Differential methylation pattern of ID4, SFRP1, and SHP1 between acute myeloid leukemia and chronic myeloid leukemia

The Critical Role of Inhibitor of Differentiation 4 in Breast Cancer: From Mammary Gland Development to Tumor Progression

Inhibitor of differentiation 4 (ID4) is a highly conserved DNA-binding inhibitory protein of mammals, and its main role is to bind basic helix-loop-helix (b-HLH) so that it loses its DNA-binding activity, which in turn regulates the transcription of key genes, regulating cell differentiation and proliferation as the physiological function. Breast tissue is a highly heterogeneous tissue organ with a strong capacity for remodeling and differentiation, and studies of breast carcinogenesis suggest that the mechanisms regulating the differentiation of breast tissue interact critically with tumorigenesis. The expression level of ID4 and its regulatory mechanism play a crucial role in the study of breast cancer, but its oncogenic or oncostatic role has not yet been unanimously identified, and its regulatory mechanism in breast cancer still needs to be further elucidated. This review summarizes and analyzes the relevant studies of ID4 and the research progress in breast cancer, integrating the development of breast tissue and tumorigenesis with the regulatory role of ID4, to provide some insights into develop new treatment strategies and diagnostic biomarkers.

Small RNA activation of CDH13 expression overcome BCR-ABL1-independent imatinib-resistance and their signaling pathway studies in chronic myeloid leukemia

BCR-ABL1-independent resistance to imatinib has no effective treatment due to its complexity and diversity. We previously reported that the CDH13 oncogene was expressed at low levels in BCR-ABL1-independent resistant CML cell lines. However, its effects on CML resistant cells and mechanisms remain unknown. This study investigated the effects of saRNA-based CDH13 activation on BCR-ABL1-independent imatinib resistance in CML and its underlying mechanism, and proposes a unique treatment method to overcome imatinib resistance. Specifically, this study demonstrated that using the DSIR (Designer of Small Interfering RNA) website tool, saRNAs targeting the CDH13 promoter region were generated and validated using qPCR and western blotting. Among the predicted sequences, C2 and C3 efficiently elevated CDH13 mRNA and protein expression, as well as inhibited the relative vitality of cells and the ability to form clones. After promoting CDH13 expression in K562-IMR cells, it inhabited the NF-κB signaling pathway and induced apoptosis in imatinib-resistant CML cells. LNP-saRNA (C3) was also observed to limit the growth of K562-IMR cells in vivo. From the above, the activation of CDH13 expression by saRNA promotes cell apoptosis by inhibiting the NF-κB signaling pathway to overcome to BCR-ABL1-independent resistance to imatinib in patients with CML.

Thymoquinone Enhances Apoptosis of K562 Chronic Myeloid Leukemia Cells through Hypomethylation of SHP-1 and Inhibition of JAK/STAT Signaling Pathway

The epigenetic silencing of tumor suppressor genes (TSGs) is critical in the development of chronic myeloid leukemia (CML). SHP-1 functions as a TSG and negatively regulates JAK/STAT signaling. Enhancement of SHP-1 expression by demethylation provides molecular targets for the treatment of various cancers. Thymoquinone (TQ), a constituent of Nigella sativa seeds, has shown anti-cancer activities in various cancers. However, TQs effect on methylation is not fully clear. Therefore, the aim of this study is to assess TQs ability to enhance the expression of SHP-1 through modifying DNA methylation in K562 CML cells. The activities of TQ on cell cycle progression and apoptosis were evaluated using a fluorometric-red cell cycle assay and Annexin V-FITC/PI, respectively. The methylation status of SHP-1 was studied by pyrosequencing analysis. The expression of SHP-1, TET2, WT1, DNMT1, DNMT3A, and DNMT3B was determined using RT-qPCR. The protein phosphorylation of STAT3, STAT5, and JAK2 was assessed using Jess Western analysis. TQ significantly downregulated the DNMT1 gene, DNMT3A gene, and DNMT3B gene and upregulated the WT1 gene and TET2 gene. This led to hypomethylation and restoration of SHP-1 expression, resulting in inhibition of JAK/STAT signaling, induction of apoptosis, and cell cycle arrest. The observed findings imply that TQ promotes apoptosis and cell cycle arrest in CML cells by inhibiting JAK/STAT signaling via restoration of the expression of JAK/STAT-negative regulator genes.

