The patients with a less-invasive primary tumor may gain a survival benefit from aggressive multimodality therapeutic approaches.

ABSTRACT:Multidrug resistance protein 1 (MRP1) confers drug resistance and also mediates cellular efflux of many organic anions. MRP1 also transports glutathione (GSH); furthermore, this tripeptide stimulates transport of several substrates, including estrone 3-sulfate.

Purpose: The Y-box binding protein 1 (YB-1) regulates expression of P-glycoprotein encoded by the MDR1 gene. There have been no previous studies regarding the involvement of YB-1 in the development of resistance to paclitaxel. The present study was done to examine how paclitaxel affects the localization and expression of YB-1 in breast cancer. Experimental Design: We evaluated the expression and localization of YB-1 and P-glycoprotein in breast cancer tissues obtained from 27 patients before and after treatment with paclitaxel. The effect of paclitaxel on localization of cellular YB-1 was examined by using GFP-YB-1. Interaction of YB-1 with the Y-box motif of the MDR1 promoters was studied by electrophoretic mobility shift assay. The effects of paclitaxel on MDR1 promoter activity were examined by luciferase assay. Results: Of 27 breast cancer tissues treated with paclitaxel, nine (33%) showed translocation of YB-1 from the cytoplasm to the nucleus together with increased expression of P-glycoprotein during the course of treatment. Twelve breast cancer tissues (44%) showed neither translocation of YB-1 nor increased expression of P-glycoprotein. Nuclear translocation of YB-1 was correlated significantly with increased expression of P-glycoprotein (P = 0.0037). Confocal analysis indicated that paclitaxel induced nuclear translocation of green fluorescent fused YB-1 in MCF7 cells. Furthermore, binding of YB-1 to the Y-box of MDR1 promoter was increased in response to treatment with paclitaxel. In addition, MDR1 promoter activity was significantly up-regulated by paclitaxel in MCF7 cells (P < 0.001). Conclusions:The results of the present study suggested that YB-1 may be involved in the development of resistance to paclitaxel in breast cancer.

Background: The prognostic nutritional index (PNI), which is an easily calculated nutritional index, is significantly associated with patient outcomes in various solid malignancies. This study aimed to evaluate the prognostic impact of PNI changes in patients with breast cancer undergoing neoadjuvant chemotherapy (NAC). Methods: We reviewed patients with breast cancer who underwent NAC and a subsequent surgery for breast cancer between 2005 and 2016. PNI before and after NAC were calculated using the following formula: 10 × serum albumin (g/dl) + 0.005 × total lymphocyte count/mm 3. The relationship between PNI and prognosis was retrospectively analyzed. Results: In total, 191 patients were evaluated. There was no significant difference in disease-free survival (DFS) between the pre-NAC PNI high group and the pre-NAC PNI low group (cutoff: 53.1). However, PNI decreased in 181 patients (94.7%) after NAC and the mean PNI also significantly decreased after NAC from 52.6 ± 3.8 pre-NAC to 46.5 ± 4.4 post-NAC (p < 0.01). The mean ΔPNI, which was calculated as pre-NAC PNI minus post-NAC PNI, was 5.4. The high ΔPNI group showed significantly poorer DFS than the low ΔPNI group (cut off: 5.26) (p = 0.015). Moreover, high ΔPNI was an independent risk factor of DFS on multivariate analysis (p = 0.042). Conclusions: High decrease of PNI during NAC predicts poor prognosis. Thus, maintaining the nutritional status during NAC may result in better treatment outcomes in patients with breast cancer.