Anticancer Effects of Nortriptyline Hydrochloride in Osteosarcoma Cells Including Doxorubicin-resistant Cells

<h3>Background/Aim:</h3> Osteosarcoma (OS), the most common primary malignant bone tumor, is associated with a high risk of recurrence and metastasis, leading to poor prognosis. This study explored the potential use of drug repositioning by investigating nortriptyline hydrochloride (NTP) in osteosarcoma treatment. NTP, a classic tricyclic antidepressant used to treat psychiatric disorders, has been shown to have antitumor activity against several cancer types. <h3>Materials and Methods:</h3> We investigated the inhibitory effects of NTP on OS cell proliferation and migration. The anticancer activity of NTP was evaluated in terms of cell viability, chemical rescue by cell death inhibitors, lactate dehydrogenase (LDH) release, cytoskeletal staining, and cell cycle analysis. NTP inhibited the proliferation of OS cells and induced G₀/G₁ phase cell cycle arrest in a dose-dependent manner. <h3>Results:</h3> The IC₅₀ values of NTP were 24.2 μM and 15.8 μM for U2OS and MG-63 cell proliferation, respectively. Chemical rescue using cell death inhibitors and LDH release assays showed that the anticancer effects of NTP was mainly attributed to the inhibition of cell proliferation. Additionally, NTP inhibited cell migration, disrupted actin filament formation, and altered intracellular distribution. Furthermore, NTP retained growth inhibitory activity in doxorubicin-resistant OS cells. <h3>Conclusion:</h3> NTP may serve as a novel therapeutic agent for preventing OS growth and metastasis.