Association between SFRP promoter hypermethylation and different types of cancer: A systematic review and meta-analysis

Abnormal methylation of secreted frizzled-related proteins (SFRPs) has been observed in various human cancer types. The loss of SFRP gene expression induces the activation of the Wnt pathway and is a vital mechanism for tumorigenesis and development. The aim of the present systematic review was to assess the association between SFRP methylation and cancer risk. A meta-analysis was systematically conducted to assess the clinicopathological significance of SFRP methylation in cancer risk. The Cochrane Library, PubMed and Web of Science databases were comprehensively searched, and 83 publications with a total of 21,612 samples were selected for the meta-analysis. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated to evaluate the degree of associations between SFRP promoter methylation and cancer risk. Subgroup analysis, meta regression and sensitivity analysis were used to identify the potential sources of heterogeneity. SFRP1, SFRP2, SFRP4 and SFRP5 hypermethylation was significantly associated with cancer risk, with ORs of 8.48 (95% CI, 6.26-11.49), 8.21 (95% CI, 6.20-10.88), 11.41 (95% CI, 6.42-20.30) and 6.34 (95% CI, 3.86-10.42), respectively. SFRP2 methylation was significantly associated with differentiation in colorectal cancer (OR, 2.16; 95% CI, 1.02-4.56). The results of the present study demonstrated that SFRP methylation may contribute to carcinogenesis, especially in certain cancer types, including hepatocellular carcinoma and colorectal cancer.

Re-Expression of Bone Marrow Proteoglycan-2 by 5-Azacytidine is associated with STAT3 Inactivation and Sensitivity Response to Imatinib in Resistant CML Cells

Background:

Epigenetic silencing of tumor suppressor genes (TSG) is involved in development and progression of cancers. Re-expression of TSG is inversely proportionate with STAT3 signaling pathways. Demethylation of DNA by 5-Azacytidine (5-Aza) results in re-expression of silenced TSG. Forced expression of PRG2 by 5-Aza induced apoptosis in cancer cells. Imatinib is a tyrosine kinase inhibitor that potently inhibits BCR/ABL tyrosine kinase resulting in hematological remission in CML patients. However, majority of CML patients treated with imatinib would develop resistance under prolonged therapy.

Methods:

CML cells resistant to imatinib were treated with 5-Aza and cytotoxicity of imatinib and apoptosis were determined by MTS and annexin-V, respectively. Gene expression analysis was detected by real time-PCR, STATs activity examined using Western blot and methylation status of PRG2 was determined by pyrosequencing analysis.

Result:

Expression of PRG2 was significantly higher in K562-R+5-Aza cells compared to K562 and K562-R (p=0.001). Methylation of PRG2 gene was significantly decreased in K562-R+5-Aza cells compared to other cells (p=0.021). STAT3 was inactivated in K562-R+5-Aza cells which showed higher sensitivity to imatinib.

Conclusion:

PRG2 gene is a TSG and its overexpression might induce sensitivity to imatinib. However, further studies are required to evaluate the negative regulations of PRG2 on STAT3 signaling.

Secreted Wnt antagonists in leukemia: A road yet to be paved

Wnt signaling has been a topic of research for many years for its diverse and fundamental functions in physiological (such as embryogenesis, organogenesis, proliferation, tissue repair and cellular differentiation) and pathological (carcinogenesis, congenital/genetic diseases, and tissue degeneration) processes. Wnt signaling pathway aberrations are associated with both solid tumors and hematological malignancies. Unregulated Wnt signaling observed in malignancies may be due to a wide spectrum of abnormalities, from mutations in the genes of key players to epigenetic modifications of Wnt antagonists. Of these, Wnt antagonists are gaining significant attention for their potential of being targets for treatment and inhibition of Wnt signaling. In this review, we discuss and summarize the significance of Wnt signaling antagonists in the pathogenesis and treatment of hematological malignancies.

Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification

Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.

Role and mechanism of decitabine combined with tyrosine kinase inhibitors in advanced chronic myeloid leukemia cells

Patients with advanced chronic myeloid leukemia (CML) have a poor prognosis, with the use of tyrosine kinase inhibitors (TKIs) to treat CML demonstrating poor results. The results of the present study revealed that, following Cell Counting Kit-8 analysis, treatment of K562 cells with decitabine (DAC) combined with TKIs exhibits synergic effects. Co-immunoprecipitation indicated that tyrosine-protein phosphatase non-receptor type 6 (SHP-1) and BCR-ABL fusion protein (BCR-ABL) (p210) form a complex in the K562 cell line, and in the primary cells derived from patients with CML. These results suggested that SHP-1 serves a role in regulating the tyrosine kinase activity of BCR-ABL (p210). In addition, SHP-1 expression increased, while BCR-ABL expression decreased in the group treated with DAC and TKIs combined group compared with the TKI monotherapy group. Treatment with imatinib (IM) demonstrated no effect on SHP-1 methylation in the K562 cell line; however, the methylation of SHP-1 was not determined in the combined IM and DAC therapy group. Treatment with DAC demonstrated the ability to activate the expression of silenced SHP-1 through demethylation, thus decreasing BCR-ABL tyrosine kinase activity, resulting in an improved therapeutic effect on CML.

Notable roles of EZH2 and DNMT1 in epigenetic dormancy of the SHP1 gene during the progression of chronic myeloid leukaemia

Tumor development is associated with the methylation of cytosine-guanine (CpG) islands. The occurrence of methylation requires several factors, such as DNA methylation systems and polycomb group (PcG) proteins. At present, novel drugs are needed for the treatment of chronic myeloid leukaemia (CML), particularly considering the current prognosis of CML. The methylation status of the Src homology 2 domain-containing tyrosine phosphatase 1 (SHP1) gene, a negative regulator of signal transduction, has been identified as being altered in numerous haematological malignancies. DNA methyltransferase 1 (DNMT1) and the PcG protein complex member enhancer of zeste homolog 2 (EZH2) participate in a number of gene methylation processes. The present study investigated the methylation status of the SHP1 gene in CML, and examined the association between DNMT1 and EZH2 activity and the SHP1 gene methylation status to develop novel strategies for the treatment of CML. The results revealed that SHP1 gene methylation status was altered during the progression of CML. These data indicated that SHP1 gene methylation is associated with the progression of this disease. The associations of DNMT1 and EZH2 activities with the methylation status of the SHP1 gene were additionally investigated via chromatin immunoprecipitation. DNMT1 and EZH2 were revealed to be bound to the promoter region of the SHP1 gene, and were involved in the process of SHP1 methylation. Furthermore, DNMT1 and EZH2 were associated with disease progression. Thus, the findings of the present study suggest a new target for the treatment of CML, particularly for future drug development.

Inhibitory leukocyte immunoglobulin-like receptors: Immune checkpoint proteins and tumor sustaining factors

Inhibitory leukocyte immunoglobulin-like receptors (LILRBs 1-5) transduce signals via intracellular immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that recruit protein tyrosine phosphatase non-receptor type 6 (PTPN6 or SHP-1), protein tyrosine phosphatase non-receptor type 11 (PTPN11 or SHP-2), or Src homology 2 domain-containing inositol phosphatase (SHIP), leading to negative regulation of immune cell activation. Certain of these receptors also play regulatory roles in neuronal activity and osteoclast development. The activation of LILRBs on immune cells by their ligands may contribute to immune evasion by tumors. Recent studies found that several members of LILRB family are expressed by tumor cells, notably hematopoietic cancer cells, and may directly regulate cancer development and relapse as well as the activity of cancer stem cells. LILRBs thus have dual concordant roles in tumor biology - as immune checkpoint molecules and as tumor-sustaining factors. Importantly, the study of knockout mice indicated that LILRBs do not affect hematopoiesis and normal development. Therefore LILRBs may represent ideal targets for tumor treatment. This review aims to summarize current knowledge on expression patterns, ligands, signaling, and functions of LILRB family members in the context of cancer development.

