title: Inhibition of MEK/ERK activation attenuates autophagy and potentiates pemetrexed-induced activity against HepG2 hepatocellular carcinoma cells.
abstract: Identification of efficient chemo-therapeutic/chemo-preventive agents for treatment of hepatocellular carcinoma (HCC) is important. In this study, we examined the activity of pemetrexed, an anti-folate chemotherapy drug, against HepG2 human HCC cells. Pemetrexed treatment in vitro exerted weak but significant cytotoxic activity against HepG2 cells. When analyzing the possible pemetrexed-resistance factors, we indentified that pemetrexed treatment in HepG2 cells induced cyto-protective autophagy activation, evidenced by GFP-light chain 3B (LC3B) puncta formation, p62 downregulation and Beclin-1/LC3B-II upregulation. Correspondingly, autophagy inhibitors, including bafliomycin A1, 3-methyladenine and chloroquine, enhanced pemetrexed-induced cytotoxicity against HepG2 cells. Further, RNAi-mediated knockdown of Beclin-1 in HepG2 cells also increased pemetrexed sensitivity. Pemetrexed activated MEK (mitogen-activated protein kinase/ERK kinase)/ERK (extracellular-signal-regulated kinase) signaling in HepG2 cells, which was required for autophagy induction. Pharmacological inhibition of MEK/ERK activation attenuated pemetrexed-induced autophagy, enhanced HepG2 cell death and apoptosis. In summary, pemetrexed activates MEK/ERK-dependent cyto-protective autophagy, and inhibition of this pathway potentiates pemetrexed's activity in HepG2 cells.
authors.affiliation: Department of Infectious Disease, Zhejiang Province People's Hospital, Hangzhou, China. Electronic address: tongyongxi75@2980.com.
authors.forename: Yongxi
authors.initials: Y
authors.lastname: Tong
authors.affiliation: Department of Infectious Disease, Zhejiang Province People's Hospital, Hangzhou, China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Infectious Disease, Zhejiang Province People's Hospital, Hangzhou, China. Electronic address: panhongyinghz@126.com.
authors.forename: Hongying
authors.initials: H
authors.lastname: Pan
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy; D000071186:Beclin-1; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death; D002470:Cell Survival; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005971:Glutamates / Q000494:pharmacology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D000068437:Pemetrexed; D034622:RNA Interference; D015398:Signal Transduction
chemical_list: D000964:Antimetabolites, Antineoplastic; D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D005971:Glutamates; D008565:Membrane Proteins; D000068437:Pemetrexed; D049452:Green Fluorescent Proteins; D006147:Guanine; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases
keywords: Autophagy; Chemo-sensitization; Hepatocellular carcinoma (HCC); MEK/ERK signaling; Pemetrexed