Frequent up-regulation of WNT5A mRNA in primary gastric cancer

WNT signal is transduced to the beta-catenin - TCF pathway, the JNK pathway, or the Ca2+-releasing pathway through seven-transmembrane-type WNT receptors encoded by Frizzled genes (FZD1-FZD10). We have previously cloned and characterized human WNT2B/WNT13, WNT3, WNT3A, WNT5B, WNT6, WNT7B, WNT8A, WNT8B, WNT10A, WNT10B, WNT11, WNT14, and WNT14B/WNT15 by using bioinformatics, cDNA-library screening, and cDNA-PCR. Here, we investigated expression of human WNT5A mRNA in various normal tissues, 66 primary tumors derived from various tissues, and 15 human cancer cell lines. WNT5A mRNA was relatively highly expressed in salivary gland, bladder, uterus, placenta, and fetal kidney. Up-regulation of WNT5A mRNA was detected in 5 out of 8 cases of primary gastric cancer, 5 out of 18 cases of primary colorectal tumors, and in 2 out of 7 cases of primary uterus tumors by using matched tumor/normal expression array analysis. Up-regulation of WNT5A mRNA was also detected in 7 out of 10 other cases of primary gastric cancer by using cDNA-PCR. Although low-level expression of WNT5A mRNA was detected in gastric cancer cell line MKN45, WNT5A mRNA was almost undetectable in gastric cancer cell lines OKAJIMA, TMK1, MKN7, MKN28, MKN74, and KATO-III. Compared with frequent up-regulation of WNT5A mRNA in primary gastric cancer, expression levels of WNT5A mRNA in 7 gastric cancer cell lines were significantly lower than that in normal stomach. Frequent up-regulation of WNT5A mRNA in human primary gastric cancer might be due to cancer-stromal interaction.     

Expression and regulation of WNT5A and WNT5B in human cancer: up-regulation of WNT5A by TNFalpha in MKN45 cells and up-regulation of WNT5B by beta-estradiol in MCF-7 cells

WNT signaling pathway plays key roles in carcinogenesis and embryogenesis, and WNT signaling molecules are potent targets for diagnosis, prevention and treatment of cancer as well as for regenerative medicine or tissue engineering. We have so far cloned and characterized human WNT2B/WNT13, WNT3, WNT3A, WNT5B, WNT6, WNT7B, WNT8A, WNT8B, WNT10A, WNT10B, WNT11, WNT14 and WNT14B/WNT15 using bioinformatics and cDNA-PCR. We have also reported frequent up-regulation of WNT2 and WNT5A in primary gastric cancer, which is probably due to cancer-stromal interaction. Here, expression and regulation of WNT5A and WNT5B in human cancer were investigated. WNT5A was relatively highly expressed in TE6 and TE10 among 12 esophageal cancer cell lines, and WNT5B was expressed in the majority of esophageal cancer cell lines. Among 7 pancreatic cancer cell lines, WNT5A was up-regulated in Hs700T, and WNT5B in PANC-1. WNT5A, but not WNT5B, was up-regulated by TNFalpha in MKN45 cells derived from gastric cancer. WNT5B, but not WNT5A, was up-regulated by beta-estradiol in MCF-7 cells derived from breast cancer. WNT5A and WNT5B were expressed together in 5 embryonal tumor cell lines, and were slightly down-regulated by all-trans retinoic acid in NT2 cells. Up-regulation of WNT5A and WNT5B in several types of human cancer expressing FZD5 might lead to more malignant phenotype through activation of the beta-catenin - TCF pathway.     

Differential regulation of WNT2 and WNT2B expression in human cancer.

