Designing a cancer therapeutic peptide by combining the mitochondrial targeting domain of Noxa and ErbB2-targeting moieties.

Many anticancer drugs target epidermal growth factor receptors to inhibit receptor tyrosine kinases and tumor growth. Here, we show that an ErbB2-targeting pronecrotic peptide (KWSY:MTD) selectively kills tumor cells expressing ErbB2 in vitro. An antibody against ErbB2 inhibits KWSY:MTD-induced cell death. KWSY:MTD causes membrane permeability which allows propidium iodide entry into the cytosol and the release of HMGB1 into the media, indicative of necrosis. Mitochondrial swelling occurs in response to KWSY:MTD. Moreover, in vivo analysis using a mouse model shows that KWSY:MTD partially suppressed growth in tumor tissue bearing ErbB2-expressing cells, but did not have obvious toxicity in mouse liver or kidney tissue. Taken together, KWSY:MTD has potential as an ErbB2-targeting anticancer drug.