Modulation of apoptosis, tumorigenesity and metastatic potential with antisense H-ras oligodeoxynucleotides in a high metastatic tumor model of hepatoma: LCI-D-20

Background/Aims: To investigate the effect of antisense H-ras DNA on tumori genesity, apoptosis and metastasis of a high metastatic tumor model of huma n hepatocellular carcinoma in nude mice LCI-D-20. Methodology: LCI-D-20 cells in primary culture were treated with 10 mu m/L antisense oligodeoxynucleotide (ODN) drugs in vitro. 1.5x10(6) LCI-D-20 cel ls with or without pretreatment were inoculated into each elevated subcutan eous (s.c.) flap in 14 nude mice, 6 animals for antisense X-ras oligodeoxyn ucleotide treated cells, 4 for H-ras non-specific antisense oligodeoxynucle otide treated cells, and the rest 4 for cells without pretreatment. Results: In in vitro cell culture study, 5-day continuous suppression of H- ras expression by antisense H-ras oligodeoxynucleotide resulted in signific ant inhibition of the proliferation of LCI-D-20 cells (t=31.529, P<0.01). I n situ end-labeling detection showed that apoptotic cell death was signific antly increased in cells with 5-day treatment of antisense H-ras oligodeoxy nucleotide (34.0+/-4.5%) in comparing with cells without treatment (2.5+/-1 .2%, t=13.434, P<0.01) or treated with non-specific antisense oligodeoxynuc leotide (4.8+/-1.4%, t=12.453, P<0.01) at the corresponding time. In the in , vivo experiment, at week 6, no palpable tumor could be found in 50% (3/6) of animals receiving cells with pretreatment of antisense H-ras oligodeoxy nucleotide, while 100% (4/4, 4/4) of animals in the 2 control groups develo ped palpable tumors. Tumor growth in antisense H-ras treated animals was si gnificantly retarded in comparison with that of the untreated (t=3.509, P<0 .01) or non-specific antisense oligodeoxynucleotide treated animals (t=3.45 2, P<0.01). 75% to 100% of animals in the 2 control groups developed lung m etastases, while in antisense H-ras treated animals lung metastasis foci co uld not be found by random serial section and microscopy (u=2.536, P<0.01; u=3.162, P<0.01, respectively). Conclusions: Specific inhibition of H-ras expression by antisense H-ras oli godeoxynucleotides could not only induce apoptotic cell death, inhibit the growth rate of LCI-D-20 cells in vitro and in vivo, but also alter in vivo tumorigenesity and metastatic potential of LCI-D-20 cells.