WNT2 is one of proto-oncogenes to activate the beta-catenin - TCF signaling pathway. WNT2B is a paralogue of WNT2, which encodes WNT2B1 and WNT2B2 isoforms due to alternative splicing using alternative promoter. Here, regulation of WNT2, WNT2B1, and WNT2B2 mRNAs in MCF-7 cells (breast cancer), NT2 cells (teratocarcinoma), and MKN45 cells (gastric cancer) were investigated. WNT2B2, but not WNT2 and WNT2B1, was expressed in MCF-7 cells. beta-estradiol (100 nM) induced a transient up-regulation of WNT2 in MCF-7 cells, and also induced down-regulation of WNT2B2. WNT2B2, but not WNT2B1, was expressed in NT2 cells, and WNT2 was slightly expressed in NT2 cells. Retinoic acid (10 microM) induced a transient up-regulation of WNT2 in NT2 cells. WNT2B2, but not WNT2 and WNT2B1, was slightly expressed MKN45 cells, and tumor necrosis factor alpha did not affect expression of WNT2, WNT2B1, and WNT2B2 mRNAs in MKN45 cells. This is the first report on differential regulation of WNT2, WNT2B1, and WNT2B2 mRNAs in human cancer cell lines. Up-regulation of WNT2 mRNA by estrogen might play a key role in some cases of human breast cancer through activation of the beta-catenin - TCF signaling pathway.     

Regulation of WNT signaling molecules by retinoic acid during neuronal differentiation in NT2 cells: threshold model of WNT action (review)

NT2/NTera2 cells, derived from human embryonal tumor, differentiate into neuronal cells after treatment with all-trans-retinoic acid (ATRA). We have cloned and characterized 13 out of 19 human WNT genes, and also 9 out of 10 human Frizzled (FZD) genes encoding seven-transmembrane-type WNT receptors, which are potent targets for pharmacogenomics in the post-genomic era, especially in the field of regenerative medicine and clinical oncology. Because WNT signals are implicated in morphogenesis of neural tissues, regulation of 19 WNT genes and 10 FZD genes during the early phase of neuronal differentiation in NT2 cells is reviewed. Multiple WNTs and FZDs are expressed in NT2 cells. WNT2B/WNT13 gene encode 2 isoforms due to alternative splicing of alternative promoter type, and WNT2B isoform 2 (WNT2B2) rather than WNT2B isoform 1 (WNT2B1) is expressed in NT2 cells. WNT3A, WNT8A, WNT8B, WNT10B and WNT11 are down-regulated in NT2 cells after ATRA treatment, while WNT2, WNT7B and WNT14B are up-regulated. FZD4 and FZD10 are up-regulated in NT2 cells after ATRA treatment. Expression of multiple WNT signaling molecules are dramatically changed during the early phase of neuronal differentiation in NT2 cells. Each WNT activates the beta-catenin - TCF pathway, the JNK pathway or the Ca2+-releasing pathway in NT2 cells, and summed effects of multiple WNTs might determine the fate of NT2 cells (self-renewal or differentiation) through switching intracellular WNT signaling pathways. The author proposes the threshold model of WNT action.     

Frizzled10 mediates WNT1 and WNT3A signaling in the dorsal spinal cord of the developing chick embryo

Background: WNT1 and WNT3A drive a dorsal to ventral gradient of β‐catenin‐dependent Wnt signaling in the developing spinal cord. However, the identity of the receptors mediating downstream functions remains poorly understood. Results: In this report, we show that the spatiotemporal expression patterns of FZD10 and WNT1/WNT3A are highly correlated. We further show that in the presence of LRP6, FZD10 promotes WNT1 and WNT3A signaling using an 8xSuperTopFlash reporter assay. Consistent with a functional role for FZD10, we demonstrate that FZD10 is required for proliferation in the spinal cord. Finally, by using an in situ proximity ligation assay, we observe an interaction between FZD10 and WNT1 and WNT3A proteins. Conclusions: Together, our results identify FZD10 as a receptor for WNT1 and WNT3A in the developing chick spinal cord. Developmental Dynamics 243:833–843, 2014. © 2014 Wiley Periodicals, Inc.     

