Targeting Endoplasmic Reticulum Stress and Akt with OSU-03012 and Gefitinib or Erlotinib to Overcome Resistance to Epidermal Growth Factor Receptor Inhibitors

Abstract

Preexisting and acquired resistance to epidermal growth factor receptor (EGFR) inhibitors limits their clinical usefulness in patients with advanced non-small cell lung cancer (NSCLC). This study characterizes the efficacy and mechanisms of the combination of gefitinib or erlotinib with OSU-03012, a celecoxib-derived antitumor agent, to overcome EGFR inhibitor resistance in three NSCLC cell lines, H1155, H23, and A549. The OSU-03012/EGFR inhibitor combination induced pronounced apoptosis in H1155 and H23 cells, but not in A549 cells, suggesting a correlation between drug sensitivity and basal phospho-Akt levels independently of EGFR expression status. Evidence indicates that this combination facilitates apoptosis through both Akt signaling inhibition and upregulation of endoplasmic reticulum (ER) stress-induced, GADD153-mediated pathways. For example, ectopic expression of constitutively active Akt significantly attenuated the inhibitory effect on cell survival, and small interfering RNAmediated knockdown of GADD153 protected cells from undergoing apoptosis in response to drug cotreatments. Furthermore, the OSU-03012/EGFR inhibitor combination induced GADD153-mediated up-regulation of death receptor 5 expression and subsequent activation of the extrinsic apoptosis pathway. It is noteworthy that the ER stress response induced by this combination was atypical in that the cytoprotective pathway was not engaged. In addition, in vivo suppression of tumor growth and modulation of intratumoral biomarkers were observed in a H1155 tumor xenograft model in nude mice. These data suggest that the concomitant modulation of Akt and ER stress pathways with the OSU-03012/EGFR inhibitor combination represents a unique approach to overcoming EGFR inhibitor resistance in NSCLC and perhaps other types of cancer with elevated basal Akt activities. [Cancer Res 2008;68(8):2820-30]

ER stress negatively regulates AKT/TSC/mTOR pathway to enhance autophagy

“…However, as drug resistance ultimately occurs, patients with poor prognosis have made up a considerable part. 42,45 Our data showed a significant deactivation of this signaling pathway, which may imply a more widely downregulatory effect. Thus, chemotherapy triggering ER stress for the cancer induced by hyperactivated AKT may be helpful for overcoming drug resistance.…”

“…39 Our study here revealed that the deactivation of AKT, as a downstream event of ER stress, led to the suppression of mTOR thus inducing autophagy. Interestingly, while large number of evidence support that ER stress downregulates AKT activity, 38,[40][41][42][43] it was also reported that AKT and ERK are rapidly activated and act as downstream effectors of PI3K in acute ER stress. 44 Considering that AKT and MAPK pathways are two major survival signaling cascades, cells may activate them through UPR to transmit survival signals and overcome the adverse condition, when ER stress is moderate and recoverable.…”

OSU-03012, a Novel Celecoxib Derivative, Induces Reactive Oxygen Species–Related Autophagy in Hepatocellular Carcinoma

“…OSU-03012 has been shown to induce apoptosis in non-small cell lung cancer (26) and breast cancer cells (27,28) through inhibition of PDK/AKT signaling pathway. However, only very limited PDK1 and AKT inhibition were detected in OSU-03012-treated Huh7 cells in this study, suggesting that OSU-03012 suppresses the growth of Huh7 cells through a mechanism different from PDK1 and AKT inhibition.…”

Matched miRNA and mRNA signatures from a hESC-based in vitro model of pancreatic differentiation reveal novel regulatory interactions

“…Equivalent amounts of proteins (,10 ng) were resolved by SDS-PAGE and then transferred to nitrocellulose membranes for immunoblotting as described previously (Wang et al, 2008b). The primary antibodies (SOX17 and CDH1) used here were the same as used for immunocytochemistry.…”