Transcript levels of ten-eleven translocation type 1-3 in cervical cancer and non-cancerous cervical tissues

The level of active DNA demethylation compounds in leukocytes and urine samples as potential epigenetic biomarkers in breast cancer patients

The active DNA demethylation process, which involves TET proteins, can affect DNA methylation pattern. TET dependent demethylation results in DNA hypomethylation by oxidation 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC) and its derivatives. Moreover, TETs' activity may be upregulated by ascorbate. Given that aberrant DNA methylation of genes implicated in breast carcinogenesis may be involved in tumor progression, we wanted to determine whether breast cancer patients exert changes in the active DNA demethylation process. The study included blood samples from breast cancer patients (n = 74) and healthy subjects (n = 71). We analyzed the expression of genes involved in the active demethylation process (qRT-PCR), and 5-mC and its derivatives level (2D-UPLC MS/MS). The ascorbate level was determined using UPLC-MS. Breast cancer patients had significantly higher TET3 expression level, lower 5-mC and 5-hmC DNA levels. TET3 was significantly increased in luminal B breast cancer patients with expression of hormone receptors. Moreover, the ascorbate level in the plasma of breast cancer patients was decreased with the accompanying increase of sodium-dependent vitamin C transporters (SLC23A1 and SLC23A2). The presented study indicates the role of TET3 in DNA demethylation in breast carcinogenesis.

The prognostic role of C-KIT, TET1 and TET2 gene expression in Acute Myeloid Leukemia

AIM

was to assess the role of C-KIT, TET1 and TET2 expression in the diagnosis and prognosis of acute myeloblastic leukemia (AML).

METHODS

The expression levels of C-KIT, TET1 and TET2 were assessed in the bone marrow (BM) aspirate of 152 AML patients compared to 20 healthy control using quantitative real-time polymerase chain reaction (qRT-PCR). Data were correlated with the clinico-pathological features of the patients, response to treatment, disease-free survival (DFS), and overall survival (OS) rates.

RESULTS

C-KIT, TET1 and TET2 were significantly upregulated in AML patients [0.25 (0-11.6), 0.0113 (0-3.301), and 0.07 (0-4); respectively], compared to the control group [0.013 (0.005-0.250), P < 0.001, 0.001 (0-0.006), P < 0.001, and 0.02 (0.008-0.055), P = 0.019; respectively]. The sensitivity, specificity, and area under curve of of C-KIT were (48.7%, 100%, 0.855; respectively, P = 0.001), and that of TET1 were (63.4%, 100%, 0.897; respectively, P = 0.001), while that of TET2 were (56.8%, 100%, 0.766; respectively, P = 0.019). When combining the three markers, the sensitivity was 77.5%, however it reached the highest sensitivity (78.6%) and specificity (100%) when combining both c-KIT + TET1 together for the diagnosis of AML. C-KIT overexpression associated with shorter DFS (P = 0.05) and increased incidence of relapse (P = 0.019). Lymph nodes involvement [HR = 2.200, P = 0.005] is an independent risk factor for shorter OS rate of AML patients. Increased BM blast % [HR = 7.768, P = 0.002], and FLT3-ITD mutation [HR = 2.989, P = 0.032] are independent risk factors for shorter DSF rate of the patients.

CONCLUSION

C-KIT, TET1, and TET2 could be used as possible useful biomarkers for the diagnosis of AML.

TET1 Isoforms Have Distinct Expression Pattern, Localization and Regulation in Breast Cancer

