TY - JOUR
T1 - Sensitization of a human ovarian cancer cell line to temozolomide by simultaneous attenuation of the Bcl-2 antiapoptotic protein and DNA repair by O6-alkylguanine-DNA alkyltransferase
AU - Barvaux, Vincent A.
AU - Lorigan, Paul
AU - Ranson, Malcolm
AU - Gillum, Amanda M.
AU - McElhinney, R. Stanley
AU - McMurry, T. Brian H
AU - Margison, Geoffrey P.
PY - 2004/10/14
Y1 - 2004/10/14
N2 - Temozolomide is an alkylating agent that mediates its cytotoxic effects via O6-methylguanine (O6-meG) adducts in DNA. O6-alkylguanine-DNA-alkyltransferase (MGMT) can repair such adducts and therefore constitutes a major resistance mechanism to the drug. MGMT activity can be attenuated in vitro and in vivo by the pseudosubstrate O6-(4-bromothenyl)guanine (PaTrin-2, Patrin, Lomeguatrib), which in clinical trials is in combination with temozolomide. Resistance to cytotoxic agents can also be mediated by the Bcl-2 protein, which inhibits apoptosis and is frequently up-regulated in tumor cells. Attenuation of Bcl-2 expression can be affected by treatment of cells with the antisense oligonucleotide, oblimersen sodium (Genasense), currently in phase III clinical trials in combination with the methylating agent dacarbazine. Using a human ovarian cancer cell line (A2780) that expresses both Bcl-2 and MGMT, we show that cells treated with active dose levels of either oblimersen (but not control reverse sequence or mismatch oligonucleotides) or PaTrin-2 are substantially sensitized to temozolomide. Furthermore, the exposure of oblimersen-pretreated cells to PaTrin-2 leads to an even greater sensitization of these cells to temozolomide. Thus, growth of cells treated only with temozolomide (5 μg/mL) was 91% of control growth, whereas additional exposure to PaTrin-2 alone (10 μmol/L) or oblimersen alone (33 nmol/L) reduced this to 81% and 66%, respectively, and the combination of PaTrin-2 (10 μmol/L) and oblimersen (33 nmol/L reduced growth to 25% of control. These results suggest that targeting both Bcl-2 with oblimersen and MGMT with PaTrin-2 would markedly enhance the antitumor activity of temozolomide and merits testing in clinical trials. Copyright © 2004 American Association for Cancer Research.
AB - Temozolomide is an alkylating agent that mediates its cytotoxic effects via O6-methylguanine (O6-meG) adducts in DNA. O6-alkylguanine-DNA-alkyltransferase (MGMT) can repair such adducts and therefore constitutes a major resistance mechanism to the drug. MGMT activity can be attenuated in vitro and in vivo by the pseudosubstrate O6-(4-bromothenyl)guanine (PaTrin-2, Patrin, Lomeguatrib), which in clinical trials is in combination with temozolomide. Resistance to cytotoxic agents can also be mediated by the Bcl-2 protein, which inhibits apoptosis and is frequently up-regulated in tumor cells. Attenuation of Bcl-2 expression can be affected by treatment of cells with the antisense oligonucleotide, oblimersen sodium (Genasense), currently in phase III clinical trials in combination with the methylating agent dacarbazine. Using a human ovarian cancer cell line (A2780) that expresses both Bcl-2 and MGMT, we show that cells treated with active dose levels of either oblimersen (but not control reverse sequence or mismatch oligonucleotides) or PaTrin-2 are substantially sensitized to temozolomide. Furthermore, the exposure of oblimersen-pretreated cells to PaTrin-2 leads to an even greater sensitization of these cells to temozolomide. Thus, growth of cells treated only with temozolomide (5 μg/mL) was 91% of control growth, whereas additional exposure to PaTrin-2 alone (10 μmol/L) or oblimersen alone (33 nmol/L) reduced this to 81% and 66%, respectively, and the combination of PaTrin-2 (10 μmol/L) and oblimersen (33 nmol/L reduced growth to 25% of control. These results suggest that targeting both Bcl-2 with oblimersen and MGMT with PaTrin-2 would markedly enhance the antitumor activity of temozolomide and merits testing in clinical trials. Copyright © 2004 American Association for Cancer Research.
UR - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=pure_starter&SrcAuth=WosAPI&KeyUT=WOS:000224488400005&DestLinkType=FullRecord&DestApp=WOS
U2 - 10.1158/1535-7163.1215.3.10
DO - 10.1158/1535-7163.1215.3.10
M3 - Article
C2 - 15486188
SN - 1535-7163
VL - 3
SP - 1215
EP - 1220
JO - Molecular Cancer Therapeutics
JF - Molecular Cancer Therapeutics
IS - 10
ER -