IKKα inactivation promotes Kras-initiated lung adenocarcinoma development through disrupting major redox regulatory pathways.

Abstract

Lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC) are two distinct and predominant types of human lung cancer. IκB kinase α (IKKα) has been shown to suppress lung SCC development, but its role in ADC is unknown. We found inactivating mutations and homologous or hemizygous deletions in the <i>CHUK</i> locus, which encodes IKKα, in human lung ADCs. The <i>CHUK</i> deletions significantly reduced the survival time of patients with lung ADCs harboring <i>KRAS</i> mutations. In mice, lung-specific <i>Ikkα</i> ablation (<i>Ikkα</i>^<i>ΔLu</i> ) induces spontaneous ADCs and promotes Kras^G12D-initiated ADC development, accompanied by increased cell proliferation, decreased cell senescence, and reactive oxygen species (ROS) accumulation. IKKα deletion up-regulates NOX2 and down-regulates NRF2, leading to ROS accumulation and blockade of cell senescence induction, which together accelerate ADC development. Pharmacologic inhibition of NADPH oxidase or ROS impairs Kras^G12D-mediated ADC development in <i>Ikkα</i>^<i>ΔLu</i> mice. Therefore, IKKα modulates lung ADC development by controlling redox regulatory pathways. This study demonstrates that IKKα functions as a suppressor of lung ADC in human and mice through a unique mechanism that regulates tumor cell-associated ROS metabolism.