Antisense approaches to in vitro organ culture

Comparative studies of suppression of malignant cancer cell phenotype by antisense oligo DNA and small interfering RNA

One of the distinguishing features of malignant tumor cells is the ability to proliferate in an anchorage-independent manner; methods that effectively suppress this phenotype may be applicable to the therapeutic inhibition of the malignancy of cancers. Interfering RNA is a potentially powerful tool for cancer therapy because of its specificity of target selection and remarkably high efficiency in target mRNA suppression. We studied the use of two knockdown strategies, antisense oligo DNA (AS-ODN) and small interfering RNA (siRNA), and showed how the anchorage-independent proliferation of malignant cells could be blocked efficiently. Anchorage-independent proliferation of rat fibroblasts transformed with v-src was suppressed with only a single 1-microM dose of AS-ODN; similar suppression using siRNA required treatment with 1 nM siRNA every 12 h. With our experimental system, the molecular stability of AS-ODN allowed the use of a simple treatment regimen to control the amount of the target molecule, providing that the treatment dose was sufficiently high. In comparison, siRNA treatment was effective at lower doses, but more frequent treatment was necessary to achieve the same suppression of proliferation.

Antisense oligodeoxynucleotide against HST-1/FGF-4 suppresses tumorigenicity of an orthotopic model for human germ cell tumor in nude mice

BACKGROUND

Overexpression of the fibroblast growth factor HST-1/FGF-4 gene is thought to mediate growth properties and malignancy in human testicular germ cell tumors. We have studied the effect that an antisense oligodeoxynucleotide against HST-1/FGF-4 suppresses tumorigenicity of a human germ cell tumor.

METHODS AND RESULTS

To test whether HST-1/FGF-4 could be the target of gene therapy for testicular carcinoma, 20-mer phosphorothioate oligodeoxynucleotides (ODNs) directed against human HST-1/FGF-4 were analyzed for their antitumor activity. The antisense HST-1/FGF-4 ODNs suppressed HST-1/FGF-4 production by NEC8 human nonseminomatous germ cells and inhibited their cell growth in vitro. Furthermore, after orthotopic implantation of NEC8 cells, combined treatment with antisense HST-1/FGF-4 ODNs and Atelocollagen significantly inhibited the growth of testicular tumors as well as the incidence of lymph node metastasis. In contrast, administration of antisense ODNs alone was less effective.

CONCLUSIONS

Collectively, these results indicate that the antisense method against HST-1/FGF-4 gene expression will be a novel therapeutic approach for male germ cell tumors. The use of Atelocollagen-mediated administration of the antisense HST-1/FGF-4 ODNs may be useful in enhancing the effects of antisense therapy.