Kimie Kondo

Aberrant CpG island methylation in acute myeloid leukemia is accentuated at relapse

DNA methylation of CpG islands around gene transcription start sites results in gene silencing and plays a role in leukemia pathophysiology. Its impact in leukemia progression is not fully understood. We performed genomewide screening for methylated CpG islands and identified 8 genes frequently methylated in leukemia cell lines and in patients with acute myeloid leukemia (AML): NOR1, CDH13, p15, NPM2, OLIG2, PGR, HIN1, and SLC26A4. We assessed the methylation status of these genes and of the repetitive element LINE-1 in 30 patients with AML, both at diagnosis and relapse. Abnormal methylation was found in 23% to 83% of patients at diagnosis and in 47% to 93% at relapse, with CDH13 being the most frequently methylated. We observed concordance in methylation of several genes, confirming the presence of a hypermethylator pathway in AML. DNA methylation levels increased at relapse in 25 of 30 (83%) patients with AML. These changes represent much larger epigenetic dysregulation, since methylation microarray analysis of 9008 autosomal genes in 4 patients showed hypermethylation ranging from 5.9% to 13.6% (median 8.3%) genes at diagnosis and 8.0% to 15.2% (median 10.6%) genes in relapse (P < .001). Our data suggest that DNA methylation is involved in AML progression and provide a rationale for the use of epigenetic agents in remission maintenance.

Sensitive and Specific Detection of Early Gastric Cancer with DNA Methylation Analysis of Gastric Washes

BACKGROUND & AIMS Aberrant DNA methylation is an early and frequent process in gastric carcinogenesis and could be useful for detection of gastric neoplasia. We hypothesized that methylation analysis of DNA recovered from gastric washes could be used to detect gastric cancer. METHODS We studied 51 candidate genes in 7 gastric cancer cell lines and 24 samples (training set) and identified 6 for further studies. We examined the methylation status of these genes in a test set consisting of 131 gastric neoplasias at various stages. Finally, we validated the 6 candidate genes in a different population of 40 primary gastric cancer samples and 113 nonneoplastic gastric mucosa samples. RESULTS Six genes (MINT25, RORA, GDNF, ADAM23, PRDM5, MLF1) showed frequent differential methylation between gastric cancer and normal mucosa in the training, test, and validation sets. GDNF and MINT25 were most sensitive molecular markers of early stage gastric cancer, whereas PRDM5 and MLF1 were markers of a field defect. There was a close correlation (r = 0.5-0.9, P = .03-.001) between methylation levels in tumor biopsy and gastric washes. MINT25 methylation had the best sensitivity (90%), specificity (96%), and area under the receiver operating characteristic curve (0.961) in terms of tumor detection in gastric washes. CONCLUSIONS These findings suggest MINT25 is a sensitive and specific marker for screening in gastric cancer. Additionally, we have developed a new method for gastric cancer detection by DNA methylation in gastric washes.

Aberrant DNA Methylation Is Associated with Disease Progression, Resistance to Imatinib and Shortened Survival in Chronic Myelogenous Leukemia

The epigenetic impact of DNA methylation in chronic myelogenous leukemia (CML) is not completely understood. To elucidate its role we analyzed 120 patients with CML for methylation of promoter-associated CpG islands of 10 genes. Five genes were identified by DNA methylation screening in the K562 cell line and 3 genes in patients with myeloproliferative neoplasms. The CDKN2B gene was selected for its frequent methylation in myeloid malignancies and ABL1 as the target of BCR-ABL translocation. Thirty patients were imatinib-naïve (mostly treated by interferon-alpha before the imatinib era), 30 were imatinib-responsive, 50 were imatinib-resistant, and 10 were imatinib-intolerant. We quantified DNA methylation by bisulfite pyrosequencing. The average number of methylated genes was 4.5 per patient in the chronic phase, increasing significantly to 6.2 in the accelerated and 6.4 in the blastic phase. Higher numbers of methylated genes were also observed in patients resistant or intolerant to imatinib. These patients also showed almost exclusive methylation of a putative transporter OSCP1. Abnormal methylation of a Src suppressor gene PDLIM4 was associated with shortened survival independently of CML stage and imatinib responsiveness. We conclude that aberrant DNA methylation is associated with CML progression and that DNA methylation could be a marker associated with imatinib resistance. Finally, DNA methylation of PDLIM4 may help identify a subset of CML patients that would benefit from treatment with Src/Abl inhibitors.

