Drug resistance is a major obstacle to the successful chemotherapy. Several ATP-binding cassette (ABC) transporters including ABCB1, ABCC1 and ABCG2 have been known to be important mediators of chemoresistance. Using oligonucleotide microarrays (HG-U133 Plus 2.0; Affymetrix), we analyzed the ABC transporter gene expression profiles in breast cancer patients who underwent sequential weekly paclitaxel/FEC (5-fluorouracil, epirubicin and cyclophosphamide) neoadjuvant chemotherapy. We compared the ABC transporter expression profile between two classes of pretreatment tumor samples divided by the patients' pathological response to neoadjuvant chemotherapy (residual disease [RD] versus pathologic complete response [pCR]) ABCB3, ABCC7 and ABCF2 showed significantly high expression in the pCR. Several ABC transporters including ABCC5, ABCA12, ABCA1 ABCC13, ABCB6 and ABCC11 showed significantly increased expression in the RD (p<0.05). We evaluated the feasibility of developing a multigene predictor model of pathologic response to neoadjuvant chemotherapy using gene expression profiles of ABC transporters. The prediction error was evaluated by leave-one-out cross-validation (LOOCV). A multigene predictor model with the ABC transporters differentially expressed between the two classes (p

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Caffeine is thought to increase the antitumor effect of cisplatin or DNA-damaging agents because it is known that caffeine inhibits DNA repair. Caffeine-assisted chemotherapy has been used in the treatment of osteosarcomas. In addition, there are several reports about combination chemotherapy with caffeine for certain malignancies other than osteosarcomas. However, there are no reports that show the utility of combination chemotherapy with caffeine for hepatocellular carcinoma (HCC). We examined the combined effects of caffeine and cisplatin in human HCC cell lines, and screened for a more effective administration method of caffeine in vitro. Human HCC cell lines (HepG2, HLF, HuH-7, and Li-7) were exposed to caffeine (0-0.5 mM) and cisplatin (0-1.2 μg/mL) for 72 h, either alone or in combination. Cell numbers were measured by WST-8 assay, and cell apoptosis was determined by annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) binding assay. As a result, caffeine increased the antitumor effect of cisplatin on cell proliferation and cell apoptosis in the HCC cell lines. Moreover, this effect was dependent on the amount of exposure to caffeine. These results suggest that caffeine-assisted chemotherapy is useful for HCC treatment.

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