National Chung Hsing University

About: National Chung Hsing University is a education organization based out in Taichung, Taiwan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 19443 authors who have published 24060 publications receiving 540154 citations. The organization is also known as: NCHU.

Differential expression of branchial Na+/K(+)-ATPase of two medaka species, Oryzias latipes and Oryzias dancena, with different salinity tolerances acclimated to fresh water, brackish water and seawater.

Abstract: Previous studies on non-diadromous euryhaline teleosts introduced a hypothesis that the lowest level of gill Na + /K + -ATPase (NKA) activity occurs in the environments with salinity close to the primary natural habitats of the studied species. To provide more evidence of the hypothesis, two medaka species, Oryzias latipes and O. dancena , whose primary natural habitats are fresh water (FW) and brackish water (BW) environments, respectively, were compared from levels of mRNA to cells in this study. The plasma osmolalities of O. latipes and O. dancena were lowest in the FW individuals. The muscle water contents of O. latipes decreased with elevated external salinities, but were constant among FW-, BW-, and seawater (SW)-acclimated O. dancena . Expression of NKA, the primary driving force of ion transporters in gill ionocytes, revealed different patterns in the two Oryzias species. The highest NKA α-subunit mRNA abundances were found in the gills of the SW O. latipes and the FW O. dancena , respectively. The pattern of NKA activity and α-subunit protein abundance in the gills of O. latipes revealed that the FW group was the lowest, while the pattern in O. dancena revealed that the BW group was the lowest. Immunohistochemical staining showed similar profiles of NKA immunoreactive (NKIR) cell activities (NKIR cell number × cell size) in the gills of these two species among FW, BW, and SW groups. Taken together, O. latipes exhibited better hyposmoregulatory ability, while O. dancena exhibited better hyperosmoregulatory ability. Our results corresponding to the hypothesis indicated that the lowest branchial NKA activities of these two medaka species were found in the environments with salinities similar to their natural habitats.

Ursolic acid, a naturally occurring triterpenoid, suppresses migration and invasion of human breast cancer cells by modulating c-Jun N-terminal kinase, Akt and mammalian target of rapamycin signaling

Abstract: Metastasis is one of the most important factors related to breast cancer therapeutic efficacy. Ursolic acid, a naturally occurring triterpenoid, has various anticancer activities. In this study, we first observed that ursolic acid exerted a dose- and time-dependent inhibitory effect on the migration and invasion of highly metastatic breast MDAMB231 cells at non-cytotoxic concentrations. This effect was associated with reduced activities of metalloproteinase-2 (MMP-2) and u-PA, which correlated with enhanced expression of tissue inhibitor of MMP-2 and plasminogen activator inhibitor-1, respectively. Ursolic acid suppressed the phosphorylation of Jun N-terminal kinase, Akt and mammalian target of rapamycin, but had no effect on the phosphorylation of ERK and p38. Ursolic acid also strongly reduced the levels of NFκB p65, c-Jun and c-Fos proteins in the nucleus of MDAMB231 cells. A time-dependent inhibition of the protein levels of Rho-like GTPases, growth factor receptor-bound protein 2, Ras and vascular endothelial growth factor in cytosol by ursolic acid treatment was also observed. In conclusion, we demonstrated that the anti-invasive effects of ursolic acid on MDAMB231 cells might be through the inhibition of Jun N-terminal kinase, Akt and mammalian target of rapamycin phosphorylation and a reduction of the level of NFκB protein in the nucleus, ultimately leading to downregulation of MMP-2 and u-PA expression. These results suggest that ursolic acid has potential as a chemopreventive agent for metastatic breast cancer.