DNA Methylation Inhibitor Decitabine Research Articles

Abnormal Weakening of DNA Methylation around the SLC6A1 Gene Promoter in Temporal Lobe Epilepsy.

The solute carrier (SLC) superfamily, which transports solutes across biological membranes, includes four members (SLC2A1, SLC6A1, SLC9A64, and SLC35A2) that have been linked to epilepsy. This study sought to examine the DNA methylation patterns near the promoters of these genes in temporal lobe epilepsy (TLE), as DNA methylation is a crucial epigenetic modification that can impact gene expression. The study comprised 38 individuals with TLE and 38 healthy controls. Methylation experiments were performed using peripheral blood, while demethylation experiments were carried out using SH-SY5Y cells with the DNA methylation inhibitor decitabine. A significant difference was observed in the DNA methylation rate of SLC6A1 between TLE patients and controls, with TLE patients showing a lower rate (4.81% vs. 5.77%, p = 0.0000), which remained significant even after Bonferroni correction (p = 0.0000). Based on the hypomethylated SLC6A1 in TLE, a predictive model was established that showed promise in distinguishing and calibrating TLE. In the TLE group, there were differences in DNA methylation rates of SLC6A1 between the young patients and the older controls (4.42% vs. 5.22%, p = 0.0004). A similar trend (p = 0.0436) was noted after adjusting for sex, age at onset, and drug response. In addition, the study found that DNA methylation had a silencing impact on the expression of the SLC6A1 gene in SH-SY5Y cells, which were treated with decitabine at a set dose gradient. The evidence suggests that lower methylation of SLC6A1 may stimulate transcription in TLE, however, further investigation is necessary to confirm the exact mechanism.

Nanotherapeutic System with Effective Microwave Sensitization and Pyroptosis Programming Enable Synergistic Microwave-Immunotherapy in Bladder Cancer

Currently, the prognosis for patients with advanced bladder cancer remains poor, with only a minority being sensitive to immune checkpoint inhibitors. There is a need to develop additional treatment strategies. Microwave therapy, as a promising approach for some inoperable tumors, still faces challenges such as limited efficacy and high recurrence rates. Additionally, the cell damage and necrosis induced by conventional microwave treatment only act as weak immunostimulatory factors for antitumor immunity, failing to activate effective antitumor immune responses. Recent discoveries have shown that inducing pyroptosis can provide a good opportunity for enhancing systemic immune responses and alleviating immune suppression in cancer therapy. Here, we have developed Mn-ZrMOF@DAC, a microwave-sensitized nanoparticle loaded with the DNA methylation inhibitor decitabine. The Mn-ZrMOF@DAC can enhance the effect of microwave thermal therapy and generate reactive oxygen species under microwave irradiation, causing thermal and oxidative damage to cancer cells. Furthermore, there was an important up-regulation of the key pyroptosis protein GSDME, with a marked increase in pyroptotic cell numbers. In vivo experiments demonstrated that mice injected with Mn-ZrMOF@DAC nanoparticles followed by microwave radiation treatment exhibited potent antitumor effects and enhanced the efficacy of anti-PD-1 therapy. This therapy not only enhanced the efficacy of microwave treatment, exhibiting significant antitumor effects, but also activated antitumor immunity by inducing pyroptosis, thus enhancing the efficacy of immunotherapy for bladder cancer. It holds promise for providing new avenues in the treatment of bladder cancer.

Tissue explants as tools for studying the epigenetic modulation of the GH-IGF-I axis in farmed fish.

Somatic growth in vertebrates is mainly controlled by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. The role of epigenetic mechanisms in regulating this axis in fish is far from being understood. This work aimed to optimize and evaluate the use of short-term culture of pituitary and liver explants from a farmed fish, the gilthead seabream Sparus aurata, for studying epigenetic mechanisms involved in GH/IGF-I axis regulation. Our results on viability, structure, proliferation, and functionality of explants support their use in short-term assays. Pituitary explants showed no variation in gh expression after exposure to the DNA methylation inhibitor decitabine (5-Aza-2'-deoxycytidine; DAC), despite responding to DAC by changing dnmt3bb and tet1 expression, and TET activity, producing an increase in overall DNA hydroxymethylation. Conversely, in liver explants, DAC had no effects on dnmt s and tet s expression or activity, but modified the expression of genes from the GH-IGF-I axis. In particular, the expression of igfbp2a was increased and that of igfbp4, ghri and ghrii was decreased by DAC as well as by genistein, which is suggestive of impaired growth. While incubation of liver explants with S-adenosylmethionine (SAM) produced no clear effects, it is proposed that nutrients must ensure the methylation milieu within the liver in the fish to sustain proper growth, which need further in vivo verification. Pituitary and liver explants from S. aurata can be further used as described herein for the screening of inhibitors or activators of epigenetic regulators, as well as for assessing epigenetic mechanisms behind GH-IGF-I variation in farmed fish.