Comparative genomics on DKK2 and DKK4 orthologs

WNT family proteins activate the beta-catenin - TCF pathway to induce carcinogenesis through cell fate determination, and also activate the planar cell polarity (PCP) pathway to induce cell motility and metastasis. DKK1, DKK2, DKK3 and DKK4 are secreted-type WNT signaling modulators belonging to the Dickkopf family. Here, we identified and characterized rat Dkk2 and Dkk4 genes by using bioinformatics. Rat Dkk2 and Dkk4 genes, consisting of four exons, were located within AC120263.4 and AC109661.6 genome sequences, respectively. Rat Dkk2 gene encoded a 259-aa protein, showing 95.8% total-amino-acid identity with human DKK2. Rat Dkk4 gene encoded a 221-aa protein, showing 75.4% total-amino-acid identity with human DKK4. Mammalian Dkk family members were secreted proteins with two Cys-rich regions, each containing ten conserved Cys residues. Asn-linked glycosylation site at codon 52 was conserved among mammalian Dkk2 orthologs; however, Asn-linked glycosylation site was not identified among mammalian Dkk4 orthologs. Dkk2 proteins were more conserved than Dkk4 proteins, while Dkk4 promoters were more conserved than Dkk2 promoters. TATA-box was identified within Dkk2 and Dkk4 promoters. MYOD and triple TCF/LEF binding sites were conserved between human DKK4 promoter and rodent Dkk4 promoter. DKK2 mRNA was expressed in Ewing's sarcoma, and fetal heart. DKK4 mRNA was expressed in human embryonic stem (ES) cells differentiated to an early endodermal cell type, breast cancer, and diffuse type gastric cancer. DKK4 orthologs are implicated in the negative feed back mechanism of the WNT/beta-catenin signaling pathway (the canonical WNT signaling pathway).     

Differential expression of frpHE: a novel human stromal protein of the secreted frizzled gene family, during the endometrial cycle and malignancy

By using the differential display technique to identify genes that are differentially expressed in human endometrial carcinoma compared with normal endometrium, we have cloned frpHE, a novel member of the secreted frizzled gene family. By in situ hybridization, we have determined that frpHE is expressed by mesenchymal cells but not by epithelial cells. The expression of frpHE is modulated during the endometrial cycle: it is expressed in the stroma of proliferative endometrium and not significantly detectable in secretory or menstrual endometrium, suggesting that frpHE is under hormonal regulation. In addition, the expression of frpHE mRNA is markedly up-regulated in the stroma of endometrial hyperplasia and carcinoma and in the stroma of in situ and infiltrating breast carcinomas. Injection of frpHE mRNA in Xenopus embryos inhibited the Wnt-8 mediated dorsal axis duplication. These results indicate that frpHE functions as a regulator of the Wnt-frizzled signaling pathway and is involved in endometrial physiology and carcinogenesis.     

Comparative genomics on FGF8, FGF17, and FGF18 orthologs

FGF and WNT signaling pathways network together during embryogenesis and carcinogenesis. Among 22 FGF family members within human and rodents genomes, FGF20 orthologs are evolutionarily conserved targets of the WNT/beta-catenin signaling pathway. FGF8, FGF17, and FGF18 constitute one of FGF subfamilies. Here, comparative proteomics and comparative genomics analyses on FGF8, FGF17, and FGF18 orthologs were performed. Rat Fgf8 and Fgf17 genes, consisting of five exons, were located within AC096326.7 and AC097410.12 genome sequences, respectively. FGF8, FGF17, and FGF18 orthologs were FGF family members with the N-terminal signal peptide. Human FGF8 isoform F showed 90.6% total-amino-acid identity with rat Fgf8 (268 aa). Human FGF17 showed 98.6% total-amino-acid identity with rat Fgf17 (216 aa). Human FGF18 also showed 98.6 total-amino-acid identity with rat Fgf18. FBXW1 (betaTRCP1 or BTRC1)-FGF8-NPM3 locus at human chromosome 10q24.32, FBXW11 (betaTRCP2 or BTRC2)-FGF18-NPM1 locus at human chromosome 5q35.1, and FGF17-NPM2 locus at human chromosome 8p21.3 were paralogous regions within the human genome. FGF8 mRNA was expressed in DMSO-treated embryonic stem (ES) cells. FGF17 mRNA was expressed in ES cells differentiated to an early endodermal phenotype. FGF18 mRNA was expressed in fetal lung, fetal heart, lung carcinoid, colorectal cancer, and ovarian cancer. FGF18 promoter with double TCF/LEF binding sites rather than FGF8 promoter and FGF17 promoter was more conserved between human and rodents. These facts indicate that FGF18 orthologs were evolutionarily conserved targets of the WNT/beta-catenin signaling pathway.     

