Abnormal Localization and Tumor Suppressor Function of Epithelial Tissue-Specific Transcription Factor ESE3 in Esophageal Squamous Cell Carcinoma

Abstract

Esophageal cancer is one of the most common malignant cancers worldwide. The molecular mechanism of esophageal squamous cell carcinoma (ESCC) is still poorly understood. ESE3 is a member of the Ets transcription family, which is only expressed in epithelial tissues and acts as a tumor suppressor gene in prostate cancer. Our study aim was to confirm whether ESE3 is involved in the carcinogenesis of ESCC. Immunohistochemical analysis revealed that ESE3 was mainly located in cell nuclei of normal tissues and the cytoplasm in ESCC tissues. Immunofluorescence and western blot analyses of the normal esophageal cell line HEEpiC and ESCC cell lines EC9706 TE-1, KYSE150, and KYSE410 confirmed these results. pEGFP-ESE3 and pcDNA3.1-V5/HisA-ESE3 plasmids were constructed for overexpression of ESE3 in EC9706 and KYSE150 cells. The stably transfected cells showed restoration of the nuclear localization of ESE3. EC9706 cells with re-localization of ESE3 to the nucleus showed inhibition of proliferation, colony formation, migration, and invasion. To explore the possible mechanism of the differences in localization of ESE3 in normal esophageal cells and ESCC cells, ESCC cell lines were treated with the nuclear export inhibitor leptomycin B, transcription inhibitor actinomycin D, PKC inhibitor sphinganine, P38 MAPK inhibitor SB202190, and CK II inhibitor TBCA. These reagents were chosen according to the well-known mechanisms of protein translocation. However, the localization of ESE3 was unchanged after these treatments. The sequence of ESE3 cDNA in ESCC cells was identical to the standard sequence of ESE3 in the NCBI Genebank database, indicating that there was no mutation in the coding region of ESE3 in ESCC. Taken together, our study suggests that ESE3 plays an important role in the carcinogenesis of ESCC through changes in subcellular localization and may act as a tumor suppressor gene in ESCC, although the mechanisms require further study.

Increased expression of EHF via gene amplification contributes to the activation of HER family signaling and associates with poor survival in gastric cancer

“…EHF has been demonstrated to be a potential tumor-suppressor in prostate cancer and ESCC, 19, 22, 23 whereas our data suggest that EHF may be a functional oncogene in gastric cancer. We thus speculate that EHF derived from different types of cells or tissues has strikingly distinct functional activities in tumorigenesis.…”

“…18, 19, 20 Moreover, EHF may regulate epithelial growth and differentiation and have an important role in oncogenesis of epithelium-derived tumors. 18, 21 EHF has been demonstrated to function as a potential tumor suppressor gene in prostate cancer and esophageal squamous cell carcinoma (ESCC), 19, 22, 23 and be frequently downregulated by promoter methylation. 22 On the other hand, it is overexpressed in ovarian and mammary cancers 24, 25, 26 and may be a predictive marker for poor survival in ovarian cancer.…”

ELF3, ELF5, EHF and SPDEF Transcription Factors in Tissue Homeostasis and Cancer

“…In oesophageal squamous cell carcinoma (ESCC), the primary mechanism of EHF protein dysregulation is altered subcellular localization, where in contrast to its predominantly nuclear expression in the normal oesophageal epithelium, EHF is localized to the cytoplasm. While the mechanisms driving the cytoplasmic localization of EHF are yet to be defined, re-expression of EHF in ESCC cell lines which restored its nuclear expression, inhibited cell proliferation, colony formation, migration, and invasion [ 85 ].…”

ESE3 Inhibits Pancreatic Cancer Metastasis by Upregulating E-Cadherin

“…Authors have reported loss of ESE3 expression in esophageal squamous cell carcinoma (17) and prostate tumor (13,15,16) cases. We found that ESE3 expression levels were lower in PDACs than in matched normal pancreatic tissue specimens.…”

“…A subset of ETS factors known as epithelium-specific ETS (ESE) factors, including ESE1 (Ert/Jen/Elf3/Esx), ESE2 (Elf5), ESE3 (EHF), and Pdef (Pse), are expressed in epithelial tissues (12). Authors reported that ESE3 in particular binds directly to target genes to control epithelial-to-mesenchymal transition (EMT), stem-like features (13,14), and tumor progression (15–17). Feldman and coworkers have analyzed the expression patterns of ESE factors in diverse types of tissues and cell lines, and found that in normal human pancreas only ESE1 and ESE3 but not ESE2 and Pdef proteins are expressed (5).…”