In vivo study on IL-37 inhibition of malignant melanoma metastasis.

OBJECTIVES

Malignant melanoma is highly aggressive, prone to early metastasis, and associated with extremely poor prognosis, posing a serious threat to human health. Identifying molecular mechanisms that inhibit metastasis is of great significance for improving treatment and prognosis. Interleukin-37 (IL-37), an anti-inflammatory cytokine, has not only been linked to various inflammatory diseases but also exhibits anti-tumor properties. This study aims to explore the effect of IL-37 on melanoma metastasis in vivo by establishing a murine model of pulmonary metastasis.

METHODS

Mouse melanoma B16F1 cells were transfected with either IL-37 overexpression plasmid (IL-37 oe) or empty vector. Three groups were set: An IL-37 oe group (transfection reagent+IL-37 oe plasmid), a Vector group (transfection reagent+vector plasmid), and a Blank group (transfection reagent only). C57 mice were randomly divided into 3 groups (=3 per group) and injected intravenously with logarithmic-phase B16F1 cells under sterile conditions. Mice were weighed every 3 days. After 1 month, mice were euthanized by cervical dislocation, and organs including lungs, heart, liver, spleen, and kidneys were harvested. Lung metastases were photographed and counted. Organs were fixed in 4% paraformaldehyde, embedded in paraffin, and stained with hematoxylin and eosin (HE).

RESULTS

Western blotting confirmed successful plasmid transfection. There were no significant differences in body weight among the 3 groups over the 28-day period (>0.05). Lung tumors were observed upon dissection, indicating successful metastasis modeling. HE staining showed no morphological differences in the heart, liver, spleen, and kidneys between groups. The numbers of lung metastases in the Blank, Vector, and IL-37 oe groups were (24.00±2.08), (24.67±0.88), and (5.33±1.45), respectively. The IL-37 oe group had significantly fewer lung metastases than the other 2 groups (<0.05), while no difference was observed between the Blank and Vector groups.

CONCLUSIONS

IL-37 significantly inhibits lung metastasis of malignant melanoma cells in mice without affecting body weight or major organs. It may serve as a potential molecular target for gene therapy or immunotherapy of malignant melanoma.