Antitumor Potential of Guttiferone E Combined With Carboplatin Against Osimertinib-resistant H1975 Lung Cancer Through Apoptosis.

Background/aim: Low selectivity and high frequency of side-effects are the major problems of currently used chemotherapeutics. Among natural compounds, the polyprenylated acylphloroglucinol, guttiferone E, isolated from Brazilian red propolis, has attracted attention due to its marked anticancer properties and was evaluated here for its role against osimertinib-resistant H1975 cells (with double mutations of epidermal growth factor receptor: EGFR L858R/T790M).

Materials and methods: Guttiferone E was obtained from red propolis using established extraction procedures. Guttiferone E was tested using the H1975 cell line in in vitro (2D and 3D) cell cultures and in vivo in BALB/c athymic nude mice. Live/dead assay was also performed to support the results. Tumor tissues obtained from in vivo studies were used for western blotting. Guttiferone E reduced H1975 cell viability in a concentration-dependent manner. The IC₅₀ values in 2D and 3D cell lines were 2.56±0.12 μM and 11.25±0.34 μM. Furthermore, at 10 mg/kg intraperitoneally, guttiferone E significantly reduced the tumor volume in tumor xenografts when used alone and in combination with carboplatin. Guttiferone E and carboplatin displayed synergistic inhibition of H1975 cells and animal tumors. Co-treatment of guttiferone E with carboplatin induced more prominent apoptosis than treatment with either drug alone. Guttiferone E treatment induced cleavage of poly-ADP ribose polymerase and induced apoptosis by significantly reducing levels of mammalian target of rapamycin, sirtuin 1, sirtuin 7, superoxide dismutase, programmed death-ligand 1, and programmed cell death 1 in tumor tissues.

Conclusion: Our results show guttiferone E to be a promising, novel and potent antitumor drug candidate for osimertinib-resistant lung cancer with EGFR L858R/T790M mutations.