Combined inhibition of histone deacetylase and cytidine deaminase improves epigenetic potency of decitabine in colorectal adenocarcinomas

BackgroundTargeting the epigenome of cancerous diseases represents an innovative approach, and the DNA methylation inhibitor decitabine is recommended for the treatment of hematological malignancies. Although epigenetic alterations are also common to solid tumors, the therapeutic efficacy of decitabine in colorectal adenocarcinomas (COAD) is unfavorable. Current research focuses on an identification of combination therapies either with chemotherapeutics or checkpoint inhibitors in modulating the tumor microenvironment. Here we report a series of molecular investigations to evaluate potency of decitabine, the histone deacetylase inhibitor PBA and the cytidine deaminase (CDA) inhibitor tetrahydrouridine (THU) in patient derived functional and p53 null colon cancer cell lines (CCCL). We focused on the inhibition of cell proliferation, the recovery of tumor suppressors and programmed cell death, and established clinical relevance by evaluating drug responsive genes among 270 COAD patients. Furthermore, we evaluated treatment responses based on CpG island density.ResultsDecitabine caused marked repression of the DNMT1 protein. Conversely, PBA treatment of CCCL recovered acetylation of histone 3 lysine residues, and this enabled an open chromatin state. Unlike single decitabine treatment, the combined decitabine/PBA treatment caused > 95% inhibition of cell proliferation, prevented cell cycle progression especially in the S and G2-phase and induced programmed cell death. Decitabine and PBA differed in their ability to facilitate re-expression of genes localized on different chromosomes, and the combined decitabine/PBA treatment was most effective in the re-expression of 40 tumor suppressors and 13 genes typically silenced in cancer-associated genomic regions of COAD patients. Furthermore, this treatment repressed expression of 11 survival (anti-apoptotic) genes and augmented expression of X-chromosome inactivated genes, especially the lncRNA Xist to facilitate p53-mediated apoptosis. Pharmacological inhibition of CDA by THU or its gene knockdown prevented decitabine inactivation. Strikingly, PBA treatment recovered the expression of the decitabine drug-uptake transporter SLC15A1, thus enabling high tumor drug-loads. Finally, for 26 drug responsive genes we demonstrated improved survival in COAD patients.ConclusionThe combined decitabine/PBA/THU drug treatment improved drug potency considerably, and given their existing regulatory approval, our findings merit prospective clinical trials for the triple combination in COAD patients.

Postsurgical wound management and prevention of triple-negative breast cancer recurrence with a pryoptosis-inducing, photopolymerizable hydrogel.

Surgical removal remains the predominant treatment strategy for triple-negative breast cancer (TNBC). However, risks that include high locoregional recurrence and remote metastasis threaten patient survival and quality of life after surgery. In this study, a hydrogel based on poly (ethylene glycol) dimethacrylate and sericin methacryloyl was fabricated by photopolymerization to fill the resection cavity and prevent recurrence. The obtained hydrogel exhibited mechanical properties compatible with breast tissue and facilitated postsurgical wound management by promoting tissue regeneration. The DNA methylation inhibitor decitabine (DEC) and poly (lactic-co-glycolic acid)-encapsulated phytochemical gambogic acid (GA) were loaded into the hydrogel. The as-prepared hydrogel promoted fast release of DEC and sustained release of GA, leading to gasdermin E-mediated tumor cell pyroptosis and activating antitumor immune responses. Inducing postsurgical tumor cell pyroptosis inhibited local tumor recurrence and lung metastasis. While the dual-drug-loaded hydrogel system cured less than half of tumor-bearing mice, the cured mice survived for over half a year. These findings indicate that our hydrogel system is an excellent biocompatible platform for postsurgical TNBC therapy.

