TXR1 and TSP1 expression varies by the molecular subtypes of breast cancer patients who received previous docetaxel-based first-line chemotherapy.

The expression of taxol resistance gene 1 and thrombospondin 1 remains unknown in human breast cancer tissues. In the current study, we sought to measure the mRNA expression levels of taxol resistance gene 1 and thrombospondin 1 in breast cancer tissue and adjacent normal tissue specimens and further analyzed their expression according to the molecular subtypes and age of breast cancer patients who had received taxane-containing regimens. Archived breast cancer and adjacent non-tumor tissue specimens were obtained at Beijing Friendship Hospital, Beijing, China. The mRNA transcript levels of taxol resistance gene 1, thrombospondin 1 and multi-drug resistance 1 were determined by quantitative RT-PCR. Taxol resistance gene 1 and multi-drug resistance 1 protein levels were measured by immunoblotting assays. Forty-nine archived breast cancer tissue specimens were included. The majority of the specimens (65.3%) were of the molecular subtype A followed by triple negative breast cancer (14.3%). The mRNA transcript levels of taxol resistance gene 1 , thrombospondin 1 and multi-drug resistance 1 in breast cancer tissues were higher than those of adjacent normal tissues. The mRNA expression of TXR1 in the HER2 subtype (4.513 ± 0.810) was the highest and in the Luminal B subtype was the lowest (3.103 ± 0.417) among the four molecular subtypes. The HER2 subtype also had the highest mRNA expression of thrombospondin 1(4.827 ± 0.927) and the Luminal B subtype had the lowest TSP1 mRNA level (3.197 ± 0.565) among the four molecular subtypes. Our study represents the first attempt in delineating taxol resistance gene 1 and thrombospondin 1 expression in breast cancer and we demonstrate that taxol resistance gene 1 and thrombospondin 1 expression may vary according to the molecular subtypes of breast cancer.