TY - JOUR
T1 - An increase of cytochrome C oxidase mediated disruption of gemcitabine incorporation into DNA in a resistant KB clone
AU - Liu, Xiyong
AU - Zhou, Bingsen
AU - Mi, Shu
AU - Xue, Lijun
AU - Shih, Jennifer
AU - Lee, Janice
AU - Chau, Jennifer
AU - Un, Frank
AU - Yen, Yun
PY - 2007/6/15
Y1 - 2007/6/15
N2 - Mechanistic aberrations leading to Gemcitabine (2′,2′-dFdCyd,2,2-difluorodeoxycytidine, Gem) resistance may include alteration in its transport, metabolism and incorporation into DNA. To explore the mechanism of Gem resistance, the restriction fragment differential display PCR (RFDD-PCR) was employed to compare the mRNA expression patterns of KBGem (Gem resistant), KBHURs (hydroxyurea resistant) and KBwt (parental KB cell). Nine gene fragments were overexpressed specifically in the KBGem clone. Sequencing and BLAST results showed that three fragments represent cytochrome C oxidase (CCOX, respiration complex IV) subunit III (CCOX3). The cDNA microarray confirmed that the mRNAs of CCOX and ATP synthase subunits were upregulated in KBGem as compared to KBwt and KBHURs. The increase in CCOX1 protein and activity led to the increase of free ATP concentration, which is consistent with the gene expression profile of KBGem. Furthermore, the sensitivity to Gem could be reversed by sodium azide, a CCOX inhibitor. Following the treatment of sodium azide, the cellular accumulation of [3H]-Gem increased in a dose (of azide)-dependent manner, which is associated with increase of [3H]-Gem incorporation into DNA in KBGem. In summary, an increase of CCOX activity and free ATP level may reduce the transport, metabolism and DNA incorporation of Gem, resulting in Gem resistance.
AB - Mechanistic aberrations leading to Gemcitabine (2′,2′-dFdCyd,2,2-difluorodeoxycytidine, Gem) resistance may include alteration in its transport, metabolism and incorporation into DNA. To explore the mechanism of Gem resistance, the restriction fragment differential display PCR (RFDD-PCR) was employed to compare the mRNA expression patterns of KBGem (Gem resistant), KBHURs (hydroxyurea resistant) and KBwt (parental KB cell). Nine gene fragments were overexpressed specifically in the KBGem clone. Sequencing and BLAST results showed that three fragments represent cytochrome C oxidase (CCOX, respiration complex IV) subunit III (CCOX3). The cDNA microarray confirmed that the mRNAs of CCOX and ATP synthase subunits were upregulated in KBGem as compared to KBwt and KBHURs. The increase in CCOX1 protein and activity led to the increase of free ATP concentration, which is consistent with the gene expression profile of KBGem. Furthermore, the sensitivity to Gem could be reversed by sodium azide, a CCOX inhibitor. Following the treatment of sodium azide, the cellular accumulation of [3H]-Gem increased in a dose (of azide)-dependent manner, which is associated with increase of [3H]-Gem incorporation into DNA in KBGem. In summary, an increase of CCOX activity and free ATP level may reduce the transport, metabolism and DNA incorporation of Gem, resulting in Gem resistance.
KW - ATP
KW - Cytochrome C oxidase
KW - Drug resistance
KW - Gemcitabine
KW - Ribonucleotide reductase
UR - http://www.scopus.com/inward/record.url?scp=34247567115&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34247567115&partnerID=8YFLogxK
U2 - 10.1016/j.bcp.2007.03.014
DO - 10.1016/j.bcp.2007.03.014
M3 - Article
C2 - 17428446
AN - SCOPUS:34247567115
SN - 0006-2952
VL - 73
SP - 1927
EP - 1938
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 12
ER -