New NCI-N87-derived human gastric epithelial line after human telomerase catalytic subunit over-expression

AIM:To establish a cellular model correctly mimicking the gastric epithelium to overcome the limitation in the study of Helicobacter pylori(H.pylori) infection.METHODS:Aiming to overcome this limitation,clones of the heterogenic cancer-derived NCI-N87 cell line were isolated,by stably-transducing it with the human telomerase reverse-transcriptase(h TERT) catalytic subunit gene.The clones were first characterized regarding their cell growth pattern and phenotype.For that we measured the clones' adherence properties,expression of cell-cell junctions' markers(ZO-1 and E-cadherin) and ability to generate a sustained transepithelial electrical resistance.The gastric properties of the clones,concerning expression of mucins,zymogens and glycan contents,were then evaluated by haematoxylin and eosin staining,Periodic acid Schiff(PAS) and PAS/Alcian Blue-staining,immunocytochemistry and Western blot.In addition,we assessed the usefulness of the h TERT-expressing gastric cell line for H.pylori research,by performing co-culture assays and measuring the IL-8 secretion,by ELISA,upon infection with two H.pylori strains differing in virulence.RESULTS:Compared with the parental cell line,themost promising NCI-hT ERT-derived clones(CL5 and CL6) were composed of cells with homogenous phenotype,presented higher relative telomerase activities,better adhesion properties,ability to be maintained in culture for longer periods after confluency,and were more efficient in PAS-reactive mucins secretion.Both clones were shown to produce high amounts of MUC1,MUC2 and MUC13.NCI-hT ERT-CL5 mucins were shown to be decorated with blood group H type 2(BG-H),Lewis-x(Lex),Ley and Lea and,in a less extent,with BG-A antigens,but the former two antigens were not detected in the NCI-h TERT-CL6.None of the clones exhibited detectable levels of MUC6 nor sialylated Lex and Lea glycans.Entailing good gastric properties,both NCIhT ERT-clones were found to produce pepsinogen-5 and human gastric lipase.The progenitor-like phenotype of NCI-hT ERT-CL6 cells was highlighted by large nuclei and by the apical vesicular-like distribution of mucin 5AC and Pg5,supporting the accumulation of mucus-secreting and zymogens-chief mature cells functions.CONCLUSION:These traits,in addition to resistance to microaerobic conditions and good responsiveness to H.pylori co-culture,in a strain virulence-dependent manner,make the NCI-hT ERT-CL6 a promising model for future in vitro studies.

Biotransformation of malabaricone C by rat hepatic microsomes and cytotoxic activities against gastric cancer cells in vitro

Malabaricone C （1）, isolated from the seeds ofMyristicafragrans Houtt., belongs to a kind of diarylnonanoid compounds that are only found in Myristicaceae till now. In this study, biotransformation of 1 was investigated using rat hepatic microsomes for the first time and the main biotransformation product was elucidated as malabaricone B （2） according to the spectroscopic data. Further evaluation on human gastric cancer cell lines showed that the cytotoxic effects of malabaricone C and its metabolite malabaricone B were comparable to those of vinorelbine, with the values of IC50 of （42.62±3.10） and （19.80±1.70） μg/mL on NCI-N87, and （22.94±1.33） and （19.60±2.21） μg/mL on MGC803, respectively. Statistical analysis revealed that malabaricone B had significantly stronger cytotoxicity than the parent compound （P〈0.01 on NCI-N87 and P〈0.05 on MGC803）, which may indicate a bioactivation of malabaricone C by hepatic microsomes. These results suggest that malabaricone C has a simple biotransformation pathway by hepatic microsomes and provide valuable information for further investigation on both the parent compound and its biotransformation product as anti-gastric cancer agents or lead compounds.