Colony formation of soft tissue sarcoma cells is inhibited by lipid-mediated antisense oligodeoxynucleotides targeting the human mdm2 oncogene

More than one third of human soft tissue sarcoma (STS) have elevated levels of the MDM2 oncoprotein, resulting either from gene amplification or alter nate mechanisms. MDM2 functions as a negative feedback regulator of the tum or suppressor p53. The aim of the present study was to investigate whether mdm2-antisense oligodeoxyribonucleotides (AS-ODNs) can influence the growth characteristics of two MDM2-overexpressing STS cell lines (US8-93, LMS6-93 ) where both have heterozygous p53 non-missense mutations. Cells were treat ed with lipofectamine-complexed mdm2 AS-ODNs complementary to a sequence of the mdm2 cDNA initiation site in comparison to sense control ODNs. After s eeding and cultivation of a defined cell number the clonogenic survival was performed. The treatment of US8-93 cells with AS-ODNs, but not with sense ODNs, decreased the number of colonies up to > 80%. Western blot analysis d emonstrated a significant decreasing of MDM2 protein level in AS-ODN transf ected cells indicating an AS-specific inhibition of mdm2 transcription in U S8-93 cells. Additionally, an increase of the G2/M population was found. In contrast, in the LMS6-93 cells treated with AS-ODNs only a decrease in clo nogenic survival up to 26%, no change in MDM2 protein level and no cell cyc le alterations were seen. All these factors taken together into considerati on can be suggest that lipid-mediated mdm2 AS-ODNs could be as an effective therapeutic strategy for STS with an abnormal mdm2 overexpression. (C) 200 0 Elsevier Science Ireland Ltd. All rights reserved.