%0 Journal Article
%T 532 nm Low-Power Laser Irradiation Recovers ¦Ã-Secretase Inhibitor-Mediated Cell Growth Suppression and Promotes Cell Proliferation via Akt Signaling
%A Yumi Fukuzaki
%A Haruna Sugawara
%A Banri Yamanoha
%A Shinichi Kogure
%J PLOS ONE
%D 2013
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0070737
%X Background and Objective The ¦Ã-secretase inhibitor (GSI) has been shown to inhibit expression of amyloid beta (A¦Â), but GSI also has a side effect of reducing cell survival. Since low-power laser irradiation (LLI) has been known to promote cell survival, we examined whether 532 nm LLI can rescue the GSI side effect or not. Study Design/Materials and Methods The human-derived glioblastoma cells (A-172) were cultured in 35 mm culture dishes or 96-well plate. The center of dish or selected wells was irradiated with 532 nm laser (Nd:YVO4, CW, 60 mW) for 20, 40 and 60 min, respectively. The irradiated cells were photographed at immediately after, 24 and 48 h later and counted. GSI was supplemented in medium 3 h before LLI. The MTT assay was also used to estimate viable cells at 48 h after irradiation. The expression of phosphorylated Akt (p-Akt) or phosphorylated PTEN (p-PTEN) was examined by immunofluorescent staining and measured by fluorescence intensity using the software (BZ-9000, KEYENCE, Japan). Results GSI application depressed cell proliferation as well as cell survival compared to control. GSI down-regulated A¦Â but up-regulated p-PTEN and suppressed p-Akt. Application of 532 nm LLI in the presence of GSI significantly recovered the GSI-mediated effects, i.e., LLI could decrease elevated p-PTEN, while increased p-Akt expression with keeping A¦Â suppression. The LLI effects had a dose-dependency. Conclusion We confirmed that GSI potently suppressed intracellular A¦Â and decreased cell survival. We conclude that a combination of GSI application and 532 nm LLI can increase cell proliferation via Akt activation while keeping PTEN and A¦Â suppressed.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0070737