1% 3. 6% and 32. 9% 3. 7% viable cells, respectively. meanwhile Interestingly, the changes in cell viability were more pronounced Inhibitors,Modulators,Libraries in the cells treated under normal culture conditions than in those grown in media contain ing 1% FBS. PARP cleavage also was not detected in H226B Akt1 DD cells exposed to glucosamine, and we detected only minimal induction of PARP cleavage in H226B Babe cells treated with 10 and 20 mM glucosamine. These results suggest that constitu tive activation of Akt1 may inhibit the anti proliferative effect of glucosamine. Glucosamine affects the stability of IGF 1R in a post translational modification and proteasome dependent manner We next investigated whether the suppression of IGF 1R Akt signal transduction by glucosamine occurred at the transcriptional and or translational level.

First, we ob served that glucosamine treatment did not change the levels of either IGF 1R or COX 2 mRNA. These findings led us to examine whether the observed decrease in the IGF 1R protein level following exposure to glucosamine was associated with the stability Inhibitors,Modulators,Libraries of the IGF 1R protein. The proteasome inhibitor MG132 restored the IGF 1R level in cells treated with 1 mM glucosamine but not in cells treated with 5 mM glucosamine. In contrast, pAkt expression was fully rescued in cells treated with 1 mM glucosamine. A previous study reported that glucosamine accelerated the proteasome dependent degradation of only the higher molecular weight species of COX 2, however, our results showed that both higher and lower molecular weight species of COX 2 were re stored when cells were treated with either 1 mM or 5 mM glucosamine.

In addition to COX 2, the molecular mass of prototype IGF 1R was also reduced by glu cosamine in a dose dependent manner. We next explored whether the glucosamine induced decrease in the level of IGF 1R protein involved the translation process. Cycloheximide, a ribosomal inhibitor, inhibited the de novo biosynthesis Inhibitors,Modulators,Libraries of pro IGF 1R in A549 cells, and glucosamine did not affect the IGF 1R, pAkt, and COX 2 levels. These findings collectively suggest that glucosamine may induce the hypoglycosylation of pro IGF 1R and COX 2 and facilitate their degradation at the post translational level. Besides, more recent studies have shown that glucosa mine inhibits N glycosylation of certain proteins including COX 2, glucose transporter1, and a lipoprotein apo B 100.

Therefore, we next tested whether glucosamine induces abnormal Inhibitors,Modulators,Libraries N glycosylation of pro IGF 1R protein. As shown in Figure 5D, glucosamine treatment obviously prevented pro IGF 1R glycosylation in concentration dependent manner, resulting in low Inhibitors,Modulators,Libraries molecular mass of that. Tunicamycin, the protein N glycosylation in hibitor, was used as a positive control to confirm the effect of Gemcitabine synthesis glucosamine on pro IGF 1R N glycosylation.