The lower right quadrant (Q3) represented the early stage apoptotic cells as (FITC+/PI-). NSCLC, we classified patients into resistant and sensitive groups based on their response to chemotherapy. Based on the clinical data of the two groups (Table 1), we found no significant differences in gender and age between the sensitive and resistant groups. However, more patients with smoking history, poor differentiation, lymph node metastasis, and II-IV TNM staging were observed in the resistant group than the sensitive group (< 0.05). According to the qRT-PCR detection of TUG1 expression level in each patient (Figure 1A), the TUG1 expression of the patients in the resistant group was significantly lower than that in the sensitive group (< 0.01). All patients were followed up for a median follow-up of 14 months. Kaplan-Meier method was used to analyze the overall survival of the NSCLC patients. The total survival time of the sensitive group (26.93 1.63 months) was significantly higher than that of the resistant group (13.48 1.17 months) (Figure 1B). Table 1 The clinical data of NSCLC patients in the resistant and sensitive groups. ItemSensitive group (n = 43)Resistant group (n = 65)valueGender0.695?Male2440?Female1925Age (years)0.879?< 602639? 601726Smoking history0.014?Yes1235?No3130Differentiation degree< 0.001?Poor1246?High/Medium3119Tumor node metatstasis0.003?Yes1543?No2822TNM staging0.006?I2418?II-IV1947 Open in a separate window Open in a separate window Figure 1 The TUG1 expression level and the intracellular localization. (A) The TUG1 expression level of NSCLC patients in the resistant and sensitive groups; (B) survival conditions of NSCLC patients in the resistant and sensitive groups; (C) expression level of TUG1 determined by qRT-PCR in NSCLC cells; (D) the intracellular localization by fluorescence hybridization in NSCLC cells. ** < 0.01. Expression level of TUG1and the intracellular localization in NSCLC cells In this study, NSCLC cell lines SPC-A1, NCI-H1650, NCI-H520 and NCI-H1299 in addition to the normal epithelial cell line 16HBE of Rp-8-Br-PET-cGMPS lung mucosa were selected. By comparing the expression of TUG1 in cells, we revealed that, SPC-A1 cells had the highest expression of TUG1 and NCI-H520 had the lowest relative to 16HBE cells (Figure 1C). So we selected these two cell lines for subsequent experiments. The effects lncRNAs exert is closely implicated in its cellular localization. LncRNAs located in the nucleus play a major role in transcriptional regulation, and lncRNAs located in the cytoplasm mainly play a role in post-transcriptional Rp-8-Br-PET-cGMPS regulation. Therefore, we isolated the nucleus and cytoplasm, and observed the intracellular localization of TUG1 by Rp-8-Br-PET-cGMPS fluorescence hybridization. Fluorescence hybridization showed that TUG1 was mainly localized in the nucleus, and a small amount was localized in the cytoplasm. CD207 The fluorescence intensity of TUG1 in drug-resistant cells was significantly weaker than that of the parental cells (Figure 1D). Overexpressed TUG1 promotes sensitivity of NSCLC cells to DDP To investigate the possible effects of lncRNA TUG1 on chemoresistance in NSCLC, SPC-A1 and H520 cells were transfected with si-TUG1 and si-NC, respectively, besides, the SPC-A1/DDP and H520/DDP cells were transfected with pcDNA-TUG1 and pcDNA3.1. The transfection efficiency of TUG1 was detected by qRT-PCR. Compared with the si-NC group, siRNAs significantly down-regulated the expression of TUG1 in SPC-A1 and H520 cell lines, with the efficiency of siTUG1-3 being the most significant. The expression of TUG1 in SPC-A1/DDP and H520/DDP cells transfected with pcDNA-TUG1 was significantly up-regulated (Figure 2A). The effect of TUG1 on the IC50 value of DDP-induced NSCLC cell line was detected by MTT assay. The IC50 values of DDP in SPC-A1/si-TUG1 or H520/si-TUG1 cells were significantly elevated, versus the si-NC group (Figure 2B, < 0.01). Conversely, IC50 values of DDP in SPC-A1/DDP/TUG1 or H520/DDP/TUG1 cells were lower than those in the si-NC group (Figure 2B, < 0.01). The results indicated that TUG1 enhanced the sensitivity to DDP in NSCLC. Through colony formation experiments, we obtained similar results. When exposed to DDP, the SPC-A1/si-TUG1 cells and H520/si-TUG1 cells displayed ability to significantly enhanced ability of forming colonies after overactivation of TUG1. Whereas, the overexpression of TUG1 reduced the ability of TUG1-SPC-A1/DDP cells and H520/DDP cells to form colonies (Figure 2C). Through scratch test and Transwell assay, we demonstrated that cell migration and invasion were enhanced after inactivation of TUG1 in SPC-A1/si-TUG1 cells and H520/si-TUG1.