Abstract: EACR22-0963
Introduction
Breast cancer remains the most commonly diagnosed type of cancer in both menopausal age women and adolescent/young adults. 10-20% of diagnosed breast cancers are deemed to be triple negative (TN), lacking expression of hormone receptors and HER2. Triple negative breast cancers (TNBC) present with poor patient prognosis, through their lack of effective treatment options. Studies report that epidermal growth factor receptor (EGFR) is expressed in 15–45% of all breast tumours and its expression is inversely related to hormone receptor expression. Expression of EGFR is indicative of poor prognosis, making it an attractive target for treatment in both TN and receptor expressing cancer subtypes. Development of resistance to current EGFR targeted therapeutics is common, leading to treatment failure and patient relapse, thus novel compound classes are needed. Venom peptides have evolved to be secreted into the lumen of the venom gland and stored ready for rapid delivery; therefore they are exceptionally stable. These proteins naturally act as ligands for a large variety of receptors and ion channels, making them a rich source of potentially novel drug like molecules.
Material and Methods
In this study the Venomtech Targeted-Venom Discovery ArrayEGFR (T-VDA™) containing 320 venom 2D HPLC fractions was screened using Abcam Human EGFR (pY1086) + total EGFR ELISA Kits to identify venom peptides with antagonistic activity against EGFR pY1086 phosphorylation. Optimal cell number, dosing and lysate concentrations were determined empirically. MDA-MB-468 TNBC cells were dosed at 20ug/ml for 2h with fractions, before being stimulated with 1x10-7M EGF for 5 mins. Further assay protocol was carried out as per manufacturer’s instructions. TMB Absorbance signal was measured using a CLARIOstarPLUS plate reader at 450nm (BMG LabTech).
Results and Discussions
Screening of the TVDAEGFR array (N=2) identified 7 hit fractions (2.2% hit rate) from the venoms of three distinct rattlesnake genera from Northern, Central and southern America, and 1 viper species from Northern Africa. These fractions were followed up with dose response, mass spec and drug like properties.
Conclusion
Purified protein components from the venoms of pit vipers and vipers show the capacity to antagonistically inhibit the phosphorylation of EGFR at specific tyrosine residues linked to downstream signalling pathways in TNBC cells. Thus, representing a novel chemical class for targeting EGF
