SIRT1 promotes EMT, migration and invasion by regulating mTORC1/4E-BP1 in colorectal cancer

Abstract Background Metastasis, rather than primary tumors, was accounted for the most cases of cancer death in colorectal cancer(CRC). The understanding of the underlying mechanism associated with tumor metastasis would improve the patient’s miserable fate. SIRT1 has been identified to play a role in tumorigenesis and progression of malignant tumors, especially in keeping the characteristics of cancer stem cells(CSCs) in CRC. This study was conducted to investigate the role of SIRT1 in the regulation of metastasis and the underlying mechanism in colorectal cancer. Methods We detected the expression of SIRT1 in 42 metastatic CRC patients. The relationship between SIRT1 and time to metastasis was also analyzed. Then the SIRT1 activity was regulated to investigate the liver metastasis in BALB/c mice. SIRT1 was knocked down to evaluate the effect on migration and invasion. Besides, exogenetic SIRT1 to assess the motile ability by wound healing assay and transwell assay. We then further explored the underlying mechanism. Results SIRT1 was overexpressed in 67% CRC metastatic patients and associated with reduced time to metastasis. High SIRT1 activity by resveratrol was companied with more liver metastasis in vivo. SIRT1 deficiency increased E-cadherin, while reduced Vimentin and Snail, attenuated migration and invasion significantly in CT26 and SW620 cells. Meanwhile, the exogenetic SIRT1 induced epithelial–mesenchymal transition (EMT) and elevated the migratory ability in SW480 cells. Further studies demonstrated that mTORC1 related genes were elevated while 4E-BP1 decayed by SIRT1 overexpression. The promotion of metastasis induced by SIRT1 overexpression could be abolished by mTOR inhibition, while the stemness of cells was not changed. Conclusions Collectively, our findings illustrated that SIRT1 was a functional regulator in the promotion of metastasis in CRC via mTORC1-4E-BP1 axis. SIRT1 was a potential independent prognostic factor of CRC metastatic patients after tumor resection, which provided a promising treatment target in CRC.