Apoptosis and lysosome membrane permeabilization induction on breast cancer cells by an anticarcinogenic Bowman–Birk protease inhibitor from Vigna unguiculata seeds

In this work, we report the effects of a Bowman–Birk protease inhibitor, the Black-Eyed Pea Trypsin/Chymotrypsin Inhibitor – BTCI, purified from Vigna unguiculata seeds, on the MCF-7 breast cancer cells. The treatment of MCF-7 with 200 μM BTCI for 72 h induced significant reduction of the cell viability and proliferation (arrest in S and G2/M phase). These cytostatic effects were accompanied by acute morphological modifications including the alteration of the nuclear morphology, plasma membrane fragmentation, cytoplasm disorganization, presence of double-membrane vesicles, mitochondrial swelling, and an increase in the size of lysosomes. Significative DNA fragmentation, annexin-V+ cell number increase, mitochondrial membrane potential reduction, and cytoplasm acidification were also detected. All together, these cytostatic and cytotoxic results point out to BTCI-induced apoptosis cell death associated with severe cell morphological alterations and lysosome membrane permeabilization. Our study confirms the anticarcinogenic potential of Bowman–Birk protease inhibitors and identifies BTCI as a promising tool for drug developments aimed at the treatment of breast cancer.