Effect of dihydroartemisinin combined irradiation on the apoptosis of human lung cancer GLC-82 cells and its mechanism study / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To study the effect of dihydroartemisinin (DHA) combined irradiation on the apoptosis of human lung cancer GLC-82 cells and to study its mechanism.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSIONS</b>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.</p>

The zinc uptake regulator Zur is essential for the full virulence of Xanthomonas campestris pv. campestris.

Zur is a regulator of the high-affinity zinc uptake system in many bacteria. In Xanthomonas campestris pv. campestris 8004, a putative protein encoded by the open reading frame designated as XC1430 shows 42% amino acid similarity with the Zur of Escherichia coli. An XC1430-disrupted mutant 1430nk was constructed by homologous suicide plasmid integration. 1430nk failed to grow in rich medium supplemented with Zn2+ at a concentration of 400 microM and in nonrich medium supplemented with Zn2+ at a concentration of 110 microM, whereas the wild-type strain grew well in the same conditions. In rich medium with 400 microM Zn2+, 1430nk accumulated significantly more Zn2+ than the wild-type strain. 1430nk showed a reduction in virulence on the host plant Chinese radish (Raphanus sativus L. var. radiculus Pers.) and produced less extracellular polysaccharide (EPS) than did the wild-type strain in the absence of added zinc. These results revealed that XC1430 is a functional member of the Zur regulator family that controls zinc homeostasis, EPS production, and virulence in X. campestris pv. campestris.