DNMT3L promotes neural differentiation by enhancing STAT1 and STAT3 phosphorylation independent of DNA methylation.

Previously, we reported global hypermethylation in DS might be attributed to the overexpression of HSA21 gene DNMT3L, which can enhance DNMT3A and DNMT3B activities in DNA methylation. To test this hypothesis, we compared the DNA methylation and RNA expression profiles of early-differentiated human neuroprogenitors with and without DNMT3L overexpression. We found DNMT3L overexpression only moderately increased the DNA methylation of limited genes, yet significantly altered global RNA expression of genes involved in neural differentiation. We further found that DNMT3L bound STAT1 or STAT3, and increased its phosphorylation and nuclear translocation, which in turn activated the expression of transcription factors including HES3, ASCL1, NEUROD2 and NEUROG2 and CDK inhibitor CDKN1A, which promoted cell cycle exit and neural differentiation. This phenomenon was also confirmed in Dnmt3l conditional knockin mice, which could be rescued by STAT1 and STAT3 phosphorylation inhibitors (Fludarabine and SH-4-54) but not DNA methylation inhibitor (Decitabine). These results suggest that DNMT3L play an important role during neurodevelopment independent of DNA methylation, which may contribute to the abnormal phenotypes observed in Down syndrome cortex.

Modeling mtDNA hypermethylation vicious circle mediating Aβ-induced endothelial damage memory in HCMEC/D3 cell.

It is well accepted that accumulation of beta-amyloid (Aβ) may involve in endothelial dysfunction during the Alzheimer’s disease (AD) progression. However, cerebrovascular function cannot be improved by removing Aβ in AD animal models. The reasons for these paradoxical results still remain to be further investigated. We hypothesize that Aβ exposure may cause persistence damage to cerebral endothelial cell even after Aβ is removed (termed as cerebrovascular endothelial damage memory) mitochondria DNA (mtDNA) hypermethylation is assumed to be involved in this process. The aim of this study is to investigate whether Aβ exposure induces cerebrovascular endothelial damage memory in endothelial cells and mtDNA hypermethylation involves in this process. The hCMEC/D3 cell is treated with Aβ1–42 for 12h and then withdraw Aβ1–42 for another 12h incubation to investigate whether cerebrovascular endothelial damage memory exists in endothelial cells. The levels of mtDNA methylation and cell vitality were not improved by removing Aβ1–42 after 12h Aβ1–42 incubation which suggested that the cerebrovascular endothelial damage memory may exist in endothelial cells. Kinetics model analysis suggested that mtDNA hypermethylation involves in initiating the cerebrovascular endothelial damage memory otherwise α-oxoglutarate (AKG) exhaustion plays a vital role in maintaining this process. DNA methylation inhibitor decitabine and AKG supplement may relieve the cerebrovascular endothelial damage memory dose dependently. This study provides a novel feature of cerebrovascular endothelial damage induced by Aβ.

DNA methylation of Hugl-2 is a prognostic biomarker in kidney renal clear cell carcinoma.

It has been reported that loss of Hugl‐2 contributes to tumour formation and progression in vitro and in vivo. However, whether Hugl‐2 levels decrease during kidney renal clear cell carcinoma (KIRC) and the mechanism involved remain unknown. This study aimed to investigate whether DNA methylation of Hugl‐2 reduces its expression, leading to the progression and poor prognosis of KIRC. Hugl‐2 methylation and mRNA expression and KIRC clinicopathological data were extracted from The Cancer Genome Atlas (TCGA), and relationships among these factors were analyzed using UALCAN, MethHC, Wanderer and LinkedOmics web tools. We found that Hugl‐2 mRNA and protein levels were reduced in KIRC tissues. Moreover, Hugl‐2 mRNA levels were related to tumour grade and overall survival, and Hugl‐2 methylation was increased in KIRC. According to the results of methylation‐specific PCR, KIRC cells had higher Hugl‐2 DNA methylation levels than HKC cells. Moreover, Hugl‐2 DNA methylation correlated negatively with Hugl‐2 mRNA and was also related to the pathology and T stage of KIRC patients. KIRC patients with high Hugl‐2 DNA methylation also had shorter overall survival. Additionally, methylation of cg08827674, a Hugl‐2 probe, was related to pathologic stage, T stage, neoplasm histologic grade, serum calcium level without laterality, M stage, N stage, and ethnicity. Furthermore, treatment with the DNA methylation inhibitor decitabine resulted in upregulation of Hugl‐2 mRNA and protein levels in KIRC cell lines. These results indicate that Hugl‐2 DNA methylation may be both a prognostic marker and a therapeutic target in KIRC.