Expression and regulation of WNT10B in human cancer: up-regulation of WNT10B in MCF-7 cells by beta-estradiol and down-regulation of WNT10B in NT2 cells by retinoic acid

WNT signaling molecules, playing key roles in embryogenesis and carcinogenesis, are potent targets for regenerative medicine and clinical oncology. We have previously cloned and characterized the human orthologue of mouse proto-oncogene Wnt-10b using bioinformatics and cDNA-PCR. Human WNT10B is moderately expressed in MKN45 and MKN74 cells derived from human gastric cancer, and is up-regulated by tumor necrosis factor alpha (TNFalpha) in MKN45 cells. Here, expression and regulation of WNT10B in human cancer other than gastric cancer were investigated using cDNA-PCR. WNT10B mRNA was expressed in the majority of squamous cell carcinoma cell lines derived from esophageal cancer and cervical cancer. WNT10B mRNA was relatively highly expressed in TE3, TE6, TE10, TE11 (esophageal cancer), Hs700T (pancreatic cancer), SKG-IIIa, HeLa S3 (cervical cancer), and T-47D (breast cancer). Expression of WNT10B mRNA was up-regulated by beta-estradiol in MCF-7 cells expressing estrogen receptors. Expression of WNT10B mRNA was down-regulated by all-trans retinoic acid in NT2 cells with the potential of self renewal and neuronal differentiation. WNT10B might be implicated in self renewal of stem cells as well as in carcinogenesis through activation of the WNT - beta-catenin pathway.     

Molecular cloning and characterization of human WNT11.

WNT signaling pathway is implicated in carcinogenesis. Here, we cloned and characterized human WNT11, which showed three amino-acid substitutions (Ala121Thr, Gly156Arg, and Ser271Trp) compared with human WNT11 cDNA previously isolated by another group. WNT11 encoded a 354 amino-acid polypeptide with five N-glycosylation sites. Gly156 of human WNT11 was conserved in other members of the human WNT family, such as WNT2B1, WNT2B2, WNT3, WNT3A, WNT5B, WNT6, WNT7B, WNT8A, WNT10A, and WNT14. The Ala121-Gly156-Ser271 WNT11 allele isolated in this study was also identified in human genome draft sequence AC069055. Expression profile of WNT11 was next investigated. The 4.3-kb WNT11 mRNA was expressed in fetal lung, kidney, adult heart, liver, skeletal muscle, and pancreas. WNT11 mRNA was significantly up-regulated in a gastric cancer cell line MKN45 and a cervical cancer cell line SKG-IIIa. Among various types of human primary tumors, WNT11 mRNA was up-regulated in four cases of colorectal adenocarcinoma, and a case of renal cell carcinoma. Up-regulation of WNT11 mRNA might play an important role in human carcinogenesis through activation of the WNT signaling pathway.     

