Abstract: Objective To study the effect of inhibition of human lung carcinoma-associated antigen gene (ALT04-AG) expression on the growth characteristic and associated gene expression of human lung carcinoma cells (L78). Methods L78 cells were transfected with recombinant plasmid vector expressing ALT04-AG antisense RNA mediated by liposome reagent, and treated with DFMO, respectively. The growth characteristics were studied by MTT, FCM analysis. The associated gene expression was detected by immunocytochemical staining，Northern blot and gene chip analysis. Results The recombinant plasmid expressing ALT04-AG antisense RNA（ pALT04-AG(as)） constructed. It was shown that down-regulation of ALT04-AG gene expression was observed not only in pALT04-AG(as) transfected L78 cells, but also did in DFMO-treated L78 cells, sequentially resulted in growth inhibition of these cells. Gene chip analysis indicated that inhibition of ALT04-AG gene expression by ALT04-AG antisense RNA could regulate some proliferation associated gene expression, while inhibition of polyamine biosynthesis by DFMO could regulate proliferation associated genes and also some apoptosis associated genes. Conclusions It is suggested that human lung carcinoma associated antigen gene ALT04-AG plays an essential role in maintaining malignant phenotype of cancer cells. The inhibition of ALT04-AG gene expression of L78 cells either by pALT04-AG(as) transfection or by polyamine biosynthesis inhibition with DFMO could promote the reversion of malignant phenotype of cancer cells, but the effect of treatment with DFMO on tumor-associated gene expression regulation is widespread than that of pALT04-AG(as) transfection. These results provide a significant clue to search new target for diagnosis and therapy of cancer.