DNA Methylation Profiles of Primary Colorectal Carcinoma and Matched Liver Metastasis

Background The contribution of DNA methylation to the metastatic process in colorectal cancers (CRCs) is unclear. Methods We evaluated the methylation status of 13 genes (MINT1, MINT2, MINT31, MLH1, p16, p14, TIMP3, CDH1, CDH13, THBS1, MGMT, HPP1 and ERα) by bisulfite-pyrosequencing in 79 CRCs comprising 36 CRCs without liver metastasis and 43 CRCs with liver metastasis, including 16 paired primary CRCs and liver metastasis. We also performed methylated CpG island amplification microarrays (MCAM) in three paired primary and metastatic cancers. Results Methylation of p14, TIMP3 and HPP1 in primary CRCs progressively decreased from absence to presence of liver metastasis (13.1% vs. 4.3%; 14.8% vs. 3.7%; 43.9% vs. 35.8%, respectively) (P<.05). When paired primary and metastatic tumors were compared, only MGMT methylation was significantly higher in metastatic cancers (27.4% vs. 13.4%, P = .013), and this difference was due to an increase in methylation density rather than frequency in the majority of cases. MCAM showed an average 7.4% increase in DNA methylated genes in the metastatic samples. The numbers of differentially hypermethylated genes in the liver metastases increased with increasing time between resection of the primary and resection of the liver metastasis. Bisulfite-pyrosequencing validation in 12 paired samples showed that most of these increases were not conserved, and could be explained by differences in methylation density rather than frequency. Conclusions Most DNA methylation differences between primary CRCs and matched liver metastasis are due to random variation and an increase in DNA methylation density rather than de-novo inactivation and silencing. Thus, DNA methylation changes occur for the most part before progression to liver metastasis.

MEK1/2 Inhibitor Selumetinib (AZD6244) Inhibits Growth of Ovarian Clear Cell Carcinoma in a PEA-15–Dependent Manner in a Mouse Xenograft Model

Clear cell carcinoma (CCC) of the ovary tends to show resistance to standard chemotherapy, which results in poor survival for patients with CCC. Developing a novel therapeutic strategy is imperative to improve patient prognosis. Epidermal growth factor receptor (EGFR) is frequently expressed in epithelial ovarian cancer. One of the major downstream targets of the EGFR signaling cascade is extracellular signal–related kinase (ERK). PEA-15, a 15-kDa phosphoprotein, can sequester ERK in the cytoplasm. MEK1/2 plays a central role in integrating mitogenic signals into the ERK pathway. We tested the hypothesis that inhibition of the EGFR–ERK pathway suppresses tumorigenicity in CCC, and we investigated the role of PEA-15 in ERK-targeted therapy in CCC. We screened a panel of 4 CCC cell lines (RMG-I, SMOV-2, OVTOKO, and KOC-7c) and observed that the EGFR tyrosine kinase inhibitor erlotinib inhibited cell proliferation of EGFR-overexpressing CCC cell lines through partial dependence on the MEK/ERK pathway. Furthermore, erlotinib-sensitive cell lines were also sensitive to the MEK inhibitor selumetinib (AZD6244), which is under clinical development. Knockdown of PEA-15 expression resulted in reversal of selumetinib-sensitive cells to resistant cells, implying that PEA-15 contributes to selumetinib sensitivity. Both selumetinib and erlotinib significantly suppressed tumor growth (P < 0.0001) in a CCC xenograft model. However, selumetinib was better tolerated; erlotinib-treated mice exhibited significant toxic effects (marked weight loss and severe skin peeling) at high doses. Our findings indicate that the MEK–ERK pathway is a potential target for EGFR-overexpressing CCC and indicate that selumetinib and erlotinib are worth exploring as therapeutic agents for CCC. Mol Cancer Ther; 11(2); 360–9. ©2011 AACR.

