Photodynamic antisense regulation of human cervical carcinoma cell growth using psoralen-conjugated oligo(nucleoside phosphorothioate).

The antisense strategy has been applied to regulate gene expression in a sequence specific manner, which enables suppression of the proliferation of cancer cells and exploration of the functions of unknown genes. In order to generalize and to enhance the ability of the strategy, functionalization of antisense DNAs was done using a photo-crosslinking reagent, 4,5',8-trimethylpsoralen, and the possibility of photodynamic antisense regulation of gene expression was examined. Psoralen-conjugated oligo(nucleoside phosphorothioate)s (Ps-S-oligo) were prepared and used to inhibit the proliferation of human cervical carcinoma cells. Upon UVA irradiation of Ps-S-oligo treated cells, Ps-S-oligo complementary to the initiation codon region (Ps-P-As) of HPV18-E6*-mRNA of human cervical carcinoma cells inhibited drastically the cell growth (IC(50)=16 nM). In contrast, Ps-S-oligo with mismatched sequences and scrambled one showed lesser inhibitory effects than Ps-P-As. These results showed that the inhibition by Ps-S-oligo was dependent on (a) sequence, (b) UVA irradiation, (c) concentration and (d) cell line. The amount of intact HPV18-E6*-mRNA was decreased in a sequence dependent manner, indicating that the antiproliferative effect of Ps-P-As was an antisense manner. The psoralen-conjugated antisense DNA has significant potential to regulate gene expression, which may provide useful information to explore the novel gene regulating reagents.