Wnt Signaling and Aging of the Gastrointestinal Tract.

Aging is considered a risk factor for various diseases including cancers. In this aging society, there is an urgent need to clarify the molecular mechanisms involved in aging. Wnt signaling has been shown to play a crucial role in the maintenance and differentiation of tissue stem cells, and intensive studies have elucidated its pivotal role in the aging of neural and muscle stem cells. However, until recently, such studies on the gastrointestinal tract have been limited. In this review, we discuss recent advances in the study of the role of Wnt signaling in the aging of the gastrointestinal tract and aging-related carcinogenesis.

Sox2 induces tumorigenesis and angiogenesis of early-stage esophageal squamous cell carcinoma through secretion of Suprabasin.

Early stage of esophageal squamous cell carcinoma (ESCC) is known to be accompanied by angiogenesis and morphological changes of microvessels. Transcription factor Sox2 is amplified in various cancers including ESCC, but the role of Sox2 in the carcinogenesis and angiogenesis has not been determined. Hence, we aimed to investigate the role of Sox2 in the early stage of ESCC. We found that the expression of Sox2 was significantly higher in early-stage ESCC tissues than that in their adjacent normal tissues. We then established Sox2-inducible normal human esophageal squamous cell line (HetSox2) to investigate the role of Sox2 in esophageal carcinogenesis and angiogenesis in vitro. Sox2 overexpression led to increased cell proliferation and spheroid formation. The culture supernatant of Sox2-overexpressing HetSox2 induced migration and sprouting of endothelial cell line HUVEC (human umbilical vein endothelial cell). As for the mechanism, we found that the expression of secreted protein Suprabasin was directly induced by Sox2. Suprabasin enhanced proliferation of normal human esophageal squamous cells when added to the culture. Moreover, Suprabasin enhanced migration and sprouting of HUVEC cells, which were observed with the culture supernatant of Sox2-overexpressing HetSox2. This angiogenic effect of Suprabasin was abolished by inhibiting AKT phosphorylation, which suggested its dependence on AKT signaling. Finally, we showed that Suprabasin expression and the density of microvessels were significantly higher in ESCC tissues with high Sox2 expression. Our study suggested that increased Sox2 expression in esophageal squamous cells induced Suprabasin expression, and as a result initiated the carcinogenesis via increased cell proliferation and angiogenesis.

Sexually dimorphic expression of the sex chromosome-linked genes cntfa and pdlim3a in the medaka brain.

In vertebrates, sex differences in the brain have been attributed to differences in gonadal hormone secretion; however, recent evidence in mammals and birds shows that sex chromosome-linked genes, independent of gonadal hormones, also mediate sex differences in the brain. In this study, we searched for genes that were differentially expressed between the sexes in the brain of a teleost fish, medaka (Oryzias latipes), and identified two sex chromosome genes with male-biased expression, cntfa (encoding ciliary neurotrophic factor a) and pdlim3a (encoding PDZ and LIM domain 3 a). These genes were found to be located 3-4 Mb from and on opposite sides of the Y chromosome-specific region containing the sex-determining gene (the medaka X and Y chromosomes are genetically identical, differing only in this region). The male-biased expression of both genes was evident prior to the onset of sexual maturity. Sex-reversed XY females, as well as wild-type XY males, had more pronounced expression of these genes than XX males and XX females, indicating that the Y allele confers higher expression than the X allele for both genes. In addition, their expression was affected to some extent by sex steroid hormones, thereby possibly serving as focal points of the crosstalk between the genetic and hormonal pathways underlying brain sex differences. Given that sex chromosomes of lower vertebrates, including teleost fish, have evolved independently in different genera or species, sex chromosome genes with sexually dimorphic expression in the brain may contribute to genus- or species-specific sex differences in a variety of traits.

Role of T-box transcription factor 3 in gastric cancers.

The expression of T-box transcription factor 3 (TBX3) has been identified in various cancers, including gastric cancers. Its role in breast cancers and melanomas has been intensively studied, and its contribution to the progression of cancers through suppressing senescence and promoting epithelial-mesenchymal transition has been reported. Recent reports on the role of TBX3 in gastric cancers have implied its involvement in gastric carcinogenesis. Considering its pivotal role in the initiation and progression of cancers, TBX3 could be a promising therapeutic target for gastric cancers.

Female-specific target sites for both oestrogen and androgen in the teleost brain.

To dissect the molecular and cellular basis of sexual differentiation of the teleost brain, which maintains marked sexual plasticity throughout life, we examined sex differences in neural expression of all subtypes of nuclear oestrogen and androgen receptors (ER and AR) in medaka. All receptors were differentially expressed between the sexes in specific nuclei in the forebrain. The most pronounced sex differences were found in several nuclei in the ventral telencephalic and preoptic areas, where ER and AR expression were prominent in females but almost completely absent in males, indicating that these nuclei represent female-specific target sites for both oestrogen and androgen in the brain. Subsequent analyses revealed that the female-specific expression of ER and AR is not under the direct control of sex-linked genes but is instead regulated positively by oestrogen and negatively by androgen in a transient and reversible manner. Taken together, the present study demonstrates that sex-specific target sites for both oestrogen and androgen occur in the brain as a result of the activational effects of gonadal steroids. The consequent sex-specific but reversible steroid sensitivity of the adult brain probably contributes substantially to the process of sexual differentiation and the persistent sexual plasticity of the teleost brain.

