Silencing PADI-2 induces antitumor effects by downregulating NF-κB, Nrf2/HO-1 and AKT1 in A549 lung cancer cells.

Objective: This study aimed to investigate the tumorigenic role and regulatory pathways of peptidyl arginine deiminase 2 (PAD-2) in A549 lung cancer cells following treatment with small interfering RNA (PADI-2 siRNA) or the pharmacological pan-PAD inhibitor BB-Cl amidine.

Materials And Methods: A549 lung cancer cells were treated with PADI-2 siRNA to knock down PADI-2 expression or with BB-Cl amidine to inhibit PAD2 activity. The effects on cell proliferation, migration, invasion, and cell cycle phases were assessed. Additionally, the expression levels of nuclear factor erythroid 2 p45-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), AKT serine/threonine kinase 1 (AKT), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukin 6 (IL6), and p53 were analyzed to elucidate the underlying mechanisms involved.

Results: The manipulation of PAD-2 expression or activity significantly influenced tumor cell behavior. Knockdown of PADI-2 in A549 cells reduced cell proliferation by inhibiting the S and G2 phases and decreasing cell migration and invasion. Inhibition of PADI-2 expression also suppressed the protein levels of Nrf2 and HO-1 via suppression of the AKT/NF-κB pathway. Furthermore, this inhibition enhanced the senescence-associated secretory phenotype (SASP) through the regulation of IL6 and p53, resulted in significant upregulation of SASP factors mainly, p21, Lamin B1 and HMGB1.

Conclusion: Downregulation of PADI-2 attenuated the proliferation, migration, and invasion of A549 lung cancer cells by modulating the Nrf2/HO-1/AKT signaling pathway. It also increased senescence in A549 lung cancer cells via IL6 and p53 key regulators. These findings highlight the potential of PADI-2 as a therapeutic target in lung cancer treatment.