Unraveling ESR1 Mutations in Breast Cancer Patients from Pakistan: Implications for Therapeutic Advancements

Abstract

Breast cancer is one of the most common cancers in Pakistan and the leading cause of death among Pakistani women. The onset of breast cancer in Pakistan occurs earlier as compared to other countries. Our study investigates the prevalence of ESR1 gene mutations specifically D538G and novel SNPS including S518N, N519F and N532T in the Pakistani population. Our research aimed at the detection of D538G and other mutations in formalin-fixed tissue biopsy samples from breast cancer patients. This study also included identification of SNPs in the ESR1 gene via amplicon sequencing, in silico structural and functional analysis of SNPs and, in silico drug repurposing against identified SNPs. In total, 73 samples were collected from collaborative hospitals and categorized into wild-type and Invasive Ductal Carcinoma. DNA extraction, quantification, PCR were performed after sequencing and annotation from Macrogen. in silico tools such as PolyPhen, SNPS & GO, PANTHER, Align GVGD and Phyre2 were used to predict the deleterious effect of the detected mutation. Our findings showed the presence of ESR1 mutations in the Ligand Binding Domain of ESR1 including the D538G, S518N, N519F and N532T. The prevalence of the D538G mutation was seen significantly in middle-aged women. Through in silico analysis, these mutations were identified as deleterious leading to endocrine resistance in breast cancer and thus failure of current therapies. Moreover, the drug repurposing identified potential drugs that could target the mutated receptors to offer alternative treatment options for breast cancer. Thus, the research signifies the role of mutations in the ligand-binding domain of ESR1 gene leading to endocrine resistance in breast cancer patients. The study provides a basis for conducting in vitro and in vivo research, and for conducting epidemiological investigations that can help in overcoming endocrine resistance in the patients of breast cancer