Toshiyuki Tsunoda

The increased expression of periostin during early stages of prostate cancer and advanced stages of cancer stroma.

Three‐dimensional culture (3DC) is a relevant in vitro model used to study prostate development and carcinogenesis. Recent studies have indicated that 3DC‐associated genes would be more sensitive as prognostic markers for cancer; however, no 3DC‐associated genes in prostate cancer (CaP) have thus far been elucidated.

ZFAT is an antiapoptotic molecule and critical for cell survival in MOLT-4 cells

ZFAT (also known as ZNF406), originally identified as a candidate gene for autoimmune thyroid disease, encodes a zinc‐finger protein, however, its function has not been elucidated. Here, we report that human ZFAT protein is expressed in peripheral B and T lymphocytes and a human acute T lymphoblastic leukaemia cell line, MOLT‐4 cells. Intriguing is that mouse ZFAT expression in CD4+ lymphocytes is increased during blast formation. Furthermore, ZFAT‐knockdown in MOLT‐4 induces apoptosis via activation of caspases. These results suggested that ZFAT protein is a critical regulator involved in apoptosis and cell survival for immune‐related cells.

Immune-related zinc finger gene ZFAT is an essential transcriptional regulator for hematopoietic differentiation in blood islands

TAL1 plays pivotal roles in vascular and hematopoietic developments through the complex with LMO2 and GATA1. Hemangioblasts, which have a differentiation potential for both endothelial and hematopoietic lineages, arise in the primitive streak and migrate into the yolk sac to form blood islands, where primitive hematopoiesis occurs. ZFAT (a zinc-finger gene in autoimmune thyroid disease susceptibility region / an immune-related transcriptional regulator containing 18 C2H2-type zinc-finger domains and one AT-hook) was originally identified as an immune-related transcriptional regulator containing 18 C2H2-type zinc-finger domains and one AT-hook, and is highly conserved among species. ZFAT is thought to be a critical transcription factor involved in immune-regulation and apoptosis; however, developmental roles for ZFAT remain unknown. Here we show that Zfat-deficient (Zfat−/−) mice are embryonic-lethal, with impaired differentiation of hematopoietic progenitor cells in blood islands, where ZFAT is exactly expressed. Expression levels of Tal1, Lmo2, and Gata1 in Zfat−/− yolk sacs are much reduced compared with those of wild-type mice, and ChIP-PCR analysis revealed that ZFAT binds promoter regions for these genes in vivo. Furthermore, profound reduction in TAL1, LMO2, and GATA1 protein expressions are observed in Zfat−/− blood islands. Taken together, these results suggest that ZFAT is indispensable for mouse embryonic development and functions as a critical transcription factor for primitive hematopoiesis through direct-regulation of Tal1, Lmo2, and Gata1. Elucidation of ZFAT functions in hematopoiesis might lead to a better understanding of transcriptional networks in differentiation and cellular programs of hematopoietic lineage and provide useful information for applied medicine in stem cell therapy.

Altered Energy Homeostasis and Resistance to Diet-Induced Obesity in KRAP -Deficient Mice

Obesity and related metabolic disorders have become leading causes of adult morbidity and mortality. KRAP (Ki-ras-induced actin-interacting protein) is a cytoskeleton-associated protein and a ubiquitous protein among tissues, originally identified as a cancer-related molecule, however, its physiological roles remain unknown. Here we demonstrate that KRAP-deficient (KRAP−/−) mice show enhanced metabolic rate, decreased adiposity, improved glucose tolerance, hypoinsulinemia and hypoleptinemia. KRAP−/− mice are also protected against high-fat diet-induced obesity and insulin resistance despite of hyperphagia. Notably, glucose uptake in the brown adipose tissue (BAT) in KRAP−/− mice is enhanced in an insulin-independent manner, suggesting that BAT is involved in altered energy homeostasis in KRAP−/− mice, although UCP (Uncoupling protein) expressions are not altered. Of interest is the down-regulation of fatty acid metabolism-related molecules, including acetyl-CoA carboxylase (ACC)-1, ACC-2 and fatty acid synthase in the liver of KRAP −/− mice, which could in part account for the metabolic phenotype in KRAP−/− mice. Thus, KRAP is a novel regulator in whole-body energy homeostasis and may be a therapeutic target in obesity and related diseases.

