Abstract: Objective To explore the therapeutic potential of antisense oligodeoxynucleotide to cyclin D1 for malignant melanoma. Methods Three 20-mers phosphorothioate oligodeoxynucleotides (ODNs) were synthesized: (1)Cyclin D₁ antisense ODN (AS-ODN) targeting the initiation site of translation in cyclin D₁ mRNA;(2)Cyclin D₁ sense ODN(S ODN) homologous to the initiation site of translation in cyclin D₁ mRNA;(3)Random ODN (R-ODN). The level of cyclin D₁ mRNA was observed by RT-PCR. The level of cyclin D₁ protein and the distribution of cell cycle progression were examined by flow cytometry. The inhibitory effect of ODN for the growth of melanoma (B₁₆) cells was observed by solid green staining and colony forming inhibitory test. Results AS ODN inhibited obviously the level of cyclin D₁ mRNA expression while S-ODN and R-ODN did not. The level of cyclin D₁ protein was significantly lower in AS-ODN treated cells than that in controls (P<0.01)but not in S-ODN and R-ODN treated cells(P>0.05). AS-ODN inhibited B₁₆ cells entering S phase from G₁ phase, however, both S-ODN and R-ODN had no such effect. Cells treated with AS-ODN, S-ODN, R-ODN displayed a colony forming inhibitory rate of 63.64%, 18.19%, and 31.82%, and a cell growth inhibitory rate of 64.73%, 26.51%, and 29.64%, respectively. Conclusion Cyclin D₁ antisense oligodeoxynucleotide has strong inhibitory effect on the growth of melanoma cells.

Key words: Melanoma, Oligodeoxynucleotide,antisense, Cyclins