Role of stemness‐related genes TIMP1, PGF, and SNAI1 in the prognosis of colorectal cancer through single‐cell RNA‐seq
Yan Shen, Siyi Ni, Si Li, Bin Lv
Abstract
BACKGROUND: Colorectal cancer (CRC) is a fatal malignant tumor with poor prognosis. Cancer stem cells (CSCs) can cause metastasis, recurrence and drug resistance in CRC. This research aimed to analyze stemness-related prognostic genes of CRC based on single-cell RNA-sequencing (scRNA-seq) data. METHODS: DESeq2 was applied to analyze the differentially expressed genes (DEGs). The mRNA stemness index (mRNAsi) was calculated by one-class logistic regression (OCLR). The stemness-related cells were analyzed based on scRNA-seq dataset GSE166555. Monocle 2 algorithm was used for stemness-related cells pseudotime trajectory analysis. The stemness-related prognostic genes were analyzed by clusterProfiler and survival package. The stemness of CRC cells was detected by spheroid formation assay, and the expression of stemness-related prognostic genes was verified by qRT-PCR and Western blot. RESULTS: 7916 DEGs between the CRC and normal tissues were obtained. The mRNAsi of the CRC tissues was shown to be significantly higher than that of the normal tissues. 7 and 8 cell types were annotated respectively in the normal and CRC tissues through analysis of the scRNA-seq data. Cell-cell interactions (CCIs) in the tumor tissues were revealed to be significantly enhanced than that in the normal tissues. By calculating the 'stemness score', CSCs, epithelial cells (EPCs) and cancer-associated fibroblasts (CAFs) were defined as stemness-related cells. Through pseudotime trajectory analysis, 2111 genes were identified as state 2-specific genes. Then, 41 genes were obtained by taking intersection of the up-regulated genes with state 2-specific genes and marker genes of CSCs, EPCs and CAFs. The univariate COX regression analysis revealed 5 stemness-related prognostic genes (TIMP1, PGF, FSTL3, SNAI1 and FOXC1). Kaplan-Meier curve analysis indicated that the higher the expression of 5 genes, the lower the survival rate. In vitro cell experiment confirmed that the expression of TIMP1, PGF and SNAI1 was consistent with that revealed by bioinformatics analysis. CONCLUSIONS: TIMP1, PGF and SNAI1 were identified as stemness-related prognostic genes of CRC, and possibly potential therapeutic targets for CRC.