Differential expression and functions of Ehm2 transcript variants in lung adenocarcinoma

Abstract

Ehm2 [also known as erythrocyte membrane protein band 4.1-like protein 4B (EPB41L4B)] is a member of the NF2/ERM/4.1 superfamily. The overexpression of Ehm2 has been observed in metastatic cancer cells. Through alternative splicing, the Ehm2 gene produces two transcript variants that encode the two different isoforms, Ehm2/1 and Ehm2/2. The biological functions of these different Ehm2 transcript variants remain unclear. The present study aimed to determine the expression of the Ehm2 variants in lung adenocarcinoma and their involvement in the disease progression of the patients. The expression of Ehm2 transcript variants in human lung adenocarcinoma tissues was analyzed using immunohistochemistry and western blot analysis. Ehm2 variants were overexpressed or knocked down in A549 human lung adenocarcinoma cells. The consequent effects of the genetic modifications on the cellular functions of lung cancer cells were then examined using in vitro cell viability, invasion and migration assays. The expression of epithelial-mesenchymal transition (EMT)-related markers was evaluated by western blot analysis in the cell models. The association of Ehm2 variant expression with patient survival was analyzed using Kaplan-Meier survival analysis. The expression of Ehm2/1 was significantly decreased in lung cancers compared with the paired normal lung tissues (P<0.05), while the Ehm2/2 protein levels were higher in the tumors than in the paired normal lung tissues, although this was not statistically significant. The overexpression of Ehm2/1 exerted inhibitory effects, while the knockdown of Ehm2/1 promoted the growth, invasion and migration of A549 cells in vitro. Ehm2/2 was expressed at low levels in the A549 cells and the enforced expression of Ehm2/2 significantly increased the invasiveness and migration of the A549 cells. Immunofluorescence staining revealed that Ehm2/1 was confined to the plasma membrane, while Ehm2/2 was observed at both the plasma membrane and cytoplasm. The overexpression of Ehm2/1 resulted in the upregulation of the epithelial marker, E-cadherin, and in the decreased expression of the mesenchymal markers, N-cadherin and Snail1, while the knockdown of Ehm2/1 and the enforced expression of Ehm2/2 had the opposite effects on the protein levels of EMT-related markers. Kaplan-Meier survival analysis revealed that higher Ehm2/1 transcript levels were associated with the longer survival of patients with lung adenocarcinoma, while the lower expression of Ehm2/2 exhibited a similar association with patient survival. Taken together, the two Ehm2 variants appear to be differentially expressed in lung adenocarcinoma. Ehm2/1 may function as a putative tumor suppressor in the disease progression of lung adenocarcinoma, while Ehm2/2 may have an opposite function.

Increased expression of GIPC2 in colon adenocarcinoma is associated with a favorable prognosis and high levels of immune cell infiltration

“…The results of the co-expression analysis performed in the present study identified a significant positive correlation between GIPC2 and EPCAM, LRRC8D, EPB41L4B, ACSL5 and CDS1. Several of these genes have been reported to serve important roles in maintaining normal intestinal mucosal function and cancer resistance (31)(32)(33)(34)(35), thus indicating that GIPC2 and its co-expressed genes may serve as potential prognostic markers for COAD. At present, a large number of studies have shown that members of the GIPC family are able to fully exert their role as adaptors and interact with a variety of proteins, including RGS19/GAIP, MY06 and type III TGF-P receptors, and subsequently participate in the regulation of a variety of biological processes, including cell signaling, transmembrane protein transport, cell movement and endocytosis (36,37).…”

Ehm2 transcript variant 1 inhibits breast cancer progression and increases E-cadherin stability

“…In comparison with Ehm2/2, 382 amino acids are absent from the carboxyl-terminal region of Ehm2/1 (20). The two Ehm2 isoforms have distinct expression patterns in various cancers, including lung adenocarcinoma (LUAD) and breast cancers ( 22 ). Our previous study demonstrated that the two isoforms of Ehm2 played different roles in LUAD.…”

“…Our previous study demonstrated that the two isoforms of Ehm2 played different roles in LUAD. Overexpression of Ehm2/1 exerted inhibitory effects, while knockdown of Ehm2/1 promoted the growth, invasion and migration of A549 cells in vitro ( 22 ). In this study, we focused on the role of Ehm2/1 in breast cancer.…”

Construction and Validation of a Prognostic Nomogram for Clear Cell Renal Cell Carcinoma Based on DNA&nbsp;Methylation-driven Differentially Expressed Genes

“…Of course, there are some reports exploring the function of these signatures in other cancers. For example, HHLA2 is a new immune checkpoint in ccRCC, (Zhang et al 2020) EPB41L4B (Ehm2) has been proven to promote the proliferation and invasion of lung cancer cells, (Li et al 2019) IFI16 can impact the immune reaction, (Sui et al 2019) XAF1 has a function related to tumor apoptosis, (Jeong et al 2018) and CMTM3 has been reported to be a promoter in gastric cancer. (Yuan et al 2017) Compared with other studies, our study searched for biomarkers in multiple databases (TCGA, CPTAC, and HPA) and at multiple levels (DNAm, mRNA expression, and protein abundance).…”