Dynorphin B induces mitochondrial fragmentation in NSCLC through the PKD/DRP-1 signaling pathway

Mitochondrial fragmentation and impairment are essential targets for therapeutic approach for non-small cell lung cancer (NSCLC), given their significant contributions to the persistence and progression of malignant cells. Dynorphin B (Dyn B), an endogenous opioid peptide, has been demonstrated for its involvement in an extensive array of cellular activities; however, its specific functions and mechanisms within the context of cancer remain largely undefined. To address this, we employed NCI-H2087 NSCLC cells treated with Dyn B (0.01-100 μM) and utilized lactate dehydrogenase (LDH) release and γ-glutamyl transpeptidase (GPT) activity assays to evaluate cytotoxicity. Mitochondrial function was assessed via Complex I activity assays, adenosine triphosphate (ATP) production measurements, and MitoSOX Green staining for reactive oxygen species (ROS). MitoTracker Red staining with ImageJ quantification characterized mitochondrial morphology, while Western blot analysis probed phosphorylation of dynamin-related protein 1 (DRP1) and protein kinase D (PKD). Lentiviral shRNA-mediated PKD silencing was used to validate functional rescue of mitochondrial dynamics. This investigation reveals that Dyn B induces cytotoxic effects in NCI-H2087 NSCLC cells by facilitating mitochondrial dysfunction and fragmentation. Treatment with Dyn B resulted in a significant augmentation of LDH and elevated GPT activity, indicating cellular injury. Additionally, Dyn B compromised mitochondrial functionality by reducing Complex I activity, diminishing ATP synthesis, and promoting mitochondrial ROS generation. Mechanistically, Dyn B triggered mitochondrial fragmentation through activation of DRP1 and PKD, without affecting protein kinase C (PKC). Silencing of PKD reversed Dyn B-induced mitochondrial fragmentation and restored mitochondrial functionality. These findings underscore the promising role of Dyn B as a prospective therapeutic agent in NSCLC, targeting mitochondrial dynamics via the PKD-DRP1 signaling pathway.