Alpha-Lipoic Acid-Mediated Inhibition of LTB4 Synthesis Suppresses Epithelial-Mesenchymal Transition, Modulating Functional and Tumorigenic Capacities in Non-Small Cell Lung Cancer A549 Cells

Abstract

Background

Leukotriene B₄ (LTB₄) plays a crucial role in carcinogenesis by inducing epithelial-mesenchymal transition (EMT), a process associated with tumor progression. The synthesis of LTB₄ is mediated by leukotriene A₄ hydrolase (LTA₄H), and it binds to the receptors BLT₁ and BLT₂. Dysregulation in LTB₄ production is linked to the development of various pathologies. Therefore, the identification or design of inhibitors of LTB₄ synthesis or receptor antagonists represents an ongoing challenge. In this context, our laboratory previously demonstrated that alpha-lipoic acid (ALA) inhibits LTA₄H. The objective of this study was to evaluate the effect of ALA on the expression of canonical EMT markers and the functional and tumorigenic capacities induced by LTB₄ in A549 cells.

Methods

The expression of cPLA₂, 5LOX, FLAP, LTA₄H, BLT1, and LTB₄ production in human adenocarcinomic alveolar basal epithelial A549 cells was assessed using Western blot, RT-qPCR, and ELISA, respectively. Subsequently, the expression of canonical EMT markers was evaluated by Western blot. Functional assays were performed to assess cell viability, proliferation, invasion, migration, and clonogenicity using MTT, Western blot, Transwell assays, and colony formation assays, respectively. Results were expressed as median with interquartile range (n≥3) and analyzed using the Kruskal-Wallis or Tukey multiple comparisons tests.

Results

A549 cells express key proteins involved in LTB₄ synthesis and receptor binding, including LTA₄H and BLT₁, and ALA inhibits the production of LTB₄. Additionally, LTA₄H and BLT1 were detected in lung adenocarcinoma tissue samples. LTB₄ was found to induce EMT, whereas ALA treatment enhanced the expression of epithelial markers and reduced the expression of mesenchymal markers. Furthermore, ALA treatment resulted in a decrease in LTB₄ levels and attenuated the functional and tumorigenic capacities of A549 cells, including their viability, migration, invasion, and clonogenic potential.

Conclusions

These findings suggest that ALA may offer therapeutic potential in the context of lung cancer, as it could be integrated into conventional pharmacological therapies to enhance treatment efficacy and mitigate the adverse effects associated with chemotherapy. Further studies are warranted to confirm the clinical applicability of ALA as an adjunctive treatment in lung cancer.