Inhibition of Phosphodiesterase-4 (PDE4) activity triggers luminal apoptosis and AKT dephosphorylation in a 3-D colonic-crypt model

BackgroundWe previously established a three-dimensional (3-D) colonic crypt model using HKe3 cells which are human colorectal cancer (CRC) HCT116 cells with a disruption in oncogenic KRAS, and revealed the crucial roles of oncogenic KRAS both in inhibition of apoptosis and in disruption of cell polarity; however, the molecular mechanism of KRAS-induced these 3-D specific biological changes remains to be elucidated.ResultsAmong the genes that were upregulated by oncogenic KRAS in this model, we focused on the phosphodiesterase 4B (PDE4B) of which expression levels were found to be higher in clinical tumor samples from CRC patients in comparison to those from healthy control in the public datasets of gene expression analysis. PDE4B2 was specifically overexpressed among other PDE4 isoforms, and re-expression of oncogenic KRAS in HKe3 cells resulted in PDE4B overexpression. Furthermore, the inhibition of PDE4 catalytic activity using rolipram reverted the disorganization of HCT116 cells into the normal physiologic state of the epithelial cell polarity by inducing the apical assembly of ZO-1 (a tight junction marker) and E-cadherin (an adherens junction marker) and by increasing the activity of caspase-3 (an apoptosis marker) in luminal cavities. Notably, rolipram reduced the AKT phosphorylation, which is known to be associated with the disruption of luminal cavity formation and CRC development. Similar results were also obtained using PDE4B2-shRNAs. In addition, increased expression of PDE4B mRNA was found to be correlated with relapsed CRC in a public datasets of gene expression analysis.ConclusionsThese results collectively suggested that PDE4B is upregulated by oncogenic KRAS, and also that the inhibition of PDE4 catalytic activity can induce both epithelial cell polarity and luminal apoptosis in CRC, thus highlighting the utility of our 3-D culture (3 DC) model for the KRAS-induced development of CRC in 3-D microenvironment. Indeed, using this model, we found that PDE4B is a promising candidate for a therapeutic target as well as prognostic molecular marker in CRC. Further elucidation of the signaling network of PDE4B2 in 3 DC would provide a better understanding of CRC in vivo.

Heterogenous induction of carcinoma‐associated fibroblast‐like differentiation in normal human prostatic fibroblasts by co‐culturing with prostate cancer cells

In the tumor microenvironment, carcinoma‐associated fibroblasts (CAFs) are considered to play a critical role in the promotion of tumorigenesis. However, the mechanisms that generate CAFs are not well elucidated. To understand how CAFs are generated during primary cancer progression, we investigated the biochemical characteristics of normal human prostate stromal cells (PrSC) co‐cultured with human prostate cancer (PCa) cells in vitro. In primary cultures of human PCa‐derived stromal cells (PCaSC‐8 and PCaSC‐9), expression of TNC, ACTA2, EGF, FGF7, and IGF1 mRNA was generally higher than PrSC but gene expression patterns were not uniform between PCaSC‐8 and PCaSC‐9 cells. Transforming growth factor β (TGFβ) and vascular endothelial growth factor (VEGF) protein levels in both PCaSC‐8 and PCaSC‐9 cells were generally higher than PrSC but levels of both secreted proteins were not same. When PrSCs were co‐cultured with androgen‐sensitive LNCaP cells or its sublines, androgen‐low‐sensitive E9 cells and androgen‐insensitive AIDL cells, mRNA expression of IGF1 was significantly increased in all combinations. In contrast, expression of COL1A1, TNC, and ACTA2 mRNA was significantly increased only in LNCaP + PrSC and E9 + PrSC co‐cultures. Protein production of VEGF was significantly increased only in LNCaP + PrSC and E9 + PrSC co‐cultures. Increase of TGFβ protein was observed only in E9 + PrSC co‐cultures. These biochemical characteristics of PrSC were partially recapitulated in TGFβ‐treated PrSC. We have demonstrated that normal fibroblasts co‐cultured with cancer cells become activated and exhibit biochemical characteristics of CAFs in a heterogenous manner. Our results suggest that heterogenous induction of CAF‐like differentiation might be strongly dependent on biochemical characteristics of adjacent cancer cells. J. Cell. Biochem. 112: 3604–3611, 2011.

ZFAT is a critical molecule for cell survival in mouse embryonic fibroblasts

ZFAT was originally identified as an immune-related transcriptional regulator containing 18 C2H2-type zinc-finger domains and one AT-hook. ZFAT is highly conserved among species and functions as an anti-apoptotic molecule in the lymphoblastic leukemia cell line, MOLT-4. We recently demonstrated that ZFAT is an essential molecule for hematopoietic differentiation in blood islands through the direct regulation of particular transcriptional factors, including Tal1, for endothelial cell assembly, and for the branch point formation of capillary-like structures. However, the molecular mechanisms underlying the anti-apoptotic function of ZFAT remain unknown. Here, we report that ZFAT knockdown by small interfering RNA induced apoptosis in mouse embryonic fibroblasts (MEFs). This response had been similarly observed for MOLT-4 cells. To explore the molecular mechanisms for ZFAT in anti-apoptotic function in both MEFs and MOLT-4 cells, microarray expression analysis and quantitative RT-PCR were done. Of interest was that Bcl-2 and Il6st were identified as commonly down-regulated genes by the depletion of ZFAT for both MEFs and MOLT-4 cells. These results suggest that ZFAT is a critical molecule for cell survival in MEFs and MOLT-4 cells at least in part through the regulation of the apoptosis involved in the BCL-2- and IL6st-mediated pathways. Further elucidation of the molecular functions for ZFAT might shed light on the cellular programs in the mesoderm-derived cells.

