Cellular assays for identification of inhibitors of specific breast cancer molecular phenotypes from Texas plants

Breast cancer is the most common cancer and second leading cause of cancer death in women. New therapeutic strategies targeting the various molecular phenotypes of breast cancer are in crucial need to more effectively treat this heterogeneous disease. Natural products provide an excellent source for the identification of new probes and potential therapies for certain molecular subtypes of breast cancer. The harsh environment of Texas is likely to have a significant influence on the chemical composition of local plants, potentially producing a wide variety of biologically active compounds. A library of crude extracts from understudied Texas plants was screened for antiproliferative activity against a panel of six breast cancer cell lines with various molecular phenotypes, including estrogen receptor positive, HER2 positive and triple-negative subtypes using the sulforhodamine B assay. We identified 12 extracts with potent and selective antiproliferative activity against a specific triple-negative breast cancer subtype; basal, mesenchymal or luminal androgen receptor and one extract with selectivity against a HER2 positive breast cancer cell line. These extracts demonstrated a dose-dependent ability to selectively inhibit cells possessing each of these phenotypes. Our results demonstrate the potential to identify specific inhibitors of molecularly distinct breast cancer subtypes from Texas plants.