Fig 2: LncRNA SNHG16 sponged miR-892b to regulate PPAPDC1A. (A) SNHG16 was mainly located in the cytoplasm through LncATLAS prediction. (B) RNA FISH confirmed that SNHG16 was distributed in the cytoplasm of MDA-MB-157. (C) The heat map of downregulated miRNAs in BC in the GSE26659, the abscissa is the sample number and the ordinate is the miRNA name; the histogram at the top right is the color scale. (D) The intersection between the prediction results of RNA22 database for the downstream miRNAs of SNHG16 and the downregulated miRNAs in GSE26659; the two circles in the panel show the prediction results of RNA22 and the results of microarray analysis, and the middle part shows the intersection of the two set of data. (E) The expressions of miR-139-5p, miR-892b, and miR-486-5p in MDA-MB-157, HS578T, and MCF-10A cells were detected using RT-qPCR. (F) Kaplan–Meier curve of miR-892b in BC patients from ENCORI pancancer database. (G) MDA-MB-157 and HS578T cells were transfected with pcDNA3.1-SNHG16 and si-SNHG16, and the expression of miR-892b was detected using RT-qPCR. (H) The binding relationship between SNHG16 and miR-892b was verified using dual-luciferase gene reporter assay. (I) The heat map of downregulated genes in BC in the GSE61304. (J) Intersection of miR-892b target genes predicted by TargetScan and upregulated genes in GSE61304. (K) Differential expression of PPAPDC1A in BC samples and normal samples collected by TCGA and GTEx database. (L) Kaplan–Meier curve of PPAPDC1A in BC patients from UALCAN pancancer database. (M) MDA-MB-157 and HS578T cells were transfected with pcDNA3.1-SNHG16 and si-SNHG16, and the PPAPDC1A mRNA expression was detected using RT-qPCR. (N) The binding relationship between PPAPDC1A and miR-892b was verified using dual-luciferase gene reporter assay. (O) MDA-MB-157 and HS578T cells were treated with EVs or GW4869/Supernatant, and the expression of miR-892b was detected using RT-qPCR. (P) MDA-MB-157 and HS578T cells were treated with EVs or GW4869/Supernatant, and PPAPDC1A mRNA expression was detected using RT-qPCR. (Q) Anti-Ago2 RNA immunoprecipitation assay was used to detect the enrichment of SNHG16, miR-892b, and PPAPDC1A mRNA in the immunoprecipitation complex, with IgG as control. Cell experiment was repeated three times. Data were presented as mean ± standard deviation. Data in E, G, M, O, and P were analyzed using one-way ANOVA, and data in H and N were analyzed using two-way ANOVA, followed by Tukey’s multiple comparison test, *p < 0.05.

Fig 3: Mechanism of lncRNA SNHG16 on the miR-892b/PPAPDC1A regulatory axis. The donor BC cell-secreted EVs carried lncRNA SNHG16 into the intercellular matrix, which was then encapsulated by the receptor cells and released SNHG16. The EVs carried SNHG16 competitively bound to miR-892b to inhibit the binding of miR-892b with PPAPDC1A, thus upregulating the expression of PPAPDC1A, promoting epithelial–mesenchymal transition, and ultimately promoting the invasion and metastasis of BC cells.