TET1 regulates gene expression by demethylating their regulatory sequences through the conversion of 5-methylcytosine to 5-hyroxymethylcytosine. TET1 plays important roles in tissue homeostasis. In breast cancer, TET1 was shown to play controversial roles. Moreover, TET1 has at least two isoforms (long and short) that have distinct expression pattern and apparently different functions in tissue development and disease including breast cancer. We hypothesized that TET1 isoforms have different expression patterns, localization and regulation in different types of breast cancer. To prove our hypothesis, we studied the expression of TET1 isoforms in basal and luminal breast cancer cell lines, as well as in basal and luminal breast cancer animal models. We also studied the effect of different hormones on the expression of the two isoforms. Moreover, we assessed the distribution of the isoforms between the cytoplasm and nucleus. Finally, we overexpressed the full length in a breast cancer cell line and tested its effect on cancer cell behavior. In this study, we demonstrate that while Estrogen and GnRH downregulate the expression of long TET1, they lead to upregulation of short TET1 expression. In addition, we uncovered that luminal cells show higher expression level of the long isoform. We also show that while all TET1 isoforms are almost depleted in a basal breast cancer animal model, the expression of the short isoform is induced in luminal breast cancer model. The short form is expressed mainly in the cytoplasm while the long isoform is expressed mainly in the nucleus. Finally, we show that long TET1 overexpression suppresses cell oncogenic phenotypes. In conclusion, our data suggest that TET1 isoforms have distinct expression pattern, localization and regulation in breast cancer and that long TET1 suppresses oncogenic phenotypes, and that further studies are necessary to elucidate the functional roles of different TET1 isoforms in breast cancer.

Differential Expression of Steroid Hormone Receptors and Ten Eleven Translocation Proteins in Endometrial Cancer Cells

Steroid hormones govern the complex, cyclic changes of the endometrium, predominantly through their receptors. An interplay between steroid hormones and epigenetic mechanisms controls the dynamic endometrial gene regulation. Abnormalities in expression of genes and enzymes associated with steroid hormone signaling, contribute to a disturbed hormonal equilibrium. Limited evidence suggests the involvement of TET (Ten Eleven Translocation)-mediated DNA hydroxymethylation in endometrial cancer, with some data on the use of TET1 as a potential prognostic and diagnostic biomarker, however the mechanisms guiding it and its regulation remains unexplored. This study aims to explore the changes in the expressions of TETs and steroid hormone receptors in response to estrogen and progesterone in endometrial cancer cells. Gene expression was examined using real-time PCR and protein expression was quantified using fluorescent western blotting in endometrial cancer cell lines (AN3 and RL95-2). Results indicate that TET1 and TET3 gene and protein expression was cell-specific in cancer cell-lines. Protein expression of TET1 was downregulated in AN3 cells, while TET1 and TET3 expressions were both upregulated in RL95-2 cells in response to estrogen-progesterone. Further, a decreased AR expression in AN3 cells and an increased ERα and ERβ protein expressions in RL95-2 cells was seen in response to estrogen-progesterone. PR gene and protein expression was absent from both cancer cell-lines. Overall, results imply that expressions of steroid hormones, steroid-hormone receptors and TETs are co-regulated in endometrial cancer-cells. Further studies are needed to interpret how these mechanisms fit in with DNMTs and DNA methylation in regulating endometrial biology. Understanding the role of TETs and hydroxymethylation in steroid hormone receptor regulation is crucial to comprehend how these mechanisms work together in a broader context of epigenetics in the endometrium and its pathologies.

Ten-eleven translocase: key regulator of the methylation landscape in cancer

PURPOSE

Methylation of 5th residue of cytosine in CpG island forms 5-methylcytosine which is stable, heritable epigenetic mark. Methylation levels are broadly governed by methyltransferases and demethylases. An aberration in the demethylation process contributes to the silencing of gene expression. Ten eleven translocation (TET) dioxygenase (1-3) the de novo demethylase is responsible for conversion of 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC), 5-formylcytosisne (5-fC) and 5-carboxycytosine (5-caC) during demethylation process. Mutations and abnormal expression of TET proteins contribute to carcinogenesis. Discovery of TET proteins has offered various pathways for the reversal of methylation levels thus, enhancing our knowledge as to how methylation effects cancer progression.

METHODS

We searched "PubMed" and "Google scholar" databases and selected studies with the following keywords "TET enzyme", "cancer", "5-hmC", and "DNA demethylation". In this review, we have discussed combinatorial use of vitamin C in inhibiting tumour growth by enhancing the catalytic activity of TET enzymes and consequently, increasing the 5-hmC levels. 5-Hydroxymethylcytosine holds promise as a prognostic biomarker in solid cancers. The contribution of induction and suppression of TET enzymes and 5-hmC carcinogenesis are discussed in haematological and solid cancers.

