Trichostatin A and 5-aza-2'-deoxycytidine switch S1P from an inhibitor to a stimulator of motility through epigenetic regulation of S1P receptors

Deregulated expression of the 14q32 miRNA cluster in clear cell renal cancer cells

Clear cell renal cell carcinomas (ccRCC) are characterized by arm-wide chromosomal alterations. Loss at 14q is associated with disease aggressiveness in ccRCC, which responds poorly to chemotherapeutics. The 14q locus contains one of the largest miRNA clusters in the human genome; however, little is known about the contribution of these miRNAs to ccRCC pathogenesis. In this regard, we investigated the expression pattern of selected miRNAs at the 14q32 locus in TCGA kidney tumors and in ccRCC cell lines. We demonstrated that the miRNA cluster is downregulated in ccRCC (and cell lines) as well as in papillary kidney tumors relative to normal kidney tissues (and primary renal proximal tubule epithelial (RPTEC) cells). We demonstrated that agents modulating expression of DNMT1 (e.g., 5-Aza-deoxycytidine) could modulate 14q32 miRNA expression in ccRCC cell lines. Lysophosphatidic acid (LPA, a lysophospholipid mediator elevated in ccRCC) not only increased labile iron content but also modulated expression of a 14q32 miRNA. Through an overexpression approach targeting a subset of 14q32 miRNAs (specifically at subcluster A: miR-431-5p, miR-432-5p, miR-127-3p, and miR-433-3p) in 769-P cells, we uncovered changes in cellular viability and claudin-1, a tight junction marker. A global proteomic approach was implemented using these miRNA overexpressing cell lines which uncovered ATXN2 as a highly downregulated target. Collectively, these findings support a contribution of miRNAs at 14q32 in ccRCC pathogenesis.

Pharmacological Properties of Trichostatin A, Focusing on the Anticancer Potential: A Comprehensive Review

Trichostatin A (TSA), a natural derivative of dienohydroxamic acid derived from a fungal metabolite, exhibits various biological activities. It exerts antidiabetic activity and reverses high glucose levels caused by the downregulation of brain-derived neurotrophic factor (BDNF) expression in Schwann cells, anti-inflammatory activity by suppressing the expression of various cytokines, and significant antioxidant activity by suppressing oxidative stress through multiple mechanisms. Most importantly, TSA exhibits potent inhibitory activity against different types of cancer through different pathways. The anticancer activity of TSA appeared in many in vitro and in vivo investigations that involved various cell lines and animal models. Indeed, TSA exhibits anticancer properties alone or in combination with other drugs used in chemotherapy. It induces sensitivity of some human cancers toward chemotherapeutical drugs. TSA also exhibits its action on epigenetic modulators involved in cell transformation, and therefore it is considered an epidrug candidate for cancer therapy. Accordingly, this work presents a comprehensive review of the most recent developments in utilizing this natural compound for the prevention, management, and treatment of various diseases, including cancer, along with the multiple mechanisms of action. In addition, this review summarizes the most recent and relevant literature that deals with the use of TSA as a therapeutic agent against various diseases, emphasizing its anticancer potential and the anticancer molecular mechanisms. Moreover, TSA has not been involved in toxicological effects on normal cells. Furthermore, this work highlights the potential utilization of TSA as a complementary or alternative medicine for preventing and treating cancer, alone or in combination with other anticancer drugs.

Natural Bioactive Compounds Targeting Epigenetic Pathways in Cancer: A Review on Alkaloids, Terpenoids, Quinones, and Isothiocyanates

Cancer is one of the most complex and systemic diseases affecting the health of mankind, causing major deaths with a significant increase. This pathology is caused by several risk factors, of which genetic disturbances constitute the major elements, which not only initiate tumor transformation but also epigenetic disturbances which are linked to it and which can induce transcriptional instability. Indeed, the involvement of epigenetic disturbances in cancer has been the subject of correlations today, in addition to the use of drugs that operate specifically on different epigenetic pathways. Natural molecules, especially those isolated from medicinal plants, have shown anticancer effects linked to mechanisms of action. The objective of this review is to explore the anticancer effects of alkaloids, terpenoids, quinones, and isothiocyanates.

