No abstract

In our previous study, the Kelch domain-containing 7B (KLHDC7B) was revealed to be hypermethylated at the promoter but upregulated in breast cancer. In this study, we identified a long non-coding RNA, ST8SIA6-AS1 (STAR1), whose expression was significantly associated with KLHDC7B in breast cancer (R2 = 0.3466, P < 0.01). Involvement of the two genes in tumorigenesis was examined via monitoring their effect on cellular as well as molecular events after each gene dysregulation in cultured mammary cell lines. Apoptosis of MCF-7 decreased by 49.5% and increased by 33.1%, while proliferation noted increase and decrease by up- and downregulation of KLHDC7B, respectively, suggesting its oncogenic property. STAR1, however, suppressed cell migration and increased apoptosis. Network analysis identified many target genes that appeared to have similar regulation, especially in relation to the interferon signaling pathway. Concordantly, expression of genes such as IFITs, STATs, and IL-29 in that pathway was affected by KLHDC7B and STAR1. Taken together, KLHDC7B and STAR1 are both overexpressed in breast cancer and significantly associated with gene modulation activity in the interferon signaling pathway during breast tumorigenesis.

BackgroundGinsenoside Rg3, a derivative of steroidal saponins abundant in ginseng, has a range of effects on cancer cells, including anti-cell proliferation and anti-inflammation activity. Here, we investigate two long noncoding RNAs (lncRNAs), STXBP5-AS1 and RFX3-AS1, which are hypomethylated and hypermethylated in the promoter region by Rg3 in MCF-7 cancer cells.MethodsThe lncRNAs epigenetically regulated by Rg3 were mined using methylation array analysis. The effect of the lncRNAs on the apoptosis and proliferation of MCF-7 cells was monitored in the presence of Rg3 or Korean Red Ginseng (KRG) extract after deregulating the lncRNAs. The expression of the lncRNAs and their target genes was examined using qPCR and Western blot analysis. The association between the expression of the target genes and the survival rate of breast cancer patients was analyzed using the Kaplan-Meier Plotter platform.ResultsSTXBP5-AS1 and RFX3-AS1 exhibited anti- and pro-proliferation effects, respectively, in the cancer cells, and the effects of Rg3 and KRG extract on apoptosis and cell proliferation were weakened after deregulating the lncRNAs. Of the genes located close to STXBP5-AS1 and RFX3-AS1 on the chromosome, STXBP5, GRM1, RFX3, and SLC1A1 were regulated by the lncRNAs on the RNA and protein level. Breast cancer patients that exhibited a higher expression of the target genes of the lncRNAs had a higher metastasis-free survival rate.ConclusionThe current study is the first to identify lncRNAs that are regulated by the presence of Rg3 and KRG extract and that subsequently contribute to inhibiting the proliferation of cancer cells.

Background To comprehensively understand the molecular mechanism of tamoxifen resistance (TamR) acquisition by epigenetically regulated genes, it is essential to identify pivotal genes by genome-wide methylation analysis and verify their function in xenograft animal model and cancer patients. Methods The MCF-7/TamR breast cancer cell line was developed and a genome-wide methylation array was performed. The methylation and expression of ELOVL2 was validated in cultured cells, xenografted tumor tissue, and breast cancer patients by methylation-specific PCR, qRT-PCR, Western blot analysis, and immunohistochemistry. Deregulation of ELOVL2 and THEM4 was achieved using siRNA or generating stable transfectants. Tam sensitivity, cell growth, and apoptosis were monitored by colorimetric and colony formation assay and flow cytometric analysis. Pathway analysis was performed to generate networks for the differentially methylated genes in the MCF-7/TamR cells and for the differentially expressed genes in the ELOVL2-overexpressing cells. Results Genome-wide methylation analysis in the MCF-7/TamR cells identified elongation of very-long chain fatty acid protein 2 (ELOVL2) to be significantly hypermethylated and downregulated, which was further verified in the tumor tissues from TamR breast cancer patients (n = 28) compared with those from Tam-sensitive (TamS) patients (n = 33) (P < 0.001). Immunohistochemical analysis of tissues from cancer patients showed lower expression of ELOVL2 in the TamR than TamS tissues. Growth of the MCF-7/TamR cells overexpressing ELOVL2 was retarded in cell culture and also in xenograft tumor tissue. Strikingly, ELOVL2 attenuated resistance to Tam up to 70% judged by the colorimetric and colony formation assay and xenograft mouse model. ELOVL2 contributed to the recovery of Tam sensitivity by regulating a group of genes in the AKT and ERα signaling pathways, e.g., THEM4, which plays crucial roles in drug resistance. Conclusions ELOVL2 was hypermethylated and downregulated in TamR breast cancer patients compared with TamS patients. ELOVL2 is responsible for the recovery of Tam sensitivity. AKT- and ERα-hubbed networks are pivotal in ELOVL2 signaling, where THEM4 contributes to the relaying ELOVL2 signaling. This study implies that deregulation of a gene in fatty acid metabolism can lead to drug resistance, giving insight into the development of a new therapeutic strategy for drug-resistant breast cancer.

Cold atmospheric plasma (CAP) has been recognized as a potential alternative or supplementary cancer treatment tool, which is attributed by its selective antiproliferation effect on cancer cells over normal cells. Standardization of the CAP treatment in terms of biological outputs such as cell growth inhibition and gene expression change is essential for its clinical application. This study aims at identifying genes that show consistent expression profiles at a specific CAP condition, which could be used to monitor whether CAP is an appropriate treatment to biological targets. To do this, genes showing differential expression by two different CAP treatment conditions were screened in the MCF-7 breast cancer cells. As a result, ZNRD1 was identified as a potential marker with being consistently upregulated by 600 s but downregulated by the 10×30 s CAP treatment scheme. Expression of ZNRD1 was increased in breast cancer tissues compared to normal tissues, judged by cancer tissue database analysis, and supported by the antiproliferation after siRNA-induced downregulation in MCF-7. Interestingly, the antisense long noncoding RNA (lncRNA) of ZNRD1, ZNRD1-AS1, was regulated to the opposite direction of ZNRD1 by CAP. The siRNA-based qPCR analysis indicates that ZNRD1 downregulates ZNRD1-AS1, but not vice versa. ZNRD1-AS1 was shown to increase a few cis-genes such as HLA-A, HCG9, and PPP1R11 that were also regulated by CAP. Altogether, this study identified a pair of gene and its antisense lncRNA of which expression is precisely controlled by CAP in a dose-dependent manner. These genes could help elucidate the molecular mechanism how CAP regulates lncRNAs in cancer cells.