Background: The use of antioxidants as cancer prevention and treatment agents has become a focus of research in recent years due to their limited adverse effects. Alpha lipoic acid (α-LA), a naturally occurring antioxidant and metabolic enzyme co-factor, has been reported to inhibit the growth of various cancer cells, but the precise signaling pathways that mediate the effects of α-LA on colorectal cancer cells development remain unclear.
Methods: In this study, we combined the use of an RNA sequencing (RNA-Seq) database and isobaric tag for relative and absolute quantitation (iTRAQ)-based quantitative proteomics data to investigate the dynamic genomic/proteomic response of human colorectal cancer cells (HT29) to α-LA stress. The CCK-8 assay was used to assess cell proliferation in CRC cell lines after α-LA treatment. The expression of proteins were evaluated by western blotting. Grb2 levels were restored in α-LA-treated cells by transfection of a plasmid carrying Grb2 and were reduced in CRC cells via specific siRNA-mediated knockdown.
Results: A total of 4,107 differentially expressed genes (2,259 downregulated and 1,848 upregulated) were identified via RNA-Seq in HT29 after exposure to α-LA for 24 h. Moreover, GO and KEGG pathway analyses showed that cancer-relevant cell membrane proteins were significantly affected. An interaction network analysis predicted that Grb2 may mediate the key target pathways activated by exposure to α-LA. In verifying the multi-omics results, Grb2 was confirmed to mediate the α-LA-induced inhibition of cell proliferation in vitro. Moreover, additional experiments indicated that Grb2 inhibition partially abolished EGF-induced phospho-EGFR and phospho-ERK1/2 activity. Furthermore, the analysis of human colorectal cancer specimens obtained from the GEO database showed that the expression of EGFR correlated with that of Grb2.
Conclusion: These findings provide a novel mechanism by which α-LA regulates cell colorectal cancer proliferation via the down-regulation of growth factor-stimulated Grb2 signaling.
Citation Format: Lan Yang, Chunlei Hu, Guoqing LV, Bei Li, Shaowei Xiong. Integrated multi-omics analyses reveal α-lipoic acid-regulated cell proliferation via Grb2-mediated signaling in colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 259.