KRAS-induced actin-interacting protein is required for the proper localization of inositol 1,4,5-trisphosphate receptor in the epithelial cells.

Three inositol 1,4,5-trisphosphate receptor (IP(3)R) subtypes are differentially expressed among tissues and function as the Ca(2+) release channel on specialized endoplasmic reticulum (ER) membranes. The proper subcellular localization of IP(3)R is crucial for its proper function, but this molecular mechanism is unclear. KRAS-induced actin-interacting protein (KRAP) was originally identified as a cancer-related molecule, and is involved in the regulation of whole-body energy homeostasis and pancreatic exocrine system. We herein identified IP(3)R as an associated molecule with KRAP in vivo, and the association was validated by the co-immunoprecipitation and confocal immunostaining studies in mouse tissues including liver and pancreas. The association of KRAP with IP(3)R was also observed in the human epithelial cell lines including HCT116, HeLa and HEK293 cells. Intriguingly, KRAP interacts with distinct subtypes of IP(3)R in a tissue-dependent manner, i.e. IP(3)R1 and IP(3)R2 in the liver and IP(3)R2 and IP(3)R3 in the pancreas. The NH(2)-terminal amino acid residues 1-610 of IP(3)R are critical for the association with KRAP and KRAP-IP(3)R complex resides in a specialized ER but not a typical reticular ER. Furthermore, the localization of particular IP(3)R subtypes in tissues from KRAP-deficient mice is obviously disturbed, i.e. IP(3)R1 and IP(3)R2 in the liver and IP(3)R2 and IP(3)R3 in the pancreas. These findings demonstrate that KRAP physically associates with IP(3)R and regulates the proper localization of IP(3)R in the epithelial cells in vivo and cultured cells, and might shed light on the Ca(2+) signaling underlying physiological cellular programs, cancer development and metabolism-related diseases.

KRAS-induced actin-interacting protein regulates inositol 1,4,5-trisphosphate-receptor-mediated calcium release

KRAS-induced actin-interacting protein (KRAP) was originally characterized as a filamentous- actin-interacting protein. We have recently found that KRAP is an associated molecule with inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R) and is responsible for the proper subcellular localization of IP(3)R. Since it remains unknown whether KRAP regulates the IP(3)R-mediated Ca(2+) signaling, we herein examined the effects of KRAP on the IP(3)R-mediated Ca(2+) release by Ca(2+) imagings in the cultured HEK293 or MCF7 cells. Reduction of KRAP protein by KRAP-specific siRNA diminishes ATP-induced Ca(2+) release and the ATP-induced Ca(2+) release is completely quenched by the pretreatment with the IP(3)R inhibitor but not with the ryanodine receptor inhibitor, indicating that KRAP regulates IP(3)R-mediated Ca(2+) release. To further reveal mechanistic insights into the regulation of IP(3)R-mediated Ca(2+) release by KRAP, we examined the effects of the KRAP-knockdown on the releasable Ca(2+) content of intracellular Ca(2+) stores. Consequently, reduction of KRAP does not affect the amount of ionophore- or Ca(2+)-ATPase inhibitor-induced Ca(2+) release in the HEK293 cells, indicating that releasable Ca(2+) content of intracellular Ca(2+) stores is not altered by KRAP. Thus, KRAP is involved in the proper regulation of IP(3)R-mediated Ca(2+) release.

Oncogenic Ras influences the expression of multiple lncRNAs

Abstract Recent ultrahigh-density tiling array and large-scale transcriptome analysis have revealed that large numbers of long non-coding RNAs (lncRNAs) are transcribed in mammals. Several lncRNAs have been implicated in transcriptional regulation, organization of nuclear structure, and post-transcriptional processing. However, the regulation of expression of lncRNAs is less well understood. Here, we show that the exogenous and endogenous expression of an oncogenic form of small GTPase Ras (called oncogenic Ras) decrease the expression of lncRNA ANRIL (antisense non-coding RNA in the INK4 locus), which is involved in the regulation of cellular senescence. We also show that forced expression of oncogenic Ras increases the expression of lncRNA PANDA (p21 associated ncRNA DNA damage activated), which is involved in the regulation of apoptosis. Microarray analysis demonstrated that expression of multiple lncRNAs fluctuated by forced expression of oncogenic Ras. These findings indicate that oncogenic Ras regulates the expression of a large number of lncRNAs including functional lncRNAs, such as ANRIL and PANDA.