Importantly, we show that nucleolin and TBX3 require each other to induce sarcoma cell proliferation and migration

Importantly, we show that nucleolin and TBX3 require each other to induce sarcoma cell proliferation and migration. TBX3 interact in chondrosarcoma, liposarcoma and rhabdomyosarcoma cells where they act together to enhance proliferation and migration and regulate a common set of tumor suppressor genes. Importantly, the nucleolin targeting aptamer, AS1411, exhibits selective anti-cancer activity in these cells and mislocalizes TBX3 and nucleolin to the cytoplasm which correlates with the re-expression of the TBX3/nucleolin target tumor suppressors (p21CIP1) and (p14ARF). Our findings provide the first evidence that TBX3 requires nucleolin to promote features of sarcomagenesis and that disruption of the oncogenic TBX3-nucleolin interaction by AS1411 may be a novel approach for treating sarcomas. (QT00046046; Qiagen, USA) genes. qRT-PCR was conducted using the StepOnePlus? Real-Time PCR system (Applied Biosystems). PCR cycle parameters SPP were denaturation for 15 min at 95C and combined annealing and extension for 35 cycles at 60C for 1 min. Samples were prepared and quantified in triplicate and non-template controls were included in each run to detect nonspecific amplification or the presence of contamination. The results were analysed using the 2-Ct method SPP and relative and expression levels were normalised to KPNA3 mRNA levels of (GUSB). Proliferation assay Short-term growth was measured as described previously [36]. Briefly, cells were seeded in triplicate in 12-well or 24-well plates at densities of 2104 cells/mL, 1104 cells/mL or 2105 cells/mL for SW1353, RD and SW872 cells, respectively. Cells were collected by trypsinization at 48-72-hour intervals and counted on a haemocytometer as described previously [36]. As an alternative assay for proliferation, cell viability was quantified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Cell Proliferation Kit (Roche, Germany) according to the manufacturers instructions. Briefly, cells were seeded in quadruplicate in SPP a 96-well plate (1000 cells/well) and cell viability determined over 96 h. Absorbance (595 nm) was determined and the absorbance of the medium only control was subtracted from the samples. At least three independent experiments were performed in quadruplicate, from which the half maximal inhibitory concentration (IC50) was calculated using GraphPad Prism version 6.0 (GraphPad Software, USA). In vitro cell migration assays Cell migration was assessed using a 2-dimensional in vitro scratch motility assay, which has been described in detail previously [34]. Images of the wound were taken over time using a phase contrast microscope and migration areas were calculated using ImageJ software (National Institutes of Health, Bethesda, MD). Subcellular fractionation Nuclear and cytoplasmic extracts were prepared from sub-confluent SW1353 chondrosarcoma cells in 10 cm cell culture dishes. Briefly, cells were washed twice in cold 1 PBS, harvested in cold 1 PBS by scraping and pelleted at SPP 5000 g for 3 min at 4C. The cell pellet was resuspended in 5 volumes of solution 1 (20 mM PIPES pH 6.8, 1 mM EGTA pH 6.8, 1 mM MgCl2) plus protease inhibitors and the cells allowed to swell on ice for 5 min, then 0.5% Triton X-100 was added to lyse the cell membranes and left to incubate for further 5 min. The cells were centrifuged at 900 g and the cytosolic fraction (supernatant) was transferred to fresh tubes and stored at -80C. The pellet was washed in 5 volumes of solution 1 with protease inhibitors and centrifuged at 900 g. The supernatant was discarded and the cell nuclei (pellet) lysed in 5 volumes of solution 2 (100 mM KCl, 300 mM sucrose, 10 mM PIPES pH 6.8, 1 mM EGTA pH 6.8, 3 mM MgCl2) with protease inhibitors and RNASE-free DNASE (100 g/ml) at 30C for 45 mins followed by centrifugation at 1500 g for 5 min at 4C. The nuclear extract (supernatant) was transferred to fresh tubes and stored at -80C. SPP Protein concentration was assayed by BCA assay (Pierce, USA) with bovine serum albumin as the standard. Immunoprecipitation assay FLAG-Tbx3 or FLAG-Empty cells were plated in 15 cm tissue culture dishes at 90% confluence. Cells were lysed in 150 mM lysis buffer [50 mM Tris HCl (pH 7.4), 150 mM NaCl, 1 mM EDTA, 1% TRITON X-100, 10 mM NaF, 0.2 mM PMSF, 0.7 g/ml pepstatin A, 2 g/ml aprotinin, 2 mM NaF, 0.01 mM sodium orthovanadate, 2 complete proteinase inhibitor tablets (Roche, Germany)] and cell extracts were centrifuged at 12000 rpm for 20 min at 4C to remove cellular debris, The supernatant was incubated with anti-Flag antibody conjugated to agarose beads (anti-Flag M2 affinity gel, A2220, Sigma Aldrich, USA) with constant rotation.