Innovative role of the antidepressant imipramine in esophageal squamous cell carcinoma treatment: Promoting apoptosis and protective autophagy

Background: Esophageal squamous cell carcinoma (ESCC) is among the most prevalent malignant tumors; it is associated with dismal prognosis, and effective therapeutic agents are lacking. Depression is prevalent concern among cancer patients and is linked to diminished quality of life, poor adherence to treatment, heightened risk of suicide, and poorer prognosis. Imipramine (IM) is a tricyclic antidepressant with anti-inflammatory activity. Recent reports have indicated antitumor effects of IM in various cancers, although its role in ESCC remains unclear. Methods: The depression status of patients with ESCC was graded with the Patient Health Questionnaire-9, and the effects of antidepressants (moclobemide, milnacipran, venlafaxine, escitalopram, amitriptyline, trazodone, fluvoxamine, and IM) on cell viability were evaluated through CCK-8 assays. The effects of IM on cell proliferation were evaluated through clone formation assays, whereas Transwell assays were used to assess effects on ESCC cell migration and invasion. IM-induced apoptosis was confirmed with annexin V-FITC/Caspase-3 assays, and immunofluorescence staining was used to investigate the formation of IM-induced autophagosomes. Furthermore, western blotting analysis was conducted to determine the expression levels of apoptosis- and autophagy-related proteins. RNA sequencing (RNA-seq) was used to examine signaling pathway changes. Finally, we investigated the influence of IM on tumor progression in vivo in a xenograft model. Results: The PHQ-9 scores of patients with ESCC were higher than those of healthy controls and positively correlated with the TNM stage of ESCC. Among the antidepressants examined in our study, IM demonstrated the most potent inhibitory effect on ESCC cell viability, and effectively suppressed the proliferation, migration, and invasion of ESCC cells. Additionally, IM treatment induced apoptosis and autophagy in ESCC cells. Furthermore, blocking autophagy with chloroquine (CQ) intensified IM-induced apoptosis, thereby suggesting a protective role of cellular autophagy against apoptosis. RNA-seq results indicated that the Hippo pathway was associated with IM treatment. Upregulation of YAP reversed the apoptosis and autophagy triggered by IM, and targeting YAP intensified this effect. Finally, in animal experiments, IM hindered the growth of ESCC cells and promoted apoptosis and autophagy in tumors while causing minimal toxicity. Conclusion: Our findings provide the first reported evidence that IM triggers apoptosis and protective autophagy in ESCC cells via the Hippo signaling pathway, thus suggesting that IM may offer a promising therapeutic approach for patients with ESCC and depression.