Exosomes derived from Piwil2‑induced cancer stem cells transform fibroblasts into cancer‑associated fibroblasts

Abstract

Recently, several studies have demonstrated that cancer cell-derived exosomes can facilitate tumor development and metastasis formation. However, the detailed function of exosomes released by cancer stem cells (CSCs) requires further investigation. The aim of the present study was to investigate the role of CSC-derived exosomes in tumor development. For this purpose, Piwil2-induced cancer stem cells (Piwil2-iCSCs) were used as exosome-generating cells, while fibroblasts (FBs) served as recipient cells. Exosomes were isolated by the ultracentrifugation of Piwil2-iCSC-conditioned medium and identified by transmission electron microscopy, nanoparticle tracking analysis and western blot analysis. To evaluate the effects of the exosomes on cell proliferation, migration and invasion, cell counting assay (CCK-8), a wound healing assay and a Transwell assay were performed. Protein expression [matrix metalloproteinase (MMP)2, MMP9, α-smooth muscle actin (α-SMA) and vimentin and fibroblast-activating protein (FAP)] was examined in FBs by western blot analysis. It was found that the Piwil2-iCSC-derived exosomes (Piwil2-iCSC-Exo) were oval or spherical, membrane-coated vesicles with a uniform size (30-100 nm in diameter). They are characterized by the surface expression of CD9, CD63, Hsp70 and Piwil2 proteins. Additional results from functional analyses revealed that Piwil2-iCSC-Exo enhanced the proliferative, migratory and invasive abilities of FBs, accompanied by the upregulated expression of MMP2 and MMP9. In addition, the increased expression of α-SMA (P<0.05), vimentin (P<0.01 vs. control group, P<0.05 vs. PBS group) and FAP (P<0.001 vs. control group, P<0.01 vs. PBS group) following exposure to Piwil2-iCSC-Exo suggested that the exosomes induced FB transformation into cancer-associated fibroblasts (CAFs). On the whole, the findings of this study demonstrate that Piwil2-iCSC-Exo induce the cancer-associated phenotype in fibroblasts in vitro, suggesting that CSCs can promote tumor development through the modulation of the tumor microenvironment.

Extracellular Vesicles and Cancer Stem Cells in Tumor Progression: New Therapeutic Perspectives

“…An increasing amount of evidence suggests that CSC-derived exosomes can modulate the stromal compartment, favoring tumor progression and metastasis formation [ 108 ]. In a recent study by Zhang et al [ 49 ], the authors analyzed the effects of exosomes derived from fibroblast-derived CSCs on the proliferation, migration, and invasion of human parental fibroblasts (FBs). In particular, the treatment with CSC-derived exosomes induced FB proliferation, migration, and invasive capabilities, increasing the expression of metalloproteinase MMP2 and MMP9, smooth muscle alpha-actin (α-SMA), vimentin, and fibroblast activation protein (FAP).…”

“…For instance, CSCs release EVs that can be uptaken by stromal cells, non-CSC tumor cells, immune cells, and endothelial cells, inducing stemness regain, anticancer drug resistance, metastasis, angiogenesis, and immunosuppression [ 47 , 48 ]. In particular, fibroblasts can be transformed, through the uptake of CSC-EVs, into cancer-associated fibroblasts (CAFs), promoting tumor progression and metastasis [ 49 ]. At the same time, stromal cells and non-CSC tumor cells can also secrete EVs, favoring cell interplay and procancer functions in the tumor bulk [ 50 ].…”

Exosomes and Cancer Stem Cells in Cancer Immunity: Current Reports and Future Directions

“…The macrovesicles released from CD105 + renal cancer cells were observed to mediate the angiogenic effects, both in vitro and in vivo [ 50 ]. Furthermore, exosomes derived from Piwil2-induced CSCs have been found to alter fibroblasts into cancer-associated fibroblasts (CAFs) [ 51 ].…”

PiRNA MW557525 Promotes the Vitality and Pluripotency of Piwil2-iCSCs by Regulating NOP56.

“…At present, CSCs are mainly obtained by separating stem cells from solid tumor tissues, but there are still considerable difficulties in the extraction and culture of CSCs. The research group established a tumor-like stem cell model through PIWIL2 reprogramming fibroblasts [19,20] , called Piwil2-iCSCs. This study aimed to screen out the differentially expressed piRNAs in CSCs and further explore their effects on CSCs.…”