Dongdong Tong

MicroRNA‑101 suppresses progression of lung cancer through the PTEN/AKT signaling pathway by targeting DNA methyltransferase 3A

It is well established that transcriptional silencing of critical tumor suppressor genes by DNA methylation is a fundamental process in the initiation of lung cancer. However, the involvement of microRNAs (miRNAs) in restoring abnormal DNA methylation patterns in lung cancer is not well understood. Therefore, and since miRNA-101 is complementary to the 3′-untranslated region of DNA methyltransferase 3A (DNMT3A), we investigated whether miRNA-101 could restore normal DNA methylation patterns in lung cancer cell lines. Bioinformatics has indicated that DNMT3A is a major target of miR-101. In addition, the overexpression of miR-101 downregulates DNMT3A. Using a methylation-specific polymerase chain reaction assay, we demonstrated that methylation of the phosphatase and tensin homolog (PTEN) promoter was reduced in A549 cells transfected with miR-101, but not in the transfected control. Furthermore, overexpression of miR-101 and silencing of DNMT3A suppressed lung cell proliferation and S/G2 transition, and increased apoptosis through the PTEN/AKT pathway in vitro. Furthermore, we observed the opposite phenomenon in A549 cells transfected with a miR-101 inhibitor. Subsequent investigation revealed that overexpression of miR-101 significantly inhibited the tumorigenicity of A549 cells in a nude mouse xenograft model. These results demonstrate that miR-101 affects lung cancer progression through the PTEN/AKT signaling pathway by targeting DNMT3A in lung cells, suggesting that miR-101 may be a novel potential therapeutic strategy in lung cancer treatment.

EGR1 mediates miR-203a suppress the hepatocellular carcinoma cells progression by targeting HOXD3 through EGFR signaling pathway

EGR1 plays a critical role in cancer progression. However, its precise role in hepatocellular carcinoma has not been elucidated. In this study, we found that the overexpression of EGR1 suppresses hepatocellular carcinoma cell proliferation and increases cell apoptosis by binding to the miR-203a promoter sequence. In addition, we investigated the function of miR-203a on progression of HCC cells. We verified that the effect of overexpression of miR-203a is consistent with that of EGR1 in regulation of cell progression. Through bioinformatic analysis and luciferase assays, we confirmed that miR-203a targets HOXD3. Silencing HOXD3 could block transition of the G2/M phase, increase cell apoptosis, decrease the expression of cell cycle and apoptosis-related proteins, EGFR, p-AKT, p-ERK, CCNB1, CDK1 and Bcl2 by targeting EGFR through EGFR/AKT and ERK cell signaling pathways. Likewise, restoration of HOXD3 counteracted the effects of miR-203a expression. In conclusion, our findings are the first to demonstrate that EGR1 is a key player in the transcriptional control of miR-203a, and that miR-203a acts as an anti-oncogene to suppress HCC tumorigenesis by targeting HOXD3 through EGFR-related cell signaling pathways.

MicroRNA-302b Enhances the Sensitivity of Hepatocellular Carcinoma Cell Lines to 5-FU via Targeting Mcl-1 and DPYD

MiR-302b is a member of miR-302-367 cluster. The miR-302-367 cluster played important roles in maintaining pluripotency in human embryonic stem cells (hESCs) and has been proved to be capable of suppressing cell growth in several types of cancer cell lines including Hepatocellular Carcinoma (HCC) Cell lines. However, the role that miR-302b plays in the 5-Fluorouracil (5-FU) sensitivity of HCC has not been known. This study showed that miR-302b could enhance the sensitivity to 5-FU in HCC cell lines and verified its two putative targeted genes responsible for its 5-FU sensitivity.

miR-491-5p, mediated by Foxi1, functions as a tumor suppressor by targeting Wnt3a|[sol]||[beta]|-catenin signaling in the development of gastric cancer

