The overexpression of P-glycoprotein(P-gp)and its coding gene mdrl is regarded as the classic mechanism of muhidrug resistance(MDR).Recent studies find that pregnane X receptor(PXR)can mediate the expression of P-gp.It is confirmed that PXR can also inhibit apoptosis of tumor cells.Therefore,preventing the activation of PXR specifically may be a new method to prevent MDR.

Objective To explore effects of paclitaxel on proliferation and migration of breast cancer Michigan Cancer Foundation-7 (MCF-7) cells via mammalian target of rapamycin (mTOR) signaling pathway.Methods The cases were randomly divided into four groups,including control group,paclitaxel low-dose group (0.25 μmol/L),paclitaxel medium-dose group (0.5 μmol/L),and paclitaxel high-dose group (1 μmol/L).The viability of MCF-7 cells was measured with methyl thiazolyl tetrazolium (MTT) assay.MCF-7 cell cycle was examined with flow cytometry.MCF-7 cell migration was tested with transwell migration assay.The levels of mTOR signalling pathway-related protein were assayed with Western blot.Results Compared to the control group,MCF-7 cell viability was significantly decreased in paclitaxel low,medium and high-dose groups (P ＜ 0.05),and the inhibitory rate was highest at 48 h (P ＜ 0.05).MCF-7 cell migration was significantly inhibited in paclitaxel low,medium and high-dose groups [(98 ± 9.78) vs (86.21 ± 6.58),(53.41 ± 3.16) and (42.00 ± 4.69),P ＜ 0.05].Moreover,compared to the control group,the number of MCF-7 cells at G1 phase was significantly increased in paclitaxel low,medium and high-dose groups [(52.14±6.13)％ vs (67.93 ±8.16)％,(72.32 ±3.67)％ and (78.53 ± 6.28)％,P ＜ 0.01],the number of MCF-7 cells at G2 phase was significantly reduced in paclitaxel low,medium and high-dose group [(13.68 ± 0.85) ％ vs (8.57 ± 1.03) ％,(5.30 ± 0.89) ％ and (3.46 ± 0.78) ％,P ＜0.01].The phosphorylations of 4E binding protein (4EBP1) and mTOR proteins as well as the expressions of cell-cycle protein D1 (Cyclin D1) and matrix metalloproteinase-9 (MMP-9) were significantly inhibited in paclitaxel low,medium and high-dose groups (P ＜ 0.01).Conclusions These results suggested paclitaxel could inhibit proliferation and migration in breast cancer MCF-7 cells,which might be related to mTOR signal pathway.

Objective To investigate the effect of sentinel lymph node biopsy in the patients with early triple-negative breast cancer and its impact on patients' complications. Methods A total of 120 patients with early triple-negative breast cancer who were admitted to our hospital from October 2015 to October 2017 were selected and randomly divided into two groups. The control group was given total mastectomy+axillary lymph node dissection. The study group was given total mastectomy+sentinel lymph node biopsy. The surgical conditions and complications were compared and analyzed between the two groups. Results The operation time, length of stay and perioperative bleeding volume in the study group were significantly better than those in the control group (P<0.05). The complication rate in the study group was 1.7％, which was significantly lower than that of 11.7％ in the control group (P<0.05). The quality of life scores in the study group were significantly higher than those in the control group (P<0.05). Conclusion Sentinel lymph node biopsy used in the patients with early triple-negative breast cancer during the treatment of the patients with triple-negative breast cancer has a favorable effect and the complication rate is low. The patient's quality of life is significantly improved compared with the traditional axillary lymph node dissection, which is worthy of promotion in clinical practice.