[Effect of Pterostilbene Regulating Nuclear Factor E2-Related Factor 2 on Apoptosis of Colon Cancer Cells in Vitro].

Objective To investigate the effects of pterostilbene on human colon cancer LoVo cells and study the regulatory mechanism of nuclear factor E2-related factor 2 (Nrf2) in the process of pterostilbene acting on LoVo cells. Methods LoVo cells were treated with different concentrations (5,10,20,40,60,80,100 µmol/L) of pterostilbene.Cell viability,migration,invasion,and apoptosis were examined by CCK-8,scratch,Transwell,and TUNEL assays,respectively.The mitochondrial membrane potential was measured by the mitochondrial membrane potential assay kit with JC-1.The reactive oxygen species level was measured by 2',7'-dichlorofluorescein diacetate.The protein levels of Nrf2,phosphorylated Nrf2,heme oxygenase 1,and apoptotic proteins (Bcl2 and Bax) were determined by Western blotting.In addition,cell viability,Nrf2 expression,and apoptosis rate were determined after co-application of the Nrf2-specific agonist sulforaphane. Results Compared with the control group,40,60,80,100 µmol/L pterostilbene reduced the viability of LoVo cells (P=0.014,P<0.001,P<0.001,P<0.001).Pterostilbene at 5,10,20 µmol/L did not show effects on cell viability but inhibited cell migration (P=0.008,P<0.001,P<0.001) and invasion (all P<0.001).Pterostilbene at 40,60,80 µmol/L increased apoptosis (P=0.014,P<0.001,P<0.001),promoted mitochondrial membrane potential depolarization (P=0.026,P<0.001,P<0.001) and reactive oxygen species accumulation (all P<0.001),and down-regulated the expression of phosphorylated Nrf2 (P=0.030,P<0.001,P<0.001),heme oxygenase 1 (P=0.015,P<0.001,P<0.001),and Bcl2 (P=0.039,P<0.001,P<0.001) in LoVo cells.Pterostilbene at 60,80 µmol/L down-regulated Nrf2 expression (P=0.001,P<0.001) and up-regulated Bax expression (both P<0.001).The application of sulforaphane reversed the effects of pterostilbene on cell viability (P<0.001),apoptosis (P<0.001),and Nrf2 expression (P=0.022). Conclusion Pterostilbene is a compound that can effectively inhibit colon cancer cells by inhibiting the Nrf2 pathway.

Full-State Controls of Terahertz Waves Using Tensor Coding Metasurfaces.

Coding metasurfaces allow us to study metamaterials from a fully digital perspective, enabling many exotic functionalities, such as anomalous reflections, broadband diffusions, and polarization conversion. Here, we propose a tensor coding metasurface at terahertz (THz) frequency that could take full-state controls of an electromagnetic wave in terms of its polarization state, phase and amplitude distributions, and wave-vector mode. Owing to the off-diagonal elements that dominant in the reflection matrix, each coding particle could reflect the normally incident wave to its cross-polarization with controllable phases, resulting in different coding digits. A 3-bit tensor coding metasurface with three coding sequences is taken as an example to show its full-state controls in reflecting a normally incident THz beam to anomalous directions with cross-polarizations and making a spatially propagating wave (PW) to surface wave (SW) conversion at the THz frequency. We show that the proposed PW-SW convertor based on the tensor coding metasurface supports both x- and y-polarized normal incidences, producing cross-polarized transverse-magnetic and transverse-electric modes of THz SWs, respectively.