Sample collection Ten (10) fresh paired gliomas and adjacent normal brain were collected from the first Affiliated

Hospital of Jilin University, BV-6 order China, at the time of first resections before any therapy. All fresh samples were immediately preserved in liquid nitrogen. Prior consent from patients and approval from the Ethics Committees of this hospital were obtained for use of these clinical materials for research purposes. All specimens had confirmed pathological diagnosis. Real-time PCR Real-time PCR was performed to measure the expression of ECRG4 mRNA using SYBR Premix Ex Taq (Takara, Japan) with an Mx3000P real-time PCR system (Stratagene, La Jolla, CA, USA) as described previously [13]. The sequence for sense SGLT inhibitor primer was 5′- TTCCTTGGCAGCCTGAAGCG-3′, and for antisense primer was 5′- GGCTCCATGCCTAAAGCCGT-3′. GAPDH gene was used as an internal control using the sense primer 5′-GCACCGTCAAGGCTGAGAAC-3′ and antisense primer 5′-TGGTGAAGACGCCAGTGGA-3′. Construction of pECRG4-EGFP-N1 vector and Establishment of glioma U251 cell line stably expressing ECRG4 The ECRG4 open reading frame was amplified from Inhibitor Library cDNA clone IMAGE:5260075 using the forward primer 5′- ATAC GTCGACATGGCTGCCTCCCCCGCG-3′

and the reverse primer 5′-CGAT GGATCCGTAGTCATCGTAGTTGACGCT-3′ introducing SalI and BamHI restriction endonuclease sites. ECRG4 cDNA digested with SalI and BamHI was cloned into a pEGFP-N1 eukaryotic expression vector. The resulting vector was transfected into U251 cells using lipofectamine 2000 (Invitrogen, Carlsbad, CA). An “”empty”" vector pEGFP-N1 was utilized as a negative control. After 24 to

48 h, the transient transfection efficiency was determined using an Olympus fluorescence microscope. Cells were then passaged at appropriate ratios in six-well plates. The next day, cells were cultured in the presence of 1,000 to 2,000 μg/mL G418 (Life Technology) Calpain increased in a stepwise manner for 14 days for selection of highly expressing GFP cells. Total RNA of all single cell clones was isolated and quantitative RT-PCR performed to detect the mRNA level of ECRG4 as described above. Each sample was measured at least three times. Western blot analysis Approximately 5 × 106 U251 cells were lysed in RIPA Buffer and total protein concentration determined with BCA assay (Beyotime Inc, China). Total protein (30 μg) was loaded onto 12% SDS-PAGE gel. Antibodies used for Western blot analysis included: polyclonal anti-GFP antibody (Abcam, MA, USA, 1:400), NF-kB (Abcam, MA, USA, 1:400), and anti-ACTB antibody (Santa Cruz, USA, 1:400), and HRP-conjugated anti-rabbit secondary antibody (Zhongshan Inc, 1:2000). Each experiment was performed in triplicate. Cell proliferation analysis Cell growth was determined by MTT assay (Sigma, USA). Briefly, 1 × 103 cells were seeded into 96-well plate in quadruplicate for each condition.