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Objective@#To explore the impact of arsenic on cholesterol efflux and the expression of ATP-binding cassette, sub-family A, member 1 ( ABCA1 ), ATP-binding cassette transporter G1 ( ABCG1 ), and scavenger receptor class B member I ( SRBI ) in macrophages, so as to provide the evidence for the mechanism of arsenic induced atherosclerosis.@*Methods@#The human myeloid leukemia mononuclear cells ( THP-1 ), induced by phorbol myristate acetate, and mouse primary macrophages were treated with 0, 0.625, 1.25, 2.5 and 5 μmol/L NaAsO2 for 48 hours. Then the cells treated with 2.5 μmol/L NaAsO2 were changed to arsenic free mediums for 48 hours and collected every 12 hours to analyze the time effect of arsenic. The expression levels of ABCA1, ABCG1 and SRBI were determined by quantitative polymerase chain reaction and western blotting. Cholesterol efflux rates were measured by 3H isotope tracer. @*Results@#Arsenic significantly down-regulated the expression levels of ABCA1 and ABCG1, and cholesterol efflux in a dose-dependent manner. The levels of ABCA1 mRNA decreased by 69% and 72%, the levels of ABCG1 mRNA decreased by 42% and 34%, and the rate of cholesterol efflux decreased by 55% and 59% in THP-1 and mouse primary macrophages cells treated with 5 μmol/L NaAsO2 ( all P<0.05 ). Arsenic had no significant effect on SRBI expression ( all P>0.05 ). Arsenic inhibited ABCA1 expression and cholesterol efflux in THP-1 in a time-dependent manner. Compared with cells before the exposure of arsenic, the level of ABCA1 mRNA and the rate of cholesterol efflux in THP-1 bottomed at 48 hours by 43% and 42%, and gradually recovered when arsenic was removed. @*Conclusions@#Arsenic inhibits cholesterol efflux by down-regulating the expression of ABCA1 and ABCG1 in macrophages.
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Objective: To investigate the effects of ABC-binding cassette transporter A subfamily 8 (ABCA8) on the migration and invasion of pancreatic cancer cells and the possible mechanism. Methods: Human pancreatic cancer CFPAC-1 cells were infected with the lentivirus GV358 carrying ABCA 8 gene or the empty vector lentivirus to establish ABCA8 overexpression cells or the control cells, respectively. The ABCA8 overexpression was confirmed by real-time fluorescent quantitative PCR and Western blotting. The effects of ABCA8 overexpression on the migration and invasion of CFPAC-1 cells were analyzed by wound healing assay and Transwell assay, respectively. The expression levels of extracellular signal-regulated kinase (ERK) and phospho-ERK (p-ERK) in ABCA8-overexpressed CFPAC-1 cells were detected by Western blotting. The effects of inhibiting ERK signaling by SCH772984 on ABCA8-mediated migration and invasion of CFPAC-1 cells were detected by Transwell assay. The expression levels of matrix metalloproteinases 2 (MMP2), MMP7, MMP9 and tissue inhibitor of metalloproteinase 1 (TIMP1) mRNAs in ABCA8-overexpressed CFPAC-1 cells were detected by real-time fluorescent quantitative PCR, and the expression levels of MMP7 and TIMP1 mRNAs in ABCA8-overexpressed CFPAC-1 cells treated with SCH772984 were detected by real-time fluorescent quantitative PCR. Results: ABCA8-overexpressed CFPAC-1 cells were successfully established. ABCA8 overexpression significantly promoted the migration (P 0.01) and invasion (P 0.05) of CFPAC-1 cells. The expression level of p-ERK protein was significantly elevated in ABCA8-overexpressed CFPAC-1 cells (P 0.01), and ERK inhibitor SCH772984 could eliminate the changes of ABCA8-induced migration and invasion of CFPAC-1 cells (both P 0.05). Meanwhile, ABCA8 overexpression could significantly upregulate MMP7 expression level (P 0.001) and downregulate TIMP1 expression level (P 0.01) in CFPAC-1 cells, and ERK inhibitor SCH772984 could eliminate the changes of MMP7 and TIMP1 expression levels induced by ABCA8 overexpression (both P 0.05). Conclusion: ABCA8-induced ERK signaling activation can enhance the migratory and invasive properties of human pancreatic cancer cells, which may be related to the upregulation of MMP7 expression and the downregulation of TIMP1 expression.