Data collection
The mRNA data and related clinical data were obtained from the Cancer Genome Atlas (TCGA) database (TCGA-BLCA). mRNA data and clinical information also comes from Gene Expression Omnibus (GEO) database (GSE13507, GSE31684, https://www.ncbi.nlm.nih.gov/geo/). In this study, 411 bladder cancer tissues and 19 normal tissues in TCGA database were included to construct risk signature, and 258 bladder cancer organizations in GEO database were used to verify the risk signature. Moreover, an independent cohort of patients with metastatic urothelial cancer (mUC) receiving PD-1 blockade therapy, the IMvigor210 (mUC) trial, was included to evaluate the effects of immunotherapy.
Single Gene Analysis
The expression of SNHG16 in 411 bladder cancer samples and 19 normal tissue samples from TCGA database were compared using “ggplot2” software package of R software. 411 bladder cancer samples from the TCGA database were divided into high SNHG16 expression group and low SNHG16 expression group according to SNHG16 expression level. Kaplan–Meier survival curves were used to compare the overall survival between two groups via the “survival” and “survminer” packages of R software. Univariate Cox regression and multivariate Cox regression were used to confirm whether SNHG16 expression could be an independent prognostic factor for bladder cancer via the “survival” packages of R software.
Immune Cell Infiltration
The ssGSEA algorithm and Spearman statistical analysis were used to detect the relationship between SNHG16 expression and immune cell infiltration.
Risk Signature
Based on immune related genes from “Immport” (https://www.immport.org),we find out the differentially expressed genes in the high and low expression groups of SNHG16. Differentially expressed genes related to survival were screened using univariable Cox regression (P < 0.05). Then, using the selected genes, the risk signature was established by lasso Cox regression, and the risk score was calculated by “glmnet” software package of R software. Bladder cancer patients were divided into high-risk group and low-risk group. Kaplan–Meier survival curves were used to compare the overall survival between two groups. Receiver operating characteristic (ROC) curve was performed to estimate the accuracy of risk signature via the “survival”, “survminer” and “timeROC” package of R software. Univariate Cox regression and multivariate Cox regression were used to confirm whether risk signature could be an independent prognostic factor for bladder cancer. Finally, the risk signature was verified using GEO database. The ssGSEA algorithm was also used to detect the relationship between risk score and immune cells infiltration. The relationships with risk score and TME (stromal score, immune score and tumor purity) were evaluated via the Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data (ESTIMATE) algorithm.
Biological Functions
The gene set enrichment analysis (GSEA) was performed to analysis the risk score related functions. The “c2.cp.kegg.v7.4.symbols.gmt” and “c5.go.v7.4.symbols.gmt” were included. A nominal P value (NOM P value) < 0.05 and a false discovery rate Q value (FDR Q value) < 0.25 were considered significant.
Cell Culture And Sirna Transfection
Human BC cell lines UMUC3 were purchased from Cell Bank of Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. They were maintained in DMEM medium supplemented with 10% fetal bovine serum (FBS). Cells were incubated at 37°C in 5% CO2. For siRNA transfection, Lipofectamine (Invitrogen) was used. The siRNA sequences were as follows:
CTSE: forward 5’ GAC CUU UGU GGA UGC AGA GUU UGA U 3’
reverse 5’ AUC AAA CUC UGC AUC CAC AAA GGU C 3’
UNC93B1: forward 5’ CAC CUC GUG CCU UUC UUU AUC UAC A 3’
reverse 5’ UGU AGA UAA AGA AAG GCA CGA GGU G 3’
CCL17: forward 5’ GAG UGA AGA AUG CAG UUA AAU ACC U 3’
reverse 5’ AGG UAU UUA ACU GCA UUC UUC ACU C 3’
TNFRSF14:forward 5’ CAU CGU CAU UGU UUG CUC CAC AGU U 3’
reverse 5’ AAC UGU GGA GCA AAC AAU GAC GAU G 3’
Rna Extraction And Real-time Qpcr
We selected samples from 20 patients with bladder cancer, and obtained the cancer tissue and paracancer tissue respectively.
Total RNA was extracted using the Eastep Super TotalRNA Extraction Kit (Promega). miRNA was extractedusing the miRcute miRNA Isolation Kit (Tiangen Bio-tech, Beijing, China). cDNA was synthesized using the Mir-XTM miRNA First-Strand Synthesis Kit (TaKaRa). qPCR was conducted using SYBRGreen PCR Master Mix (TaKaRa) on a LightCycler480 Real-Time PCR instrument (Roche, Indianapolis, IN, USA). Thesequences of the primers were as follows:
SNHG16: forward 5’AAG ACA TGG CCA CTC CAG TC 3’
reverse 5’AGG CTG ACT GCA CCA TCA TC 3’
GAPDH: forward 5’GGA GCG AGA TCC CTC CAA AAT 3’
reverse 5’GGC TGT TGT CAT ACT CTC ATG G 3’
Transwell Assay
Cell migration assay was conducted with a 24-well insert Trans-well chambers (corning Costar, USA). Transfected cells (20000/200µl) were suspended in serum-free medium and then added to the upper chamber. 600µL of complete medium containing 10% FBS was injected into the lower chamber. After 24 h, wipe the cells on the upper filter membrane with a cotton swab, and clean the chamber with PBS. After staining with crystal violet solution for 30 minutes, observed invading and migrating cells.
Cell Proliferation Assays
RTCA S16 (Agilent, USA) was used in cell proliferation assays. Transfected cells (3000/500µl) were suspended in complete medium containing 10% FBS and then added to the well. And the E-Plates placed on the RTCA single plate station in the cell culture incubator. Cell proliferation were monitored every 15 minutes up to 72 hours.
Statistical analysis
When comparing the two groups of data, if the data conforms to the normal distribution, the unpaired t-student test was used, otherwise the Wilcoxon rank sum test was selected. Log rank test was used in survival analysis. All statistical calculations are completed on R software.