Suppressed Cellular Senescence Mediated by T-box3 in Aged Gastric Epithelial Cells may Contribute to Aging-related Carcinogenesis.

Aging is a risk factor for cancers in various organs. Recent advances in the organoid culturing system have made it viable to investigate the influence of aging utilizing these mini organs. In this study, we aimed to examine the implications of aging for gastric carcinogenesis. Gastric organoids established from aged mice grew larger, proliferated vigorously, and survived longer than that from young mice. Because Wnt/ß-catenin signaling was intensified in the aged organoids and because removal of Wnt-related factors diminished their proliferation, we investigated for Wnt target gene that contributed to enhanced proliferation and discovered that the aged organoids expressed the transcription factor T-box3 (Tbx3), which has been reported to suppress cellular senescence. Indeed, cellular senescence was suppressed in the aged organoids, and this resulted from enhanced G2-M transition. As for the mechanism involved in the intensified Wnt/ß-catenin signaling, we identified that Dickkopf3 (Dkk3) expression was reduced in the aged organoids due to methylation of the Dkk3 gene. Finally, the expression of TBX3 was enhanced in human atrophic gastritis and even more enhanced in human gastric cancers. In addition, its expression correlated positively with patients' age. These results indicated that the emergence of antisenescent property in aged gastric organoids due to enhanced Tbx3 expression led to accelerated cellular proliferation and organoid formation. Because the enhanced Tbx3 expression seen in aged gastric organoids was also observed in human gastric cancer tissues, this Dkk3-Wnt-Tbx3 pathway may be involved in aging-related gastric carcinogenesis. Significance: This work provides an insight into the mechanism involved in aging-related gastric carcinogenesis through studies utilizing organoids established from young and aged murine stomachs.

Asymptomatic gastric anisakiasis detected in gastric cancer screening: A case report.

Anisakiasis is a parasitic disease caused by Anisakis simplex and has become an emerging zoonosis as preferences for eating raw or undercooked seafood have become more common. Few case reports of asymptomatic anisakiasis have been published to date. A 79-year-old asymptomatic man underwent esophagogastroduodenoscopy (EGD) for gastric cancer screening. The gastroenterologist diagnosed superficial gastritis without any malignant lesions but found an Anisakis larva while reviewing EGD images. The physician performed a second EGD and removed the larva. The patient reported that he ate the flatfish sashimi for dinner on the day before the first EGD. This case indicates the existence of asymptomatic gastric anisakiasis, indicating that anisakiasis incidence may have previously been underestimated.

Male-predominant galanin mediates androgen-dependent aggressive chases in medaka.

Recent studies in mice demonstrate that a subset of neurons in the medial preoptic area (MPOA) that express galanin play crucial roles in regulating parental behavior in both sexes. However, little information is available on the function of galanin in social behaviors in other species. Here, we report that, in medaka, a subset of MPOA galanin neurons occurred nearly exclusively in males, resulting from testicular androgen stimulation. Galanin-deficient medaka showed a greatly reduced incidence of male-male aggressive chases. Furthermore, while treatment of female medaka with androgen induced male-typical aggressive acts, galanin deficiency in these females attenuated the effect of androgen on chases. Given their male-biased and androgen-dependent nature, the subset of MPOA galanin neurons most likely mediate androgen-dependent male-male chases. Histological studies further suggested that variability in the projection targets of the MPOA galanin neurons may account for the species-dependent functional differences in these evolutionarily conserved neural substrates.

A rare case of gastric squamous-cell carcinoma metastasized from the cervix.

Gastric squamous-cell carcinoma (SqCC) metastasized form the cervix is rarely detected in endoscopic examination, although cervical carcinoma is the second most common in gynecologic malignancy. A 59-year-old female visited a clinic for anorexia, and an esophago-gastro-duodenoscopy (EGD) revealed multiple submucosal tumors (SMTs) of the stomach. After she was referred, an image-enhanced endoscopy enhanced multiple SMTs with white spots, whose findings were irregular micro-vascular patterns in the mucosa with irregular/absent micro-surface pattern. We took endoscopic biopsies, whose histological diagnoses were SqCC in the layer of the lamina propria under normal epithelium. Positron emission tomography-CT, CT and magnetic resonance imaging revealed an irregularly enhanced mass of the cervix, the irregularly thickening wall of the stomach and peritoneal nodules. Palliative care alone was administered based on poor condition associated with the Stage IV cervical carcinoma. In this case, endoscopic detection of gastric SqCC might provide a tip to make final diagnosis of primary site of cervical SqCC. The numbers of endoscopic examination become increasing, so further deep awareness of such patterns of metastasis in cervical cancer are required.