Reactive oxygen species regulate miR-17-5p expression via DNA methylation in paraquat-induced nerve cell damage.

There is emerging evidence suggesting that oxidative stress and DNA methylation can alter miRNA expression. However, little is known on the mechanism of miR-17-5p expression changes in paraquat (PQ)-induced nerve cell damage. In the present study, neuro-2a cells were pretreated with antioxidant N-acetylcysteine (NAC) or DNA methylation inhibitor decitabine (DAC), then exposed to different concentrations of PQ, while the expression levels of miR-17-5p were detected by qRT-PCR. Here, it is showed that PQ downregulated the expression of miR-17-5p dose-dependently in neuro-2a cells. The DNA methylation level was upregulated after PQ exposure, while downregulated with the pretreatment of NAC in the above content, detected by 5-mC immunofluorescence technique. The interaction effect of NAC and PQ in alternating DNA methylation level was further confirmed by flow cytometry. NAC and DAC individually had an interaction effect in PQ-induced nerve cell damage. After using NAC, PQ-induced ROS elevation and DNA methylation are reduced, thereby preventing the proapoptotic effect of miR-17-5p. Above all, PQ can induce DNA methylation variations through ROS production, leading to the downregulation of miR-17-5p expression in PQ-induced nerve cell damage.

Combination of oral recombinant methioninase and decitabine arrests a chemotherapy-resistant undifferentiated soft-tissue sarcoma patient-derived orthotopic xenograft mouse model

Cancer cells are methionine (MET) and methylation addicted and are highly sensitive to MET restriction. The present study determined the efficacy of oral-recombinant methioninase (o-rMETase) and the DNA methylation inhibitor, decitabine (DAC) on restricting MET in an undifferentiated-soft tissue sarcoma (USTS) patient-derived orthotopic xenograft (PDOX) nude-mouse model. The USTS PDOX models were randomized into five treatment groups of six mice: Control; doxorubicin (DOX) alone; DAC alone; o-rMETase alone; and o-rMETase-DAC combination. Tumor size and body weight were measured during the 14 days of treatment. Tumor growth was arrested only in the o-rMETase-DAC condition. Tumors treated with the o-rMETase-DAC combination exhibited tumor necrosis with degenerative changes. This study demonstrates that the o-rMETase-DAC combination could arrest the USTS PDOX tumor suggesting clinical promise.

DNA methylation of CRB3 is a prognostic biomarker in clear cell renal cell carcinoma

Our previous study revealed that CRB3 protein expression was reduced in clear cell renal cell carcinoma (ccRCC) and was associated with TNM stage, pathological grade, and poor prognosis of ccRCC. This study aimed to investigate if DNA methylation of CRB3 decreases its expression, subsequently leading to the progression and poor prognosis of ccRCC. Data for DNA methylation of CRB3, CRB3 mRNA expression, and ccRCC clinicopathological parameters were extracted from the cancer genome atlas (TCGA) database. The relationships among DNA methylation of CRB3, CRB3 mRNA expression, and ccRCC clinicopathological parameters were analyzed using UALCAN, MethHC, LinkedOmics, and Wanderer. We found that CRB3 mRNA levels were lower in ccRCC compared to normal tissues. Methylation of CRB3 increased in ccRCC, with all probes showing differences between ccRCC and normal tissues. Furthermore, CRB3 DNA methylation negatively correlated with CRB3 mRNA expression. CRB3 DNA methylation was also related to pathologic stage, T stage, N stage, and M stage of ccRCC. Overall survival was shorter in ccRCC patients with high CRB3 DNA methylation compared to ccRCC patients with low CRB3 DNA methylation. Methylation of cg24798010, a CRB3 probe, was related to laterality, pathologic stage, T stage, M stage, neoplasm-histologic-grade without N stage, and race. Furthermore, treatment with the DNA methylation inhibitor Decitabine resulted in the upregulation of CRB3 mRNA in ccRCC cell lines. These results indicate that DNA methylation of CRB3 may be both a prognostic marker and therapeutic target for ccRCC.