RESULTS

We found that TET enzymes play central role in maintaining the methylation balance. Any anomaly in their expression may dip the balance towards cancer progression. Low levels of TET enzymes and 5-hmC correlate with tumour invasion, progression and metastasis. Also, use of vitamin C enhances TET activity.

CONCLUSION

TET enzymes play vital role in shaping the methylation landscape in body. 5-hmC can be used as prognostic marker in solid cancers.

Expression and prognosis analysis of TET family in acute myeloid leukemia

TET family members (TETs) encode proteins that represent crucial factors in the active DNA demethylation pathway. Evidence has proved that TET2 mutation is associated with leukemogenesis, drug response, and prognosis in acute myeloid leukemia (AML). However, few studies revealed the TETs expression and its clinical significance in AML. We conducted a detailed expression and prognosis analysis of TETs expression in human AML cell lines and patients by using public databases. We observed that TETs expression especially TET2 and TET3 was closely associated with AML among various human cancers. TET1 expression was significantly reduced in AML patients, whereas TET2 and TET3 expression was significantly increased. Kaplan-Meier analysis showed that only TET3 expression was associated with overall survival (OS) and disease-free survival (DFS) among both total AML as well as non-M3 AML, and was confirmed by another independent cohort. Moreover, Cox regression analysis revealed that TET3 expression may act as an independent prognostic factor for OS and DFS in total AML. Interestingly, patients that received hematopoietic stem cell transplantation (HSCT) did not show significantly longer OS and DFS than those who did not receive HSCT in TET3 high-expressed groups; whereas, in TET3 low-expressed groups, patients that accepted HSCT showed significantly longer OS and DFS than those who did not accept HSCT. By bioinformatics analysis, TET3 expression was found positively correlated with tumor suppressor gene including CDKN2B, ZIC2, miR-196a, and negatively correlated with oncogenes such as PAX2 and IL2RA. Our study demonstrated that TETs showed significant expression differences in AML, and TET3 expression acted as a potential prognostic biomarker in AML, which may guide treatment choice between chemotherapy and HSCT.

Epigenetic Regulation of p21cip1/waf1 in Human Cancer

p21^cip1/waf1 is a central regulator of cell cycle control and survival. While mutations are rare, it is commonly dysregulated in several human cancers due to epigenetic mechanisms influencing its transcriptional control. These mechanisms include promoter hypermethylation as well as additional pathways such as histone acetylation or methylation. The epigenetic regulators include writers, such as DNA methyltransferases (DNMTs); histone acetyltransferases (HATs) and histone lysine methyltransferases; erasers, such as histone deacetylases (HDACs); histone lysine demethylases [e.g., the Lysine Demethylase (KDM) family]; DNA hydroxylases; readers, such as the methyl-CpG-binding proteins (MBPs); and bromodomain-containing proteins, including the bromo- and extraterminal domain (BET) family. We further discuss the roles that long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play in the epigenetic control of p21^cip1/waf1 expression and its function in human cancers.

Epigenetic Dysregulation at the Crossroad of Women's Cancer

An increasingly number of women of all age groups are affected by cancer, despite substantial progress in our understanding of cancer pathobiology, the underlying genomic alterations and signaling cascades, and cellular-environmental interactions. Though our understanding of women’s cancer is far more complete than ever before, there is no comprehensive model to explain the reasons behind the increased incidents of certain reproductive cancer among older as well as younger women. It is generally suspected that environmental and life-style factors affecting hormonal and growth control pathways might help account for the rise of women’s cancers in younger age, as well, via epigenetic mechanisms. Epigenetic regulators play an important role in orchestrating an orderly coordination of cellular signals in gene activity in response to upstream signaling and/or epigenetic modifiers present in a dynamic extracellular milieu. Here we will discuss the broad principles of epigenetic regulation of DNA methylation and demethylation, histone acetylation and deacetylation, and RNA methylation in women’s cancers in the context of gene expression, hormonal action, and the EGFR family of cell surface receptor tyrosine kinases. We anticipate that a better understanding of the epigenetics of women’s cancers may provide new regulatory leads and further fuel the development of new epigenetic biomarkers and therapeutic approaches.