In the present study, we investigated the activation of protein kinase C （PKC） family in mouse embryonic fibroblast NIH3T3 cells using gadolinium chloride as a representative lanthanide ion. With live cell imaging system and confocal laser scanning microscopy, we found that the treatment of 50 μM GdCI3 promoted cell survival under the condition of serum-starvation. Moreover, better cell attachment and cytoskeleton reorganization were also observed. Additionally, GdC13 treatment resulted in the phosphorylation of PKC family at different time points. Furthermore, bisindolylmaleimide （a PKCpan inhibitor） could efficiently reduce the level of phosphorylated PKCpan （βIISer660）, alleviating ERK activation induced by GdC13. This finding indicated that the PKC activation was involved in GdC13-induced MAPK/ERK signaling and thus might contribute to GdClβ-indueed cell cycle progression and cell survival.
In the present study, we investigated the transformed species and the absorptive mechanism of rare earth elements（REEs） in gastrointestinal（GI） tract, using La Cl3 and La Cit as representative compounds. Artificial gastric and intestinal fluids were used to simulate the environment of the digestive tract in vivo. The inductively coupled plasma mass spectrometry（ICP-MS） result showed that more than 99.9% of La Cl3 and La Cit formed precipitation in artificial intestinal fluid, with the average size distribution of 200 nm（2-h incubation） increasing to 600 nm（24-h incubation） determined by dynamic light scattering（DLS）, indicating the aggregation of the particles. The Fourier transform infrared spectroscopy（FTIR） analysis demonstrated that the constituents of these particles were mainly in the form of lanthanum phosphates. To explore the transport mechanism of REEs in GI tract, the mice Peyer＇s patches（PPs） and intestinal epithelium were separated to evaluate the content of lanthanum by ICP-MS following oral administration with 2 or 100 mg/kg/day of La Cit for 7 d. The results showed that the amount of lanthanum phosphate particles absorbed by PPs was significantly greater than that of intestinal epithelium, indicating that lanthanum particles might be phagocytosed mainly by M cells located in the follicle-associated epithelium（FAE） overlying PPs. Furthermore, Caco-2 cell monoculture and Caco-2/Raji B cell coculture models were established to simulate intestinal epithelial cells and FAE, respectively. The result showed that the transport of lanthanum in Caco-2/Raji B coculture model was significantly higher than that in Caco-2 monoculture model（about 60 times higher）, and the level of lanthanum in the basal compartment of Caco-2 monoculture model was very low, supporting that M cells were the main route for lanthanum phosphate particles to be transported and absorbed. Taken together, these data suggested that La Cl3 and La Cit in GI tract were absorbed mainly via M cells wit
Huixia HuangHuixue LiuXiaojie MaHui GuanXiaogai Yang
