Mayumi Iwakawa

Loss of CpG Methylation Is Strongly Correlated with Loss of Histone H3 Lysine 9 Methylation at DMR-LIT1 in Patients with Beckwith-Wiedemann Syndrome

To clarify the chromatin-based imprinting mechanism of the p57(KIP2)/LIT1 subdomain at chromosome 11p15.5 and the mouse ortholog at chromosome 7F5, we investigated the histone-modification status at a differentially CpG methylated region of Lit1/LIT1 (DMR-Lit1/LIT1), which is an imprinting control region for the subdomain and is demethylated in half of patients with Beckwith-Wiedemann syndrome (BWS). Chromatin-immunoprecipitation assays revealed that, in both species, DMR-Lit1/LIT1 with the CpG-methylated, maternally derived inactive allele showed histone H3 Lys9 methylation, whereas the CpG-unmethylated, paternally active allele was acetylated on histone H3/H4 and methylated on H3 Lys4. We have also investigated the relationship between CpG methylation and histone H3 Lys9 methylation at DMR-LIT1 in patients with BWS. In a normal individual and in patients with BWS with normal DMR-LIT1 methylation, histone H3 Lys9 methylation was detected on the maternal allele; however, it disappeared completely in the patients with the DMR-LIT1 imprinting defect. These findings suggest that the histone-modification status at DMR-Lit1/LIT1 plays an important role in imprinting control within the subdomain and that loss of histone H3 Lys9 methylation, together with CpG demethylation on the maternal allele, may lead to the BWS phenotype.

Expression profiles are different in carbon ion-irradiated normal human fibroblasts and their bystander cells

Evidence has accumulated that ionizing radiation induces biological effects in non-irradiated bystander cells having received signals from directly irradiated cells; however, energetic heavy ion-induced bystander response is incompletely characterized. Here we performed microarray analysis of irradiated and bystander fibroblasts in confluent cultures. To see the effects in bystander cells, each of 1, 5 and 25 sites was targeted with 10 particles of carbon ions (18.3 MeV/u, 103 keV/microm) using microbeams, where particles traversed 0.00026, 0.0013 and 0.0066% of cells, respectively. diated cells, cultures were exposed to 10% survival dose (D), 0.1D and 0.01D of corresponding broadbeams (108 keV/microm). Irrespective of the target numbers (1, 5 or 25 sites) and the time (2 or 6h postirradiation), similar expression changes were observed in bystander cells. Among 874 probes that showed more than 1.5-fold changes in bystander cells, 25% were upregulated and the remainder downregulated. These included genes related to cell communication (PIK3C2A, GNA13, FN1, ANXA1 and IL1RAP), stress response (RAD23B, ATF4 and EIF2AK4) and cell cycle (MYCN, RBBP4 and NEUROG1). Pathway analysis revealed serial bystander activation of G protein/PI-3 kinase pathways. Instead, genes related to cell cycle or death (CDKN1A, GADD45A, NOTCH1 and BCL2L1), and cell communication (IL1B, TCF7 and ID1) were upregulated in irradiated cells, but not in bystander cells. Our results indicate different expression profiles in irradiated and bystander cells, and imply that intercellular signaling between irradiated and bystander cells activate intracellular signaling, leading to the transcriptional stress response in bystander cells.

Upregulation of stress-response genes with cell cycle arrest induced by carbon ion irradiation in multiple murine tumors models