Accumulated evidence has suggested that microRNAs (miRNAs) have an important role in tumor development and progression by regulating diverse signaling pathways. However, the precise role of miRNAs in gastric cancer (GC) has not been elucidated. In this study, we describe the function and regulation network of miR-491-5p in GC. miR-491-5p is frequently downregulated in GC tissues compared with adjacent non-cancerous tissues. Forced expression of miR-491-5p significantly inhibits proliferation and colony formation, and promotes apoptosis in GC cells. Through bioinformatic analysis and luciferase assays, we confirm that miR-491-5p targets Wnt3a. Silencing Wnt3a inhibits cell proliferation and induces apoptosis. Similarly, restoration of Wnt3a counteracts the effects of miR-491-5p expression. Moreover, bioinformatic and luciferase assays indicate that the expression of miR-491-5p is regulated by Foxi1, which binds to its promoter and activates miR-491-5p expression. In conclusion, to the best of our knowledge, our findings are the first to demonstrate that Foxi1 is a key player in the transcriptional control of miR-491-5p and that miR-491-5p acts as an anti-oncogene by targeting Wnt3a/β-catenin signaling in GC. Our study reveals that Foxi1/miR-491-5p/Wnt3a/β-catenin signaling is critical in the progression of GC. Targeting the pathway described in this study may open up new prospects to restrict the progression of GC.

MeCP2 Promotes Gastric Cancer Progression Through Regulating FOXF1/Wnt5a/β-Catenin and MYOD1/Caspase-3 Signaling Pathways

Methyl-CpG binding protein 2 (MeCP2) has recently been characterized as an oncogene frequently amplified in several types of cancer. However, its precise role in gastric cancer (GC) and the molecular mechanism of MeCP2 regulation are still largely unknown. Here we report that MeCP2 is highly expressed in primary GC tissues and the expression level is correlated with the clinicopathologic features of GC. In our experiments, knockdown of MeCP2 inhibited tumor growth. Molecular mechanism of MeCP2 regulation was investigated using an integrated approach with combination of microarray analysis and chromatin immunoprecipitation sequencing (ChIP-Seq). The results suggest that MeCP2 binds to the methylated CpG islands of FOXF1 and MYOD1 promoters and inhibits their expression at the transcription level. Furthermore, we show that MeCP2 promotes GC cell proliferation via FOXF1-mediated Wnt5a/β-Catenin signaling pathway and suppresses apoptosis through MYOD1-mediated Caspase-3 signaling pathway. Due to its high expression level in GC and its critical function in driving GC progression, MeCP2 represents a promising therapeutic target for GC treatment.

MECP2 promotes the growth of gastric cancer cells by suppressing miR-338-mediated antiproliferative effect

The methyl-CpG-binding protein 2 (MECP2), a transcriptional suppressor, is involved in gene regulation by binding to methylated promoters. We found that MECP2 is overexpressed in gastric cancer (GC), and that Mecp2 knockdown affects the growth of GC cells both in vitro and in vivo. MECP2 can directly bind to the methylated-CpG island of miR-338 promoter and suppress the expression of two mature microRNAs, namely, miR-338-3p and miR-338-5p. Furthermore, miR-338-5p can suppress GC cell growth by targeting BMI1 (B lymphoma Mo-MLV insertion region 1 homolog). We additionally found that decreased miR-338-5p expression in GC tissues, relative to normal tissues, was significantly negatively correlated with increased BMI1 expression. Silencing MECP2 can indirectly lead to reduced expression of P-REX2, which has been identified as the miR-338-3p target, as well as BMI1 and increasing expression of P16 or P21 both in vitro and in vivo. Altogether, our results indicate that MECP2 promote the proliferation of GC cells via miR-338 (miR-338-3p and miR-338-5p)-mediated antitumor and gene regulatory effect.

MeCP2 regulated glycogenes contribute to proliferation and apoptosis of gastric cancer cells.

Aberrant glycogene and glycan expression is intimately associated with carcinogenesis, invasion, and metastasis of gastric cancer (GC); however the regulatory mechanisms for glycogenes in GC cells remain unclear. Methyl-CpG-binding protein 2 (MeCP2) regulates genes by binding to methylated promoters, and in our previous work we found that it is overexpressed in GC cell lines and tissues, functioning as an oncogene. In this study we detected the expression of 212 glycogenes in MeCP2 silenced GC cells versus control using the Agilent Whole Human Genome Microarray and mining the data through bioinformatic analysis. A total of 10 glycogenes exhibited increased expression (FC ≥ 2, P < 0.05), while 16 showed decreased expression (FC ≤ 2, P < 0.05) in the MeCP2 silenced cells, which corresponded to down-regulation of Lewis antigens (UEA-I), T/Tn antigens (PNA), and mature N-glycans (PHA-E and PHA-E+L) and up-regulation of lactosylceramide, a precursor oligosaccharide of N-glycans. Examination of the TCGA Gastric Cancer databases demonstrated that nine glycogenes (24.6%) were oppositely regulated by MeCP2 in MeCP2 knockdown BGC-823 cells relative to their expression level in GC tissues, and might be downstream genes of MeCP2. Individual gene analysis suggested that neutral alpha-glucosidase AB (GANAB) knockdown can rescue the effects of MeCP2 overexpression on GC cells. MeCP2 promotes GANAB by binding to the second methylated CpG island (206 bp, -12916 to -13122) of the GANAB promoter. In conclusion, glycogenes can be either up- or down-regulated by MeCP2 directly or indirectly to alter the glycopatterning and affect the proliferation and apoptosis of GC cells.

