Antisense Oligodeoxynucleotides Targeting survivin Gene Reverse Apoptotic Resistance Induced by Cisplatin in Human Lung Adenocarcinoma Cells

Objective 　The acquisition of resistance to apoptosis is a major reason behind t reatment failures.Ectopic expression of some apoptosis related factors, such as bcl-2 family and inhibitor apoptosis family proteins ( IAPs), can result in inhibition of apoptosis induced by chemotherapy agent s and thereby confer to drug resistance in malignancies. Regulation of those gene expressions may reverse the apoptosis resistance to chemical agents. In the present study, we t ransfect cisplatin-resistant human lung adeno-carcinoma A549/ CDDP cell lines to explore whether antisense oligodeoxynucleotides (ASODN) targeting survivin gene can reverse apoptotic resistance induced by cisplatin in human lung adenocarcinoma cells. Methods 　A549/ CDDP cell lines were cultured routinely with RPMI-1640 medium. survivin ASODN mediated by cytofectin was t ransfected into the A549/ CDDP cells . The influence of ASODN t ransfection on apoptosis was determined by Diphenylamine assay(DPA), caspase-3 colorimet ric assay and flow cytometry. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay was performed to detect the cell viability, half-maximum inhibitory concent ration ( IC₅₀ ) and cisplatin resistant index ( R I) was thereby calculated, respectively. Results 　In the A549/ CDDP cells t ransfected by survivin ASODN for 48hr, the percentage of DNA f ragmentation, apoptotic index and Caspase23 activity was enhanced to (43. 55 ±6. 07) %, (34. 03 ±2. 25) % and 1. 1298 ±0. 2502, respectively ( P < 0. 05), it was obviously significant, compared to the controls. While combination with ASODN and 10μmol/ L cisplatin caused far more obvious apoptotic alterations in the cells, of which the percentage of DNA fragmentation, AI and Caspase-3 activity was reached to (76. 73 ±2. 04) %, (65. 85 ±5. 47) % and 1. 6805 ±0. 2758 ( P < 0. 05), respectively, and even compared to single ASODN group, it was still significant ( P < 0. 05) . Transfected with survivin ASODN single and with combination of cisplatin for 48hrs, the rate of cell growth inhibition in the resistant cells was enhanced to 59. 3 % and 83. 7 %, respectively( P < 0. 05), while cell viability inversely had the lowest reduction. And the half-maximum inhibitory concent ration of cisplatin was reduced from 225. 03 ±10. 59μmol/ L to 158. 84 ±4. 256μmol/ L, while the resistant index was conversely reduced from 11. 9 to 8. 39. Non-sense oligodeoxynucleotides (NSODN) and liposome had no effect on the cells ( P> 0. 05) . Conclusion 　Transfection of antisense oligodeoxynucleotides targeting survivin gene can reduce the apoptosis threshold, thereaf ter to great extent reverse apoptotic resistance induced by cisplatin in cisplatin-resistant human lung adenocarcinoma in vitro.