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Figure 1 | Breast Cancer Research

Figure 1

From: The estrogen receptor influences microtubule-associated protein tau (MAPT) expression and the selective estrogen receptor inhibitor fulvestrant downregulates MAPT and increases the sensitivity to taxane in breast cancer cells

Figure 1

MAPT expression and drug sensitivity. A: MAPT mRNA expression in human breast cancer cell lines. PCR was used to assess MAPT mRNA levels in 12 human breast cancer cell lines. Since MAPT expression was lowest in SK-BR-3 cells, this expression level was taken as the standard for comparison with other cell lines. Cell line ZR75-1 has a naturally high MAPT expression [5, 6]. Other cell lines with an mRNA expression higher than that of cell line ZR75-1 were classified as high mRNA expression cell lines. Real-time PCR revealed six cell lines in this category: MDA-MB-134-VI, ZR75-1, YMB1-E, MCF-7, HCC1143, and HCC3153. B: The correlation between MAPT protein expression and sensitivity to anti-cancer drugs. Western blot analysis shows that four cell lines (MDA-MB-134-VI, ZR75-1, YMB1-E, and MCF-7) have multiple protein bands ranging from 50 to 70 kDa. Cell lines HCC1143 and HCC3153 each show only one band at around 70 kDa, despite having a high MAPT mRNA expression. Cell lines HCC38, MDA-MB-231 and SK-BR-3 have low MAPT mRNA expression, but show one band at around 70 kDa. MTS assays were used to assess the sensitivity to paclitaxel, docetaxel, vinorelbine, and doxorubicin, and to determine the IC50 values for drug sensitivity. The upper figure shows the sensitivity to vinorelbine and doxorubicin, and the lower figure shows the sensitivity to paclitaxel and docetaxel. Four cell lines with multiple protein bands show a low sensitivity to taxanes, and five cell lines with only one band at around 70 kDa show a high sensitivity to taxanes. This trend was not observed for vinorelbine and doxorubicin. Cell lines HCC1569 and HCC1937, both having a low MAPT expression, show a low sensitivity to all four anti-cancer drugs. Cell line HCC1937 was the BRCA1-defective breast cancer cell line. The characteristics of HCC1569 are unclear.

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