Radiosensitization effect of overexpression of adenovirus-mediated SIRT6 on A549 non-small cell lung cancer cells.

OBJECTIVE: To explore the radiosensitization effect of overexpression of silent information regulator 6 (SIRT6) on A549 non-small cell lung cancer (NSCLC) cells. METHODS: Adenovirus vector Ad-SIRT6 causing overexpression of SIRT6 was established. Western blotting and MTT assay were adopted to detect the level of SIRT6 protein and the inhibitory rate of A549 cell proliferation after different concentrations of adenovirus transduction (0, 25, 100, 200, and 400 pfu/cell) for 24 h. Control group, Ad-null group and Ad-SIRT6 group were designed in this experiment and virus concentration of the latter two groups was 200 pfu/cell. Colony formation assays were employed to test survival fraction (SF) of the 3 groups after 0, 2, 4, 6, 8, 10 X-ray irradiation. Flow cytometry was used to detect the status of cell cycle of 3 groups after 48 h of 4 Gy X-ray irradiation and Western blotting was used to determine the expression of apoptosis-related genes of 3 groups after 48 h of 4 Gy X-ray irradiation. RESULTS: In the range of 25 ~ 400 pfu/cell, the inhibitory rate of A549 cell proliferation increased as adenovirus concentration raised. The inhibitory rates under the concentrations of 0, 25, 100, 200, and 400 pfu/cell were 0%, 4.23 ± 0.34%, 12.7 ± 2.57%, 22.6 ± 3.38%, 32.2 ± 3.22%, 38.7 ± 4.09% and 47.8 ± 5.58% and there were significantly differences among groups (P < .05). SF in Ad-SIRT6 group was lower than Ad-null and control groups after 4 ~ 10 Gy X-ray irradiation (P < 0.05) and the sensitization enhancement ratio (SER) was 1.35 when compared with control group. Moreover, after 48 h of 4 Gy X-ray irradiation, there appeared a significant increase in G1-phase cell proportion, up-regulated expression of the level of apoptosis-promoting genes (Bax and Cleaved caspase-3), but a obvious decline in S-phase and G2-phase cell proportion and a significant decrease of the level of apoptosis- inhibiting gene (Bal-2) in the Ad-SIRT6 group (P<0.05). CONCLUSION: The over-expression of adenovirus-mediated SIRT6, which has radiosensitization effect on A549 cells of NSCLC, can inhibit the proliferation of A549 cells and cause G0/G1 phase retardation as well as induce apoptosis of cells.

Effect of Withaferin A on A549 cellular proliferation and apoptosis in non-small cell lung cancer.

OBJECTIVE: To explore the effect of Withaferin A on A549 cellular proliferation and apoptosis in non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: NSCNC cell line A549 was selected to explore the effect of Withaferin A on A549 cellular proliferation, apoptosis and the PI3K/Akt signal pathway capable of regulating tumor biological behavior by assessment of cellular proliferation, cellular apoptotic rates and cellular cycling as well as by immuno-blotting. RESULTS: Withaferin A could inhibit A549 cellular proliferation and the control rate was dosage-dependent (P<0.05), which also increased time-dependently with the same dosage of Withaferin A (P<0.05). The apoptotic indexes in A549 cells treated with 0, 2.5, 5.0, 10.0 and 20.0 µmol·L-1 Withaferin A for 48 h were significantly different (P<0.05). In addition, the apoptotic rates of each group in both early and advanced stages were higher than those in 0 µmol·L-1 (P<0.05), which were evidently higher after 48 h than those after 24 h (P<0.05). A549 cells treated by Withaferin A for 48 h were markedly lower in Bcl-2 level and obviously higher in Bax and cleaved caspase-3 levels than those treated by 0 µmol·L-1 Withaferin A (P<0.05), and there were significant differences among 5, 10 and 20 µmol·L-1 Withaferin A (P<0.05). The ratios of A549 cells treated by Withaferin A for 48 h in G0/G1 stage were higher than those in 0 µmol·L-1 , while those in S and G2/M stages were obviously lower than those in G2/M stage, and there were significant differences in 5.0, 10.0 and 20.0 µmol·L-1 Withaferin A (P<0.05). Additionally, p-Akt/Akt values were in reverse association with dosage, and the differences were significant (P<0.05). CONCLUSION: Withaferin A can inhibit the proliferation and apoptosis of A549 cells by suppressing activation of the PI3K/Akt pathways.

[Prognostic analysis of advanced non small cell lung cancer treated by sequential chemo-radiation therapy combined with traditional Chinese medicine: a report of 54 cases].

OBJECTIVE: To evaluate the influence of fewer courses and prolonged intervals of chemotherapy on survival rate of advanced non small cell lung cancer (NSCLC) patients treated by sequential chemo-radiation therapy combined with traditional Chinese medicine (TCM). METHODS: From Jan. 2000 to Dec. 2001, 54 untreated advanced NSCLC patients (2 stage IIIa, 18 stage IIIb, 34 stage IV) were treated by sequential chemo-radiation therapy combined with TCM. The courses of chemotherapy were reduced and the intervals of chemotherapy were longer than that of the standard regimen. The efficacy and survival rate were documented and the prognostic factors were analyzed. RESULTS: Complete remission (CR) was observed in 1 case and partial remission (PR) in 20 cases. The overall objective response rate was 40.4%. Median survival was 15.3 months, 1-, 2- and 3-year survival rate were 53.7%, 28.9% and 9.6% respectively. The median survival of stage III and IV were 21.8 months and 12.5 months respectively. The 1-, 2-, and 3-year survival rates of stage III were 65.0%, 49.5%, 24.7% and that of stage IV were 47.0%, 23.3%, 0%, respectively. The quality of life was improved in most of the patients. Cox's proportional hazards regression showed that improved quality of life and treatment of TCM were the significant prognostic factors of overall survival. CONCLUSION: Chemotherapy and radiotherapy combined with TCM is beneficial to extending the interval of chemotherapy, improving the quality of life, and increasing the survival rate of advanced NSCLC patients.