Decreased DEPTOR expression is involved in enhanced cell motility and invasion capability of ASS1 (Argininosuccinate synthetase 1) -KO cells

To elucidate the mechanisms underlying the enhanced sensitivity to arginine in the absence of ASS1 expression in endometrial cancer cells, we performed DNA microarray-based gene expression profiling using HEC1B harboring the empty vector (EV) and ASS1-knockout (KO) HEC1B cells. Since accumulating evidence has shown that arginine regulates mTORC1 activity, we focused on the expression patterns of genes related to the mTOR complex. ASS1-KO HEC1B cells had lower DEPTOR transcript abundance than EV cells, while no significant difference was observed in the expression levels of genes coding for other mTOR complex components such as mTOR, RAPTOR, or RICTOR. Indeed, immunoblot analysis confirmed that the expression level of DEPTOR protein was significantly decreased in ASS1-KO HEC1B cells, which were cultured in arginine-replete conditions. The labeled cRNAs were hybridized on a Whole Human Genome Oligo Microarray ver. 2 (G4845A) in two dye swap experiments, resulting in four individual microarrays.