Quantitative Detection of ID4 Gene Aberrant Methylation in the Differentiation of Myelodysplastic Syndrome from Aplastic Anemia

BACKGROUND

The diagnosis of myelodysplastic syndrome (MDS), especially hypoplastic MDS, and MDS with low blast counts or normal karyotype may be problematic. This study characterized ID4 gene methylation in patients with MDS and aplastic anemia (AA).

METHODS

The methylation status of ID4 was analyzed by bisulfite sequencing polymerase chain reaction (PCR) and quantitative real-time methylation-specific PCR (MethyLight PCR) in 100 patients with MDS and 31 patients with AA.

RESULTS

The MDS group had a higher ID4 gene methylation positivity rate (22.22%) and higher methylation levels (0.21 [0-3.79]) than the AA group (P < 0.05). Furthermore, there were significant differences between the hypoplastic MDS and AA groups, the MDS with low blast count and the AA groups, and the MDS with normal karyotype and the AA groups. The combination of genetic and epigenetic markers was used in much more patients with MDS (62.5% [35/56]) than the use of genetic markers only (51.79% [29/56]).

CONCLUSIONS

These results showed that the detection of ID4 methylation positivity rates and levels could be a useful biomarker for MDS diagnosis.

Enhancing SHP-1 expression with 5-azacytidine may inhibit STAT3 activation and confer sensitivity in lestaurtinib (CEP-701)-resistant FLT3-ITD positive acute myeloid leukemia

Background

Tumor-suppressor genes are inactivated by methylation in several cancers including acute myeloid leukemia (AML). Src homology-2 (SH2)-containing protein-tyrosine phosphatase 1 (SHP-1) is a negative regulator of the JAK/STAT pathway. Transcriptional silencing of SHP-1 plays a critical role in the development and progression of cancers through STAT3 activation. 5-Azacytidine (5-Aza) is a DNA methyltransferase inhibitor that causes DNA demethylation resulting in re-expression of silenced SHP-1. Lestaurtinib (CEP-701) is a multi-targeted tyrosine kinase inhibitor that potently inhibits FLT3 tyrosine kinase and induces hematological remission in AML patients harboring the internal tandem duplication of the FLT3 gene (FLT3-ITD). However, the majority of patients in clinical trials developed resistance to CEP-701. Therefore, the aim of this study, was to assess the effect of re-expression of SHP-1 on sensitivity to CEP-701 in resistant AML cells.

Methods

Resistant cells harboring the FLT3-ITD were developed by overexposure of MV4-11 to CEP-701, and the effects of 5-Aza treatment were investigated. Apoptosis and cytotoxicity of CEP-701 were determined using Annexin V and MTS assays, respectively. Gene expression was performed by quantitative real-time PCR. STATs activity was examined by western blotting and the methylation profile of SHP-1 was studied using MS-PCR and pyrosequencing analysis. Repeated-measures ANOVA and Kruskal–Wallis tests were used for statistical analysis.

Results

The cytotoxic dose of CEP-701 on resistant cells was significantly higher in comparison with parental and MV4-11R-cep + 5-Aza cells (p = 0.004). The resistant cells showed a significant higher viability and lower apoptosis compared with other cells (p < 0.001). Expression of SHP-1 was 7-fold higher in MV4-11R-cep + 5-Aza cells compared to parental and resistant cells (p = 0.011). STAT3 was activated in resistant cells. Methylation of SHP-1 was significantly decreased in MV4-11R-cep + 5-Aza cells (p = 0.002).

