Psoralen-modified clamp-forming antisense oligonucleotides reduce cellular c-Myc protein expression and B16-F0 proliferation

AUTOR(ES)

Stewart, Delisha A.

FONTE

Oxford University Press

RESUMO

The c-myc protooncogene plays an important role in the abnormal growth pattern of melanoma cells. In an attempt to inhibit c-Myc expression and the growth of an established murine melanoma cell line, we targeted homopurine sequences within the mouse myc mRNA with modified antisense oligonucleotides (AS ODNs). Psoralen was conjugated to the 5′-end of these clamp-forming oligonucleotides (clamp ODNs). Gel mobility shift analysis demonstrated a sequence-specific interaction between the active clamp ODNs (Myc-E2C and Myc-E3C) and the 1.4 kb c-myc mRNA, but no interaction with the control clamp ODN (SCR**). This association was further confirmed by thermal denaturation studies. In vitro translation assays demonstrated that both Myc-E2C and Myc-E3C at 5 µM inhibited c-Myc expression >99% after UV activation at 366 nm. Immunostaining of B16-F0 cells with a c-Myc monoclonal antibody revealed a significant reduction in c-Myc after clamp ODN treatment compared with the untreated or SCR** control-treated cells. This result was corroborated by western blot analysis. Utilizing the MTT assay to determine the effects of ODN-mediated c-Myc reduction on B16-F0 growth, we observed 60 and 64% reductions in growth after treatment with 5 µM Myc-E3C and Myc-E2C, respectively. We attribute the enhanced effectiveness of the clamp ODNs to psoralen activation. Our preliminary data suggest that inhibiting c-Myc overexpression results in a significant reduction in abnormal proliferation of B16-F0 melanoma cells and that the increased efficiency of clamp ODNs may provide an important advantage for their use in antisense therapies.

Documentos Relacionados

• Acridine-modified, clamp-forming antisense oligonucleotides synergize with cisplatin to inhibit c-Myc expression and B16-F0 tumor progression
• Human promyelocytic leukemia HL-60 cell proliferation and c-myc protein expression are inhibited by an antisense pentadecadeoxynucleotide targeted against c-myc mRNA.
• c-myc antisense oligonucleotides inhibit the colony-forming capacity of Colo 320 colonic carcinoma cells.
• Loss of FBP function arrests cellular proliferation and extinguishes c-myc expression
• Antiproliferative effects of antisense oligonucleotides directed to the RNA of c-myc oncogene.