ficant reduction in growth in the presence of ciglita zone Navitoclax Bcl-w as determined by cell viability assay. Overe pression of PDK1 has been reported to correlate with tumor progression. We found that overe pression of PDK1 abrogated the effect of ciglitazone on cell growth and caspase 3 7 activity. Transfection with PDK1 e pression vector was confirmed by Western blot. Together, this suggested that ciglitazone not only inhibited growth but also increased apoptosis of lung cancer cells through, at least in part, the inhibition of PDK1. The role of AMPK and SAPK JNK in mediating the effect of ciglitazone on PDK1 protein e pression Studies by this group and others also demonstrated a role for AMPK in mediating the effect of PPAR�� ligands, such as thiazolinediones compounds, in different cell systems.
We showed that ciglitazone Inhibitors,Modulators,Libraries increased phosphorylation of AMPK and SAPK JNK with ma imal effect observed at 2 4 h in H1650 cells. Interestingly, the inhibitors of AMPK, compound C, but not of SAPK JNK, SP600125, blocked the inhibitory ef fect of ciglitazone on PDK1 protein e pression in both H1650 and H1299 Inhibitors,Modulators,Libraries cells. Similarly, silencing of AMPK abrogated the effect of ciglitazone on PDK1 protein. This indicates the specificity of AMPK activation in this process. Interestingly, com bination treatment of ciglitazone and metformin, an ac tivator of AMPK, further reduced the PDK1 protein e pression. Ciglitazone decreases PDK1 promoter activity independent of PPAR�� activation We also e amined if the effects of ciglitazone on PDK1 e pression occurred at the transcriptional level.
As shown in Figure 4A, the PDK1 gene promoter contains multiple transcription factor binding sites including PPRE, Egr 1, nuclear factor ��B and p53, Inhibitors,Modulators,Libraries among others. We found that NSCLC cells transfected with wild type PDK1 promoter luciferase reporter construct showed decreased activity when e posed to ciglitazone. As e pected, metformin enhanced the inhibitory effect of ciglitazone. Ne t, we assessed whether PPAR�� activation played a role in mediating the effect of ciglitazone on PDK1 pro moter activity. The effect of ciglitazone on inhibition of PDK1 promoter activity was not abrogated by PPAR�� siRNA. Note that PPAR�� siRNA blocked PPAR�� protein e pression. As e pected, we found Inhibitors,Modulators,Libraries that compound C re duced the effect of ciglitazone on PDK1 promoter activity.
The role of transcription factor Egr 1 in mediating the effect of ciglitazone on e pression of PDK1 and cell growth We further tested the role of the transcription factors in mediating the effect of ciglitazone on PDK1 e pression in human lung carcinoma cells. We showed that ciglita zone significantly induced the e pression of Egr 1 protein in a time dependent manner, while it had little Entinostat effect on p65 and p53. Note that a synergy was observed in the combination of ciglitazone and met formin treatment. Interestingly, we also found Y-27632 that silencing of AMPK abolished the effect of ciglitazone on Egr 1 protein e pression, further suggesting the critical