Unraveling the molecular mechanism underlying the anticancer activity of CISD2/NAF-1⁴⁴⁻⁶⁷

We recently reported on the development of a unique cancer-targeting peptide called NAF-1⁴⁴⁻⁶⁷ (derived from CISD2/NAF-1). NAF-1⁴⁴⁻⁶⁷ selectively permeates the plasma membrane (PM) of cancer cells, but not healthy cells, causing the activation of apoptotic and ferroptotic cell death pathways specifically in cancer cells. NAF-1⁴⁴⁻⁶⁷ also targets and shrinks human breast and ovarian cancer tumors in a xenograft mice model system without any apparent side effects. Although the specific permeation of NAF-1⁴⁴⁻⁶⁷ through cancer cell PMs was studied, and its cancer killing effects validated in vitro and in vivo, little is known about how NAF-1⁴⁴⁻⁶⁷ exerts its biological activity once it enters cancer cells. Here, we report that NAF-1⁴⁴⁻⁶⁷ targets the CISD2/NAF-1 protein of cancer cells and disrupts its homodimeric structure. We further reveal that a peptide derived from the same domain of the human CISD1 (mitoNEET; mNT^19-42) protein, a close family member to CISD2, has no killing activity towards cancer cells, and that dimers of NAF-1⁴⁴⁻⁶⁷ (at two different orientations) have higher anticancer activity compared to monomeric NAF-1⁴⁴⁻⁶⁷. Our findings shed new light on the biological activity of NAF-1⁴⁴⁻⁶⁷ and bring it closer to becoming a potential new anticancer drug.