A Primary Barrett's Adenocarcinoma with a Squamous Cell Carcinoma Component.

The present report describes an extremely rare case of Barrett's adenocarcinoma (BAC) with a squamous cell carcinoma (SCC) component. A 55-year-old man was diagnosed with esophageal adenocarcinoma on Barrett's esophagus. The patient underwent endoscopic submucosal dissection, but the pathology revealed deep submucosal invasive, moderately differentiated tubular adenocarcinoma and focal SCC with vascular invasion. In addition, morphological transition between adenocarcinoma and SCC components was confirmed. The patient underwent additional surgery, which revealed lymph node metastasis, and then received S-1 adjuvant chemotherapy. Based on the pathological findings, the transdifferentiation process may have a role in the histogenesis of this tumor.

Teleocortin: A Novel Member of the CRH Family in Teleost Fish.

The CRH family of neuropeptides, including CRH and urocortins, plays pivotal roles in the regulation of physiological and behavioral stress responses in vertebrates. In this study, we identified a previously undescribed member of the CRH family of peptides in a teleost fish species (medaka; Oryzias latipes) and named this peptide teleocortin (Tcn). Medaka Tcn is a 41-amino acid polypeptide derived from the C terminus of a larger precursor protein that is encoded by a 2-exon gene, thus sharing common structural features with known CRH family peptides. tcn was found exclusively in teleost fish. Phylogenetic analysis suggested that tcn probably has an ancient origin but was lost from the tetrapod lineage shortly after the divergence of the teleost and tetrapod lineages. In the medaka brain, tcn was expressed in nuclei of the telencephalon, preoptic area, hypothalamus, tegmentum, and isthmic region. Because none of these nuclei have been implicated in the control of ACTH secretion from the pituitary, Tcn may exert its effects centrally in the brain rather than via stimulation of the pituitary-adrenal/interrenal axis. Most, if not all, tcn-expressing neurons also expressed crh, suggesting that Tcn and Crh share common physiological functions. Moreover, Tcn activated Crh receptors 1 and 2 with equivalent or slightly higher potency than Crh, further suggesting that these peptides share common functions. Taken together, these data identified Tcn as a novel, teleost-specific member of the CRH family of peptides that may act centrally with Crh to regulate physiological and behavioral stress responses.

Post-proliferative immature radial glial cells female-specifically express aromatase in the medaka optic tectum.

Aromatase, the key enzyme responsible for estrogen biosynthesis, is present in the brain of all vertebrates. Much evidence has accumulated that aromatase is highly and exclusively expressed in proliferating mature radial glial cells in the brain of teleost fish even in adulthood, unlike in other vertebrates. However, the physiological significance of this expression remains unknown. We recently found that aromatase is female-specifically expressed in the optic tectum of adult medaka fish. In the present study, we demonstrated that, contrary to the accepted view of the teleost brain, female-specific aromatase-expressing cells in the medaka optic tectum represent a transient subset of post-proliferative immature radial glial cells in the neural stem cell lineage. This finding led us to hypothesize that female-specific aromatase expression and consequent estrogen production causes some sex difference in the life cycle of tectal cells. As expected, the female tectum exhibited higher expression of genes indicative of cell proliferation and radial glial maturation and lower expression of an anti-apoptotic gene than did the male tectum, suggesting a female-biased acceleration of the cell life cycle. Complicating the interpretation of this result, however, is the additional observation that estrogen administration masculinized the expression of these genes in the optic tectum, while simultaneously stimulating aromatase expression. Taken together, these results provide evidence that a unique subpopulation of neural stem cells female-specifically express aromatase in the optic tectum and suggest that this aromatase expression and resultant estrogen synthesis have an impact on the life cycle of tectal cells, whether stimulatory or inhibitory.

Cloning and expression in Escherichia coli of a gene, hup, encoding the histone-like protein HU of Bifidobacterium longum.

A genomic DNA library of Bifidobacterium longum ATCC15707 was transfected into an Escherichia coli strain deficient in both HU and IHF, the growth of which is cold-sensitive because of the deficiency in these proteins. Cold-resistant colonies were selected and the DNA was cloned and sequenced. A polypeptide consisted of 93 amino acids, a predicted molecular mass of 9983 Da with an isoelectric point of 10.35, was deduced from an orf in the middle of the DNA fragment. The amino acid sequence was highly similar to HU family proteins, and 26 aas of N terminal was identical to a histone-like protein, HBI, a HU family protein of B. longum. Incapabilities of Mu phage propagation in an E. coli mutant deficient in HU or IHF could be suppressed by DNA bearing this orf. These results showed that the orf is a gene hup encoding HBI, a histone-like protein HU of B. longum.