Mechanistic Regulation of Epidermal Growth Factor and Hormonal Receptors by Kinase Inhibitors and Organofluorines in Breast Cancer Therapy.

Abstract

Differential expression patterns of growth factor (EGFR, HER-2) and hormonal (ER, PR) receptors in breast cancer (BC) remain crucial for evaluating and tailoring therapeutic interventions. This study investigates differential expression profiles of hormonal and growth factor receptors in BC patients and across age groups, major subclasses, disease stages and tumor histology and survival rates, the efficacy of emerging clinical trial drugs (Dabrafenib and Palbociclib) and elucidating their molecular interaction mechanisms for efficient therapeutic strategies. Gene and protein expression analysis in the normal vs BC and across age groups and major subclasses reveals divergent patterns as EGFR and HER-2 levels are reduced in tumors versus normal tissue, while ER and PR levels are higher, particularly in luminal subtypes. However, there was no significant difference in survival rates among high and low/medium expression levels of EGFR and PR receptors. Conversely, patients with high HER-2 and ER expression exhibited poorer survival rates compared to low or medium expression levels. The in vitro findings indicate that Dabrafenib exhibits greater effectiveness than Palbociclib in suppressing various BC cells such as MCF-7 (Luminal), MDA-MB-231 (Triple-Negative), SKBR-3 (HER-2 + ) proliferation, promoting cell death, (IC₅₀ of Dab < Pal) at 24 and 48 h, ROS production, and reduced ER and PR, elevated HER-2 with no change in EGFR expression. Molecular simulation studies revealed Dabrafenib's thermodynamically stable interactions (ΔG), tighter binding, and less structural deviation in the order EGFR > HER-2 > ER > PR as compared to Palbociclib (HER-2 > ER > PR = EGFR). These results indicate that Dabrafenib, compared to Palbociclib, more effectively regulates breast cancer cell proliferation through specific interactions with hormonal and growth factor receptors towards a repurposing approach.