Regulation of OCT2 transcriptional repression by histone acetylation in renal cell carcinoma

ABSTRACTRenal cell carcinoma (RCC) is a common malignant tumour affecting the urinary system, and multidrug resistance is one of the major reasons why chemotherapy for this type of cancer often fails. Previous studies have shown that loss of the human organic cation transporter OCT2 is the main factor contributing to oxaliplatin resistance in RCC, and that DNA hypermethylation and histone methylation play important roles in the transcriptional repression of OCT2 in RCC. In this study, we found that histone acetylation also regulates OCT2 repression in RCC and elucidated the underlying mechanisms. In normal renal cells, HDAC7 combines with MYC at the OCT2 promoter, resulting in a decrease in free HDAC7, which in turn increases the levels of H3K18ac and H3K27ac at the OCT2 promotor and activates OCT2 expression. In RCC cells, however, the interaction between HDAC7 and MYC does not occur, which leads a high abundance of HDAC7 and low levels of H3K18ac and H3K27ac at the OCT2 promoter, thereby resulting in the inhibition of OCT2 transcription. We found that combined treatment using the DNA methylation inhibitor decitabine and the histone deacetylase inhibitor vorinostat significantly increased the expression of OCT2 in RCC cell lines, which sensitized these cells to oxaliplatin. We accordingly propose that the combination of anticancer agents and epigenetic drugs can provide a novel chemotherapeutic regimen.

Low doses of decitabine improve the chemotherapy efficacy against basal-like bladder cancer by targeting cancer stem cells.

Low dose treatment with the DNA methylation inhibitor decitabine has been shown to be applicable for the management of certain types of cancer. However, its antitumor effect and mechanisms are context dependent and its activity has never been systematically studied in bladder cancer treatment. We used mouse models, cultured cell lines and patient-derived xenografts to demonstrate that low dose decitabine treatment remarkably enhanced the effects of cisplatin and gemcitabine on basal-like bladder cancer both in vivo and in vitro. Genetic lineage tracing revealed that the stemness of a bladder cancer stem cell population was inhibited by decitabine treatment in mice. These effects were accompanied by decreases in genome-wide DNA methylation, gene re-expression, and changes in key cellular regulatory pathways such as STAT3 signaling. These results indicate that this DNA-demethylating reagent is a promising therapeutic approach for basal-like bladder cancer treatment.

An Epigenomic Approach to Improving Response to Neoadjuvant Cisplatin Chemotherapy in Bladder Cancer.

Bladder cancer is among the five most common cancers diagnosed in the Western world and causes significant mortality and morbidity rates in affected patients. Therapeutic options to treat the disease in advanced muscle-invasive bladder cancer (MIBC) include cystectomy and chemotherapy. Neoadjuvant cisplatin-based combination chemotherapy is effective in MIBC; however, it has not been widely adopted by the community. One reason is that many patients do not respond to neoadjuvant chemotherapy, and no biomarker currently exists to identify these patients. It is also not clear whether a strategy to sensitize chemoresistant patients may exist. We sought to identify cisplatin-resistance patterns in preclinical models of bladder cancer, and test whether treatment with the epigenetic modifier decitabine is able to sensitize cisplatin-resistant bladder cancer cell lines. Using a screening approach in cisplatin-resistant bladder cancer cell lines, we identified dysregulated genes by RNA sequencing (RNAseq) and DNA methylation assays. DNA methylation analysis of tumors from 18 patients receiving cisplatin-based chemotherapy was used to confirm in vitro results. Cisplatin-resistant bladder cancer cells were treated with decitabine to investigate epigenetic sensitization of resistant cell lines. Our results show that HOXA9 promoter methylation status is associated with response to cisplatin-based chemotherapy in bladder cancer cell lines and in metastatic bladder cancer. Bladder cancer cells resistant to cisplatin chemotherapy can be sensitized to cisplatin by the DNA methylation inhibitor decitabine. Our data suggest that HOXA9 promoter methylation could serve as potential predictive biomarker and decitabine might sensitize resistant tumors in patients receiving cisplatin-based chemotherapy.

