title: Dose-Dependent AMPK-Dependent and Independent Mechanisms of Berberine and Metformin Inhibition of mTORC1, ERK, DNA Synthesis and Proliferation in Pancreatic Cancer Cells.
abstract: Natural products represent a rich reservoir of potential small chemical molecules exhibiting anti-proliferative and chemopreventive properties. Here, we show that treatment of pancreatic ductal adenocarcinoma (PDAC) cells (PANC-1, MiaPaCa-2) with the isoquinoline alkaloid berberine (0.3-6 µM) inhibited DNA synthesis and proliferation of these cells and delay the progression of their cell cycle in G1. Berberine treatment also reduced (by 70%) the growth of MiaPaCa-2 cell growth when implanted into the flanks of nu/nu mice. Mechanistic studies revealed that berberine decreased mitochondrial membrane potential and intracellular ATP levels and induced potent AMPK activation, as shown by phosphorylation of AMPK α subunit at Thr-172 and acetyl-CoA carboxylase (ACC) at Ser79. Furthermore, berberine dose-dependently inhibited mTORC1 (phosphorylation of S6K at Thr389 and S6 at Ser240/244) and ERK activation in PDAC cells stimulated by insulin and neurotensin or fetal bovine serum. Knockdown of α1 and α2 catalytic subunit expression of AMPK reversed the inhibitory effect produced by treatment with low concentrations of berberine on mTORC1, ERK and DNA synthesis in PDAC cells. However, at higher concentrations, berberine inhibited mitogenic signaling (mTORC1 and ERK) and DNA synthesis through an AMPK-independent mechanism. Similar results were obtained with metformin used at doses that induced either modest or pronounced reductions in intracellular ATP levels, which were virtually identical to the decreases in ATP levels obtained in response to berberine. We propose that berberine and metformin inhibit mitogenic signaling in PDAC cells through dose-dependent AMPK-dependent and independent pathways.
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Ming
authors.initials: M
authors.lastname: Ming
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; CURE: Digestive Diseases Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Sinnett-Smith
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.affiliation: Division of Hematology-Oncology, Department of Medicine David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Heloisa P
authors.initials: HP
authors.lastname: Soares
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; CURE: Digestive Diseases Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Young
authors.affiliation: Department of Surgery, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; CURE: Digestive Diseases Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Guido
authors.initials: G
authors.lastname: Eibl
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; CURE: Digestive Diseases Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America; Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Enrique
authors.initials: E
authors.lastname: Rozengurt
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000230:Adenocarcinoma / Q000188:drug therapy* / Q000473:pathology; D000818:Animals; D001599:Berberine / Q000494:pharmacology*; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004261:DNA Replication / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D008687:Metformin / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors*; D009368:Neoplasm Transplantation; D009496:Neurotensin / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D014183:Transplantation, Heterologous
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin; D046912:Multiprotein Complexes; D034741:RNA, Small Interfering; D001599:Berberine; D009496:Neurotensin; D008687:Metformin; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase