DOT1L promotes expression of CD44 through the Wnt/ß-catenin signaling pathway in early gastric carcinoma.

To assess telomere silencing 1-like (DOTIL) gene expression within gastric cancer (GC) tissues as well as its function of promoting cancer stem cell (CSC)-mediated epithelial-mesenchymal switching, tissue samples from 8 patients each in 3 stages (normal, low-grade intraepithelial neoplasia (LGIN), as well as early gastric carcinoma (EGC)) were collected for whole-exome sequencing, which revealed differentially expressed genes (DEGs). The DEGs and their prognostic value were verified through TCGA and GTEx analyses. We also verified the role of DOT1L in EGC development. We collected samples from three patients each with LGIN and EGC for single-cell sequencing. We conducted single-cell transcriptomic analysis, DEG analysis, cell‒cell interaction analysis, and pseudotime analysis using R language. Sites and levels of DOT1L, CD44 and DOT1L expression were verified by IF. We found 703 deleterious mutation sites in the LGIN group and 389 deleterious mutation sites in the EGC group. The LGIN as well as EGC categories exhibited increased levels of DOT1L expression compared to the standard category (P<0.05) in TCGA and GTEx. DOT1L also correlated significantly with TMB (P=8.45E-06), MSI (P=0.001), and tumor proliferation index (P=7.17E-09) in the TCGA and GTEx datasets. In single cells, we found that DOT1L promotes CD44 expression via the Wnt/ß-catenin signaling pathway and the development for stemness properties within GC. In addition, we found that DOT1L, CD44 and CTNNB1 colocalize and correlate positively. In conclusion, one important CSC regulator in GC, DOT1L may be crucial in coordinating the expression of genes specific to a certain lineage during MSC development.

Clinicopathological significance of intestinal metaplasia in endoscopically resected early gastric carcinoma.

OBJECTIVE: To investigate the clinicopathological and prognostic significance of intestinal metaplasia (IM) in endoscopically resected early gastric carcinoma (EGC). METHODS: Altogether 136 consecutive cases with EGC resected by endoscopic submucosal dissection over 5 years were included and divided into the early gastric cardiac (EGCC; n = 60) and non-cardiac carcinoma (EGNCC; n = 76) groups. Goblet cell IM and subtypes were determined with histology and immunostaining. Recurrence-free survival (RFS) was compared among various IM groups. RESULTS: IM was identified in 128 (94.1%) EGC cases, including complete IM (n = 39), incomplete IM (n = 27), and mixed IM (n = 62). Incomplete IM was significantly more common in EGCC and exhibited a lower frequency of en bloc resection than the complete subtype. The frequency of synchronous or metachronous gastric tumor was significantly more common in EGCC with complete IM than in those with incomplete IM. Compared to EGC without IM, EGC with IM showed a significantly higher frequency of non-poorly cohesive carcinoma, en bloc resection, and non-eCuraC-1 grade. EGNCC with IM was significantly associated with negative resection margins and en bloc resection. The 5-year RFS was significantly lower in EGNCC patients with incomplete IM compared with those with mixed IM. The independent risk factors for RFS included tumor size >2 cm and eCuraC-1 grade. CONCLUSIONS: Subtyping IM in EGC helped predict endoscopic resectability, prognosis, and risk of synchronous or metachronous gastric tumor. The significance of IM differed between EGCC and EGNCC. Large studies with longer follow-up are warranted to validate our findings.