Niclosamide suppresses T‑cell acute lymphoblastic leukemia growth through activation of apoptosis and autophagy.

T‑cell acute lymphoblastic leukemia (T‑ALL) is a common pediatric malignancy, characterized by the abnormal presence of immature T‑cell progenitors. Conventional treatments for T‑ALL fail to prevent or cure the disease, with a high‑risk of recurrence after the first remission. Thus, medical options are in demand to develop novel therapies for patients suffering with T‑ALL. Niclosamide, a traditional oral anti‑helminthic drug, has been reported to be a potential anticancer agent that regulates intracellular signaling pathways. Few studies have yet investigated the effects of niclosamide on the development of T‑ALL. Here, the present study aimed to investigate the anti‑leukemia effects of niclosamide on T‑ALL. We first hypothesized that the suppressive effects of niclosamide on the tumor growth of T‑ALL are exerted by regulating autophagy and apoptosis. Following niclosamide treatment, T‑ALL cell viability was evaluated using MTT assay, and apoptosis with Annexin V/propidium iodide staining. In T‑ALL cells treated with niclosamide, changes in apoptosis‑ and autophagy‑related proteins were analyzed by western blotting. In addition, in an model, T‑ALL xenograft mice were used to study the anti‑leukemia effects of niclosamide. The results showed that niclosamide significantly reduced the viability of Jurkat and CCRF‑CEM T‑ALL cells in both a dose‑ and time‑dependent manner. Niclosamide significantly activated the early and late phases of apoptosis in Jurkat (at 2 µM) and CCRF‑CEM cells (at 1 µM). Furthermore, niclosamide upregulated protein expression of cleaved caspase‑3 and LC3B, while downregulated those of Bcl‑2 and p62, in a dose‑dependent manner in both Jurkat and CCRF‑CEM cells. The results showed that niclosamide treatment significantly suppressed tumor growth and the disease progression in T‑ALL xenograft mice by activating cleaved caspase‑3 and LC3B. We conclude that niclosamide plays an anti‑leukemia role, and that it represents a novel approach for the treatment of T‑ALL.