Observation of radiobiological characteristics in a HepG2 cell line with mitochondrial DNA deletion / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the radiobiological characteristics of a HepG2 cell line with mitochondrial DNA (mtDNA) deletion.</p><p><b>METHODS</b>HepG2 cells were cultured in a medium containing ethidium bromide, acetylformic acid and uracil. The HepG2 cell line with mtDNA deletion (ρ(0)HepG2 cells) were acquired after 30 subcultures by limited dilution cloning. The cell survival was then observed in the absence of acetylformic acid and uracil, and the total mtDNA deletion in the cells was confirmed by PCR. The radiosensitivity of HepG2 and ρ(0)HepG2 cells was evaluated by exposure to gradient doses of 6 MV X ray irradiation. The cell apoptosis was assessed following a 2 Gy X-ray exposure with Hochest33342 staining, and the invasiveness of ρ(0)HepG2 cells was measured by Transwell assay.</p><p><b>RESULTS</b>HepG2 cells could survive 30 subcultures in the presence of ethidium bromide, and massive cell death occurred after removal of acetylformic acid and uracil from the medium. PCR confirmed total mtDNA deletion from ρ(0)HepG2 cells, whose α/β value was significantly lower than that of HepG2 cells. ρ(0)Hep-G2 cells showed an obviously lowered cell apoptosis rate following X-ray exposure with enhanced cell invasiveness.</p><p><b>CONCLUSION</b>HepG2 cells can be induced by ethidium bromide into ρ(0)HepG2 cells with an increased radiation resistance, anti-apoptosis ability and cell invasiveness.</p>

siRNA in silencing the expression of DNA-dependent protein kinase and its effect on radiosensitivity of lung adenocarcinoma cells / 中华放射肿瘤学杂志

Objective To discuss the role of DNA-dependent protein kinase catalytic subunit (DNA-DPKCS) in human lung adenocarcinoma cell line (A549) by using small interfering RNA (siRNA) to specifically knockdown DNA-DPKCS expression and its effects on cell proliferation, cell cycle and radio-sensitivity. Methods The DNA-DPKCS-siRNA expression vector was constructed and transfected into A549 cell line. The transformed clones were randomly selected and isolated. The cell cycle distribution and apop-tesis were analyzed by flowcytometry analysis. Cell survival was detected by using clonogenic formation as-say. Results With specific inhibition of DNA-DPKCS expression, stable transfected cell line 549pRNA-DNA-DPKCS was constructed by RNA interference technique. The 549pRNA-C and 549pSUPER cell lines were the control cell lines tansfected with control and blank plasmids, respectively. Compared with A549 cells, the expression levels of DNA-DPKCS mRNA (0.110: 1. 000), protein (0. 870: 2.967) and activity of DNA-DPKCS (0.004: 0.266) in 549pRNA-DNA-DPKCS cells were significantly lower (F = 80.55 ,P < 0.01;F=63.96, P<0.01;F=51.62,P<0.01, respectively). The analysis of SF_2(0.25:0.76), D_0 (1.42:1.62) and D_q (0.06: 1. 00) showed significant difference between 549pRNA-DNA-DPKCS and A549 cells (F = 996.86, P < 0.01 ; F = 17.41, P < 0.05 ; F = 68.92, P < 0.01). The number of 549pRNA-DNA-DPKCS cells in S (24.5%: 35.5%) and G_2 (10.7%: 11.0%) phases was significantly decreased (F = 4.83, P<0.05 and F=32.04, P <0.01, respectively). Conclusions In A549 cells, inhibit of DNA-DPKCS gene expression can enhance the radiosensitivity and affect cell cycle distribution.

Relationship between tumor differentiation and related pathologic factors in Esophago-gastric junction adenocarcinoma / 中国综合临床

Objective To investigate the relationship between the tumor differentiation and the related pathologic factors in Esophago-gastric junction adenocarcinoma. Methods The pathological data from 163 patients of Esophago-gastric junction adenocarcinoma underwent radical surgical resections were randomly divided two groups (group1: well-differentiated,group2: poor-differentiated). The composition of N stages,T stages,morphological type and vessel carcinoma embolus were compared between the two groups ,respectively. The tumor sizes and the number of metastases lymph nodes were compared between the two groups. Results The cases with lower N stages or T stages in group1 were dominant(T1 and T2:55. 74%,N1 and N2:75.41%). Oppositely,those with higher N stages or T stages were dominant(T3 and T4:59.81%,N1 and N2:57.85%)in group 2. The differences were significant Incidence of vessel carcinoma embolus was 44. 26%(27/61)in group 1 and 63. 73%(65/102)in group 2,with a significant difference. There was no significant difference for morphological type in the two groups. The tumor sizes and the number of metastases lymph was 4. 27 ±2. 00 cm and 4. 15 ±5.27 respectively in group 1 ,and 5. 87 ± 3. 26 cm and 8. 80 ± 7.65 respectively in group 2. The differences were significantly different(Ps ＜ 0. 01).Conclusions The tumor differentiation has significant effect on N stages,T stages,vessel carcinoma embolus,tumor size and the number of metastases lymph nodes in Esophago-gastric junction adenocarcinoma.