Objective: To elucidate the in vivo biological effects induced by carbon-ion irradiation using comprehensive expression analysis. Materials and Methods: We examined gene expression changes after carbon-ion (C-ion) irradiation (290 MeV/m, SOBP 6 cm middle, 50 kev/μm) with a single dose of 30 Gy in four mouse tumors (NR-S1, SCCVII, NFSa, and #8520) transplanted into the hind legs of C3H/HeNrs mice, using 44K single-color oligo-microarrays at 6 hours (h), 1 day, and 3 days after irradiation. Gamma rays of 30 Gy and 50 Gy were used as a reference beam. Identification of C-ion-responsive genes was based on a false discovery rate of < 5% using the Wilcoxon test (P < 0.001) and the Benjamini-Hochberg correction. Results: In all tumors, the level of expression of several tens of genes, including Ccl3, Ccng1, Cd80, Cdkn1a, Cxcl2, IL7r, Lrdd, Mgmt, Mmp8, and Polk, was significantly altered 6 h and day 1 following C-ion irradiation. At day 3, several hundred genes, many of which are also classified as stress-response or cell-communication genes, including Tnfrsf5, Ikbke, and Icam1, were upregulated following C-ion irradiation. The expression level of the majority of these genes was similar following γ-ray treatment, although the change was not as extensive and intertumor variance was apparent. Several genes, including Ikbke, Serpina3n, and Saa3, responded differentially following C-ion irradiation than after γ-ray irradiation. Pathological investigation and immunohistochemical analysis of Cdkn1a revealed cell cycle arrest with mitotic catastrophe in tumors irradiated by C-ions. Conclusions: This study revealed significant C-ion induced upregulation of stress-responsive and cell-communication genes common to different tumor types. These findings provide evidence for the efficacy of this modality for the treatment of local tumors.

Combination effects of distinct cores in 11q13 amplification region on cervical lymph node metastasis of oral squamous cell carcinoma

Lymph node metastasis (LNM) in oral squamous cell carcinoma (OSCC) is known to associate with a significant decrease of 5-year survival. Genetic factors related to the difference of the LNM status in the OSCC have been not fully elucidated. Array-based comparative genomic hybridization (CGH) with individual gene-level resolution and real-time quantitative polymerase chain reaction (QPCR) were conducted using primary tumor materials resected from 54 OSCC patients with (n=22) or without (n=32) cervical LNM. Frequent gain was observed at the 11q13 region exclusively in patients with cervical LNM, which was confirmed by real-time QPCR experiments using 11 genes (TPCN2, MYEOV, CCND1, ORAOV1, FGF4, TMEM16A, FADD, PPFIA1, CTTN, SHANK2 and DHCR7) in this region. It was revealed that two distinct amplification cores existed, which were separated by a breakpoint between MYEOV and CCND1 in the 11q13 region. The combination of copy number amplification at CTTN (core 2) and/or TPCN2/MYEOV (core 1), selected from each core, was most significantly associated with cervical LNM (P=0.0035). Two amplification cores at the 11q13 region may have biological impacts on OSCC cells to spread from the primary site to local lymph nodes. Further study of a larger patient series should be conducted to validate these results.

Gene expression analysis in human malignant melanoma cell lines exposed to carbon beams.

Purpose: To elucidate the molecular changes in response to carbon beams (C-ions) in melanoma. Materials and methods: We examined expression profiles of 6 melanoma cell lines exposed to C-ions or X-rays with 2 Gy using single-color microarrays. Results: Twenty-two genes, including nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (NFKBIA), responded to C-ions in all six cell lines, based on analysis of variance (ANOVA) filtering (p < 0.001). We found 173 genes that responded in common to C-ions in four cell lines. We identified many down-regulated genes including the cell cycle – related genes that were more responsive to C-ions than X-rays. In contrast, most of the up-regulated genes including the tumor protein p53 (p53) target genes responded to both C-ions and X-rays. C-ions induced G2/M arrest significantly more than X-rays at 30 h (p < 0.05). Conclusion: Our findings suggest that down-regulation of gene expression plays a key role in the response to C-ions. Regulation of cell cycle – related genes and induction of prolonged G2/M arrest may be responsible for the extra sensitivity to C-ions, whereas p53-related genes may have similar roles in the sensitivities to both C-ions and X-rays.

X-ray irradiation and Rho-kinase inhibitor additively induce invasiveness of the cells of the pancreatic cancer line, MIAPaCa-2, which exhibits mesenchymal and amoeboid motility.