Promoter Methylation Analysis Reveals That KCNA5 Ion Channel Silencing Supports Ewing Sarcoma Cell Proliferation.

Polycomb proteins are essential regulators of gene expression in stem cells and development. They function to reversibly repress gene transcription via posttranslational modification of histones and chromatin compaction. In many human cancers, genes that are repressed by polycomb in stem cells are subject to more stable silencing via DNA methylation of promoter CpG islands. Ewing sarcoma is an aggressive bone and soft-tissue tumor that is characterized by overexpression of polycomb proteins. This study investigates the DNA methylation status of polycomb target gene promoters in Ewing sarcoma tumors and cell lines and observes that the promoters of differentiation genes are frequent targets of CpG-island DNA methylation. In addition, the promoters of ion channel genes are highly differentially methylated in Ewing sarcoma compared with nonmalignant adult tissues. Ion channels regulate a variety of biologic processes, including proliferation, and dysfunction of these channels contributes to tumor pathogenesis. In particular, reduced expression of the voltage-gated Kv1.5 channel has been implicated in tumor progression. These data show that DNA methylation of the KCNA5 promoter contributes to stable epigenetic silencing of the Kv1.5 channel. This epigenetic repression is reversed by exposure to the DNA methylation inhibitor decitabine, which inhibits Ewing sarcoma cell proliferation through mechanisms that include restoration of the Kv1.5 channel function. This study demonstrates that promoters of ion channels are aberrantly methylated in Ewing sarcoma and that epigenetic silencing of KCNA5 contributes to tumor cell proliferation, thus providing further evidence of the importance of ion channel dysregulation to tumorigenesis.

Epigenetic synergy between decitabine and platinum derivatives.

BackgroundAberrant epigenetic silencing of tumor suppressor genes has been recognized as a driving force in cancer. Epigenetic drugs such as the DNA methylation inhibitor decitabine reactivate genes and are effective in myeloid leukemia, but resistance often develops and efficacy in solid tumors is limited. To improve their clinical efficacy, we searched among approved anti-cancer drugs for an epigenetic synergistic combination with decitabine.ResultsWe used the YB5 cell line, a clonal derivative of the SW48 colon cancer cell line that contains a single copy of a hypermethylated cytomegalovirus (CMV) promoter driving green fluorescent protein (GFP) to screen for drug-induced gene reactivation and synergy with decitabine. None of the 16 anti-cancer drugs tested had effects on their own. However, in combination with decitabine, platinum compounds showed striking synergy in activating GFP. This was dose dependent, observed both in concurrent and sequential combinations, and also seen with other alkylating agents. Clinically achievable concentrations of carboplatin at (25 μM) and decitabine reactivated GFP in 28 % of the YB5 cells as compared to 15 % with decitabine alone. Epigenetic synergy was also seen at endogenously hypermethylated tumor suppressor genes such as MLH1 and PDLIM4. Genome-wide studies showed that reactivation of hypermethylated genes by the combination was significantly better than that induced by decitabine alone or carboplatin alone. Platinum compounds did not enhance decitabine-induced hypomethylation. Rather, we found significantly inhibited HP1α expression by carboplatin and the combination. This was accompanied by increased histone H3 lysine 4 (H3K4) trimethylation and histone H3 lysine 9 (H3K9) acetylation at reactivated genes (P < 0.0001) and reduced occupancy by methyl-binding proteins including MeCP2 and methyl-CpG-binding domain protein 2 (MBD2) (P < 0.0001).ConclusionsOur results suggest that the combination of decitabine with platinum analogs shows epigenetic synergy that might be exploited in the treatment of different cancers.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-015-0131-z) contains supplementary material, which is available to authorized users.

The DNA methylation inhibitor decitabine completely blocks autoimmune mediated CNS demyelination

The DNA methylation inhibitor decitabine completely blocks autoimmune mediated CNS demyelination

Decitabine, a new star in epigenetic therapy: the clinical application and biological mechanism in solid tumors

Epigenetic alterations are strongly associated with cancer development and drug resistance. The use of the DNA methylation inhibitor decitabine (Dacogen®) has been approved in the treatment of hematological malignancies, and its clinical effects on solid tumors have gained attention. Here, we present a review of the molecular regulation mechanisms, clinical experiences and biological evaluation for novel decitabine-based therapies in solid tumors. We also discuss the following questions: What is the best administration schedule of decitabine in solid tumors? Is there tumor type specificity for decitabine-based epigenetic therapy? What are the biological function and mechanism of decitabine in suppressing tumor development? Is there a correlation between DNA demethylation and clinical response? Importantly, low-dose decitabine and combined therapy show significant improvement in solid tumor treatment. However, the correlation studies are preliminary, and key biomarkers for prognosis need further investigation.

