Paeoniflorin promotes therapeutic senescence in melanoma through endoplasmic reticulum stress and the calpain1/ERK5/p27 axis.

BACKGROUND

Skin cutaneous melanoma (SKCM) is a highly aggressive malignancy with increasing global incidence and limited therapeutic options in advanced stages. Cellular senescence, characterized by irreversible growth arrest and tumor suppression, has emerged as a promising therapeutic approach.

PURPOSE: This study aimed to investigate the anti-tumor and senescence-inducing effects of paeoniflorin on SKCM and to elucidate its underlying molecular mechanisms.

STUDY

DESIGN

Paeoniflorin was evaluated through in vitro, in vivo, and bioinformatic analyses to determine its impact on melanoma progression and to clarify the involvement of the endoplasmic reticulum (ER) stress/calpain1/ERK5 signaling pathway.

METHODS

Publicly available SKCM datasets were analyzed to evaluate the correlation between senescence-associated genes (RRAS, CDKN1B, LAMA1, and CDC25A) and patient prognosis. The effects of paeoniflorin on melanoma cells were examined by immunofluorescence, β-galactosidase staining, western blotting, electron microscopy, and calpain activity assays. Chemical inhibitors and siRNA were applied to verify the functional role of calpain1. Positron emission tomography/computed tomography (PET/CT) imaging, histopathological analysis, and metastasis assays were performed to assess the in vivo efficacy of paeoniflorin.

RESULTS

Bioinformatic analysis revealed that high expression of RRAS and CDKN1B was associated with favorable prognosis, whereas elevated LAMA1 and CDC25A indicated poor survival outcomes in SKCM. Paeoniflorin treatment induced DNA damage, G2/M phase arrest, and senescence in melanoma cells, accompanied by enhanced ER stress, increased calpain1 activity, and downregulated ERK5 expression. Inhibition or knockdown of calpain1 reversed these effects. In mouse models, paeoniflorin markedly reduced tumor growth and metastasis, effects that were abolished by calpain1 silencing. Mechanistically, paeoniflorin triggered calpain1-dependent ERK5 degradation and p27 upregulation, leading to cellular senescence and tumor suppression.

CONCLUSIONS

Paeoniflorin induces melanoma cell senescence through the ER stress/calpain1/ERK5/p27 signaling axis, suggesting its potential as a novel therapeutic strategy against SKCM.