Circular RNA hsa_circ_0000277 promotes tumor progression and DDP resistance in esophageal squamous cell carcinoma.

BACKGROUND: Circular RNAs (circRNAs) are well-known regulators of cancer progression and chemoresistance in various types of cancers. This study was performed to investigate the function of hsa_circ_0000277 in esophageal squamous cell carcinoma (ESCC). METHODS: RNA levels were analyzed via the reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8) assay was applied to determine cell proliferation and half maximal inhibitory concentration (IC50) of cisplatin (DDP). Colony formation ability was evaluated by colony formation assay. Cell cycle and apoptosis were measured using flow cytometry. RNA immunoprecipitation (RIP), pull-down assay and dual-luciferase reporter assays were performed for target interaction analysis. The protein levels were determined through western blot. Xenograft models were established for researching hsa_circ_0000277 function in vivo. RESULTS: Hsa_circ_0000277 expression was increased in ESCC cells and tissues, and it had important clinical significance. Downregulation of hsa_circ_0000277 repressed ESCC cell proliferation, colony formation, cell cycle, and DDP resistance. Hsa_circ_0000277 acted as a microRNA-873-5p (miR-873-5p) sponge and Sry-related high-mobility group box 4 (SOX4) was validated as a target of miR-873-5p. Moreover, hsa_circ_0000277/miR-873-5p axis and miR-873-5p/SOX4 axis regulated ESCC cell progression and DDP resistance. Hsa_circ_0000277/miR-873-5p axis activated SOX4/Wnt/ß-catenin signaling pathway. Hsa_circ_0000277 facilitated tumorigenesis and DDP resistance by miR-873-5p/SOX4 axis in vivo. CONCLUSION: These findings unraveled that hsa_circ_0000277 promoted ESCC progression and DDP resistance via miR-873-5p/SOX4/Wnt/ß-catenin axis, showing a specific molecular mechanism of carcinogenesis and chemoresistance in ESCC.

The effect of microRNA-129 on the migration and invasion in NSCLC cells and its mechanism.

PURPOSE: To investigate the effect of microRNA-129 on the migration and invasion in (Non small cell lung cancer) NSCLC cells and involved mechanism. MATERIALS AND METHODS: A549 cells were cultured and transfected with microRNA-129 (miR-129) mimic. Wound-healing assay and transwell assay were used to analyses the migration and invasion of A549 cells, respectively. The SOX4 expression changes were detected by qRT-PCR and Western blot. Dual-luciferase reporter assay was used to determine the binding site between miR-129 and the 3'-UTR of SOX4. A549 cells, miR-129 up-regulated A549 cells and miR-129 + SOX4 up-regulated A549 cells were treated with TGF-ß in order to induce the epithelial-mesenchymal transition (EMT). The miR-129 and SOX4 after TGF-ß treatment were measured. The EMT markers level changes were detected by western blot. RESULTS: Up-regulation of miR-129 significantly inhibited the migration and invasion of A549 cells. miR-129 mimic transfection could reduce the mRNA and protein level of SOX4. Dual-luciferase reporter assay showed that miR-129 could bind to the 3'-UTR of SOX4. TGF-ß induced EMT accompanied by the reduction of miR-129 and elevating of SOX4. Up-regulation of miR-129 could reverse the EMT marker changes caused by TGF-ß, however, the SOX4 overexpression antagonized this effect of miR-129. CONCLUSIONS: miR-129 could suppress the migration and invasion of A549 cells. The potential mechanism may be that miR-129 inhibit EMT via targeting SOX4.

DNA methylation and histone modifications regulate SOX11 expression in lymphoid and solid cancer cells.

BACKGROUND: The neural transcription factor SOX11 is present at specific stages during embryo development with a very restricted expression in adult tissue, indicating precise regulation of transcription. SOX11 is strongly up-regulated in some malignancies and have a functional role in tumorgenesis. With the aim to explore differences in epigenetic regulation of SOX11 expression in normal versus neoplastic cells, we investigated methylation and histone modifications related to the SOX11 promoter and the possibility to induce re-expression using histone deacetylase (HDAC) or EZH2 inhibitors. METHODS: The epigenetic regulation of SOX11 was investigated in distinct non-malignant cell populations (n = 7) and neoplastic cell-lines (n = 42) of different cellular origins. DNA methylation was assessed using bisulfite sequencing, methylation-specific melting curve analysis, MethyLight and pyrosequencing. The presence of H3K27me3 was assessed using ChIP-qPCR. The HDAC inhibitors Vorinostat and trichostatin A were used to induce SOX11 in cell lines with no endogenous expression. RESULTS: The SOX11 promoter shows a low degree of methylation and strong enrichment of H3K27me3 in non-malignant differentiated cells, independent of cellular origin. Cancers of the B-cell lineage are strongly marked by de novo methylation at the SOX11 promoter in SOX11 non-expressing cells, while solid cancer entities display a more varying degree of SOX11 promoter methylation. The silencing mark H3K27me3 was generally present at the SOX11 promoter in non-expressing cells, and an increased enrichment was observed in cancer cells with a low degree of SOX11 methylation compared to cells with dense methylation. Finally, we demonstrate that the HDAC inhibitors (vorinostat and trichostatin A) induce SOX11 expression in cancer cells with low levels of SOX11 methylation. CONCLUSIONS: We show that SOX11 is strongly marked by repressive histone marks in non-malignant cells. In contrast, SOX11 regulation in neoplastic tissues is more complex involving both DNA methylation and histone modifications. The possibility to re-express SOX11 in non-methylated tissue is of clinical relevance, and was successfully achieved in cell lines with low levels of SOX11 methylation. In breast cancer patients, methylation of the SOX11 promoter was shown to correlate with estrogen receptor status, suggesting that SOX11 may be functionally re-expressed during treatment with HDAC inhibitors in specific patient subgroups.