Abstract: Objective: To observe the effect of sense and antisense oligodeoxynucleotides for tankyrase 1 (TANK 1-SODN and TANK 1-ASODN) on murine tumor growth and then to investigate the suppression mechanism of TANK 1-ASODN on cancer cell proliferation. Methods:Fourteen nude mice with lung cancer nodules were randomly divided into 3 groups. Multiple direct intratumoral injections of synthesized TANK1-ASODN were given for 15days. Mice treated with TANK 1-SODN and saline were used as the control groups. Tumor volume was measured and histopathological and ultrastructural characteristics of the tumor tissue were observed through microscopy and electron microscopy. SABC immunohistochemistry and in situ hybridization were used to detect the expression of hTERT telomerase protein and mRNA.Results: After15days of treatment, tumor size in the TANK1-ASODN treated group was much smaller than in the other 2 groups ( P<0.01). Electron microscopy images showed that TANK 1-ASODN had an apparent killing effect on lung cancer cells. Moreover, a statistically significant decrease in the positive expression ratio of telomerase hTERT protein and Mrna (P<0.01) was observed in the TANK1-ASODN group. Conclusion:TANK 1-ASODN can decrease the expression of hTERT, promote tumor cell degeneration and necrosis, and suppress proliferation of human lung cancer cells.