER-positive breast cancers, by restoring GATA3 protein expression, which is associated with a more favourable clinical outcome.

Role of GATA3 exon 6 germline mutations in breast cancer progression in Egyptian female patients

Several mutations act as driver mutations in breast cancer, including GATA3 mutations. Reports of the relation between GATA3 mutations and breast cancer prognosis remain conflicting. Also, the role of GATA3 germline mutations is not well studied. We hypothesize that different mutation types could have different effects. Also, this study aims to assess effect of GATA3 mutations on GATA3 protein function as a transcription factor, and target pathways affected. DNA from de novo breast cancer female patients was sequenced to detect exon 6 GATA3 mutation. Sequence analysis was performed along with clinical and prognostic parameters and disease-free survival. Public datasets were analyzed for differentially expressed genes and pathways with mutant GATA3 patients. Mutations in GATA3 exon 6 were detected in 56.1% of patients (including 2 novel, Lys368fs, Pro354Lys). Intronic mutations were significantly higher in long disease-free survival group, while frameshift mutations were significantly higher in short DFS group. Patients with tumor size ≥20 had significantly higher protein coding and lower intronic mutations compared to patients with tumor size <20 mm. Differential expression and pathway analysis showed that mutant GATA3 had lost its negative regulatory effect on several pathways such as: signaling by interleukins, regulation of TP53 expression, and RUNX3 regulated CDKN1A transcription pathway. PIK3CA, SKP1, FBP1, SMAD3, ANXA9 and CLSTN2 were positively correlated to wild-type GATA3 expression, but not mutant GATA3. Intronic germline mutations of GATA3 could be related to better prognosis, while protein coding GATA3 germline mutations could be related to unfavorable prognosis. GATA3 mutations lead to dysregulation of pathways related to immunity, breast cancer development, and metabolism. Impact statement GATA3 mutations are known to play an important role in breast cancer progression. The exact role and mechanisms of these mutations remain controversial as some studies suggest a relation to breast tumor growth, while others suggest a relation to longer survival. GATA3 germline mutations are not well studied in breast cancer. In this study, it was hypothesized that different types of GATA3 mutations could contribute to the breast cancer progression in different ways. GATA3 exon 6, which is important for GATA3 protein functions, was reported to have hotspots, and hence it was selected for study. Intronic GATA3 germline mutations were found to be related to favorable prognosis, while protein coding mutations were found to be related to unfavorable prognosis. Bioinformatics study of large publically available datasets showed that GATA3 mutations lead to dysregulation of pathways related to T-cells activation, inflammation, and breast cancer development.