RUNX3 promoter hypermethylation is frequent in leukaemia cell lines and associated with acute myeloid leukaemia inv(16) subtype

Correlative and functional studies support the involvement of the RUNX gene family in haematological malignancies. To elucidate the role of epigenetics in RUNX inactivation, we evaluated promoter DNA methylation of RUNX1, 2, and 3 in 23 leukaemia cell lines and samples from acute myeloid leukaemia (AML), acute lymphocytic leukaemia (ALL) and myelodysplatic syndromes (MDS) patients. RUNX1 and RUNX2 gene promoters were mostly unmethylated in cell lines and clinical samples. Hypermethylation of RUNX3 was frequent among cell lines (74%) and highly variable among patient samples, with clear association to cytogenetic status. High frequency of RUNX3 hypermethylation (85% of the 20 studied cases) was found in AML patients with inv(16)(p13.1q22) compared to other AML subtypes (31% of the other 49 cases). RUNX3 hypermethylation was also frequent in ALL (100% of the six cases) but low in MDS (21%). In support of a functional role, hypermethylation of RUNX3 was correlated with low levels of protein, and treatment of cell lines with the DNA demethylating agent, decitabine, resulted in mRNA re‐expression. Furthermore, relapse‐free survival of non‐inv(16)(p13.1q22) AML patients without RUNX3 methylation was significantly better (P = 0·016) than that of methylated cases. These results suggest that RUNX3 silencing is an important event in inv(16)(p13.1q22) leukaemias.

MEK Inhibitor Selumetinib (AZD6244; ARRY-142886) Prevents Lung Metastasis in a Triple-Negative Breast Cancer Xenograft Model

Patients with triple-negative breast cancer (TNBC) have a poor prognosis because TNBC often metastasizes, leading to death. Among patients with TNBC, those with extracellular signal-regulated kinase 2 (ERK2)-overexpressing tumors were at higher risk of death than those with low-ERK2-expressing tumors (hazard ratio, 2.76; 95% confidence interval, 1.19–6.41). The MAPK pathway has been shown to be a marker of breast cancer metastasis, but has not been explored as a potential therapeutic target for preventing TNBC metastasis. Interestingly, when we treated TNBC cells with the allosteric MEK inhibitor selumetinib, cell viability was not reduced in two-dimensional culture. However, in three-dimensional culture, selumetinib changed the mesenchymal phenotype of TNBC cells to an epithelial phenotype. Cells that undergo epithelial–mesenchymal transition (EMT) are thought to contribute to the metastatic process. EMT leads to generation of mesenchymal-like breast cancer cells with stem cell–like characteristics and a CD44+CD24−/low expression pattern. We tested the hypothesis that targeted inhibition of the MAPK pathway by selumetinib inhibits acquisition of the breast cancer stem cell phenotype and prevents lung metastasis of TNBC. TNBC cells treated with selumetinib showed inhibition of anchorage-independent growth, an indicator of in vivo tumorigenicity (P < 0.005), and decreases in the CD44+CD24−/low fraction, ALDH1 activity, and mammosphere-forming efficiency. Mice treated with selumetinib formed significantly fewer lung metastases than control mice injected with vehicle (P < 0.05). Our data demonstrate that MEK inhibitors can inhibit breast cancer stem cells and may have clinical potential for the prevention of metastasis in certain cases in which tumors are MAPK dependent. Mol Cancer Ther; 14(12); 2773–81. ©2015 AACR.

Regulation of Fas-mediated immune homeostasis by an activation-induced protein, Cyclon

Activation-induced cell death (AICD) plays an essential role in the contraction of activated T cells after eradication of pathogen. Fas (APO-1/CD95) is one of the key cell surface proteins that mediate AICD in CD4(+) and CD8(+) T cells. Despite its prime importance in cell death, regulation of Fas expression in T cells is poorly understood. Here we show that Cyclon, a newly identified cytokine-inducible protein, is induced in T cells on T-cell receptor ligation and important for immune homeostasis. Transgenic expression of Cyclon ameliorated autoimmune phenotype in mice lacking subunits of IL-2R. Transgenic expression of Cyclon markedly enhanced AICD through increased expression of Fas whose expression is essential for Cyclon action. Finally, we demonstrated that activated but not resting CD4(+) T cells with targeted deletion of a Cyclon allele show reduced AICD and expression of Fas, indicating a critical role of Cyclon in Fas expression in activated T cells. We think that our data provide insight into expression regulation of Fas in T cells.

