Huang H, Wang X, Zhang S, Bai X, Griffin N, Shan Y, Shan F. In vitro and in vivo killing effects of methionine enkephalin on osteosarcoma.
Int Immunopharmacol 2023;
125:111226. [PMID:
37976597 DOI:
10.1016/j.intimp.2023.111226]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/04/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023]
Abstract
OBJECTIVE
This study aimed to investigate the underlying regulatory effects of methionine enkephalin (MENK) on osteosarcoma.
METHODS
The Cell Counting Kit-8 assay, clone formation, wound healing, transwell assay, and flow cytometry were performed to measure the effects of MENK on the proliferation, migration, invasion, and apoptosis of MG-63 and Saos-2 cells. Opiate growth factor receptor expression (OGFr) in cells was stably knocked down using siRNA. A tumor model was established by inoculating MG-63 cells into mice. Flow cytometry was performed to identify alterations in mice bone marrow, spleen, and tumor tissue immune cells. The phenotype of tumor-associated macrophages was determined using immunohistochemistry. After OGFr knockdown or/and treatment with MENK, Bax, Bcl-2, caspase 3, caspase 9, and PARP expression levels were characterized using qRT-PCR, western blot, and WES, respectively.
RESULTS
MENK could significantly inhibit the proliferation, invasion, and migration of MG-63 and Saos-2, arrest the cell cycle in the G0/G1 phase, upregulate Bax, caspase 3, caspase 9, and PARP expression, and downregulate Bcl-2 expression. Tumor size and weight were lower in the MENK group than those in the control group. MENK-treated mice exhibited a reduced ratio of CD11b + Gr-1 + myeloid-derived suppressor cells. MENK increased the ratio of M1-type macrophages and decreased the proportion of M2-type macrophages in tumor tissue. Furthermore, the level of TNF-α significantly increased while that of IL-10 decreased in MENK-treated mice. The effect of MENK could be partly reversed by OGFr knockdown.
CONCLUSION
MENK reduces the abundance of myeloid-derived suppressor cells, induces M1 polarization of macrophages, and exhibits an inhibitory effect on osteosarcoma.
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