Inhibition of cell proliferation in HCC-9204 hepatoma cells by a c-myc specific ribozyme

A ribozyme (RZ) gene targeting c-myc mRNA was synthesized and cloned. Cleav age reaction showed that cleavage of the RZ was efficient and specific. The RZ gene-containing retrovirus vector pDOR-RZ was transfected into HCC-9204 hepatoma cells, which constitutively express high levels of c-myc using Li pofectamine. Positively transfected cells were selected using G418. In situ hybridization showed that both pDOR-RZ and pDOR vectors had been integrate d into the chromosome of HCC-9204 cells. Dot blot hybridization indicated t hat expression of the RZ was only evident in pDOR-RZ-transfected HCC-9204 c ells. Avidin-biotin complex enzyme-linked immunosorbent assay showed that c -myc expression was down-regulated. Chromatin aggregation into compact mass es, cytoplasmic vacuole degeneration, and blurring of cytoplasm structure w ere observed by transmission electron microscopy in HCC-9204-RZ cells. Thes e results suggest that the use of a c-myc mRNA cleaving enzyme could be mos t effective in tumor cells that are highly proliferative and constitutively express high levels of c-myc.