Reduction of c-myc expression by an antisense approach under Cre/loxP switching induces apoptosis in human liver cancer cells

Citation
H. Ebinuma et al., Reduction of c-myc expression by an antisense approach under Cre/loxP switching induces apoptosis in human liver cancer cells, J CELL PHYS, 188(1), 2001, pp. 56-66
Citations number
61
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF CELLULAR PHYSIOLOGY
ISSN journal
0021-9541 → ACNP
Volume
188
Issue
1
Year of publication
2001
Pages
56 - 66
Database
ISI
SICI code
0021-9541(200107)188:1<56:ROCEBA>2.0.ZU;2-S
Abstract
c-Myc has been documented to be both a positive and a negative signal for t he induction of apoptosis. It is well known that overexpression of the c-my c gene induces apoptosis of normal cells, but the result of a reduction in its expression is not fully understood. We examined whether a reduction in c-myc expression would induce apoptosis in human liver cancer cells. Specif ically, antisense and sense oligodeoxynucleotides (oligos) against the huma n c-myc mRNA were synthesized, mixed with a liposome reagent at various rat ios, and were applied to the liver cancer-derived cell lines, HCC-T, HepG2, and PLC/PRF/5. To exclude effects resulting from using oligos, plasmid vec tors expressing the full-length c-myc cDNA in both sense and antisense orie ntations under the control of the Cre/IoxP system were generated. Monoclona l cell lines including these plasmid vectors were produced and Cre was supp lied by adenovirus infection. Apoptosis was determined morphologically and c-Myc and Bcl-2 expression was examined by Western blotting. The antisense myc significantly inhibited the proliferation of the cells within two days, while neither the liposome reagent alone nor sense myc did so. Most of the cells were rounded up by the antisense-treatment and nuclear fragmentation and DNA ladder formation were detected after two days in antisense c-myc-t reated cells. Antisense c-myc largely reduced c-Myc and partially Bcl-2 exp ression; overexpression of Bcl-2 partially rescued from apoptosis in HCC-T and HepG2 cells. These results suggest that the massive reduction in c-myc mRNA induces apoptosis in liver cancer cell lines and consequent decrease i n Bcl-2 enhances the cell death. c-Myc reduction under the Cre/IoxP switchi ng system may be a useful tool for the clarification of c-myc-related cellu lar mechanisms in differentiation and proliferation. (C) 2001 Wiley-Liss, I nc.