Cepharanthine Inhibits Doxorubicin-Induced Cellular Senescence by Activating Autophagy via the mTOR Signaling Pathway

Doxorubicin (Dox) is a clinical first-line broad-spectrum anticancer agent. A dose-dependent cardiotoxic and myelosuppressive response limits the clinical use of Dox. Recent research indicates that Dox-induced cardiotoxicity is associated with senescent cell accumulation and that antiaging therapy can alleviate aging-related disorders. Cepharanthine (Cep) is commonly used to treat various acute and chronic illnesses, including leukopenia, snakebites, dry mouth, and hair loss. Whether Cep alleviates Dox-induced senescence is unknown.

The expression of genes and proteins associated with aging was examined using NIH3T3 cell lines. The experiments were divided into a control group, a Dox group, and a Cep group on different days. NIH3T3 senescent cells were detected by senescence-β-galactosidase (SA-β-Gal) staining, and Western blotting was used to detect the protein levels of p16, p53, AMP-activated protein kinase (AMPK), mammalian target of the rapamycin (mTOR), p62, and Light Chain 3 (LC3). Fluorescence was used to detect the expression of monomeric red fluorescence protein-green fluorescence protein-Light Chain 3 (mRFP-GFP-LC3) and LC3 puncta in NIH3T3 cells. Real-time quantitative reverse transcription polymerase chain reaction (RT‒qPCR) was used to test the expression of senescence-associated secretory phenotypes (SASP: Interleukin 6 (IL-6), Interleukin 1 beta (IL-1β), and Interleukin 8 (IL-8)). Cell Counting Kit-8 (CCK-8) was used to assess NIH3T3 cell viability.

Here, we reported that Cep reversed the Dox-induced increase in the proportion of SA-β-Gal-positive cells and the high expression of aging-related proteins (p53, p < 0.05; p16, p < 0.05) and aging-related genes (IL-6, p < 0.05; IL-1β, p < 0.05; IL-8, p < 0.05) on the 3rd day. Mechanistically, Cep reduced the increase in the levels of phospho-mTOR (p < 0.05) on Days 1 and 3 and p62 protein (p < 0.05) caused by Dox on Day 1 and reversed the decline in LC3II/LC3I levels (p < 0.05) caused by Dox on Day 3, which is associated with the regulation of senescence. Additionally, the viability of NIH3T3 cells was significantly increased in the concentration range of 0.5-5 μM Cep (p < 0.05).

We first found that Cep could suppress SA-β-Gal activity (p < 0.05) and the development of SASP. Additionally, in Cep-treated cells, Cep could restore autophagy dysfunction and suppress the mTOR signaling pathway. This research provides a new view on the mechanics of aging and autophagy and aids in developing novel antiaging drugs.