Autophagy inhibition mediated by MCOLN1/TRPML1 suppresses cancer metastasis via regulating a ROS-driven TP53/p53 pathway.

ABSTRACT

Compelling evidence has demonstrated that macroautophagy/autophagy plays an important role in regulating multiple steps of metastatic cascades; however, the precise role of autophagy in metastasis remains unclear. This study demonstrates that autophagy inhibition induced by MCOLN1/TRPML1 suppresses cancer metastasis by evoking the ROS-mediated TP53/p53 pathway. First, we found that MCOLN1-mediated autophagy inhibition not only profoundly inhibits both migration and invasion in malignant melanoma and glioma cell lines in vitro, but also suppresses melanoma metastasis in vivo. Second, our study reveals that autophagy inhibition induced by MCOLN1 leads to damaged mitochondria accumulation followed by large quantities of ROS release. Third, we demonstrate that the elevated ROS resulting from autophagy inhibition subsequently triggers TP53 activity, which in turn modulates expression of its downstream targets that are involved in a broad spectrum of the metastatic cascade to suppress metastasis including MMP members and TWIST. In summary, our findings have established a mechanism by which autophagy inhibition suppresses metastasis via the ROS-TP53 signaling pathway. More importantly, our study demonstrates that autophagy inhibition through stimulation of MCOLN1 could evidently be one of the therapeutic potentials for combating cancer metastasis.Abbreviations 3-MA 3-methyladenine; AA amino acid; ATG5 autophagy related 5; ATG12 autophagy-related 12; Baf-A1 bafilomycin A1; CCCP carbonyl cyanide m-chlorophenylhydrazone; CQ chloroquine; DMEM Dulbecco's Modified Eagle Medium; EMT epithelial-mesenchymal transition; FBS fetal bovine serum; GAPDH glyceraldehyde-3-phosphate dehydrogenase; HEK human embryonic kidney; LAMP1 lysosomal-associated membrane protein 1; MAP1LC3/LC3 microtubule-associated protein 1 light chain 3; MCOLN1/TRPML1 mucolipin TRP cation channel 1; MMP matrix metallopeptidase; NC negative control; NRK normal rat kidney; PBS phosphate-buffered saline; shRNA short hairpin RNA; siRNA short interfering RNA; SQSTM1/p62 sequestosome 1; ULK1 unc-51 like autophagy-activating kinase 1.