Tumor necrosis factor α (TNFα) plays a vital role in cancer progression, being associated with inflammation and promotion of cancer angiogenesis and metastasis. The effects of TNFα are mediated by its down-stream target, the oncogene, lysine-rich CEACAM1 co-isolated protein (LYRIC; also known as metadherin or astrocyte elevated gene-1). LYRIC plays an important role in activating the nuclear factor-κB (NF-κB) signaling pathway, which controls multiple cellular processes, including proliferation, apoptosis, migration, etc. In contrast, the metastasis suppressor, N-myc down-stream regulated gene 1 (NDRG1), has the opposite effect on the NF-κB pathway, being able to inhibit NF-κB activation and reduce angiogenesis, proliferation, migration and cancer cell invasion. These potent anti-cancer properties make NDRG1 an ideal therapeutic target. Indeed, a novel class of thiosemicarbazone anti-cancer agents that target this molecule have been developed, with the lead agent, di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), recently entering clinical trials for advanced and resistant cancers. To further elucidate the interaction between NDRG1 and oncogenic signaling, this study for the first time assessed the effects of NDRG1 on the tumorigenic properties of TNFα and its down-stream target, LYRIC. We demonstrate that NDRG1 inhibits the TNFα-mediated epithelial to mesenchymal transition (EMT). Further, NDRG1 also potently inhibited LYRIC expression, with a negative feedback loop existing between these two molecules. Examining the mechanism involved, we demonstrated that NDRG1 inhibited PI3K/AKT signaling, leading to reduced levels of the LYRIC transcriptional activator, c-Myc. Finally, we demonstrate that novel thiosemicarbazones that up-regulate NDRG1 also inhibit LYRIC expression, further highlighting their marked potential for cancer treatment.
- The American Society for Pharmacology and Experimental Therapeutics