Comparative integromics on non-canonical WNT or planar cell polarity signaling molecules: transcriptional mechanism of PTK7 in colorectal cancer and that of SEMA6A in undifferentiated ES cells

Non-canonical WNT and planar cell polarity (PCP) are overlapping but distinct signaling pathways, which control convergent extension, neural tube closure, orientation of cilia and sensory hair cells, axon guidance, and cell motility. Non-canonical WNT signals, regulated by the interaction of WNT, WNT antagonist, Frizzled and ROR2, are transduced to JNK, ROCK, PKC, MAP3K7, and NFAT signaling cascades. PCP signals, regulated by the interaction of VANGL-PRICKLE complex, CELSR and Frizzled-DVL complex, are transduced to JNK, ROCK, and other uncharacterized signaling cascades. PTK7 signaling, regulated by SEMA6 and Plexin-A family members, affects PCP pathway through VANGL. Here, integrative genomic analyses on WNT5A, WNT5B, WNT11, FZD3, FZD6, ROR1, ROR2, RYK, CELSR1, CELSR2, CELSR3, VANGL1, VANGL2, PRICKLE1, PRICKLE2, PTK7, SEMA6A, SEMA6B, SEMA6C and SEMA6D were carried out. PTK7 and SEMA6A were expressed in undifferentiated embryonic stem (ES) cells, SEMA6A in endodermal progenitors, CELSR1, VANGL1 and PTK7 in gastrointestinal tumors. CELSR2, PRICKLE2 and SEMA6C were expressed in fetal brain, CELSR2, PRICKLE1 and SEMA6A in adult brain, WNT5A and CELSR3 in adult brain tumors. These facts indicate class switches of non-canonical WNT or PCP signaling molecules during embryogenesis and carcinogenesis. TCF/LEF-, SP1-, and 5 bHLH-binding sites within human PTK7 promoter were conserved in chimpanzee, rhesus monkey, mouse, and rat PTK7 orthologs, which explained the mechanism of PTK7 upregulation in colorectal cancer. NANOG-, SOX2-, and POU5F1 (OCT3/OCT4)-binding sites within intron 1 of the human SEMA6A gene were conserved in chimpanzee, rhesus monkey, mouse, and rat SEMA6A orthologs, which explained the mechanism of SEMA6A upregulation in undifferentiated ES cells. Most of non-canonical WNT or PCP signaling molecules, except PTK7 and SEMA6A, were not frequently expressed in undifferentiated human ES cells. Non-canonical WNT or PCP signaling pathway, activated to orchestrate gastrulation and neurulation, was relatively downregulated in undifferentiated ES cells derived from inner cell mass of blastocysts.     

Comparative genomics on Fzd7 orthologs

WNT signaling pathway networks with Hedgehog and Notch signaling pathways during carcinogenesis and embryogenesis. FZD7 is up-regulated in gastric cancer, esophageal cancer, and hepatocellular carcinoma (HCC). Here we identified and characterized rat Fzd7 gene by using bioinformatics. Rat Fzd7 gene was identified within AC136379.2 genome sequence. The 5'-flanking region and exonic region were well conserved among mammalian Fzd7 orthologs. Nucleotide position 153000-152216 of AC136379.2 genome sequence was identified as the evolutionarily conserved promoter region of rat Fzd7 gene, and nucleotide position 2273-3046 of AC069148.6 genome sequence as the evolutionarily conserved promoter region of human FZD7 gene. Match program revealed that PAX4-binding site was conserved among rat Fzd7, mouse Fzd7 and human FZD7 promoters. Rat Fzd7 (572 aa) was a seven-transmembrane-type Wnt receptor, which showed 99.3, 96.9, 87.4, 85.5, 79.5 and 79.0% total-amino-acid identity with mouse Fzd7, human FZD7, chicken fzd7, Xenopus fzd7, zebrafish fzd7a and fzd7b, respectively. Frizzled (Fz) domain within the N-terminal extracellular region, Leucine zipper motif around the fifth transmembrane (TM5) region, Dishevelled (Dvl)- and Magi3-binding motifs within the C-terminal cytoplasmic region were conserved among vertebrate Fzd7 orthologs. Leucine zipper motif around the TM5 region of Fzd7 orthologs was disrupted in FzE3 aberrant cDNA due to multiple cloning artifacts or sequencing errors. These facts indicate that experimental data obtained by using FzE3 cDNA do not always reflect the functions of Fzd7 orthologs.