Enhanced activation of persulfate by Fe(III) and catechin without light: Reaction kinetics, parameters and mechanism.

An environmental-friendly plant polyphenol, catechin (CAT), was applied in Fe(III) activated persulfate (PS) system for naproxen (NPX) degradation in this research. Reaction kinetics, parameters, NPX degradation products and reaction mechanism were investigated. Combining the results of quenching experiments as well as Electron Spin Resonance (ESR), it was observed that SO4•- was critical in NPX degradation, and the contribution of HO• was minor in the Fe(III)/CAT/PS system. O2•- was generated during the reaction but did not contribute to NPX degradation. SO4•- and HO• were produced from the PS activation by Fe(II), which was formed from the transient complexing and reduction process between Fe(III) and CAT. The effects of Fe(III), CAT, PS concentration and pH value on NPX degradation were evaluated. Moreover, the mineralization rate was 20.2%, and the toxicity of the treated solution were lower than the initial solution. Nine possible intermediates were determined when using LC-QTOF-MS to analyze, and three degradation pathways were put ward. The results proved that CAT could accelerate the redox cycle of Fe(III)/Fe(II), consequently to strengthen PS activation without light. It was a promising oxidation technology as it offered an energy-saving and hypo-toxic way for refractory organic pollutants treatment, and it was applicable at a comparatively wide pH range.

Nuclear Her2 contributes to paclitaxel resistance in breast cancer cells.

Translocation of full-length Her2 receptor into nucleus was reported by some studies. Here, we tested whether nuclear Her2 contributes to paclitaxel resistance in Her2-overexpressing breast cancer cells. Breast cancer cell was transfected with plasmids containing cDNA of wild-type Her2 or mutant-type Her2 lacking the nuclear localization signal (NLS) sequence which is required for Her2 nuclear transport. Cell resistance to paclitaxel was analyzed. Paclitaxel-resistant breast cancer cell was also developed and nuclear Her2 expression was tested. Then, correlation between nuclear Her2 and resistance to paclitaxel were analyzed. Expression of importin ß1 was decreased to downregulate nuclear Her2 level and cell resistance to paclitaxel was tested. We found that Her2 overexpression increases Her2 nuclear expression and cells resistance to paclitaxel in MCF-7 cells. In the paclitaxel resistant cell (SK-BR-3/R), nuclear Her2 expression is upregulated compared with parental SK-BR-3 cells. Increased expression of nuclear Her2 after short-time (48 h) treatment of paclitaxel was also observed in SK-BR-3 cells. Further downregulation of Her2 nuclear expression through blocking expression of importin ß1 sensitizes the cells to paclitaxel. The analysis showed that the Her2 nuclear expression increases the survivin expression which leads to resistance to paclitaxel. Her2 nuclear expression decreases paclitaxel-induced apoptosis. However, co-immunoprecipitation was applied, and the physical interaction of nuclear Her2 and survivin was not detected. We show for the first time that nuclear Her2 contributes to paclitaxel resistance in breast cancer cells which suggests that nuclear Her2 as a potential target to sensitize breast cancers to paclitaxel treatment.