G-T haplotype (2677G>T/A and 3435C>T) of ABCB1 gene polymorphisms is associated with ethnic differences to paclitaxel sensitivity in cancer cells with different gene expression pattern.

At 2677, the GG and TT were most frequent in Asian cell lines, whereas the GT and GG were most frequent in non-Asians (p=0.032). At 3435, TT and CC was most common in Asians and non-Asians, respectively (p=0.018). A higher IC(50) was found in GG than GT/A genotype (p=0.02) and in G-C than G-T haplotype (p=0.046). Non-Asian cell lines were more sensitive to paclitaxel than Asian cell lines (p=0.01) due to different polymorphism frequencies. We identified 65 genes that were differently expressed in cell lines of the G-C and G-T ABCB1 haplotypes. Ethnic differences in the G-T haplotype of the ABCB1 gene may be a biomarker for paclitaxel sensitivity, and future clinical validation is necessary to confirm our findings.