Development of a novel zein-derived peptide: in vitro assays, and 2D- and 3D-cell models

Abstract

Maize is the most consumed staple crop worldwide. Its composition, abundant in prolamins corresponding to α-zein, represents an opportunity for the search of bioactive candidates combating diseases such as cancer. In particular, zein hydrolysates have showed activity against this disease in vitro. Nevertheless, the need for specific peptides with known peptide sequence remains. In response, this thesis work attempted to develop a new-to-nature peptide derived from zein and test its effects in vitro. First, acetone precipitation was introduced to the purification train of zein hydrolysates of blue maize. , After 48 h, the resulting hydrolysates (BmapZDH) diminished cancer cell viability to 4.3% and reduced fibroblasts’ viability to 77.3% at 125 and 93.75 ng/mL, respectively. Hypothesizing an attributing specific peptide in silico, a new-to-nature peptide from the 22-kDa α-zein was developed. The resultant peptide, nurP28, had the sequence Ac-LALLALLRLRRRATTAFIIP-NH2 after the iterations. When tested alone, nurP28 was not cytotoxic to human fibroblasts or cancer cells. Notably, higher cytotoxic effects were observed in MCF7 spheroids when combining nurP28 at 3 ng/mL and 1 µM docetaxel than 10 µM alone. Additional testing highlighted that nurP28 inhibits the migration of MDA-MB-231 breast cancer cells by ~50 %, is not-hemolytic for human red blood cells, does not alter the ACE activity when administered at 300 ng/mL, and is innocuous for murine myoblasts cells. In toto, this thesis presents the bases of the potential and capability of nurP28 peptide as a safe molecule to be tested in vivo promptly, aiming to boost breast cancer treatment.