E2F1 Maintains Gastric Cancer Stemness Properties by Regulating Stemness-Associated Genes.

Yan Fu,Guangjian Huang,Peizhun Du,Cheng’En Hu,Jie Mei

doi:10.1155/2021/6611327

Abstract

Purpose To determine the regulatory role of E2F1 in maintaining gastric cancer stemness properties and the clinical significance of E2F1 in gastric cancer. Materials and Methods We conducted a tumor spheroid formation assay to enrich gastric cancer stem-like cells. The protein and mRNA expression levels of genes were measured using Western Blot and qRT-PCR. Lentivirus-mediated overexpression and downregulation of E2F1 were performed to evaluate the effect of E2F1 on the stemness properties of gastric cancer cells. The effect of E2F1 on gastric cancer cell sensitivity of 5-Fu was evaluated using cell viability assay and TdT-mediated dUTP Nick-End Labeling staining. We also analyzed the association between E2F1 expression and clinical characteristics in gastric cancer patients. The KM plotter database was used to analyze the relationship between E2F1 and overall survival in GC patients. Results We found that E2F1 expression was significantly higher in gastric cancer tissues than in the paired adjacent normal tissues (p < 0.05) and was positively correlated with tumor size (p < 0.05), T stage (p < 0.05), and differentiation degree (p < 0.05). KM plotter database demonstrated a close association between higher E2F1 expression level and worse overall survival of gastric cancer patients (p < 0.05). In vitro assay illustrated that E2F1 could regulate the expression of stemness-associated genes, such as BMI1, OCT4, Nanog, and CD44, and maintain the tumor spheroid formation ability of gastric cancer cells. E2F1 enhanced 5-Fu resistance in gastric cancer cells, and the E2F1 expression level was correlated with the prognosis of gastric cancer patients receiving 5-Fu therapy. The expression levels of stemness-associated genes were also significantly higher in gastric cancer tissues than the paired adjacent normal tissues (p < 0.05). A positive correlation was observed between E2F1 and BMI1 (r = 0.422, p < 0.05), CD44 (r = 0.634, p < 0.05), OCT4 (r = 0.456, p < 0.05), and Nanog (r = 0.337, p < 0.05) in gastric cancer tissues. The co-overexpression of E2F1 and stemness-associated genes was associated with worse overall survival. Conclusion E2F1 plays a significant role in gastric cancer progression by maintaining gastric cancer stemness properties through the regulation of stemness-associated genes. The close association between E2F1 and poor prognosis of patients suggests that E2F1 could serve as a prognostic biomarker and a therapeutic target in gastric cancer patients.

Highlights

Gastric cancer (GC) is one of the most common gastrointestinal malignancies and the third leading cause of cancerrelated deaths worldwide [1]
E2F1 Is Significantly Overexpressed in GC Tissues. e expression level of E2F1 was found to be significantly higher in GC tissues compared with that in adjacent stomach tissues (p < 0.05) (Figure 1(a)). e data in the Gene Expression Profiling Interactive Analysis (GEPIA) database revealed increased expression of E2F1 in GC tissues (Figure 1(b))
Patients with poorly differentiated GC exhibited enhanced expression of E2F1 compared with patients with well-differentiated GC (p < 0.05) (Figure 1(d)), suggesting the potential role of E2F1 in GC progression. e association between E2F1 expression level and the risk of tumor relapse two years after surgery was analyzed

Summary

Introduction

Gastric cancer (GC) is one of the most common gastrointestinal malignancies and the third leading cause of cancerrelated deaths worldwide [1]. Despite the multidisciplinary therapeutic strategies in GC treatment, the prognosis of GC patients remains poor, with a 5-year overall survival (OS) rate of approximately 25% [2]. E prognosis of GC patients remains poor, largely due to drug resistance, frequent tumor relapse, and distant metastasis. Recent studies have suggested that a small group of cells possess stemness properties in cancer and are referred to as cancer stem-like cells (CSCs). CSCs are thought to have chemotherapy resistance, cause tumor metastasis and relapse, and might be a promising therapeutic target to overcome multidrug resistance and posttreatment relapse of cancer [3]. Stemness-associated genes, such as BMI1, Nanog, and OCT4, significantly contribute to the maintenance of stemness properties in GCSCs [5]

Methods

Results

Conclusion