A novel combination of isovanillin, curcumin, and harmine (GZ17-6.02) enhances cell death and alters signaling in actinic keratoses cells when compared to individual components and two-component combinations

Abstract

Actinic keratosis is a pre-malignant skin disease caused by excessive exposure to ultraviolet light. The present studies further defined the biology of a novel combination of isovanillin, curcumin, and harmine in actinic keratosis cells in vitro. An oral formulation (GZ17-6.02) and topical preparation (GZ21T) comprised of the same fixed, stoichiometric ratio have been developed. Together, the three active ingredients killed actinic keratosis cells more effectively than any of its component parts as either individual agents or when combined in pairs. The three active ingredients caused greater levels of DNA damage than any of its component parts as either individual agents or when combined in pairs. As a single agent, compared to isolated components, GZ17-6.02/GZ21T caused significantly greater activation of PKR-like endoplasmic reticulum kinase, the AMP-dependent protein kinase, and ULK1 and significantly reduced the activities of mTORC1, AKT, and YAP. Knockdown of the autophagy-regulatory proteins ULK1, Beclin1, or ATG5 significantly reduced the lethality of GZ17-6.02/GZ21T alone. Expression of an activated mammalian target of rapamycin mutant suppressed autophagosome formation and autophagic flux and reduced tumor cell killing. Blockade of both autophagy and death receptor signaling abolished drug-induced actinic keratosis cell death. Our data demonstrate that the unique combination of isovanillin, curcumin, and harmine represents a novel therapeutic with the potential to treat actinic keratosis in a manner different from the individual components or pairs of the components.