Conclusions

The restoration of SHP-1 expression induces sensitivity towards CEP-701 and could serve as a target in the treatment of AML. Our findings support the hypothesis that, the tumor-suppressor effect of SHP-1 is lost due to epigenetic silencing and its re-expression might play an important role in re-inducing sensitivity to TKIs. Thus, SHP-1 is a plausible candidate for a role in the development of CEP-701 resistance in FLT3-ITD+ AML patients.

A Versatile Monoclonal Antibody Specific Against Human DAB2IP

Human DAB2 interaction protein (DAB2IP) is a member of Ras-GTPase activating protein family and functions as a tumor suppressor, implying it could serve as a prognostic biomarker in cancers. Here we generated a mouse monoclonal antibody, 2A4, directed against human DAB2IP. This antibody was identified as IgG1 and specifically recognizes DAB2IP in both its native and denatured forms. It will serve as a useful and versatile tool for further mechanistic study and development of the potential prognostic significance of DAB2IP.

EZH2 dependent H3K27me3 is involved in epigenetic silencing of ID4 in prostate cancer

Inhibitor of DNA binding/differentiation protein 4 (ID4) is dominant negative helix loop helix transcriptional regulator is epigenetically silenced due to promoter hyper-methylation in many cancers including prostate. However, the underlying mechanism involved in epigenetic silencing of ID4 is not known. Here, we demonstrate that ID4 promoter methylation is initiated by EZH2 dependent tri-methylation of histone 3 at lysine 27 (H3K27me3). ID4 expressing (LNCaP) and non-expressing (DU145 and C81) prostate cancer cell lines were used to investigate EZH2, H3K27me3 and DNMT1 enrichment on ID4 promoter by Chromatin immuno-precipitation (ChIP). Enrichment of EZH2, H3K27Me3 and DNMT1 in DU145 and C81 cell lines compared to ID4 expressing LNCaP cell line. Knockdown of EZH2 in DU145 cell line led to re-expression of ID4 and decrease in enrichment of EZH2, H3K27Me3 and DNMT1 demonstrating that ID4 is regulated in an EZH2 dependent manner. ChIP data on prostate cancer tissue specimens and cell lines suggested EZH2 occupancy and H3K27Me3 marks on the ID4 promoter. Collectively, our data indicate a PRC2 dependent mechanism in ID4 promoter silencing in prostate cancer through recruitment of EZH2 and a corresponding increase in H3K27Me3. Increased EZH2 but decreased ID4 expression in prostate cancer strongly supports this model.

Clinical implications of the quantitative detection of ID4 gene methylation in myelodysplastic syndrome

Background

Myelodysplastic syndrome (MDS) eventually transforms into acute leukemia (AL) in about 30% of patients. Hypermethylation of the inhibitor of DNA binding 4 (ID4) gene may play an important role in the initiation and development of MDS and AL. The aim of this study was to quantitatively assess ID4 gene methylation in MDS and to establish if it could be an effective method of evaluating MDS disease progression.

Methods

We examined 142 bone marrow samples from MDS patients, healthy donors and MDS-AL patients using bisulfite sequencing PCR and quantitative real-time methylation-specific PCR. The ID4 methylation rates and levels were assessed.

Results

ID4 methylation occurred in 27 patients (27/100). ID4 gene methylation was more frequent and at higher levels in patients with advanced disease stages and in high-risk subgroups according to WHO (P < 0.001, P < 0.001, respectively) and International Prognostic Scoring System (IPSS) (P = 0.002, P = 0.007, respectively) classifications. ID4 methylation levels changed during disease progression. Both methylation rates and methylation levels were significantly different between healthy donor, MDS patients and patients with MDS-AL (P < 0.001, P < 0.001, respectively). Multivariate analysis indicated that the level of ID4 methylation was an independent factor influencing overall survival. Patients with MDS showed decreased survival time with increased ID4 methylation levels (P = 0.011, hazard ratio (HR) = 2.371). Patients with ID4 methylation had shorter survival time than those without ID4 methylation (P = 0.008).

