6-C-(E-Phenylethenyl)-naringenin, identified from tomato and beef soup, induces cell growth inhibition in colon cancer cells

Abstract

Introduction: 6-C-(E-phenylethenyl)naringenin (6-CEPN), found in the popular tomato and beef soup, possesses potent tumor cell-selective cytotoxicity. In this study, the mechanism of action (MOA) of 6-CEPN was investigated in four colon cancer cell lines (SW620, SW480, HCT116, and HT29). Method: Genome-wide transcriptome expression profiling by RNA-seq was conducted after the cells exposed to 10 μM of 6-CEPN for 24 hours. Subread and Limma was used to perform read mapping, count, normalization and differential expression analysis. Gene set enrichment analysis (GSEA) was conducted among the 14,336 expressed genes with the gene expression signatures of chemical and genetic perturbations in the Molecular Signatures Database to identify the probable targets of 6-CEPN. Results: Surprisingly, the gene expression pattern induced by 6-CEPN was extremely similar to the transcriptome response caused by a KRAS inhibitor salirasib (FDR q-value=0). It is hypothesized that tumor cells addicted to KRAS gain-of-function (GOF) mutation is more sensitive to KRAS inhibition compared with cells carrying wild-type KRAS but GOF mutation downstream of RAS signaling pathway, e.g. downstream BRAF V600E. Perfectly in align with this hypothesis, HT29, a cell line with wild type KRAS but mutated BRAF (V600E GOF) showed much lower sensitivity to 6-CEPN compared with three other cells with mutated KRAS GOF but wild type BRAF. Moreover, RNA-seq data mining showed that 6-CEPN treatment revealed prominent signatures of cell cycle arrest (repression of E2F-regulated genes) and stress response (induction of ATF-regulated and Bach2-regulated genes), where E2F was related to G1 phase arrest of the cell cycle, ATF was a critical transcription factor to induce autophagy to enable cells to manage stress conditions and contribute to cancer cell survival, and Bach2 was associated with cell death. In the following studies, we are planning to conduct genome editing and biochemistry experiments to further confirm whether KRAS is the bona fide target of 6-CEPN, cell cycle profile, and cell death pathways. Significance: This research helps to identify novel agents with anti-cancer properties from food processing products by providing preliminary data on their mechanism of actions.