Reciprocal Regulation of AMPK-SIRT1 Complex Control of Colorectal Cancer Cell Metastasis by Metformin

Abstract Background： Liver and lung metastases of Colorectal cancer (CRC) make it as the world’s fourth most deadly cancer. AMP-activated protein kinase (AMPK) is a key cellular sensor of metabolism that regulate cellular acetylation levels through distinct mechanisms. However, the acetylation of AMPK and its contribution to regulating CRC metastasis remain poorly understood. This aim of this study was to explore the underlying relationship between AMPK acetylation and CRC metastasis. MethodsImmunoprecipitation method was used to detected the level of AMPK acetylation in clinical tumor samples and cell samples. Spleen injection model was used to detect the effect of AMPK activator Metformin on liver and lung metastasis. Co-immunoprecipitation, Western blotting, immunofluorescence, and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were conducted to investigate the complex mechanism that reciprocal regulation of AMPK-SIRT1 Complex on CRC metastasis.ResultsIn advanced stages of CRC, we observed the increased acetylation of AMPK subunit AMPKβ2. Metformin, an AMPK activator, suppressed the metastasis of HCT-116 cells in the metastasis model. Furthermore, metformin also reduced the migration and invasion of CRC cells in vitro. Mechanistic investigation revealed that metformin activated AMPK and induced the deacetylation of AMPKβ2 which was relayed through SIRT1 accumulation. Phosphorylated AMPKα increased the deacetylating activity of SIRT1 by directly phosphorylating SIRT1 at Ser47, and the elevated SIRT1 deacetylated AMPKβ2 to further increase the selective activity of AMPKα on p300 in return. Subsequently, phosphorylated SIRT1 at Ser47 was relocated to the nucleus, and reduced the transcriptional activity of NF-kB/p65 on MMP-9 by deacetylating NF-kB/p65. SIRT1 knockdown or inhibition of AMPK phosphorylation impaired AMPK self-regulatory deacetylation and the anti-metastasis effect of metformin. ConclusionsOverall, our findings provide new insights into the self-regulatory deacetylation of AMPK in inhibiting CRC metastasis and suggest that metformin has potential therapeutic application against CRC metastasis.