Boku S, et al. Cancers (Basel) 2020.
Aspirin is one of the most promising over-the-counter drugs to repurpose for cancer treatment. In particular, aspirin has been reported to be effective against PIK3CA-mutated colorectal cancer (CRC); however, little information is available on how the PIK3CA gene status affects its efficacy. We found that the growth inhibitory effects of aspirin were impaired upon glutamine deprivation in PIK3CA-mutated CRC cells. Notably, glutamine dependency of aspirin-mediated growth inhibition was observed in PIK3CA-mutated cells but not PIK3CA wild type cells. Mechanistically, aspirin induced G1 arrest in PIK3CA-mutated CRC cells and inhibited the mTOR pathway, inducing the same phenotypes as glutamine deprivation. Moreover, our study including bioinformatic approaches revealed that aspirin increased the expression levels of glutaminolysis-related genes with upregulation of activating transcription factor 4 (ATF4) in PIK3CA-mutated CRC cells. Lastly, the agents targeting glutaminolysis demonstrated significant combined effects with aspirin on PIK3CA-mutated CRC cells. Thus, these findings not only suggest the correlation among aspirin efficacy, PIK3CA mutation and glutamine metabolism, but also the rational combinatorial treatments of aspirin with glutaminolysis-targeting agents against PIK3CA-mutated CRC.