Tumor cells can migrate and invade tissue by two modes of motility: mesenchymal and amoeboid. X‐ray or γ‐ray irradiation increases the invasiveness of tumor cells with mesenchymal motility through the induction of matrix metalloproteinases (MMP), and this increase is suppressed by MMP inhibitors (MMPI). However, the effects of X‐ray or γ‐ray irradiation on the invasiveness of tumor cells with amoeboid motility remain unclear. We investigated the effect of irradiation on amoeboid motility by using cells of the human pancreatic cancer line, MIAPaCa‐2, which exhibits both modes of motility. The X‐ray‐induced invasiveness of MIAPaCa‐2 cells was associated with the upregulation of MMP2 at both the RNA and protein levels and was inhibited by MMPI treatment. Amoeboid–mesenchymal transition was slightly induced after irradiation. The MMPI treatment caused mesenchymal–amoeboid transition without significant increase in invasiveness, while the ROCK inhibitor (ROCKI) stimulated amoeboid–mesenchymal transition and enhanced invasiveness under both non‐irradiated and irradiated conditions. This ROCKI‐induced transition was accompanied by the upregulation of MMP2 mRNA and protein. Exposure to both irradiation and ROCKI further enhanced MMP2 expression and had an additive effect on the invasiveness of MIAPaCa‐2 cells. Additionally, exposure to MMPI led to significant suppression of both radiation‐induced and the basal invasiveness of MIAPaCa‐2 cells. This suggests that ROCKI treatment, especially with concomitant X‐ray irradiation, can induce invasion of cancer cells and should be used only for certain types of cancer cells. Simultaneous use of inhibitors, ROCKI and MMPI may be effective in suppressing invasiveness under both X‐ray‐irradiated and non‐irradiated conditions. (Cancer Sci 2011; 102: 792–798)

Application of Carbon-Ion Beams or Gamma-Rays on Primary Tumors Does Not Change the Expression Profiles of Metastatic Tumors in an In Vivo Murine Model

PURPOSE To clarify how carbon-ion radiotherapy (C-ion) on primary tumors affects the characteristics of subsequently arising metastatic tumor cells. METHODS AND MATERIALS Mouse squamous cell carcinomas, NR-S1, in synergic C3H/HeMsNrs mice were irradiated with a single dose of 5-50 Gy of C-ion (290 MeV per nucleon, 6-cm spread-out Bragg peak) or gamma-rays ((137)Cs source) as a reference beam. The volume of the primary tumors and the number of metastatic nodules in lung were studied, and histologic analysis and microarray analysis of laser-microdissected tumor cells were also performed. RESULTS Including 5 Gy of C-ion and 8 Gy of gamma-rays, which did not inhibit the primary tumor growth, all doses used in this study inhibited lung metastasis significantly. Pathologic findings showed no difference among the metastatic tumor nodules in the nonirradiated, C-ion-irradiated, and gamma-ray-irradiated groups. Clustering analysis of expression profiles among metastatic tumors and primary tumors revealed a single cluster consisting of metastatic tumors different from their original primary tumors, indicating that the expression profiles of the metastatic tumor cells were not affected by the local application of C-ion or gamma-ray radiotherapy. CONCLUSION We found no difference in the incidence and histology, and only small differences in expression profile, of distant metastasis between local C-ion and gamma-ray radiotherapy. The application of local radiotherapy per se or the type of radiotherapy applied did not influence the transcriptional changes caused by metastasis in tumor cells.

The Proangiogenic Factor Ephrin-A1 Is Up-Regulated in Radioresistant Murine Tumor by Irradiation

While the pre-treatment status of cancer is generally correlated with outcome, little is known about microenvironmental change caused by anti-cancer treatment and how it may affect outcome. For example, treatment may lead to induction of gene expression that promotes resistance to therapy. In the present study, we attempted to find a gene that was both induced by irradiation and associated with radioresistance in tumors. Using single-color oligo-microarrays, we analyzed the gene expression profiles of two murine squamous cell carcinomas, NR-S1, which is highly radioresistant, and SCCVII, which is radiosensitive, after irradiation with 137-Cs gamma rays or carbon ions. Candidate genes were those differentially regulated between NR-S1 and SCCVII after any kind of irradiation. Four genes, Efna1 (Ephrin-A1), Sprr1a (small proline-rich protein 1A), Srgap3 (SLIT-ROBO Rho GTPase activating protein 3) and Xrra1 [RIKEN 2 days neonate thymus thymic cells (NOD) cDNA clone E430023D08 3′], were selected as candidate genes associated with radiotherapy-induced radioresistance. We focused on Efna1, which encodes a ligand for the Eph receptor tyrosine kinase known to be involved in the vascular endothelial growth factor (VEGF) pathway. We used immunohistochemical methods to detect expression of Ephrin-A1, VEGF, and the microvascular marker CD31 in radioresistant NR-S1 tumor cells. Ephrin-A1 was detected in the cytoplasm of NR-S1 tumor cells after irradiation, but not in SCCVII tumor cells. Irradiation of NR-S1 tumor cells also led to significant increases in microvascular density, and up-regulation of VEGF expression. Our results suggest that radiotherapy-induced changes in gene expression related with angiogenesis might also modulate microenvironment and influence responsiveness of tumors.