Conclusions

Our findings suggest that ID4 gene methylation might be a new biomarker for MDS monitoring and the detection of minimal residual disease.

Inhibitor of differentiation 4 (ID4): From development to cancer

Highly conserved Inhibitors of DNA-Binding (ID1-ID4) genes encode multi-functional proteins whose transcriptional activity is based on dominant negative inhibition of basic helix-loop-helix (bHLH) transcription factors. Initial animal models indicated a degree of compensatory overlap between ID genes such that deletion of multiple ID genes was required to generate easily recognizable phenotypes. More recently, new model systems have revealed alterations in mice harboring deletions in single ID genes suggesting complex gene and tissue specific functions for members of the ID gene family. Because ID genes are highly expressed during development and their function is associated with a primitive, proliferative cellular phenotype there has been significant interest in understanding their potential roles in neoplasia. Indeed, numerous studies indicate an oncogenic function for ID1, ID2 and ID3. In contrast, the inhibitor of differentiation 4 (ID4) presents a paradigm shift in context of well-established role of ID1, ID2 and ID3 in development and cancer. Apart from some degree of functional redundancy such as HLH dependent interactions with bHLH protein E2A, many of the functions of ID4 are distinct from ID1, ID2 and ID3: ID4 proteins a) regulate distinct developmental processes and tissue expression in the adult, b) promote stem cell survival, differentiation and/or timing of differentiation, c) epigenetic inactivation/loss of expression in several advanced stage cancers and d) increased expression in some cancers such as those arising in the breast and ovary. Thus, in spite of sharing the conserved HLH domain, ID4 defies the established model of ID protein function and expression. The underlying molecular mechanism responsible for the unique role of ID4 as compared to other ID proteins still remains largely un-explored. This review will focus on the current understanding of ID4 in context of development and cancer.

Expression patterns of human DAB2IP protein in fetal tissues

Human DOC-2/DAB2-interacting protein (DAB2IP) is encoded by a tumor suppressor gene and a newly recognized member of the Ras-GTPase-activating family. DAB2IP is a critical component of many signal transduction pathways mediated by Ras and tumor necrosis factors including apoptosis pathways, and it is involved in the formation of many types of tumors. DAB2IP participates in regulation of gene expression and pluripotency of cells. It has been reported that DAB2IP was expressed in different tumor tissues. Little information is available concerning the expression levels of DAB2IP in normal tissues and cells, however, and no studies of its expression patterns during the development of human embryos have been reported. We examined the expression of DAB2IP during human embryonic development to understand better DAB2IP functions. Human fetuses, weeks 9 to 38, and a newborn were obtained from miscarriages or stillbirths. Tissues were embedded in paraffin to construct arrays that were stained immunohistochemically. The DAB2IP-positive cells were identified and scored based on both the percentage of stained cells and their staining intensities. DAB2IP was expressed in most fetal tissues examined. DAB2IP was expressed primarily in cell cytoplasm throughout the fetal development. The expression levels varied among tissues and different gestational ages. Virtually no expression was observed in the cerebrum, parotid gland, thymus, thyroid gland and spleen. Expression was much greater in the adrenal gland and pancreas; weakly to moderately strong in the endocardium, stomach, kidney, testis and small intestine; and lower in liver, trachea, skin, ovary and endometrium. Its expression in the lung, esophagus and bladder were much weaker to absent.

Epigenomics of leukemia: from mechanisms to therapeutic applications

Leukemogenesis is a multistep process in which successive transformational events enhance the ability of a clonal population arising from hematopoietic progenitor cells to proliferate, differentiate and survive. Clinically and pathologically, leukemia is subdivided into four main categories: chronic lymphocytic leukemia, chronic myeloid leukemia, acute lymphocytic leukemia and acute myeloid leukemia. Leukemia has been previously considered only as a genetic disease. However, in recent years, significant advances have been made in the elucidation of the leukemogenesis-associated processes. Thus, we have come to understand that epigenetic alterations including DNA methylation, histone modifications and miRNA are involved in the permanent changes of gene expression controlling the leukemia phenotype. In this article, we will focus on the epigenetic defects associated with leukemia and their implications as biomarkers for diagnostic, prognostic and therapeutic applications.

