MMP28 recruits M2-type tumor-associated macrophages through MAPK/JNK signaling pathway-dependent cytokine secretion to promote the malignant progression of pancreatic cancer.

Abstract

Background: Crosstalk between pancreatic cancer cells and tumor-associated macrophages (TAMs) is a critical driver of malignant progression, and plays an important role in the low response rate to immunotherapy in patients with for pancreatic cancer. Although it is known that cancer cells induce TAM infiltration and M2 polarization, the underlying mechanisms remain elusive. Herein, we identified matrix metalloproteinase 28 (MMP28), a highly expressed protein, as a key regulator of this process.

Methods: Immunohistochemical staining and qRT-PCR were used to validate MMP28 as a potential marker for the prognosis of patients with pancreatic cancer. We evaluated the tumor-promoting effect of MMP28 in vitro with CCK-8, Transwell, and EdU assay and Western blotting and explored the potential mechanism of MMP28-induced M2 polarization of TAMs with a coculture system, immunofluorescence staining and flow cytometry. A subcutaneous graft tumor model was constructed to assess the tumor-promoting effect of MMP28 and its ability to induce M2 TAM infiltration.

Results: The relevant results of this study revealed a strong correlation between MMP28 expression and TAM infiltration, with a predominance of M2-polarized TAMs in pancreatic cancer tissues. Mechanistic investigations demonstrated that MMP28 promotes the secretion of multiple cytokines, including IL-8 and VEGFA through the activation of the MAPK/JNK signaling pathway. These cytokines act as potent chemoattractants and polarizing factors for TAMs. Additionally, we discovered an interaction between MMP28 and ANXA2, which contributes to the regulation of TAM recruitment and polarization. In vivo studies confirmed the critical role of MMP28 in tumor growth and TAM infiltration. Depletion of macrophages, inhibition of JNK, or neutralization of IL-8 and VEGFA significantly suppressed tumor progression. Transcriptomic analysis suggested that IL-8 and VEGFA induce M2 TAM polarization by modulating TAM amino acid metabolism.

Conclusions: Collectively, our findings elucidate a novel mechanism by which pancreatic cancer cells manipulate the tumor microenvironment through MMP28-dependent cytokine secretion, promoting TAM infiltration and M2 polarization. These results highlight MMP28 as a promising therapeutic target for pancreatic cancer.