OncoTargets and Therapy (Feb 2020)
Knockdown of HMGB1 Suppresses Hypoxia-Induced Mitochondrial Biogenesis in Pancreatic Cancer Cells
Abstract
Liangchun Yang,1 Fanghua Ye,1 Li Zeng,2 Yanling Li,2 Wenwen Chai2 1Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, People’s Republic of China; 2Department of Nuclear Medicine, Hunan Cancer Hospital, Changsha, Hunan 410008, People’s Republic of ChinaCorrespondence: Wenwen ChaiDepartment of Nuclear Medicine, Hunan Cancer Hospital, No. 283 Tongzipo Road, Changsha, Hunan 410008, People’s Republic of ChinaTel +86 159 7425 5021Email [email protected]: To explore the regulatory effect of HMGB1 upon hypoxia-induced mitochondrial biogenesis in pancreatic cancer PANC1/CFPAC1 cells.Methods: After a down-regulation of HMGB1 expression by lentivirus-mediated RNAi, the effect of knocking down HMGB1 on hypoxia-induced mitochondrial biogenesis was examined. NRF-1/TFAM expression, mtDNA copy number, ATP content and mitochondrial number/morphology in hypoxia-treated pancreatic cancer cells were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blot, mtDNA and ATP assay kits and electron microscopy, respectively. Cell proliferation was measured by MTS assay. And protein and acetylation levels of PGC-1α and SIRT1 activity were detected by Western blot, immunoprecipitation (IP) and SIRT1 activity kit.Results: Hypoxia enhanced the expressions of NRF-1/TFAM, boosted mtDNA copy number and ATP content and increased the number of mitochondria in pancreatic cancer cells while induction was suppressed by a knockdown of HMGB1. Knocking down HMGB1 expression lowered hypoxia-induced PGC-1α/SIRT1 expression and activity, phosphorylation of AMPK. PGC-1α over-expression by a plasmid transfection failed to boost mtDNA copy number or ATP content in HMGB1-knockdown cells. A knockdown of HMGB1 attenuated hypoxia with AICAR (an AMPK activator)-induced expression of NRF-1, TFAM, PGC-1α, SIRT1 and the proteins of complexes Ⅰ& Ⅲ and reduced the acetylation level of PGC-1α/SIRT1 activity. Additionally, SRT1720 (a SIRT1 activator)-induced elevation in SIRT1 activity boosted hypoxia-induced PGC-1α deacetylation, except in HMGB1-knockdown cells.Conclusion: As a novel regulator of mitochondrial biogenesis via AMPK/SIRT1 pathway under hypoxia, HMGB1 may become a potential drug target for therapeutic interventions in pancreatic cancer.Keywords: HMGB1, mitochondrial biogenesis, PGC-1α, AMPK/SIRT1 pathway, pancreatic cancer