Role of spermatogonial stem cells extract in transdifferentiation of 5-Aza-2'-deoxycytidine-treated bone marrow mesenchymal stem cells into germ-like cells

As one of the induced pluripotent stem cells (iPSCs) methods, spermatogonial stem cells (SSCS ) extract is considered as new approach in stem cell therapy of infertility. 5-aza-2'-deoxycytidine (5-aza-dC) inhibits methyltransferase enzyme, and induces gene reprogramming; herein, the effects of SSCS extract incubation in 5-aza-dC-treated bone marrow mesenchymal stem cells (BMMSCs) has been surveyed. BMMSCs were isolated from femurs of three to four weeks old male NMRI mice, and the cells at passage three were treated with 2 µM 5-aza-dC for 72 hours. SSCs were isolated, cultured, and harvested at passage three to collect SSCS extract; BMMSCs were then incubated with SSCS extract in the three time periods: 72 hours, one week and two weeks. There were five groups: control, sham, extract, 5-aza-dC and extract-5-aza-dC. After one week of incubation, flow cytometry and real-time polymerase chain reaction (PCR) exhibited high levels of expression for β1- and α6-integrins and promyelocytic leukaemia zinc finger (PLZF) in extract and extract-5-aza-dC groups (P < 0.05 vs. control and 5-aza-dC), and cells in these two groups had two forms of morphology, round and fusiform, similar to germ-like cells. 5-aza-dC had no significant effects during the three time periods of evaluation. These data disclose the effectiveness of SSCs extract incubation in transdifferentiation of BMMSCs into germ-like cells; this strategy could introduce a new approach for treatment of male infertility in clinic.

Transcriptional suppression, DNA methylation, and histone deacetylation of the regulator of G-protein signaling 10 (RGS10) gene in ovarian cancer cells

RGS10 regulates ovarian cancer cell growth and survival, and RGS10 expression is suppressed in cell models of ovarian cancer chemoresistance. However, the mechanisms governing RGS10 expression in ovarian cancer are poorly understood. Here we report RGS10 suppression in primary ovarian cancer and CAOV-3 ovarian cancer cells compared to immortalized ovarian surface epithelial (IOSE) cells, and in A2780-AD chemoresistant cells compared to parental A2780 cells. RGS10-1 and RGS10-2 transcripts are expressed in ovarian cancer cells, but only RGS10-1 is suppressed in A2780-AD and CAOV-3 cells, and the RGS10-1 promoter is uniquely enriched in CpG dinucleotides. Pharmacological inhibition of DNA methyl-transferases (DNMTs) increased RGS10 expression, suggesting potential regulation by DNA methylation. Bisulfite sequencing analysis identified a region of the RGS10-1 promoter with significantly enhanced DNA methylation in chemoresistant A2780-AD cells relative to parental A2780 cells. DNA methylation in CAOV-3 and IOSE cells was similar to A2780 cells. More marked differences were observed in histone acetylation of the RGS10-1 promoter. Acetylated histone H3 associated with the RGS10-1 promoter was significantly lower in A2780-AD cells compared to parental cells, with a corresponding increase in histone deacetylase (HDAC) enzyme association. Similarly, acetylated histone levels at the RGS10-1 promoter were markedly lower in CAOV-3 cells compared to IOSE cells, and HDAC1 binding was doubled in CAOV-3 cells. Finally, we show that pharmacological inhibition of DNMT or HDAC enzymes in chemoresistant A2780-AD cells increases RGS10 expression and enhances cisplatin toxicity. These data suggest that histone de-acetylation and DNA methylation correlate with RGS10 suppression and chemoresistance in ovarian cancer. Markers for loss of RGS10 expression may identify cancer cells with unique response to therapeutics.

Up-regulation of miR-182 expression after epigenetic modulation of human melanoma cells

PURPOSE

We sought to investigate the epigenetic regulation of microRNAs (miRNAs) in melanoma.

