NF-κB activation as a pro-survival signal from pharmacological inhibition of pyruvate dehydrogenase kinase 1 in non-small-cell lung carcinoma cell models

Targeting Pyruvate dehydrogenase kinase (PDK) has emerged as one of the potential therapeutic strategies for non-small cell lung carcinoma (NSCLC). 64, a recently reported PDK1 inhibitor derived from 2,2-dichloroacetophenone (DAP), exhibited promising anticancer effects in NSCLC models. Herein, we sought to investigate the mechanism of action of 64 in two NSCLC cell lines, namely, NCI-H1975 and NCI-H1650. We found that 64 induced intrinsic cancer cell apoptosis by releasing cytochrome C (CytC) from mitochondria, leading to caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavage, which was mediated by reactive oxygen species (ROS). Moreover, we have shown that 64 induced mitochondrial membrane potential (MMP) depolarization and AMPK/MAPK activations were also ROS driven. With the aid of sequencing studies and follow-up biochemical evaluations, we found that 64 activated the NF-κB pathway through P38 MAPK, while the combination of P38 MAPK inhibitor SB203580 with 64 diminished such activation. Interestingly, the combined use of 64 and NF-κB inhibitor (JSH-23) increased pro-apoptosis protein (Bax) expression and decreased pro-survival protein (Bcl-2) expression, resulting in enhanced cancer cell apoptosis via JNK pathway. Our results suggested that 64 induces cancer cell apoptosis in NSCLC models through ROS, while NF-κB activation serves as a survival mechanism upon PDK1 inhibition.