Glutamine Deprivation Suppresses Lung Cancer Metastasis via Inducing the Activation of ZAKα and Translation Inhibition

Abstract

Abstract Background Amino acids are not only components of proteins, but also play important roles in many cellular processes, such as regulating the mTORC1 activity, controlling the translation. However, the role of each amino acid on lung cancer metastasis is still uncertain. Methods Transwell assays were used to detect to migration and invasion of cancer cells. Real Time PCR was used to detect the transcription of genes. RNA-seq was performed to analyze the signature of EMT-related genes. Western blot was used to detect the level of proteins. Phospho-gel was used to detect the activation of ZAKα. Puromycin incorporation assay was conducted to show the extent of translation. Lentivirus packaging was used to construct stable cell lines. Mutagenesis was conducted to mimic the dominant-negative or activation of proteins. Mouse lung seeding was used to detect the metastasis of tumor cells in vivo. Results Here, we found that, among the 20 basic amino acids, glutamine deprivation specifically inhibits EMT, migration and invasion of lung cancer cells. While, this effect of glutamine is independent of its metabolism. Mechanistically, we found that glutamine promotes A549 cell migration and invasion by enhancing the translation of Zeb1 and Snail. The phosphorylation of translation factors: eIF2α S51, eIF4E S209 and eEF2 S57 induced by glutamine limitation is dispensable for the translation of Zeb1 and Snail. Further, glutamine deprivation dramatically activates ZAKα and its substrates JNK and p38. Knockdown of ZAKα rescues lung cancer cell migration and invasion under glutamine deprivation, while constitutive activation of ZAKα W347S or F368C inhibits lung cancer cell migration and invasion in the presence of glutamine. In mouse models, ZAKα W347S or F368C inhibits the lung seeding of A549 cells. Conclusions Glutamine depletion could activate ZAKα to inhibit the translation of EMT-TFs and thus suppress the lung cancer cell metastasis. Our findings uncover the special effect of glutamine on the regulation of translation and lung cancer metastasis, which may give us a new insight into nutrient and cell fate during lung cancer development.