METHODS

We treated two highly metastatic human melanoma cell lines, C8161.9 and WM266-4, with the demethylating agents DAC (5-aza-2'-deoxycytidine) and trichostatin A. Locked nucleic acid-based miRNA expression profiling was utilized to examine the differential expression of miRNAs before and after treatment.

RESULTS

We found that miR-182, a miRNA with oncogenic properties, was significantly up-regulated in human melanoma cells after epigenetic modulation. Genome sequence analysis revealed the presence of a prominent CpG island 8-10 kb upstream of mature miR-182. Methylation analysis showed that this genomic region was exclusively methylated in melanoma cells but not in human melanocytes, skin, or peripheral blood mononuclear cells.

DISCUSSION

These results indicate that an epigenetic mechanism is likely involved in modulating the expression level of miR-182 in melanoma, and increased expression of oncogenic-like miR-182 could be a concern for melanoma patients after epigenetic therapy.

Epigenetics in human melanoma

BACKGROUND

Recent technological advances have allowed us to examine the human genome in greater detail than ever before. This has opened the door to an improved understanding of the gene expression patterns involved with cancer.

METHODS

A review of the literature was performed to determine the role of epigenetic modifications in human melanoma. We focused the search on histone deacetylation, methylation of gene promoter regions, demethylation of CpG islands, and the role of microRNA. We examined the relationship between human melanoma epigenetics and their importance in tumorigenesis, tumor progression, and inhibition of metastasis. The development and clinical application of select pharmacologic agents are also discussed.

RESULTS

We identified several articles that have extensively studied the role of epigenetics in melanoma, further elucidating the complex processes involved in gene regulation and expression. Several new agents directly affect epigenetic mechanisms in melanoma, with divergent affects on the metastatic potential of melanoma.

CONCLUSIONS

Epigenetic mechanisms have emerged as having a central role in gene regulation of human melanoma, including the identification of several putative tumor suppressor genes and oncogenes. Further research will focus on the development of novel therapeutics that will likely target and alter such epigenetic changes.

Effects of 5-azacytidine on the growth inhibition of human hepatocellular carcinoma cells and reversion of p16 hympermethylation

AIM: To investigate correlation between DNA methylation alteration and hepatocellular carcinoma as well as to explore mechanisms of 5-aza-CR inhibiting hepatoma cell lines and reversed methylation.

METHODS: Human hepatoma cell lines, HuH-7, and the murine xenograft model were treated with 5-aza-CR. Cell morphology changes were determined under phase contrast microscopy, cell growth speed was measured using MTT assay, cell cycle distribution and apoptosis rate were estimated using flow cytometry, methylation status of p16 was determined using methylation-specific PCR and mRNA expression of p16 was determined using RT-PCR.

RESULTS: After treatment with 5-aza-CR, significant inhibiting effects were detected both in hepatoma cell lines HuH-7 and the murine xenograft model cells. In the treatment group, G₁ of HuH-7 increased by 41.1% ± 3.2%, S and G₂ + M decreased by 39.0% ± 1.4% and 2.2% ± 0.7%, respectively, and apoptosis rate increased by 30.0% ± 4.5%. In the murine xenograft model group, G₁ increased by 27.4% ± 3.1%, S and G₂ + M decreased by 25.8% ± 2.1% and 1.6% ± 1.8%, respectively, and apoptosis rate increased by 2.9% ± 0.6%. Only methylating PCR product appeared before treatment with drugs, Conversely while only demethylating PCR amplification product was detected after drug treatment. For the murine xenograft model group, methylated PCR product was detected in the control group, however, methylated and demethylated PCR amplification products were observed in the experimental group. Both cell and xenografted nude mice presented the expression of p16 mRNA in experimental group. No expression of p16 mRNA was detected in the control group.

CONCLUSION: 5-aza-CR inhibits tumor cell growth, decreases cell cycle and increases mRNA expression of p16 in hepatoma cell lines both in vitro and in vivo. 5-aza-CR inhibits the malignant phenotypes of human hepatocellular carcinoma cells and reverses hympermethylation of p16.