Metformin suppressed tendon injury-induced adhesion via hydrogel-nanoparticle sustained-release system.

Tendon adhesion is one of the sequelae of tendon injury and can lead to disability in severe cases. Metformin is a commonly used antidiabetic drug. Some studies had shown that metformin could reduce tendon adhesion as well. Considering the characteristic of low absorption rate and short half-life, we established a sustained-release system, i.e., hydrogel-nanoparticle system to deliver metformin. In vitro, metformin could effectively suppress TGF-ß1-induced cell proliferation and accelerate cell apoptosis, according to cell counting kit-8, flow cytometry, and 5-ethynyl-2'-deoxyuridine (EdU) staining studies. In vivo, hydrogel-nanoparticle/metformin system could significantly lower adhesion scores and improve the gliding function of repaired flexor tendons, as well as decrease the expression of fibrotic proteins Col1a1, Col3a1, and α-smooth muscle actin (α-SMA). Histological staining revealed that the inflammation had subsided and that the gap between the tendon and the surrounding tissue was wider in the hydrogel-nanoparticle/metformin treatment group. Finally, we speculated that effect of metformin on reducing tendon adhesion might be achieved by regulating both Smad and MAPK-TGF-ß1 signaling pathways. In conclusion, metformin delivered through hydrogel-nanoparticle sustained-release system may be a promising strategy for coping with tendon adhesion.

Autophagy-related gene expression classification defines three molecular subtypes with distinct clinical and microenvironment cell infiltration characteristics in colon cancer.

BACKGROUND: Multiple molecular subtypes with distinct clinical outcomes in colon cancer have been identified in recent years. Nonetheless, the autophagy-related molecular subtypes as well as its mediated tumor microenvironment (TME) cell infiltration characteristics have not been fully understood. METHODS: Based on the seven colon cancer cohorts with 1580 samples, we performed a comprehensive genomic analysis to explore the molecular subtypes mediated by autophagy-related genes. The single-sample gene-set enrichment analysis (ssGSEA) was used to quantify the relative abundance of each cell infiltration in the TME. Unsupervised methods were used to perform autophagy subtype clustering. Least absolute shrinkage and selection operator regression (LASSO) was used to construct autophagy characterization score (APCS) signature. RESULTS: We determined three distinct autophagy-related molecular subtypes in colon cancer. The three autophagy subtypes presented significant survival differences. Microenvironment analyses revealed the heterogeneous TME immune cell infiltration characterization between three subtypes. Cluster 1 autophagy subtype was characterized by abundant innate and adaptive immune cell infiltration. This subtype exhibited an enhanced stromal activity including activated pathways of epithelial-mesenchymal transition, TGF-ß and angiogenesis, and an increased infiltration of fibroblasts and endothelial cells. The expression of immune checkpoint molecules was also significantly up-regulated, which may mediate immune escape in Cluster 1 subtype. Cluster 2 subtype was characterized by relatively lower TME immune cell infiltration and enhanced DNA damage repair pathways. Cluster 3 subtype was characterized by the suppression of immunity. Patients with high APCS, with poorer survival, presented a significantly positive correlation with TME stromal activity. Low APCS, relevant to activated damage repair pathways, showed enhanced responses to anti-PD-1/PD-L1 immunotherapy. Two immunotherapy cohorts confirmed patients with low APCS exhibited prominently enhanced clinical response and treatment advantages. CONCLUSIONS: This study may help understand the molecular characterization of autophagy-related subtypes. We demonstrated the autophagy genes in colon cancer could drive the heterogeneity of TME immune cell infiltration. Our study represented a step toward personalized immunotherapy in colon cancer.