TRA2A Promoted Paclitaxel Resistance and Tumor Progression in Triple-Negative Breast Cancers via Regulating Alternative Splicing
MOLECULAR CANCER THERAPEUTICS
Authors: Liu, Tieju; Sun, Huizhi; Zhu, Dongwang; Dong, Xueyi; Liu, Fang; Liang, Xiaohui; Chen, Chen; Shao, Bing; Wang, Meili; Wang, Yi; Sun, Baocun
Abstract
Treatment of triple-negative breast cancer (TNBC) has been challenging, and paclitaxel resistance is one of the major obstacles to the better prognosis. Deregulation of alternative splicing (AS) may contribute to tumor progression and chemotherapy resistance. Human AS factor TRA2 has two separate gene paralogs encoding TRA2A and TRA2B proteins. TRA2B is associated with cancer cell survival and therapeutic sensitivity. However, the individual role of TRA2A in cancer progression has not been reported. Here we report that TRA2A facilitates proliferation and survival and migration and invasion of TNBC cells. In addition, TRA2A promotes paclitaxel resistance of TNBC by specifically controlling cancer-related splicing, which is independent of other splicing factors. TRA2A overexpression could promote AS of CALU, RSRC2, and PALM during paclitaxel treatment of TNBC cells. The isoform shift of RSRC2 from RSRC2s to RSRC2l leads to a decreased RSRC2 protein expression, which could contribute to TNBC paclitaxel resistance. TRA2A can regulate RSRC2 AS by specifically binding upstream intronic sequence of exon4. Strikingly, TRA2A expression is increased dramatically in patients with TNBC, and has a close relationship with decreased RSRC2 expression; both are associated with poor survival of TNBC. Collectively, our findings suggest that paclitaxel targets the TRA2A-RSRC2 splicing pathway, and deregulated TRA2A and RSRC2 expression may confer paclitaxel resistance. In addition to providing a novel molecular mechanism of cancer- related splicing dysregulation, our study demonstrates that expression of TRA2A in conjunction with RSRC2 may provide valuable molecular biomarker evidence for TNBC clinical treatment decisions and patient outcome. (C)2017 AACR.
Size effect of curcumin nanocrystals on dissolution, airway mucosa penetration, lung tissue distribution and absorption by pulmonary delivery
COLLOIDS AND SURFACES B-BIOINTERFACES
Authors: He, Yuan; Liang, Yingmin; Mak, Judith Choi Wo; Liao, Yonghong; Li, Ting; Yan, Ru; Li, Hai-Feng; Zheng, Ying
Abstract
Nanocrystals (NCs) have been introduced for use in pulmonary delivery in recent decades. Although the deposition and bioavailability have been extensively studied, little is known about the biofate, which influences the drug release and absorption process of NCs. In this study, we fabricated three different sized curcumin NCs by adjusting the parameters of mill machine using a wet milling method and studied the size effect on pulmonary absorption. The small nanocrystals (NC-S, 246.16 +/- 21.98 nm) exhibited a faster dissolution rate and higher diffusion percentage in vitro compared with middle (NC-M, 535.26 +/- 50.33 nm) and large nanocrystals (NC-L, 1089.53 +/- 194.34 nm). Multiple particle tracking experiments revealed that NC-S had larger mean squared displacement during diffusion in simulated mucus of 0.5% hydroxyethyl cellulose solution. Moreover, enhanced cellular uptake and transport efficiency were achieved by NC-S in Calu-3 cells and an air-liquid interface culturing model. NCs were mainly absorbed in the dissolved drug form, as assessed by using the Forster resonance energy transfer (FRET) technique. In vivo lung retention and distribution revealed that few smaller sized nanocrystals were retained in the lung after intratracheal administration. The pharmacokinetic study showed that the AUC((0,t)) values of small sized nanocrystals were 1.75- and 3.32-fold greater than NC-M and NC-L, respectively. In conclusion, this study demonstrated that smaller sized nanocrystals were more easily absorbed into the blood system by increasing the dissolution rate.