TY - JOUR
T1 - Inhibition of Akt/protein kinase B signaling by naltrindole in small cell lung cancer cells
AU - Chen, Yulong L.
AU - Law, Ping-Yee
AU - Loh, Horace H
PY - 2004/12/1
Y1 - 2004/12/1
N2 - The phosphatidylinositol 3-kinase-Akt/protein kinase B (PKB) survival signaling is very important for cancer cell survival and growth. Constitutively active phosphatidylinositol 3-kinase-Akt/PKB signaling in small cell lung cancer (SCLC) is a major factor for the survival of SCLC cells. Inhibitors of this signaling pathway would be potential antitumor agents, particularly for SCLC. Here we report that naltrindole, which has been used as a classic δ opioid antagonist, inhibited growth and induced apoptosis in the three characteristic SCLC cell lines, NCI-H69, NCI-H345, and NCI-H510. Naltrindole treatment reduced constitutive phosphorylation of Akt/PKB on serine 473 and threonine 308 in cells. We found that the levels of constitutive phosphorylation of Akt/PKB on serine 473 correlate with the sensitivity of the three cell lines to naltrindole treatment. Furthermore, naltrindole treatment not only reduced the phosphorylation of the Akt/PKB upstream kinase phosphoinositide-dependent kinase-1. but also its downstream effectors glycogen synthase kinase-3β and the Forkhead transcription factors AFX and FKHR. DNA array analysis of 205 apoptosis-related genes indicated that some Akt/PKB-dependent genes were either up- or down-regulated by naltrindole. Flow cytometric and microscopic analyses clearly showed that naltrindole induced apoptosis in SCLC cells. RNA interference experiments confirmed that naltrindole-induced cell death was associated with the Akt/PKB survival pathway. Together, these results show that naltrindole is a new inhibitor of the Akt/PKB signaling pathway, suggesting that naltrindole could be a potential lead for the development of a new type of inhibitors that target the constitutively active Akt/PKB signaling-dependent SCLC cells.
AB - The phosphatidylinositol 3-kinase-Akt/protein kinase B (PKB) survival signaling is very important for cancer cell survival and growth. Constitutively active phosphatidylinositol 3-kinase-Akt/PKB signaling in small cell lung cancer (SCLC) is a major factor for the survival of SCLC cells. Inhibitors of this signaling pathway would be potential antitumor agents, particularly for SCLC. Here we report that naltrindole, which has been used as a classic δ opioid antagonist, inhibited growth and induced apoptosis in the three characteristic SCLC cell lines, NCI-H69, NCI-H345, and NCI-H510. Naltrindole treatment reduced constitutive phosphorylation of Akt/PKB on serine 473 and threonine 308 in cells. We found that the levels of constitutive phosphorylation of Akt/PKB on serine 473 correlate with the sensitivity of the three cell lines to naltrindole treatment. Furthermore, naltrindole treatment not only reduced the phosphorylation of the Akt/PKB upstream kinase phosphoinositide-dependent kinase-1. but also its downstream effectors glycogen synthase kinase-3β and the Forkhead transcription factors AFX and FKHR. DNA array analysis of 205 apoptosis-related genes indicated that some Akt/PKB-dependent genes were either up- or down-regulated by naltrindole. Flow cytometric and microscopic analyses clearly showed that naltrindole induced apoptosis in SCLC cells. RNA interference experiments confirmed that naltrindole-induced cell death was associated with the Akt/PKB survival pathway. Together, these results show that naltrindole is a new inhibitor of the Akt/PKB signaling pathway, suggesting that naltrindole could be a potential lead for the development of a new type of inhibitors that target the constitutively active Akt/PKB signaling-dependent SCLC cells.
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U2 - 10.1158/0008-5472.CAN-03-3091
DO - 10.1158/0008-5472.CAN-03-3091
M3 - Article
C2 - 15574783
AN - SCOPUS:9244256817
VL - 64
SP - 8723
EP - 8730
JO - Cancer Research
JF - Cancer Research
SN - 0008-5472
IS - 23
ER -