KRAB zinc-finger protein 382 regulates epithelial-mesenchymal transition and functions as a tumor suppressor, but is silenced by CpG methylation in gastric cancer

Several studies have recently reported that KRAB zinc finger protein 382 (ZNF382) is downregulated in multiple carcinoma types due to promoter methylation. The exact role of ZNF382 in gastric carcinogenesis, however, remains elusive. In this study, we investigated the alterations and functions of ZNF382 in the pathogenesis of gastric cancer (GC). Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), quantitative (real-time) PCR (qPCR) and immunohistochemistry were carried out to detect the expression patterns of ZNF382 in GC cell lines and gastric tissue samples. Furthermore, its methylation status in GC cell lines, tumor tissues and adjacent non-tumor tissues was detected by methylation-specific PCR (MSP). We observed that ZNF382 was silenced due to promoter methylation in MKN45 and SGC7901 cell lines, and that its silencing could be reversed with 5-aza-2′-deoxycytidine, indicating that its downregulation in GC is due to promoter methylation. In addition, the ectopic expression of ZNF382 significantly inhibited gastric tumor cell clonogenicity, proliferation, migration and epithelial-mesenchymal transition (EMT) through the induction of apoptosis. ZNF382 expression downregulated the expression of SNAIL, Vimentin, Twist, NOTCH1, NOTCH2, NOTCH3, NOTCH4, HES-1, JAG1, matrix metalloproteinase (MMP)2 and MMP11, as well as that of the stem cell markers, NANOG, octamer-binding transcription factor 4 (OCT4) and SOX2. ZNF382 also upregulated the expression of E-cadherin. On the whole, the findings of this study suggest that ZNF382 functions as a tumor suppressor in GC cells, but is frequently methylated in both GC cell lines and primary gastric tumors. ZNF382 can reverse the EMT process in GC cells through NOTCH signaling. Our findings further illustrate the molecular pathogenesis of GC and establish potential biomarkers for this type of cancer.