5-Aza-2′-Deoxycytidine Improves the Sensitivity of Endometrial Cancer Cells to Progesterone Therapy

NrCAM secreted by endometrial stromal cells enhances the progestin sensitivity of endometrial cancer cells through epigenetic modulation of PRB

Progestin is one of the main hormone treatment regimens for early-stage estrogen receptor- and progesterone receptor (PR)-positive endometrial cancer (EC). However, the response rate of EC to progestins is unsatisfactory. Investigating the mechanisms related to progestin treatment could help improve treatment efficacy. Studies have demonstrated that normal endometrial stromal cells (ESCs) increase the inhibitory effect of progestin on EC cell proliferation via paracrine signaling, but the mechanisms involved remain unclear. In this study, we found that ESCs had different morphological features between progestin-sensitive and -insensitive EC tissues. ESCs presented typical decidualization changes in progestin-sensitive cases, while they remained slim in progestin-insensitive EC lesions, indicating no response. Furthermore, ESCs enhanced the inhibitory effect of medroxyprogesterone acetate (MPA) on EC cell proliferation by secreting neuron cell adhesion molecule (NrCAM). MPA treatment enhanced NrCAM secretion by ESCs. EC xenografts in BALB/C nude mice demonstrated that MPA combined with NrCAM had an increased tumor inhibitory effect compared with MPA or NrCAM alone. Mechanistically, MPA upregulated NrCAM expression in ESCs through PR. Specifically, NrCAM increased PR expression in EC cells through TET1-induced hydroxymethylation of the PRB gene promoter region. These findings indicate that NrCAM or NrCAM combined with progestins could be a new EC treatment.

Downregulation of thrombospondin-1 by DNA hypermethylation is associated with tumor progression in laryngeal squamous cell carcinoma

Thrombospondin-1 (THBS-1) has been demonstrated to have a complicated role in human cancer and to exert stimulatory and inhibitory effects in different types of tumors. DNA methylation, as the most frequent mechanism for gene silencing, has been widely investigated in regards to the development of tumors. However, the expression levels and methylation status of THBS-1, and their roles in laryngeal squamous cell carcinoma (LSCC) remain to be elucidated. The present study detected downregulated THBS-1 mRNA and protein expression levels in LSCC by using reverse transcription-quantitative polymerase chain reaction (PCR) and western blotting, while decreased expression levels of THBS-1 mRNA and protein were significantly associated with lymph node metastasis and tumor-node-metastasis (TNM) stage. Furthermore, aberrant methylation of THBS-1 was frequently observed in LSCC by methylation-specific PCR, particularly in tumor tissues from lymph node metastasis or samples from cancer with advanced TNM stage. Furthermore, the current study demonstrated that downregulated expression of THBS-1 in LSCC was consistent with aberrant methylation of this gene. Treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxy-cytidine in Hep-2 cells induced demethylation of THBS-1, enhanced THBS-1 expression, and inhibited the proliferative and invasive ability of Hep-2 cells. Collectively, the results of the present study suggest that THBS-1 may exert an inhibitory effect in the development of LSCC. Aberrant methylation was an important reason for the downregulation of THBS-1 and was involved in the invasion and metastasis of LSCC. Demethylating agents may be effective candidates for the treatment of LSCC.

Association of RUNX3 Methylation with Clinical Outcome and Cell Migration/Invasion in Laryngeal Squamous Cell Carcinoma

This study identifies promoter methylation status of RUNX3 in 77 LSCC patient tissues and their paired adjacent healthy tissues. Hypermethylation percentage RUNX3 occurred in LSCC samples was significantly higher than that in normal tissues, as well as associated with suppression of RUNX3 expression, TNM classification of malignant tumors stage, lymph node metastasis and poor overall survival rate. Reduced methylation and increased expression of RUNX3 genes in vitro was observed and decreased cell migration was further confirmed following 5-azacytidine treatment. RUNX 3 promoter hypermethylation can lead to down-regulation of RUNX3 in LSCC cancerous tissue.

Clinical significance of epigenetic silencing and re-expression of O6-methylguanine-DNA methyltransferase using epigenetic agents in laryngeal carcinoma

The aim of the present study was to investigate the association between O6-methylguanine-DNA methyltransferase (MGMT) gene expression levels, and DNA methylation status and histone modifications in laryngeal squamous cell carcinoma (LSCC). Chromatin immunoprecipitation, methylation-specific polymerase chain reaction (PCR), and reverse transcription-quantitative PCR were performed to analyze histone modifications, DNA methylation status and mRNA expression levels in the promoter region of the MGMT gene in laryngeal carcinoma HEp-2 cells, as well as in 50 paired healthy and LSCC tissue samples. The present study demonstrated that treatment of HEp-2 cells with 5-aza-2′-deoxycytidine (Aza), a DNA methyltransferase inhibitor, significantly upregulated MGMT mRNA expression levels, reduced MGMT DNA methylation, reduced MGMT histone H3 lysine 9 (H3K9) di-methylation, and increased MGMT histone H3 lysine 4 di-methylation without a significant change in H3K9 acetylation. Trichostatin A (TSA), a histone deacetylase inhibitor, marginally upregulated MGMT mRNA expression levels without affecting the DNA methylation status, or H3K9 or H3K4 di-methylation, however, TSA treatment caused a significant increase in H3K9 acetylation. Furthermore, Aza and TSA combination treatment produced a synergistic effect. In the LSCC samples, the rate of DNA methylation in the MGMT gene was 54%, compared with 24% in the healthy control group (P<0.05). Therefore, data from the present study indicates that MGMT may serve as a novel therapeutic target in the treatment of LSCC.

