Melatonin attenuates cisplatin-induced HepG2 cell death via the regulation of mTOR and ERCC1 expressions

AIM:To elucidate the effects of melatonin on cisplatininduced hepatocellular carcinoma(HepG2) cell death and to identify potential cross-talk pathways.METHODS:Hepatocellular carcinoma HepG2 cells were treated with melatonin and/or cisplatin for 24 to 48 h.Cell viability and the 50% cytotoxic concentration(CC50) were calculated by MTT assays.The effects and intracellular events induced by the selected concentrations of melatonin(1 mmol/L) and cisplatin(20 μmol/L) were investigated.Cell death and survival detection were primarily evaluated using a fluorescence microscope to assess 4',6 diamideno-2-phenylindol DNA staining and acridine orange lysosome staining and then further analyzed with immunocytochemistry using an anti-LC3 antibody.The potential molecularresponses mediated by melatonin against cisplatin after the combined treatment were investigated by reverse transcription-polymerase chains reaction and Western blot analyses of the genes and proteins associated with cell survival and death.A cell cycle analysis was performed using a flow cytometry assay.RESULTS:Melatonin had a concentration-dependent effect on HepG2 cell viability.At 1 mmol/L,melatonin significantly increased the cell viability percentage and decreased reactive oxygen species production due to cisplatin.Melatonin reduced cisplatin-induced cell death,decreasing phosphorylated p53 apoptotic protein,cleaved caspase 3 and Bax levels but increasing anti-apoptotic Bcl-2 gene and protein expression.When combined with cisplatin,melatonin induced S phase(DNA synthesis) cell cycle arrest and promoted autophagic events in HepG2 cells.Melatonin also had a concentration-dependent effect on Beclin-1 and its autophagic regulator mammalian target of rapamycin(mTOR) as well as the DNA excision repair cross complementary 1(ERCC1) protein.The expression levels of these proteins were altered in HepG2 cells during cisplatin or melatonin treatment alone.In the combination treatment,melatonin reversed the effects of cisplatin by suppressing the over-expression of mTOR and ERCC 1 and enhancing the expression levels of Beclin-1 and microtubule-associated protein-light chain3-Ⅱ,leading to intracellular autophagosome progression.CONCLUSION:Melatonin attenuated cisplatin-induced cell death in HepG2 cells via a counter-balance between the roles of apoptotic- and autophagy-related proteins.

Common molecular subtypes among Asian hepatocellular carcinoma and cholangiocarcinoma

Objective:Intrahepatic cholangiocarcinoma(ICC)and hepatocellular carcinoma(HCC)are clinically disparate primary liver cancers with etiological and biological heterogeneity.In Thailand,both cancer types represent the primary cause of cancer-related deaths and are a major public health concern.

Kaemtakols A-D,highly oxidized pimarane diterpenoids with potent anti-inflammatory activity from Kaempferia takensis

Four highly oxidized pimarane diterpenoids were isolated from Kaempferia takensis rhizomes.Kaemtakols A-C pos-sess a tetracyclic ring with either a fused tetrahydropyran or tetrahydrofuran motif.Kaemtakol D has an unusual rearranged A/B ring spiro-bridged pimarane framework with a C-10 spirocyclic junction and an adjacent 1-methyltri-cyclo[3.2.1.02,7]octene ring.Structural characterization was achieved using spectroscopic analysis,DP4+and ECD calculations,as well as X-ray crystallography,and their putative biosynthetic pathways have been proposed.Kaemtakol B showed significant potency in inhibiting nitric oxide production with an IC50 value of 0.69μM.Molecular docking provided some perspectives on the action of kaemtakol B on iNOS protein.

Tungstophosphoric acid catalyzed synthesis of N-sulfonyl-1,2,3,4-tetrahydroisoquinoline analogs

An operationally simple and eco-friendly protocol has been developed for the synthesis of N-sulfonyl- 1,2,3,4-tetrahydroisoquinolines 3 using the modified Pictet-Spengler reaction of N-sulfonylphenylethy- lamines 1 and various aldehydes 2 in the presence of tungstophosphoric acid hydrate.