| Backgroud: Hepatocellular carcinoma (HCC) is one of the most common malignanttumor of the digestive system. Since often diagnosed at an advanced stage, the5-yearrelative survival rate of HCC patients is about7%. microRNAs (miRNAs or miRs) areendogenously expressed non-coding small RNAs of about22nucleotides in length thatnegatively regulate gene expression post-transcriptionally. The relationship betweenendoplasmic reticulum(ER) stress and miRNAs becomes a research hotspot. Manystudies indicate that miRNAs can either directly regulate the ER stress response orthemselves be regulated by ER stress. Our previous study showed that human livercancer cells resisted to ER stress-induced apoptosis, as compared with human liver cells.Than we tested the miRNA expression profile of HepG2cells using miRNA array, andfound that the expression level of miR-107significantly down-regulated in HepG2cellsunder ER-stress. The expression level of miR-107is abnormal in various tumors, andinvolved in biological processes such as proliferation, apoptosis, cell cycle, invasion andmetastasis of tumor cells. This study was designed to investigate whether ER stress caneffect the expression level of miR-107in HepG2cells by PCR technology and lookedfor the effects of miR-107on resistance of HepG2cells to ER stress-induced apoptosis.Hoping to find a new strategy in the therapy of HCC.Objectives: To investigate the influence of ER-stress on the expression level of miR-107in HepG2cells and the influence of miR-107on resistance of HepG2cells toER stress-induced apoptosis.Methods:1. ER stress was induced by3μmol/L TM in HepG2cells. The expression level ofmiR-107in HepG2cells without TM treated and treated with TM for24h was tested byqRT-PCR.2. miR-107mimics and miR-107inhibitor were transfected into HepG2cells usingLipofectamine2000. The transfection efficiency was tested by fluorescence microscope24h post-transfection.3. The expression level of miR-107was detected by qRT-PCR24h post-transfection.4. The influence on cell proliferation was tested by MTT assay when the expressionlevel of miR-107was up-regulated or down-regulated in HepG2cells under ER stress.5. The influence on cell apoptosis was tested by FCM when the expression level ofmiR-107was up-regulated or down-regulated in HepG2cells under ER stress.Results:1. qRT-PCR demonstrated that the relative expression level of miR-107in TM treatedgroup was (0.39±0.05) times as much as untreated group.2. The transfection efficiencies of miR-107mimics group and miR-107inhibitor groupwere all over90%which observed by fluorescence microscope24h post-transfection.3. qRT-PCR demonstrated that the relative expression level of miR-107in miR-107mimics group and miR-107inhibitor group was respectively (72.27±3.57) and(0.07±0.02) times as much as blank control group24h post-transfection.4. MTT assay demonstrated that, the cell inhibitory rate of HepG2cells in TM andmiR-107mimics combined treatment group was significantly higher than cells treatedwith TM alone, the cell inhibitory rate of HepG2cells in TM and miR-107inhibitor combined treatment group was significantly lower than cells treated with TM alone.5. FCM demonstrated that, the cell apoptosis rate of HepG2cells in TM and miR-107mimics combined treatment group was significantly higher than cells treated with TMalone, the cell apoptosis rate of HepG2cells in TM and miR-107inhibitor combinedtreatment group was significantly lower than cells treated with TM alone.Conclusion:1. The expression level of miR-107was down-regulated in HepG2cells underER-stress.2. Up-regulation of miR-107could inhibit cell proliferation of HepG2cells andincrease cell apoptosis of HepG2cells under ER stress.3. Down-regulation of miR-107could relatively promote cell proliferation of HepG2cells and decrease cell apoptosis of HepG2cells under ER stress.4. The resistance of HepG2cells to ER stress-induced apoptosis might be linked to thedown-regulation of miR-107. |
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