Pomalidomide sensitizes lung cancer cells to TRAIL/CDDP-induced apoptosis via directly targeting electron transfer flavoprotein alpha subunit

Immunomodulatory drugs (IMiDs) represented by thalidomide exhibit benefits when combined with other chemotherapeutic drugs for patients with lung cancer, which inspired the exploration of combining pomalidomide with another agent to treat lung cancer as it is more potent than thalidomide. However, the drugs that can be combined with pomalidomide to benefit patients and related mechanisms remain unclear. Here, we performed a proteomic analysis based on the streptavidin pull-down to identify the potential target of pomalidomide in non-small cell lung cancer (NSCLC). In this work, electron transfer flavoprotein alpha subunit (ETFA), an important enzyme involved in electron transport in the respiratory chains was identified as a crucial cellular target of pomalidomide in NCI-H460 cells. Using apoptosis model and combination analyses, we found that pomalidomide directly targeted ETFA, and increased ATP generation, thereby significantly promoting tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Specific knockdown of ETFA could effectively eliminate the promoting effect of pomalidomide on energy production. Furthermore, respiratory chain inhibitors can effectively block cell apoptosis induced by TRAIL and pomalidomide. These results suggested that pomalidomide may promote apoptosis by facilitating energy production by targeting ETFA and thus enhanced the anticancer effects of chemotherapeutic drugs. It is noteworthy that pomalidomide noticeably increased the anticancer efficacy of cisplatin (CDDP) in NCI-H460 xenograft model with the main mechanisms by inducing apoptosis. Collectively, our data not only provide new insights into the anticancer mechanisms of pomalidomide but also reflect translational prospects of combining pomalidomide with CDDP for NSCLC treatment.