The absorbance was recorded on the microplate reader (ELX 800; Bio-Tek Instruments, Inc.

Winooski, VT, USA) at a 570 nm wavelength. The effect of SPARC siRNA on cell growth inhibition was assessed as percentage cell viability where vehicle treated cells were taken as 100% viable. Cell cycle analysis and annexin V staining For flow cytometric cell cycle analysis, the cells treated with siRNA were collected, washed with PBS, fixed in cold 70% ethanol, and stored at -20°C until staining. After fixation, the cells were washed with PBS and incubated with 50 μg ⁄mL RNaseA (Sigma) for 30 min at 37°C, before staining with 50 μg ⁄mL propidium iodide (Sigma). Apoptotic cells in early and late stages were detected using an annexin V-FITC Apoptosis Detection Kit from BioVision (Mountain View, CA, USA). In brief, the cells were transfected Selleckchem AP24534 with siRNA. At 96 h post-transfection, culture media and cells were collected and centrifuged. After washing, cells were resuspended in 490 μL annexin V binding buffer, followed by the addition of 5 μL annexin V-FITC and 5 μL propidium

iodide. The samples were incubated in the dark for 5 min at room temperature and analyzed using flow cytometry. Statistics Results were expressed as mean expression PD0332991 supplier levels (± SD). Student’s t-test or rank sum test were used for statistical analysis. A p-value < 0.05 was taken as level of significance (two-sided). Results Expression of SPARC in cultured gastric cancer cells We first evaluated the endogenous expression of SPARC in several human gastric cancer cell lines. We found that SPARC protein and mRNA were prevalent in MGC803 and HGC27 cells, were produced at lower levels by SGC7901 cell line were undectable in NCI-N87 and BGC823 cell lines(Figure 1). Figure 1 Expression of SPARC in gastric cancer cell lines. Tryptophan synthase A, Immunoblot analysis using a rabbit polyclonal SPARC antibody (1:500). B, Specific reverse transcriptase polymerase chain reaction (RT-PCR) analysis for SPARC. β-actin was used as loading control. C, Relative SPARC mRNA expression levels. Autoradiographs

were scanned and analyzed by densitometry followed by quantitation relative to β-actin. Results are shown as expression (in %) relative to β-actin and are means (± SD) of 3 experiments. Inhibition of endogenous SPARC expression Following this initial screening, MGC803 cells and HGC27 cells expressing relatively high endogenous SPARC were established knockdown expressing SPARC in a transient manner to determine the importance of endogenous SPARC expression. As shown in Figure 2A, SPARC expression was inhibited with SPARC siRNA transfectants in protein levels. These results suggest that these SPARC siRNAs successfully exert a silencing effect for SPARC expression. Figure 2 Effect of SPARC knockdown on cell migration in gastric cancer cell lines MGC 803 and HGC 27 cells. A.