Open AccessBcl‐X L Antisense Sensitizes Human Colon Cancer Cell Line to 5‐Fluorouracil
Author(s) -
Nita Marcelo Eidi,
OnoNita Suzane Kioko,
Tsuno Nelson,
Tominaga Osamu,
Takenoue Tomohiro,
Sunami Eiji,
Kitayama Joji,
Nakamura Yusuke,
Nagawa Hirokazu
Publication year - 2000
Publication title -
japanese journal of cancer research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 0910-5050
DOI - 10.1111/j.1349-7006.2000.tb01020.x
Subject(s) - apoptosis , transfection , sense (electronics) , endogeny , colorectal cancer , microbiology and biotechnology , cell culture , cancer research , western blot , biology , cancer cell , messenger rna , chemistry , cancer , gene , biochemistry , genetics
Resistance to 5‐fluorouracil (5‐FU) has been frequently found in the treatment of digestive tract cancer patients. Our previous study suggested that high expression of endogenous Bcl‐X L , might be associated with resistance to 5‐FU in colorectal cancer. The aim of this study is to analyze the role of Bcl‐X L in 5‐FU resistance and to explore a new therapeutic strategy using Bcl‐X L antisense. First, western blot analysis shows that Bcl‐X L rather than Bcl‐2 is overexpressed in primary adenocarcinoma of colon. Second, when Colo320 cells, with undetectable endogenous Bcl‐X L expression, were transfected with Bcl‐X L gene, they acquired high resistance to 5‐FU. Finally, antisense oligodeoxynucleotides (ODNs) that targeted the start codon of Bcl‐X L mRNA (ASI) prove to be the most effective in DLD1 cells with high endogenous Bcl‐X L expression. Bcl‐X L protein expression was decreased in a dose‐dependent manner when the cells were treated with AS1 ODNs, while non‐sense and sense controls and 5‐FU had no effect on Bcl‐X L protein. 5‐FU treatment induced a level of apoptosis 10‐fold higher in DLD1 cells than in untreated control cells, while the same dose of 5‐FU induced a 55‐fold higher level of apoptosis in DLD1 cells treated with Bcl‐X L antisense oligodeoxynucleotides ( P =0.0003). Moreover, AS1 ODNs coupled with 5‐FU decreased viable colon cancer cells 40% more than did 5‐FU alone ( P < 0.05). These results suggest that Bcl‐X L is an important factor for 5‐FU resistance and the suppression of Bcl‐X L expression by the specific antisense ODNs can increase the sensitivity of colon cancer cells to 5‐FU.