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

Med Oncol. 2015 Apr;32(4):115. doi: 10.1007/s12032-015-0564-4. Epub 2015 Mar 17.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Blotting, Western
  • Carcinoma
  • Cell Adhesion / drug effects
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Epithelial-Mesenchymal Transition*
  • ErbB Receptors / antagonists & inhibitors*
  • ErbB Receptors / metabolism
  • Flow Cytometry
  • GTPase-Activating Proteins / pharmacology*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Membrane Potential, Mitochondrial / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mitochondria / pathology*
  • NF-kappa B / antagonists & inhibitors*
  • NF-kappa B / metabolism
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / drug therapy
  • Nasopharyngeal Neoplasms / metabolism
  • Nasopharyngeal Neoplasms / pathology*
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Tumor Cells, Cultured
  • Tumor Suppressor Proteins / pharmacology*

Substances

  • DLC1 protein, human
  • GTPase-Activating Proteins
  • NF-kappa B
  • Tumor Suppressor Proteins
  • EGFR protein, human
  • ErbB Receptors
  • AKT1 protein, human
  • Proto-Oncogene Proteins c-akt