Callinice D. Capo-chichi^{1, 2,}, Sara Y. Houngue^{1, 2}, Freddy H.R. Gnangnon²

Breast cancer is the number 1 silent killer of women in Benin. For preventive screening some women relies on lump palpation and often disregard molecular biomarker profiling that could prevent them from developing this disease if performed early. Our objective is to investigate the biomarkers involved in breast cell differentiation (GATA3), growth regulation and genomic stability (BRCA1) to delineate them as biomarker to screen for breast cancer risk ahead of clinical symptoms. Key exons involved in each biomarker function are investigated Materials and methods: Upon ethical approval and signed informed consent, microbiopsy tissues was collected from 54 women diagnosed with breast cancer. Exon 4 of GATA3, Exon 1 and Exon 2 of BRCA1 were amplified by polymerase chain reaction (PCR) to investigate their integrity. The presence of amplification with one band is classified as no abnormality, the absence of amplification is classified as deletion while the presence of multiple bands is classified as polymorphism (mutation). Protein expression of GATA3 and BRCA1 were determined by western blot with anti-GATA3 and anti-BRCA1 IgG. Results: The PCR analyses revealed that in 13% cases, all 3 biomarkers targeted sequence were mutated and not amplified. Regarding GATA3-exon 4 amplification, 31% of samples have only 1 band while 54% have more than 2 bands. Regarding BRCA1-exon 1, one band is present in 63% while for BRCA1-exon 2 one band is present in 48% of samples. The Chi square test showed that GATA3-exon 4 and BRCA1-exon 2 have significant inverse variation (p < 0.05). Western blot analyses showed an existence of heterogeneity in GATA3 protein profile with many mutant bands while BRCA1 protein is absent in the majority of samples. Conclusion: It is worthy to emphasis a molecular screening for breast cancer patients before commencing therapy to prevent drug resistance due to matchless between cancer initiation mechanism and targeted therapy.

Breast, cancer, GATA3-exon 4, BRCA1-Exon 2, genes, proteins