DLC-1 induces mitochondrial apoptosis and epithelial mesenchymal transition arrest in nasopharyngeal carcinoma by targeting EGFR/Akt/NF-κB pathway

Loss of deleted in liver cancer-1 (DLC-1) can induce apoptosis and inhibit the mobility, migration and metastasis in several cancers. Previously, we revealed that ectopic expression of DLC-1 can suppress proliferation, mobility, migration and tumorigenesis in nasopharyngeal carcinoma (NPC). However, the molecular mechanisms accounting for the roles of DLC-1 in NPC are still obscure. In the present work, we attempted to study and uncover the mechanisms underlying the functions of DLC-1 in NPC. The apoptosis of 5-8F-DLC-1 cells, established previously, was analyzed by mitochondrial membrane potentials assay and flow cytometer analysis. And the antibodies involving pathways such as mitochondrial-associated apoptosis, epithelial mesenchymal transition and metastasis were applied to detect and compare the expression level of targeted proteins. The obvious apoptosis of 5-8F-DLC-1 cells was observed reflected by mitochondrial depolarization and lower ratio in cell viability. Subsequently, the activation of mitochondrial apoptosis was verified by the increased expressions of Bax, Apaf1, cleave-caspases and cleave-PARP, etc, and the decreased expressions of Bcl-2, Bcl-xL, Mcl-1, Survivin, etc, in 5-8F-DLC-1 cells. Then, the inhibited epithelial mesenchymal transition of 5-8F-DLC-1 cells was validated by upregulated expression of E-cadherin and downregulated expression of N-cadherin, Snail, Vimentin. Subsequently, downregulated expressions of proteins such as FAK, RhoA, ROCK1 and cdc25 related to cell adhesion and cytoskeleton organization were also observed. And expressions of MMPs were inhibited in 5-8F-DLC-1 cells. At last, the inhibited activity of EGFR/Akt/NF-κB axis was revealed by the decreased expressions of phosho-EGFR, phosho-Akt, phosho-p38MAPK, phosho-IKKα and phosho-p65. Here, we systematically explored the mechanisms underlying the negative roles of DLC-1 in NPC cells. For the first time, we confirmed that the ectopic expression DLC-1 can induce mitochondrial apoptosis, inhibit EMT and related processes by targeting the EGFR/Akt/NF-κB pathway, which, beyond all doubt, offered beneficial guidelines for other studies and laid a good foundation for its clinical applications ultimately.