HOXD3 targeted by miR-203a suppresses cell metastasis and angiogenesis through VEGFR in human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC), one of the most common aggressive tumors worldwide has a relatively high mortality rate among malignant tumors. MicroRNAs (miRNAs), acting as tumor suppressors, are involved in the regulation of invasion, metastasis, and angiogenesis of tumor cells. However, a potential role for miR-203a in HCC has not been described yet. In this study, we show that miR-203a markedly suppresses HCC cell migration, invasion, and angiogenesis. In addition, the transcription factor HOXD3 appears to be a direct target of miR-203a. HOXD3 knockdown substantially decreased HCC cell migration, invasion, and angiogenesis, effects similar to those seen for miR-203a expression. Rescuing the function of HOXD3 attenuated the effect of miR-203a overexpression in HCC cells. Furthermore, HOXD3 can directly target the promoter region of VEGFR and increase VEGFR expression. Taken together, our findings indicate that miR-203a inhibits HCC cell invasion, metastasis, and angiogenesis by negatively targeting HOXD3 and suppressing cell signaling through the VEGFR pathway, suggesting that miR-203a might represent a potential therapeutic target for HCC intervention.

Hypermethylation of miR-338-3p and Impact of its Suppression on Cell Metastasis Through N-Cadherin Accumulation at the Cell -Cell Junction and Degradation of MMP in Gastric Cancer

Background/Aims: MicroRNAs (miRNAs) have been well studied in human carcinogenesis and cancer progression. Our previous study showed the down-regulation of miR-338-3p expression in human gastric cancer (GC). However, the reasons of this dysregulation remain largely unclear. Methods: Bisulfite sequence analysis was performed to explore the methylation status of the promoter region of miR-338-3p. Cell wound-healing and transwell assays were performed to examine the capacity of cell migration and cell interaction. A dual-luciferase reporter was used to validate the bioinformatics-predicted target gene of miR-338-3p. Western blotting, RNA interference, and immunofluorescence (IF) were used to evaluate the expression of MMPs and the location of N-cadherin to determine the mechanism underlying miR-338-3p-induced anti-tumor effects. Results: miR-338-3p was epigenetically silenced, and this loss of expression was significantly correlated with the Borrmann Stage in GC. Restoring miR-338-3p expression in BGC-823 cells inhibited cell migration and invasion. Moreover, Ras-related protein (Rab-14) and Hedgehog acyltransferase (Hhat) were identified as direct targets of miR-338-3p. Both enforced expression of miR-338-3p and small interfering RNA induced Rab14-mediated accumulation of N-cadherin in the cell -cell junctions or Hhat-associated matrix metalloproteinase (MMP) degradation, which may underline the metastasis defects caused by loss of miR-338-3p in GC. Conclusion: These data indicate that miR-338-3p functions as a tumor suppressor in GC, and that the hypermethylation status of its CpG island might be a novel potential strategy for treating GC.

FAM196B acts as oncogene and promotes proliferation of gastric cancer cells through AKT signaling pathway

Gastric cancer (GC) is the second leading cause of cancer-related deaths worldwide, but the mechanisms remain unknown. Here we report that family with sequence similarity 196 member B (FAM196B) is highly expressed in primary GC tissues and the expression level is correlated with the clinicopathologic characteristics of GC. In this experiment, knockdown of FAM196B suppressed GC cell proliferation and induced G1/G0 to S phase cell cycle arrest by regulating Cyclin D1, Cyclin A and CDK2 expressions. Furthermore, we investigated the molecular mechanism of FAM196B action in GC. The results showed that knockdown of FAM196B inhibited the activation of AKT signaling pathway. We further revealed that activating of AKT rescued the effect of FAM196B knockdown on cell proliferation and drove cell re-enter into the S phase of the cell cycle with SC79 (a AKT activator). Our findings demonstrated that FAM196B may promote GC cell proliferation by activating AKT signaling pathway. Taken together, this study provides a new evidence that FAM196B functions as a novel oncogene and could be a potential therapeutic target in therapy of GC.