Antitumor Activity of KW-2450 Against Triple-Negative Breast Cancer by Inhibiting Aurora A and B Kinases

Currently, no targeted drug is available for triple-negative breast cancer (TNBC), an aggressive breast cancer that does not express estrogen receptor, progesterone receptor, or HER2. TNBC has high mitotic activity, and, because Aurora A and B mitotic kinases drive cell division and are overexpressed in tumors with a high mitotic index, we hypothesized that inhibiting Aurora A and B produces a significant antitumor effect in TNBC. We tested this hypothesis by determining the antitumor effects of KW-2450, a multikinase inhibitor of both Aurora A and B kinases. We observed significant inhibitory activities of KW-2450 on cell viability, apoptosis, colony formation in agar, and mammosphere formation in TNBC cells. The growth of TNBC xenografts was significantly inhibited with KW-2450. In cell-cycle analysis, KW-2450 induced tetraploid accumulation followed by apoptosis or surviving octaploid (8N) cells, depending on dose. These phenotypes resembled those of Aurora B knockdown and complete pharmaceutical inhibition of Aurora A. We demonstrated that 8N cells resulting from KW-2450 treatment depended on the activation of mitogen-activated protein kinase kinase (MEK) for their survival. When treated with the MEK inhibitor selumetinib combined with KW-2450, compared with KW-2450 alone, the 8N cell population was significantly reduced and apoptosis was increased. Indeed, this combination showed synergistic antitumor effect in SUM149 TNBC xenografts. Collectively, Aurora A and B inhibition had a significant antitumor effect against TNBC, and this antitumor effect was maximized by the combination of selumetinib with Aurora A and B inhibition. Mol Cancer Ther; 14(12); 2687–99. ©2015 AACR.

Abstract 1624: Silencing of ERK2 reverses EMT and suppresses the CSC phenotype, inhibiting lung metastasis in triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive subtype lacking estrogen receptor, progesterone receptor, and HER2 overexpression. Patients with TNBC have a generally poor prognosis due to metastasis, high rates of recurrence, and lack of FDA-approved targeted therapies. We previously showed using functional proteomics that patients with high-ERK2-expressing TNBC tumors had a higher risk of death than those with low-ERK2-expressing tumors. Moreover, ERK2 but not ERK1 plays an important role in epithelial-mesenchymal transition (EMT) and is required for acquisition of stem cell-like characteristics. Compared to other breast cancer subtypes, TNBC has a higher proportion of cancer stem cells (CSCs) and is linked to EMT, two critical features associated with breast cancer progression, metastasis, and recurrence in patients. The MAPK signaling pathway is activated in TNBC, but the roles of ERK isoforms in tumor progression and metastasis are not well defined. We hypothesized that ERK2 but not ERK1 promotes EMT, the CSC phenotype, and metastasis in TNBC. Methods and Results: Knockdown of ERK2 in SUM149 and BT549 TNBC cells significantly inhibited anchorage-independent colony formation (p Conclusions and Future Directions: Our findings support our hypothesis, indicating that ERK2 promotes EMT and the CSC phenotype through EGR1 and mediates metastasis in TNBC. Future studies will determine ERK activity and pathway engagement using a novel peptide sensor based on the Sox fluorophore. We will pursue a therapeutic approach using siRNA against ERK2 incorporated in a DOTAP:cholesterol liposome. Citation Format: Mary Kathryn Pitner, Hitomi Saso, Richard Larson, Rachel M. Sammons, Huiqin Chen, Caimiao Wei, Gaurav Chauhan, Kimie Kondo, Naoto T. Ueno, Kevin Dalby, Bisrat G. Debeb, Chandra Bartholomeusz. Silencing of ERK2 reverses EMT and suppresses the CSC phenotype, inhibiting lung metastasis in triple-negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1624.