Lung cancer persists in being the predominant contributing factor contributing to illness and death attributed to cancer worldwide, posing a significant public health challenge. Among its various subtypes, represents the most prevalent subtype of lung cancer, constituting approximately 80–85 % of the total number of lung cancer diagnoses globally (Sung et al., 2021). Alarmingly, around 68 % of NSCLC patients receive their diagnosis at advanced stages, frequently accompanied by distant metastases, rendering surgical interventions unfeasible and contributing to a dismal 5-year survival rate that falls below 5 % (Bade and Dela Cruz, 2020). The current therapeutic modalities, which include surgical procedures, chemotherapy, radiotherapy, targeted therapies, and immunotherapy, exhibit considerable limitations and fail to adequately manage the progression of NSCLC (Kopinski et al., 2021). Consequently, there is an imperative requirement to discover innovative therapeutic targets and develop strategies that will boost clinical outcomes and refine prognostic indicators for patients.

The state of mitochondrial dynamic imbalance, marked by an exaggerated occurrence of fission reactions within mitochondria or an overly extensive fusion of mitochondrial structures, plays a crucial role in influencing the energy metabolism of tumor cells, the control of apoptosis, and the potential for metastatic spread (Giacomello et al., 2020). When mitochondrial fission is excessively activated, it leads to fragmentation of mitochondria, disrupting the functionality of the respiratory chain, diminishing ATP production, and elevating the concentrations of reactive oxygen species (ROS) (Pickles et al., 2018). This persistent fragmentation can obstruct mitophagy, resulting in the accumulation of dysfunctional mitochondria (Chan, 2020). Conversely, excessive mitochondrial fusion can lead to abnormal mitochondrial enlargement, compromising their functionality and further escalating ROS production (Kraus and Ryan, 2017). Several critical regulators govern mitochondrial dynamics, including dynamin-related protein 1 (DRP1), mitofusin 2 (MFN2), mitofusin 1 (MFN1), mitochondrial fission 1 protein (FIS1), and optic atrophy 1 (OPA1) (Losón et al., 2013). DRP1, a cytosolic guanosine triphosphatase (GTPase), is indispensable for the fission of mitochondria. Under physiological conditions, DRP1 is predominantly found as monomeric units within the cytosol and relocates to the outer external of the mitochondria during the process of mitochondrial fission. This translocation is modulated by post-translational modifications, including phosphorylation (Kashatus et al., 2015). For example, protein kinase D (PKD), a serine/threonine kinase, phosphorylates DRP1 at serine 637, enhancing its recruitment to mitochondria and promoting fission activity (Jhun et al., 2018). Excessive expression of PKD causes an increase in the fragmentation of mitochondria. Additionally, phosphorylation of serine 616 on DRP1 by protein kinase C (PKC) enhances its GTPase activity, further propelling the mitochondrial fission process (Tseng et al., 2019).

Dyn B, an endogenous opioid peptide, exerts biological effects primarily through κ-opioid receptor (KOR) activation (Shippenberg et al., 2007). Accumulating evidence indicates that Dyn B exerts significant effects in diverse physiological and pathological processes, including regulating neurotransmission, modulating mood, and influencing pain perception (Bustamante-Barrientos et al., 2023; Schwarzer, 2009; Fallon and Leslie, 1986). Disruption of the equilibrium between mitochondrial fusion and fission is recognized as a critical pathological feature of neurodegenerative diseases and Dyn B may influence the progression of these diseases by regulating mitochondrial dynamism (Bustamante-Barrientos et al., 2023; Osellame and Duchen, 2013). For instance, in Parkinson's disease models, Dyn B ameliorates neuronal damage by enhancing mitochondrial fusion capacity (Mandal et al., 2022). In neuronal cells, Dyn B modulates DRP1 expression and activity (Wang et al., 2020), potentially via protein kinase A (PKA)- and PKC-dependent phosphorylation cascades (Terrian et al., 1991; Bu et al., 2020). Emerging evidence implicates Dyn B in cancer pathogenesis, particularly in NSCLC, where its expression correlates with tumor aggressiveness, metastatic potential, and patient survival (Dalefield et al., 2022). Mechanistically, Dyn B activates KOR to induce apoptosis via caspase-3/caspase-9 pathways and suppresses proliferation by downregulating cyclin D1 (Maestroni, 1998). However, the molecular mechanisms through which Dyn B regulates mitochondrial dynamics and function in NSCLC have not been explored to date.

The objective of this research is to conduct a thorough examination of the effects of Dyn B on both the functionality and structural characteristics of mitochondria within NSCLC cells. Furthermore, this study seeks to clarify the molecular mechanisms involved, ultimately offering new perspectives for the creation of targeted treatment approaches for NSCLC.