Ten chemicals were screened for sensitizing ovarian cancer cells\#8217; response to cisplatin, and the expressions of several genes by cisplatin/kaempferol were examined to learn possible mechanisms of this sensitization effect. The interactive effects of cisplatin and ten chemicals were examined in OVCAR-3 ovarian cancer cells by fitting a linear regression model. The ten chemicals are: kaempferol, \#945;-tocopherol succinate, rutin hydrate, apigenin, taxifolin, luteolin, naringin, \#945;-tocopherol, genistein, and quercetin. OVCAR-3 cells were seeded in 96-well plates, treated with 0-, 40-, 80-uM cisplatin with or without 20-uM chemicals for 24 hours, and determined for cell viability with MTS-based assays. Cell viabilities were expressed as percentages, and their logarithms were plotted to fit linear regression models to analyze effects of cisplatin, chemicals, and interactions between cisplatin and tested chemicals. For kaempferol which shows a significant interaction with cisplatin, expression of ABCC1, ABCC5, ABCC6, NF\#954;B1, cMyc, and CDKN1A genes were further examined by qRT-PCR. Gene mRNA abundances were normalized to GAPDH levels and expressed as percentages of controls. The mRNA levels of CDKN1A gene were further plotted against cMyc to view their relationship. All data come from 3 independent experiments. In screening of chemicals for their interactive effects with cisplatin, goodness of fit in linear regression models is good (R2>0.8) for kaempferol, \#945;-tocopherol succinate, apigenin, luteolin, and genistein. Significant synergistic effect was found between cisplatin/kaempferol (p=0.001) and cisplatin/\#945;-tocopherol succinate (p=0.015). For cisplatin/kaempferol treatments on OVCAR-3 cancer cells, the mRNA levels of ABCC1, ABCC5, and NF\#954;B1 do not have obvious changes. However, significant inhibition of ABCC6 and cMyc mRNA levels was observed for cisplatin treatment alone as well as cisplatin/kaempferol combined treatment (p<0.05). The mRNA levels of CDKN1A gene were significantly up-regulated by cisplatin and/or kaempferol treatment. A plot of CDKN1A mRNA levels against that of cMyc gene further revealed a reverse, linear relationship, proving cMyc\#8217;s regulation on CDKN1A gene expressions. Our screening work found that kaempferol, a natural flavonoid widely present in fruits and vegetables, works synergistically with cisplatin in inhibiting ovarian cancer cell viabilities, and their inhibition on cell viabilities may be induced through inhibiting ABCC6 and cMyc gene transcription. CDKN1A gene is up-regulated by cisplatin and kaempferol treatment, and its linear, reverse relationship with cMyc gene reflects its regulation by cMyc gene. As a dietary component, kaempferol sensitizes ovarian cancer cells to cisplatin treatment and deserves further studies for possible applications in chemotherapy of ovarian cancers.

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 2960.

100th AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO

American Association for Cancer Research
2009