Analysis of AC3-33 gene expression in multiple organ cancer and adjacent normal tissue by RNA in situ hybridization

Expression and role of HEPIS in breast cancer

Human embryo lung cellular protein interacting with severe acute respiratory syndrome-coronavirus nonstructural protein-10 (HEPIS) is expressed at varying levels in multiple organs and breast cancer cell lines. However, its expression and function in breast cancer cells has yet to be studied. Therefore, RNA in situ hybridization was used to detect the expression of HEPIS in breast cancer and cancer-adjacent normal breast tissue. HEPIS was expressed at lower levels in breast cancer compared with that in adjacent normal tissue. Subcellular localization of HEPIS was mainly found in the cytoplasm of HeLa cells. Cell Counting Kit-8 and 5-ethynyl-2′-deoxyuridine cell proliferation assays were used to investigate the role of HEPIS in cancer cell proliferation. Ectopic expression of HEPIS in MCF-7 cells was found to significantly inhibit cell proliferation. In contrast, knockdown of HEPIS by RNA interference exhibited the opposite effect. Furthermore, a dual-luciferase reporter assay was performed and HEPIS overexpression specifically inhibited the activity of the NF-κB reporter gene. Results of the gene chip assay revealed that 2,231 genes were differentially expressed in HEPIS-overexpressing cells. Results of the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that these genes were enriched in the ‘mitogen-activated protein kinase signaling pathway’, ‘JAK-STAT signaling pathway’ and ‘focal adhesion’. Reverse transcription-quantitative PCR was used to confirm the expression levels of the differentially expressed genes interleukin 2 receptor subunit α (IL2RA), interferon α and β receptor subunit 2 (IFNAR2) and IFα8 (IFNA8). In conclusion, the results of the present study indicated that HEPIS may function as a potential repressor of breast cancer.

Expression profile and promoter analysis of HEPIS

Human embryo lung cellular protein interacting with severe acute respiratory syndrome-coronavirus nonstructural protein-10 (HEPIS) is a novel transcriptional repressor, the expression profile and promoter activity of which have not been well studied. In the present study, in situ hybridization of RNA was used to study differential HEPIS expression levels in different types of cancer and normal tissues. A total of six truncated lengths of the HEPIS promoter regulatory sequences were cloned into the pGL3-basic vector, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and dual luciferase reporter assays were performed. The results of RT-qPCR demonstrated that HEPIS expression levels differed across four breast cancer cell lines. The results of the dual luciferase reporter assays revealed that the activities of the reporter gene fragments spanning -1334/+373, -1203/+373, -1060/+373 and -899/+373 bp were higher compared with the reporter gene fragments spanning -759/+373 and -279/+373 bp. A search of the transcription factor database TRANSFAC identified numerous octamer transcription factor-1 (OCT-1), nuclear factor (NF)-κB and C-JUN transcription factor binding sites located on the HEPIS promoter (pHEPIS). Furthermore, the results revealed that mutations of the OCT-1 (-1236/-1223 bp), NF-κB (-1186/-1176 bp) and C-JUN (-856/-846 bp) sites on the human pHEPIS resulted in a decrease in luciferase activity. A chromatin immunoprecipitation assay revealed that OCT-1, NF-κB and C-JUN bound to pHEPIS in a site-dependent manner at the basal state. The TRANSFAC database was used to analyze the pHEPIS of multiple species and several activator protein-1, NF-κB and OCT-1 transcription factor binding sites were predicted. In conclusion, the results of the present study suggest that HEPIS is expressed at different levels in multiple organs and breast cancer cell lines. Furthermore, these findings indicate that OCT-1, NF-κB and C-JUN transcription factors are associated with transcriptional regulation of the HEPIS gene.