[Effect of dihydroartemisinin combined irradiation on the apoptosis of human lung cancer GLC-82 cells and its mechanism study].

OBJECTIVE: To study the effect of dihydroartemisinin (DHA) combined irradiation on the apoptosis of human lung cancer GLC-82 cells and to study its mechanism. METHODS: The growth inhibition rate of GLC-82 cells acted by different concentrations DHA was detected using MTT assay at 24, 48, and 72 h, respectively. Clone forming test was used. With multi-target single-hit model, the radiosensitization effect was assessed by calculating sensitizing enhancement ratio (SER).The effect of DHA combined irradiation on the apoptosis of GLC-82 cell cycle distribution and apoptosis were measured by flow cytometry. The protein expression of p53, p21, Bcl-2, and Bax were detected by Western blot. RESULTS: Different concentrations DHA (4, 8, 16, 32, 64, and 128 µg/mL) had cytotoxicity on GLC-82 cells. The IC50 for 24, 48, and 72 h was 38.25,20.58, and 10.36 µg/mL, respectively, in obvious dose- and time-dependent manner. The growth inhibition rate was more significantly increased than that of the blank control group (P < 0.01, P<0.05). DHA had sensitization enhancement effect on GLC-82 cells, with SER of 1.4. DHA combined irradiation could obviously change the structure of GLC-82 cells cell cycle and induce apoptosis (with the apoptosis rate of 21.5%), which was significantly different from that of the blank control group (P < 0.05). Western blot showed the expression of p53 and p21 protein could be increased by DHA combined irradiation, and the expression of Bcl-2 protein down-regulated (P <0.01, P <0. 05). CONCLUSIONS: DHA had stronger cytotoxicity and radiosensitization on GLC-82 cells. Its mechanisms might lie in making the arrest of GLC-82 cells' growth at G0/G1 phase, decreasing the ratio of cells at S phase, restoring the function of p53, decreasing the expression of Bcl-2 protein, and inducing apoptosis in GLC-82 cells.

Circ_0017639 facilitates proliferative, migratory, and invasive potential of non-small cell lung cancer (NSCLC) cells via PI3K/AKT signaling pathway.

Non-small cell lung cancer (NSCLC) has increased morbidity and mortality rate worldwide. The current NSCLS therapies are associated with poor outcomes and need further improvement. CircRNAs were shown to regulate NSCLC progression. However, little is known re garding the functions and mechanisms of circ_0017639 in NSCLC, which requires further extensive studies. The circ_0017639 expression in NSCLC tissues and cell lines was evaluated via qRT-RCR. Moreover, using ectopic plasmid incorporation and shRNA assays, we analyzed the circ_0017639-mediated cellular proliferative, migratory and invasive processes in NSCLC cell lines, using CCK-8, EdU, and transwell assays. Furthermore, the core proteins (p-PI3K, PI3K, p-AKT, and AKT) levels of the PI3K/AKT signaling cascade were investigated via immunoblotting. Finally, we tested the functional role of circ_0017639 by examining its regulation of xenograft tumor growths in nude mice in vivo. Circ_0017639 expression was remarkably high in the NSCLC tissues and cell lines. The transfection experiments showed that circ_0017639 overexpression was able to promote proliferative, migratory, and invasive properties of NSCLC cells, while sh-circ_0017639 showed opposing effects. We further showed that circ_0017639 knockdown suppressed the cellular development via PI3K/AKT cascade inactivation. Additionally, in-vivo experiment in nude mice demonstrated that sh-circ_0017639 could reduce the tumor growth of NSCLC. Circ_0017639 may promote the development of NSCLC by accelerating NSCLC metastasis through stimulating the PI3K/AKT cascade.