Search

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 β1 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 β1 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.

—This paper proposes a new three-port, T-type multi-level converter (TPTMC) that simultaneously outputs two sinusoidal AC voltages with different frequencies: 50 Hz and 60 Hz. The proposed TPTMC is composed of a DC voltage source, two T-type power electronic legs, a filter inductor set, a frequency separated transformer (FST), a 60 Hz filter capacitor, a 50-Hz filter capacitor, and a DSP controller. The most salient feature is that the proposed TPTMC outputs two sinusoidal AC voltages with different frequencies using only a power converter. A hardware prototype is developed to verify the performance of the proposed TPTMC. The experimental results are as expected.

A DC power distribution interface for data centers is developed in this paper. This DC power distribution interface is composed of two power stages, a three-phase T-type multi-level AC-DC power converter and an isolated multi-level DC-DC power converter. The first power stage, three-phase T-type multi-level AC-DC power converter, is used to convert the utility AC voltage to a constant DC voltage and control the utility current to be sinusoidal and unity power factor. The isolated multi-level DC-DC power converter is the second power stage, and it converts the output DC voltage of the first power stage to the desired DC voltage of the DC power distribution system with galvanic isolation. This isolated multi-level DC-DC power converter consists of an isolated power converter with a three-winding transformer, a series/parallel switching circuit and an output L-C filter. Only three power electronics switches are used in the isolated multi-level DC-DC power converter to generate a two-level output DC voltage. Hence, the control circuit is simplified and the capacity of output L-C filter is reduced. Computer simulation is carried out to verify the developed DC power distribution interface. The simulation results show that the developed DC power distribution interface has the expected performance.