Alpha-Lipoic Acid Modulates Melanoma Survival Networks via ER Stress Induction, Mitochondrial Apoptosis, and Kinase Pathway Suppression in B16F10 Cells

Abstract

Background/Objectives: Malignant melanoma is characterized by constitutive PI3K/Akt/mTOR and MAPK activation, driving aggressive behavior and therapeutic resistance. Alpha-lipoic acid (αLA), a naturally occurring dithiol compound with an established clinical safety profile, has shown anticancer potential; however, its integrated molecular mechanisms in melanoma remain poorly defined. This study aimed to comprehensively evaluate the cytotoxic and mechanistic effects of αLA in B16F10 murine melanoma cells. Methods: Antiproliferative effects were assessed by MTT assay at four concentrations (250, 500, 750, 1000 µM) over 48 h. Protein levels of apoptotic markers (Bax, Bcl-2, Caspase-3, AIF), kinase signaling components (p-Akt, p-mTOR, p-ERK, p-JNK), ER stress markers (GRP78, GADD153/CHOP), and cell cycle regulator Wee1 were quantified by ELISA at a specifically selected sub-lethal concentration of 750 µM (inducing ~38% growth inhibition). Results: αLA dose-dependently inhibited B16F10 proliferation. At 750 µM, it triggered robust intrinsic apoptotic signaling, evidenced by a nearly 10-fold shift in the Bax/Bcl-2 ratio and greater than 9-fold Caspase-3 activation. Elevated AIF suggested profound mitochondrial stress and the potential priming of concurrent caspase-independent cell death mechanisms. αLA suppressed survival signaling by reducing p-Akt (44%), p-mTOR, p-ERK, and p-JNK. Treatment triggered lethal ER stress via GRP78 and GADD153/CHOP upregulation and upregulated Wee1, suggesting the induction of stress-responsive checkpoint signaling. The simultaneous CHOP upregulation and p-Akt suppression highlight a concurrent dysregulation of stress and survival pathways, suggesting a potential pro-apoptotic interplay. Conclusions: αLA exerts potent multi-target anticancer effects by inducing a broad spectrum of associated molecular changes, including the suppression of PI3K/Akt/mTOR and MAPK networks, induction of ER stress, engagement of cell cycle checkpoints, and activation of the mitochondrial Bax/Bcl-2/Caspase-3 axis. Importantly, these correlative findings do not establish proven pathway dependencies. Nevertheless, this concurrent dysregulation positions αLA as a potential disruptor of inter-pathway resilience underlying drug resistance.