Epigenetics in myeloid malignancies

Myeloid hematological malignancies are among the epigenetically best characterized neoplasms. The comparatively low number of recurring balanced and unbalanced chromosomal abnormalities as well as common genetic mutations has enabled scientists to relate epigenetic states to these. The ease of accessing malignant cells through bone marrow aspiration has certainly contributed to the fast expansion of knowledge. Even so, the clinical and pathogenetic relevance of epigenetic changes is still not known, and the field will certainly evolve very fast with the development of new analytic techniques. The first example of successful epigenetic therapy is seen in myeloid malignancies, in the high-risk myelodysplastic syndromes (MDS) which are routinely treated with the demethylating agent azacytidine.This chapter will concentrate on describing the epigenetic changes in acute myeloid leukemia (AML), chronic myeloid leukemia (CML) and MDS. An overview of clinical relevance and epigenetic therapeutic approaches is also made.

SHP-1 expression accounts for resistance to imatinib treatment in Philadelphia chromosome-positive cells derived from patients with chronic myeloid leukemia

We prove that the SH2-containing tyrosine phosphatase 1 (SHP-1) plays a prominent role as resistance determinant of imatinib (IMA) treatment response in chronic myelogenous leukemia cell lines (sensitive/KCL22-S and resistant/KCL22-R). Indeed, SHP-1 expression is significantly lower in resistant than in sensitive cell line, in which coimmunoprecipitation analysis shows the interaction between SHP-1 and a second tyrosine phosphatase SHP-2, a positive regulator of RAS/MAPK pathway. In KCL22-R SHP-1 ectopic expression restores both SHP-1/SHP-2 interaction and IMA responsiveness; it also decreases SHP-2 activity after IMA treatment. Consistently, SHP-2 knocking-down in KCL22-R reduces either STAT3 activation or cell viability after IMA exposure. Therefore, our data suggest that SHP-1 plays an important role in BCR-ABL-independent IMA resistance modulating the activation signals that SHP-2 receives from both BCR/ABL and membrane receptor tyrosine kinases. The role of SHP-1 as a determinant of IMA sensitivity has been further confirmed in 60 consecutive untreated patients with chronic myelogenous leukemia, whose SHP-1 mRNA levels were significantly lower in case of IMA treatment failure (P < .0001). In conclusion, we suggest that SHP-1 could be a new biologic indicator at baseline of IMA sensitivity in patients with chronic myelogenous leukemia.

Cadherin 13 in cancer

We review the evidence suggesting the involvement of Cadherin 13 (CDH13, T-cadherin, H-cadherin) in various cancers. CDH13 is an atypical member of the cadherin family, devoid of a transmembrane domain and anchored to the exterior surface of the plasma membrane via a glycosylphosphatidylinositol anchor. CDH13 is thought to affect cellular behavior largely through its signaling properties. It is often down-regulated in cancerous cells. CDH13 down-regulation has been associated with poorer prognosis in various carcinomas, such as lung, ovarian, cervical and prostate cancer. CDH13 re-expression in most cancer cell lines inhibits cell proliferation and invasiveness, increases susceptibility to apoptosis, and reduces tumor growth in in vivo models. These properties suggest that CDH13 may represent a possible target for therapy in some cancers. At the same time, CDH13 is up-regulated in blood vessels growing through tumors and promotes tumor neovascularization. In contrast to most cancer cell lines, CDH13 overexpression in endothelial cells promotes their proliferation and migration, and has a pro-survival effect. We also discuss molecular mechanisms that may regulate CDH13 expression and underlie its roles in cancer.