C-myc Gene Expression In Sharp Inhibition Led To Terminal Differentiation And Apoptosis Of Human Esophageal Cancer Cell Lines

It is widely accepted that c-myc gene plays a pivotal role in regulating cell proliferation and differentiation. Almost in every fast proliferating cell, whatever normal or malignant, one can see active expression of this oncogene. In contrast, c-myc barely expresses in quiescent or well differentiated cells. C-myc is an immediate early response gene whose oncoprotein is a trans-acting factor and located in nucleus. Some studies indicated that c-myc gene has a close relationship with carcinogenesis.Antisense RNA that binds specifically with its sense counterpart can selectively neutralize the functions of an interested gene. It is an efficient tool to precisely inhibit the overexpression of a dominant oncogene in tumor cells. Hence, reducing the expression level of c-myc by antisense technique may effectively suppress the proliferation and malignant phenotype of cancer cells.A retroviral vector, called pDOR-BD9 containing the neomycin resistant gene and the human c-myc antisense fragment, including part of the first intron, the second exon and first 3 base pairs of the second intron, total of 1.53kb of c-myc proto-oncogene was constructed.pDOR-BD9 was introduced into PA317 amphotropic packaging cells by lipofectin. G418-resistant clones with high virus producing titer (10° CFU/ml) were isolated. Retrovirus-like vircsomes in diameter of 90 nm were also found in culture fluid of the PA317 clones by electron microscopy. Southern blot analysis confirmed the presence of the antisense c-myc insert. The virus stock can be concentrated 100 times and stored at -80℃. It can be freeze-thawed several times with no apparent decrease of activity for a long period.A human esophageal cancer cell line EC8712 was infected with this recombinant retrovirus(moi-1:1). The infected G418-resistant EC8712...