Combination of gefitinib and DNA methylation inhibitor decitabine exerts synergistic anti-cancer activity in colon cancer cells.

Despite recent advances in the treatment of human colon cancer, the chemotherapy efficacy against colon cancer is still unsatisfactory. In the present study, effects of concomitant inhibition of the epidermal growth factor receptor (EGFR) and DNA methyltransferase were examined in human colon cancer cells. We demonstrated that decitabine (a DNA methyltransferase inhibitor) synergized with gefitinib (an EGFR inhibitor) to reduce cell viability and colony formation in SW1116 and LOVO cells. However, the combination of the two compounds displayed minimal toxicity to NCM460 cells, a normal human colon mucosal epithelial cell line. The combination was also more effective at inhibiting the AKT/mTOR/S6 kinase pathway. In addition, the combination of decitabine with gefitinib markedly inhibited colon cancer cell migration. Furthermore, gefitinib synergistically enhanced decitabine-induced cytotoxicity was primarily due to apoptosis as shown by Annexin V labeling that was attenuated by z-VAD-fmk, a pan caspase inhibitor. Concomitantly, cell apoptosis resulting from the co-treatment of gefitinib and decitabine was accompanied by induction of BAX, cleaved caspase 3 and cleaved PARP, along with reduction of Bcl-2 compared to treatment with either drug alone. Interestingly, combined treatment with these two drugs increased the expression of XIAP-associated factor 1 (XAF1) which play an important role in cell apoptosis. Moreover, small interfering RNA (siRNA) depletion of XAF1 significantly attenuated colon cancer cells apoptosis induced by the combination of the two drugs. Our findings suggested that gefitinib in combination with decitabine exerted enhanced cell apoptosis in colon cancer cells were involved in mitochondrial-mediated pathway and induction of XAF1 expression. In conclusion, based on the observations from our study, we suggested that the combined administration of these two drugs might be considered as a novel therapeutic regimen for treating colon cancer.

Human Equilibrative Nucleoside Transporter 1 (hENT1) Expression Level Is a Potential Predictive Tool For Response To Decitabine In Patients With Myelodysplastic Syndrome

ObjectiveThe DNA methylation inhibitor decitabine is approved for the treatment of myelodysplastic syndromes (MDS). But there remains no effective factor to predict response to decitabine before therapy. Expression level of genes related to decitabine metabolism (including human equilibrative nucleoside transporter 1 (hENT1), hENT2, deoxycytidine kinase (dCK) and cytidine deaminase (CDA)) may influence the therapeutic effect of decitabine. In this study, we aimed to investigate whether the expression level of these genes could predict response to decitabine in MDS patients. Patients and MethodsWe performed Quantitative Real-Time PCR to examine expression of hENT1, hENT2, dCK and CDA prior to therapy in 60 MDS patients initially treated with decitabine. Response to decitabine and overall survival of patients treated with decitabine was analyzed grouped by the genes expression level. ResultsThe patients responded to decitabine presented increased mean hENT1 expression levels compared to non-responders (0.8± 0.2 fold vs. 1.6±0.2 fold, p = 0.008). Among the 31 hENT1 high expression patients, 27(87.1%) achieved response, compared to 15/29 (51.7%) in low hENT1 patients (χ2=8.927, p=0.003). 41.9% (13/31) in hENT1 high expression patients and 10.3% (3/29) in low hENT1 patients achieved CR (χ2=7.646, p=0.006). Patients with hENT1 high expression showed longer survival time compared to low hENT1 patients (22 vs. 16 months; p = 0.027). However, the expression level of hENT2, dCK and CDA did not affect response rate and survival in MDS patients treated with decitabine. ConclusionhENT1 expression level is a potential predictive tool for response to decitabine in patients with MDS. High expression of hENT1 predicts prolonged survival in MDS patients treated with decitabine. Disclosures:No relevant conflicts of interest to declare.