Pituitary neuroendocrine tumours (PitNETs) are the second most common type of intracranial tumour in humans. They are benign neoplasms that account for 10 % to 15 % of all intracranial masses [1], [2]. Among the key pituitary transcription factors, PitNETs can be classified into three major lineages: PIT1 (pituitary-specific transcriptional factor-1), TPIT (T-box transcription factor 19), and SF1 (Steroidogenic factor1) [3]. Currently, medical treatment, either as first-line or adjuvant treatment, plays a significant role in the treatment of PitNETs,. Dopamine agonists (bromocriptine and cabergoline) and somatostatin receptor agonists (octreotide, lanreotide, and pasireotide) are the few approved medications for the pharmacological treatment of PIT1 and TPIT lineage PitNETs, such as prolactinoma, acromegaly and Cushing's disease [4]. These drugs are effective in reducing tumour size and inhibiting hormone secretion. However, up to 25 % of prolactinoma patients and over 50 % of acromegaly and Cushing's disease patients experience drug resistance, and there are no effective drugs available to treat PitNETs of the SF1 lineage [4], [5], [6]. Thus, the identification of potential therapeutic targets and drugs is urgently needed.

High-throughput screening (HTS), a crucial technology used in compound discovery to identify hits from compound libraries of interest, is widely used in relation to traditional tumours. For diffuse midline glioma, a combinatorial high-throughput drug screen of a group of 2706 approved and investigational drugs was conducted and identified concomitant histone deacetylase (HDAC) and proteasome inhibition was identified as promising therapeutic strategies [7]. Similar attempts have also been made in relation to PitNETs. Due to the application of high-throughput drug screening, a novel inhibitor (Fimepinostat) of corticotroph tumour adrenocorticotropic hormone (ACTH) secretion and growth was identified from a kinase inhibitor library [8]. Therefore, the identification of novel, efficacious drugs for the treatment of pituitary neuroendocrine tumours via high-throughput drug screening is entirely feasible.

Cuproptosis, a recently discovered new type of cell death, is distinct from other types of cell death such as apoptosis, necroptosis, autophagy [9] and ferroptosis [10]. Like ferroptosis, cuproptosis is a copper-dependent cell death pathway characterized by the accumulation of intracellular copper ions [11]. A previous study [11], [12] showed that the lethal mechanism of cuproptosis involves the disruption of specific mitochondrial metabolic enzymes in the mitochondrial tricarboxylic acid (TCA) cycle, especially the oligomerization of dihydrolipoamide S-acetyltransferase (DLAT) through lipoic acid modification and the loss of Fe-S cluster proteins, ultimately leading to proteotoxic stress and cell death. Recently, other mechanisms [13], such as p53, which acts as an important metabolic regulator that mediates the transition from glycolysis to oxidative phosphorylation, enhances Fe-S cluster biogenesis and orchestrates the level of the copper chelator glutathione (GSH) to regulate cuproptosis, have been shown to be involved in cuproptosis [14]. The role of cuproptosis has been studied in esophageal squamous cell carcinoma [15], triple- negative breast cancer [16] and glioblastoma [17].Therefore, targeting cuproptosis drugs provides a new perspective for the treatment of tumours, with an emphasis on the most representative copper ionophores and chelators [18], [19], [20].

In this study, HTS with 1913 Food and Drug Administration (FDA)-approved clinical drugs was performed using the CellTiter-Glo® luminescence assay to evaluate the viability of primary PitNET cell cultures. A class of copper ionophores that can effectively inhibit cell growth was identified. Subsequent experiments initially validated the dose-dependent cytotoxic effect of these copper ionophores on pituitary neuroendocrine tumour cell lines as well as several primary-derived PitNET cell cultures. Moreover, we determined that cell death occurs via cuproptosis. In conclusion, our findings suggest that DSF holds promise as a potential therapeutic drug for PitNETs and that the cuproptosis pathway may represent a valuable target for further investigation.