Growth of poorly differentiated endometrial carcinoma is inhibited by combined action of medroxyprogesterone acetate and the Ras inhibitor Salirasib

Type 2 endometrial carcinoma (EC) is a poorly differentiated EC. Unlike type 1 EC, which responds to hormonal treatment (progestins), type 2 EC is refractory to hormonal treatment because of its low expression of active estrogen and progesterone receptors (ER, PR). The aim of this study was to develop a novel drug combination designed to treat these aggressive type 2 EC tumors without surgery and with fertility potential preserved. We examined the effects of combined treatment with the progestin medroxyprogesterone acetate (MPA) and the Ras inhibitor S-farnesylthiosalicylic acid (FTS; Salirasib). Because FTS can induce cell differentiation in tumor cells, we examined whether FTS could induce re-differentiation of type 2 EC cells, thereby sensitizing them to MPA. We found that FTS reduced Ras-GTP, phospho-Akt, and phospho-ERK, and that these reductions all correlated with a decrease in ERα phosphorylation. Combined treatment with FTS and MPA induced stronger reduction in USPC1 type 2 EC cell numbers than the reduction induced by either drug alone. MPA caused ERα degradation. Death of the cells was caused by MPA but not by FTS. The phosphorylated ERα induces gene transcription manifested by enhanced cell proliferation and survival. The combination of FTS and MPA, by reducing the mRNA expression of ERα-mediated genes (i.e. PR, c-fos and ps2/TFF1), inhibited tumor growth and enhanced the death of type 2 EC cells. These promising results might herald a novel treatment for the highly aggressive, incurable type 2 endometrial carcinoma.

CpG island hypermethylation-associated silencing of microRNAs promotes human endometrial cancer

Background

Endometrial cancer (EC) is the most common gynecologic malignancy, but the molecular events involved in the development and progression of EC remain unclear. This study aimed to explore epigenetic modification of genes and miRNAs involved in EC development.

Methods

Ishikawa and AN3CA cells were treated with 5’-Aza-2-deoxycytidine or histone deacetylase inhibitor. The expression of miRNAs and related genes were detected by PCR and Western blot. Promoter methylation was detected by bisulfite specific PCR sequencing. The proliferation, colony formation, cell cycle progression, migration and invasion of EC cells were evaluated by MTT, soft agar assay, flow cytometry, wound healing and invasion assay, respectively.

Results

Aberrant expression of miRNAs including miR-200b, miR-130a/b, miR-625 and miR-222 was associated with tumorigenesis and metastasis in endometrial cancer. Silencing of miR-130b induced E-cadherin expression, while ectopic expression of miR-130b and knockdown of DICER1 increased the expression of Vimentin, zeb2, N-cadherin, Twist and Snail in EC cells. Furthermore, 5’-Aza-2-deoxycytidine and Histone deacetylase (HDAC) inhibitor inhibited the proliferation, colony formation, migration and invasion of EC cells, accompanied by reduced MMP secretion.

Conclusions

Our study provides the first description of epigenetic modification of epithelial mesenchymal transition associated genes and miRNAs in EC cells, which are extensively involved in the regulation of gene expression and subsequent accumulation of malignant features of EC cells.

5-Aza-2'-deoxycytidine enhances maspin expression and inhibits proliferation, migration, and invasion of the bladder cancer T24 cell line

BACKGROUND

Downregulation of maspin expression has been linked to bladder cancer development, and that DNA methylation may be important for regulating maspin gene activation in bladder cancer cells. Thus, we attempted to explore the effects of the DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-Aza-CdR), on the maspin expression and the biological behaviors in bladder cancer T24 cells.

METHOD

The methylation status of maspin in T24 cells was investigated by methylation-specific polymerase chain reaction (PCR). After treated with different concentrations of 5-Aza-CdR (0, 0.25, 0.5, 1, and 2 μM), the maspin gene mRNA expression and protein expression were examined by real-time PCR and western blotting analysis. Cell proliferations were evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Flow cytometry was used to identify the apoptosis rates. Migration and invasive ability were determined by the transwell assay. Using the western blotting analysis, the changes of Cyclin D1, VEGF-C, VEGFR-3, MMP-2, MMP-9, caspase-3 p17, Bax, and Bcl-2 expression were measured.

RESULTS

Promoter DNA methylation of maspin was observed in T24 cells. The expression levels of maspin mRNA and protein in T24 cells were increased in a dose manner after treatment with increasing 5-Aza-CdR (p<0.05). The proliferation, migration, and invasion of cells were significantly inhibited with increasing 5-Aza-CdR, whereas the apoptosis was greatly increased (p<0.05). These were associated with the decreased ratio of Bcl-2/Bax, activation of caspase-3, and decreased expression of Cyclin D1, VEGF-C, VEGFR-3, MMP-2 and MMP-9.

CONCLUSIONS

The present study demonstrates that maspin is silenced by DNA methylation in bladder T24 cells, and its expression can be reactivated by treatment with 5-Aza-CdR. 5-Aza-CdR could result in obvious inhibitions of the proliferation, migration, and invasion of T24 cells, which may serve as a potential strategy for the treatment of bladder cancer.