ABSTRACT
Metastasis is the main obstacle for the treatment of gastric cancer (GC), leading to low survival rate and adverse outcomes in CG patients. SLC6A14, a general amino acid transporter, can import all the essential amino acids in a manner dependent on the NaCl-generated osmotic gradients. Herein, we constructed GC cell sublines with high (SGC7901-M and MKN28-M) and low (MKN28-NM and SGC7901-NM) metastatic ability. Putative functional genes advancing GC metastasis were identified using mRNA microarray analysis and High-Content Screening. In particular, most significant change with a dampening trend in the migration potentiality of GC cells emerged after SLC6A14 gene was silenced. SLC6A14 expression was positively correlated with the migrated capability of different GC cell lines, and SLC6A14 was also constitutively expressed in GC patients with venous or lymphatic invasion, lymph node, or distant metastasis and poor prognosis, thus prompting SLC6A14 as a nonnegligible presence in supporting GC migration and invasion. Consistently, SLC6A14 depletion drastically depressed GC metastasis in vitro and in vivo. Most importantly, pharmacological blockade and gene silence of SLC6A14 both restricted epithelial-mesenchymal transition- (EMT-) driven GC metastasis, in which attenuated activation of the PI3K/AKT/mTORC1 pathway caused by amino acid starvation was involved. In summary, it is conceivable that targeting SLC6A14 has a tremendous promising for the treatment of metastatic GC.
Subject(s)
Amino Acid Transport Systems , Stomach Neoplasms , Amino Acid Transport Systems/genetics , Amino Acids/metabolism , Cell Line, Tumor , Cell Movement/genetics , Epithelial-Mesenchymal Transition/genetics , Gene Expression Regulation, Neoplastic , Humans , Mechanistic Target of Rapamycin Complex 1/genetics , Mechanistic Target of Rapamycin Complex 1/metabolism , Neoplasm Invasiveness/genetics , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction , Stomach Neoplasms/pathologyABSTRACT
KEY MESSAGE: This study provides a desirable candidate gene resource (SmAOC) to increase the content of valuable natural products via appropriate JA pathway genetic engineering. Jasmonates (JAs) are important signal molecules in plants. They regulate transcripts of defense and secondary biosynthetic metabolite genes in response to environmental stresses. Currently, JAs are widely used as elicitors to improve the content of useful secondary metabolism in plants. Synthesis of the naturally occurring enantiomer of various jasmonates is catalyzed by allene oxide cyclase (AOC, EC 5.3.99.6). Here, we cloned and characterized the AOC gene (SmAOC) from Salvia miltiorrhiza. As expected, SmAOC expression was induced by abiotic stimuli such as methyl jasmonate (MeJA), ultraviolet radiation (UV) and low temperature (4 °C) in S. miltiorrhiza plantlets. To demonstrate whether the engineered internal JAs pool by overexpressing AOC gene could promote secondary metabolism production, the SmAOC was incorporated into S. miltiorrhiza hairy roots. The results revealed that SmAOC overexpression significant enhanced the yields of tanshinone IIA, rosmarinic acid (RA) and lithospermic acid B (LAB) in S. miltiorrhiza hairy roots. In addition, expression levels for key genes involved in the biosynthetic pathway of diterpenes and phenolic acids were also altered. These suggest that genetic manipulation of AOC would be helpful for improving the production of valuable secondary metabolites by regulating the biosynthesis of JAs.
