Combinatorial treatment of ovarian cancer cells with harringtonine and cisplatin results in increased cisplatin-DNA adducts.
The current studies represent the first step in assessing the utility of harringtonine in combination with cisplatin as an improved approach for treating ovarian cancer. Three ovarian cancer cell lines, platinum-sensitive A2780, and platinum-resistant A2780/CP70 and OvCar-3, were exposed to their respective IC(50) dose of cisplatin for 1 h with or without a 24-h pretreatment with harringtonine. The level of platinum-DNA adducts was determined by atomic absorption spectrometry (AAS). These studies show for the first time that harringtonine pretreatment significantly increased the amount of platinum-DNA adducts in all ovarian cancer cell lines by 2-4 fold, immediately following 1-h exposure to cisplatin. Moreover, the level of cisplatin-DNA adducts in harringtonine-pretreated cells remained elevated by 3-4.7-fold for at least 6 h after cisplatin was removed, relative to cells only exposed to cisplatin. In all three cell lines the removal (repair) of platinum-DNA adducts was not significantly altered by harringtonine. In addition, the extent to which harringtonine altered the expression of select DNA damage response genes (p53, P16, ERCC1 and XPB) was determined using RT-PCR and Southern hybridization in A2780 and A2780/CP70 cells. The expression of ERCC1 and XPB RNAs were only modestly altered by harringtonine, consistent with a lack of effect of harringtonine on repair of cisplatin-DNA damage. However, harringtonine altered expression of p53 and P16 RNAs in both cell lines, although the down-regulation of p53 and P16 RNAs by harringtonine were more pronounced in A2780 cells. The novel observation that harringtonine augments platinum-DNA adducts in both platinum-sensitive and -resistant ovarian cancer cells indicates this combination of drugs may have utility in treating ovarian cancer and may be especially useful in managing platinum-resistant cancers. Additional studies are required to determine which sequence of these drugs is most beneficial, as well as the mechanism by which harringtonine increases cisplatin-DNA damage in ovarian cancer cells.
Yunmbam
Manasses K
MK
Mary Babb Randolph Cancer Center, Morgantown, WV 26506-9300, USA.
Guo
Yi
Y
Miller
Michael R
MR
Yu
Jing Jie
JJ
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D018929:Cell Culture Techniques; D002945:Cisplatin / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D018736:DNA Adducts / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006248:Harringtonines / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
D000199:Actins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D018736:DNA Adducts; D004268:DNA-Binding Proteins; D006248:Harringtonines; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; C057270:cisplatin-DNA adduct; C062500:harringtonin; C072022:XPBC-ERCC-3 protein; C071447:ERCC1 protein, human; D004720:Endonucleases; D004265:DNA Helicases; D002945:Cisplatin