EZH2 inhibition confers PIK3CA-driven lung tumors enhanced sensitivity to PI3K inhibition

• Published in: Cancer letters Vol. 524; pp. 151 - 160
• Main Authors: Chen, Fan, Liu, Jinpeng, Song, Xiulong, DuCote, Tanner J., Byrd, Aria L., Wang, Chi, Brainson, Christine F.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01-01-2022; Elsevier Limited
• Subjects: 1-Phosphatidylinositol 3-kinase; Adenocarcinoma; AKT protein; Animals; Antineoplastic Agents - pharmacology; Benzamides - pharmacology; Biphenyl Compounds - pharmacology; Cell culture; Cell Line, Tumor; Chronic lymphocytic leukemia; Class I Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Class I Phosphatidylinositol 3-Kinases - genetics; Clinical trials; Combination therapy; Drug dosages; Drug Resistance, Neoplasm - genetics; Enhancer of Zeste Homolog 2 Protein - genetics; Epigenetic therapy; Epigenetics; Epithelial cells; Experiments; EZH2; FDA approval; Gene expression; Humans; Kinases; Laboratories; Lung cancer; Lung Neoplasms - drug therapy; Lung Neoplasms - genetics; Lung Neoplasms - pathology; Lymphatic leukemia; Lymphoma; Mice; Morpholines - pharmacology; Mutation; Non-small cell lung carcinoma; p53 Protein; Phosphoinositide-3 Kinase Inhibitors - pharmacology; PI3K; Protein Kinase Inhibitors - pharmacology; Pyridones - pharmacology; Pyrimidines - pharmacology; Quinazolines - pharmacology; Signal transduction; Signal Transduction - drug effects; Small cell lung carcinoma; Tumors; Xenograft Model Antitumor Assays; United States > US; Kentucky; PI3K; LSCC; Lung cancer; LADC; SV40; Epigenetic therapy; Combination therapy; EZH2; H3K27me3; AT2
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/j.canlet.2021.10.010

Members of the PI3K signaling pathway, especially PIK3CA, the gene encoding the catalytic subunit of the PI3K complex, are highly mutated and amplified in various cancer types, including non-small cell lung cancer. Although PI3K inhibitors have been used in clinics for follicular lymphoma and chronic lymphocytic leukemia, no agents targeting PI3K aberrations in lung cancer have been approved by the FDA so far. In this study, we observed that PIK3CA-E545K, the most common mutation in lung cancer, harbored a modest induction of stem-like properties in lung epithelial cells, and drove development of adenocarcinoma autochthonously when paired with p53 loss in a murine mouse model. We also found that PIK3CA-mutant of amplified lung cancer cells were sensitive to EZH2 inhibition. EZH2 inhibition synergized with PI3K inhibition in human cancer cells in vitro and worked together efficiently in vivo. Mechanistically, EZH2 inhibition cooperated with PI3K inhibition to produce a more potent suppression of phospho-AKT downstream of PI3K. This study suggests a promising combination therapy to combat lung cancers with PIK3CA mutation or amplification. Both copanlisib, the PI3K inhibitor, and tazemetostat, the EZH2 inhibitor, are FDA-approved, which should enhance the clinical translation of this work.
•Alterations in PIK3CA show mutually exclusivity to KRAS mutations in lung cancer.•PIK3CA-mutant and amplified lung cancer cells have increased sensitivity to EZH2 inhibition.•EZH2 inhibition and PI3K inhibition combine effectively in lung cancer xenograft models.•A knock-in allele of the most common PIK3CA mutation drives lung adenocarcinoma in a mouse model.