The Radiation-Induced Cell-Death Signaling Pathway is Activated by Concurrent Use of Cisplatin in Sequential Biopsy Specimens from Patients with Cervical Cancer

Objective: To identify changes in gene expression related to the concurrent use of platinum compounds with radiotherapy, in the treatment of cervical cancer. Patients and Methods: Biopsy specimens were obtained from 39 patients with squamous cell carcinoma of the uterine cervix, before and during fractionated radiotherapy. Twenty patients were treated with radiotherapy (RT) alone, while 19 received the same radiotherapy plus concomitant chemotherapy with cisplatin (CRT). Changes in gene expression induced by treatment were investigated using single-color oligo-microarrays consisting of 44K human sequences. Paraffin-embedded samples were used to examine apoptosis and the expression of protein by treatment-responsive genes. Changes in mRNA expression were assessed for these genes by real-time reverse transcriptase-polymerase chain reaction. Aberrant genomic change (detected using microarray-based comparative genomic hybridization), human papillomavirus infection, and p53 status were also evaluated. Results: The expression of CDKN1A, BAX, TNFSF8, and RRM2B was consistently upregulated by CRT (9 Gy with a single administration of cisplatin). Similar expression changes were induced by RT (9 Gy) alone, although the variability between tumors was greater. Apoptotic cells were significantly increased in both groups. CRT significantly increased the numbers of cases with diffusely distributed CDKN1A-positive cells. Genetic losses at 2q33-ter and gains of 3q26-ter were detected in the samples with high frequency; 60% were positive for human papillomavirus DNA; and 3 tumors had deletions/mutations of the p53 gene. There was no difference in the incidence of these genomic changes between the groups, and no association was found with the changes in expression of CDKN1A, BAX, TNFSF8, or RRM2B. Conclusions: Using biopsy samples from pretreatment and midtreatment cervical tumors, we identified therapy-induced genes related to the cell death signaling pathway. CRT produced a homogenous pattern of changes in expression of known radiation-responsive genes.

A murine model for bone marrow metastasis established by an i.v. injection of C-1300 neuroblastoma in A/J mice

A reproducible tumor model for bone marrow metastasis has been developed by an injection of murine C-1300 neuroblastoma (C-1300 NB) cells into the tail vein of syngeneic A/J mice. The animals died with liver metastases at 18–21 days after an injection of 105 tumor cells and often had bone marrow metastasis in the femur. N-methylformamide (NMF), a maturational agent, was administered to inhibit liver metastases and to extend survival in mice with advancing bone metastasis. Histological examination of bone marrow metastasis, demonstrated lesions varying from a few small colonies of C-1300 NB cells either in metaphysis or diaphysis to large foci replacing normal hematopoietic bone marrow, simultaneously invading epiphysis or cortex of bone as bone metastasis. This assay demonstrated the ability to detect neuroblastoma cells in the bone marrow histologically and could determine bone marrow TD50 by extraction of bone marrow cells after treatment with various doses of drug. Fifty per cent of mice injected with cyclophosphamide (CY) developed bone marrow metastasis without liver metastasis. Treatment with tamoxifen, an anti-calmodulin drug, suppressed tumor takes in the recipient mice with tamoxifen-dose-dependent fashion. This experimental system allows for investigations into the therapeutic response and biology of neuroblastoma metastases in the bone marrow.