Fig 2: Volcano plot of quantified proteins of WCLs and exosomes after knocking out CD151.A, volcano plot of quantified proteins of exosomes. B, volcano plot of quantified proteins of WCLs. The threshold for determining DEPs is indicated by the dashed lines (adjusted p value < 0.01, fold change > 1.5). Red dots indicate significantly upregulated proteins, and green dots indicate significantly downregulated proteins. DEPs, differentially expressed proteins; WCLs, whole-cell lysates.

Fig 3: Expression of CD151 in exosomes derived from patients with TNBC and TNBC cell lines.A, top 20 upregulated proteins identified in TNBC patient-derived exosomes ranked by p value. Significance of their upregulation in TNBC patient–derived exosomes is listed accordingly. B, immunoblot was performed to access the expression levels of exosomal CD151 expression in additional patients with TNBC and healthy donors. “30 to 37” and “23 to 30” represent the individual healthy donors and patients with TNBC. Flotillin-1 was used as a loading control. C, the relative quantified results of the immunoblots are represented as mean ± SEM (n = 4). ∗p < 0.05. D, immunoblot analysis of CD151 expression in WCLs of breast cancer cell lines (non-TNBC cell lines: T47D and MCF7; TNBC cell lines: MDA-MB-468, BT549, and MDA-MB-231). Total protein (15 μg) was loaded onto the gels. β-actin was used as a control for equal loading. E, immunoblot analysis of CD151 expression in exosomes derived from breast cancer cell lines. Total protein (15 μg) was loaded onto the gels. Flotillin-1 was used as a control for equal loading. ns, not significant; TNBC, triple-negative breast cancer; WCLs, whole-cell lysates.

Fig 4: CD151 regulates the secretion of many proteins via exosomes. Western blot analysis of WCLs (A) and exosomes (B) showing CD151 was only present in the WT WCLs and exosomes compared with CD151KO WCLs and exosomes. β-actin and flotillin-1 were used as loading controls for (A) and (B), respectively. Heat map of all quantified protein in WCLs (C) and exosomes (D) performed based on Euclidean distance by the package “pheatmap” in R, revealing that the profiles of total cellular protein were alike, but the profiles of total exosomal proteins were obviously different. The heat map input was the relative intensities of whole quantified proteins. The intensity of each protein in each sample was divided by the average intensity of the same protein in all six samples, and log2 transformation was done to scale the heat map input. The red color indicates increased protein abundance, and the blue color indicates decreased protein abundance. WCLs, whole-cell lysates.