1.1 Clinical sample
Serum samples were harvested from 35 CAS patients treated in the Department of Neurology of our institution from September 2018 to December 2019 and 33 healthy volunteers. All participants were informed and signed a consent form. The collected samples were immediately preserved at −80°C. Medical ethics committee had endorsed this research protocol.
1.2 Cell culture and transfection
Our team procured VSMCs and 293T cells from Chinese Academy of Sciences Cell Bank and placed them in DMEM (Invitrogen) encompassing 10% FBS and 1% Penicillin/Streptomycin (HyClone) in a moist incubator under 5% CO2, 37°C condition. ox-LDL was acquired from UnionBiol (Beijing, China). Besides, we obtained miR-1277-5p mimic (miR-1277-5p), mimic negative control (miR-con), miR-1277 inhibitor (miR-1277-5p-in), inhibitor negative control (miR-in), KLF5 siRNA (si-KLF5) or KLF5 plasmid from GenePharma. Small interfering RNA LINC01123 (si-LINC01123#1, si-LINC01123#2, si-LINC01123#3), negative control (si-NC), pcDNA3.0 (Vector), and pcDNA-LINC01123 (LINC01123) were prepared by RiboBio. Based on producer’s descriptions, lipofectamine 2000 (Invitrogen) was employed for transfecting VSMCs.
1.3 qRT-PCR
We applied TRIzol reagent (Invitrogen) for extracting total RNA from clinical specimens and cells. Our member used NanoDrop 2000 spectrophotometer (Thermo Fisher Scientific) for checking RNA concentration, PrimeScrip-RT kit (Takara) and ABI7900 system (Applied Biosystems) for generating cDNA. Next, we performed reverse transcription reaction and used GAPDH or U6 as internal control. The primer sequence were: LINC01123, F: 5'-FACAGTGGCCGCACGCATAGCTG-3', R: 5'-RCTGACGACCGAGGTGACAACGATGA-3'; miR-1277-5p, F: 5'-GCCGAGTATATATATATGTACGTAT-3', R: 5'-CTCAACTGGTGTCGTGGA-3 ’; KLF5, F: 5’-ACCTCAGCTTCCTCCAGTTC-3’, 5’-CGCATGGTCTCTGGGATTTG-3’; U6, F: 5’-CTCGCTTCGCRCAGCACA-3’, R: 5’-AACGCTTCACGAATTTGCGT-3’; GAPDH, F: 5’ -CCTGACCTGCGTGTGGACT-3', R: 5'-GCTGTGGATGGGGAGGTGTC-3'. Using 2-ΔΔCt method, the relative expression of genes was computed. We completed each experiment in triplicate and done each measurement in triplicate too.
1.4 MTT assay
Our crew seeded the transfected VSMCs into a 96-well plate comprising ox-LDL (100 mg/L) at a density of 5×103 cells per well, and incubated them at 37°C. After incubating for 12, 24, 48, 72, and 96 h, MTT (Sigma-Aldrich) was added to each well. We incubated the mixture under 37°C and 5% CO2 condition lasting 4 h, supplemented it with 150 mL DMSO and dissolved it under room temperature lasting 20 min. The absorbance value of each well was assayed at 490 nm via a microplate reader.
1.5 BrdU analysis
After seeding the transfected cells into a 96-well culture plate at a density of 2×103 cells/well, we fostered them lasting 24 h or 48 h, and incubated them with a final concentration of 10 μM BrdU (BD Pharmingen) 2 to 24 h. In the next step, we withdrew the medium, fixed the cells at room temperature lasting 30 min, incubated them with the peroxidase-conjugated anti-BrdU antibody (Sigma-Aldrich) at room temperature lasting 60 min, washed them 3 times applying PBS, and incubated them with the oxidase substrate lasting 30 min. The absorbance value was assayed at 450 nm. Background BrdU immunofluorescence was assayed in cells not exposed to BrdU but dyed with BrdU antibody.
1.6 Transwell assay
The cell migration detection was accomplished making use of a 24-well Transwell chamber (8μm pore size; BD Biosciences). About 1×105 cells were resuspended in 100 μL serum-free medium, and DMEM comprising 10% FBS was filled into the lower chamber. After incubating lasting 24 h under 37°C condition, the upper chamber was fixed in anhydrous methanol lasting 20 min, dyed applying 0.1% crystal violet lasting 20 min, then washed and dried. An inverted microscope (Nikon, Japan) was applied for measuring the number of migrating cells.
1.7 Dual Luciferase reporter experiment
The LINC01123 or KLF5 fragment encompassing the forecasted miR-1277-5p binding site, as well as the wild-type or mutant hypothetical sequence of the binding site, was subcloned into the pMiRGLO dual luciferase vector (Promega) to construct report vectors, pMiRGLO-LINC01123-wild type (LINC01123-WT), pMiRGLO-KLF5-wild type (KLF5-WT) or pMiRGLO-LINC01123-mutant (LINC01123-MUT), pMiRGLO-KLF5-mutant (KLF5-MUT). Subsequently, we applied lipofectamine 2000 for co-transfecting SNHG16-WT/KLF5-WT or LINC01123-MUT/KLF5-MUT with miR-1277-5p mimic or miR-con into 293T. After transfecting for 48 h, we measured the luciferase activity making use of dual-luciferase reporter assay system (Promega).
1.8 Western blot analysis
The total cell protein was extracted applying RIPA buffer (Pierce). The protein concentration was determined utilizing Bradford method (Pierce). The same amount of protein (40μg) was disassociated on 10% SDS-PAGE, and then transferred to a PVDF membranes (Millipore). We blocked the PVDF membrane applying 5% bovine serum albumin in TBST for 2 h at 37 ℃. Subsequently, the membrane was incubated with anti-KLF5 antibody (Abcam, ab137676, 1:500) or anti-GAPDH antibody (Abcam, ab8245, 1:3000) at 4°C nightlong. We washed the membrane 3 times adopting TBST and incubated it with goat anti-rabbit HRP (IgG) (Abcam, ab6721, 1:2000) at 37°C lasting 1 h. An enhanced chemiluminescence detection system (ECL) was adopted to visualize proteins.
1.9 Statistical Analysis
All the data were expressed as the mean±SD. Each assay was applied at least three independent experiments or replicates. Student’s t-test was utilized for analyzing the significance between groups. *P <0.05. All statistical analyses were performed by LSD post-hoc analysis employing SPSS 18.0 and GraphPad Prism 8.0 software.