Galectin-9 exhibits anti-myeloma activity through JNK and p38 MAP kinase pathways.

Galectins constitute a family of lectins that specifically exhibit the affinity for beta-galactosides and modulate various biological events. Galectin-9 is a tandem-repeat type galectin with two carbohydrate recognition domains and has recently been shown to have an anti-proliferative effect on cancer cells. We investigated the effect of recombinant protease-resistant galectin-9 (hGal9) on multiple myeloma (MM). In vitro, hGal9 inhibited the cell proliferation of five myeloma cell lines examined, including a bortezomib-resistant subcell line, with IC(50) between 75.1 and 280.0 nM, and this effect was mediated by the induction of apoptosis with the activation of caspase-8, -9, and -3. hGal9-activated Jun NH(2)-terminal kinase (JNK) and p38 MAPK signaling pathways followed by H2AX phosphorylation. Importantly, the inhibition of either JNK or p38 MAPK partly inhibited the anti-proliferative effect of hGal9, indicating the crucial role of these pathways in the anti-MM effect of hGal9. hGal9 also induced cell death in patient-derived myeloma cells, some with poor-risk factors, such as chromosomal deletion of 13q or translocation t(4;14)(p16;q32). Finally, hGal9 potently inhibited the growth of human myeloma cells xenografted in nude mice. These suggest that hGal9 is a new therapeutic target for MM that may overcome resistance to conventional chemotherapy.

Oral administration of pulverized Konjac glucomannan prevents the increase of plasma immunoglobulin E and immunoglobulin G levels induced by the injection of syngeneic keratinocyte extracts in BALB/c mice.

BACKGROUND: Immunoglobulin (Ig) E plays a key role in the pathogenesis of atopic diseases, such as asthma, atopic dermatitis and allergic rhinitis. Oral administration of pulverized Konjac glucomannan (PKGM) has recently been demonstrated to prevent both plasma IgE elevation and developing dermatitis in NC/Nga mice, a model of atopic dermatitis. OBJECTIVE: To clarify the direct effect of PKGM on the increase of plasma IgE, we employed the system of BALB/c mouse that increases IgE level without developing dermatitis in response to continuous injection of the extract of syngeneic keratinocytes, PAM 212 cells (PAM extract). METHODS: Three weeks after the start of feeding with either control or PKGM diet, mice were injected subcutaneously with PAM extract bi-weekly for 10 weeks. The levels of plasma Igs were measured by enzyme-linked immunosorbent assay every 2 weeks after the injection. The levels of epsilon germline transcription and the amounts of mRNA for IL-4, IFN-gamma, GATA-3 and T bet gene in the spleen were evaluated by real-time RT-PCR at the end of the experiment. RESULTS: On the one hand, PKGM prevented the increase of plasma IgE and IgG (IgG1, IgG2b) induced by PAM extract, and on the other hand, it enhanced the levels of plasma IgG3. However, it did not affect the level of plasma IgM. PKGM also reduced the levels of plasma ovalbumin (OVA)-specific IgE in OVA-sensitized mice. Moreover, PKGM attenuated the induction of epsilon germline transcription and expression levels of mRNA for IL-4, IFN-gamma and GATA-3 in the spleen of PAM extract-injected mice. PKGM also attenuated the induction of epsilon germline transcription and mRNA for IFN-gamma and T bet in the spleen of phosphate-buffered saline-injected control mice. CONCLUSIONS: These results suggested that oral administration of PKGM prevents the elevation of plasma IgE by suppressing IgE class switching in B cells and/or the commitment development of naive lymphocytes to both T-helper type 1 (Th1) and Th2.

Dopamine, dopamine D2 receptor short isoform, transforming growth factor (TGF)-beta1, and TGF-beta type II receptor interact to inhibit the growth of pituitary lactotropes.

The neurotransmitter dopamine is known to inhibit prolactin secretion and the proliferation of lactotropes in the pituitary gland. In this study, we determined whether dopamine and TGFbeta1 interact to regulate lactotropic cell proliferation. We found that dopamine and the dopamine agonist bromocriptine stimulated TGFbeta1 secretion and TGFbeta1 mRNA expression but inhibited lactotropic cell proliferation both in vivo and in vitro. The dopamine's inhibitory action on lactotropic cell proliferation was blocked by a TGFbeta1-neutralizing antibody. We also found that PR1 cells, which express low amounts of the dopamine D2 receptor, demonstrated reduced expression of TGFbeta1 type II receptor and TGFbeta1 mRNA levels and had undetectable levels of TGFbeta1 protein. These cells showed a reduced TGFbeta1 growth-inhibitory response. Constitutive expression of the D2 receptor short isoform, but not the D2 receptor long isoform, induced TGFbeta1 and TGFbeta1 type II receptor gene expression and recovered dopamine- and TGFbeta1-induced growth inhibition in PR1 cells. The constitutive expression of D2 receptor short isoform also reduced the tumor cell growth rate. These data suggest that a TGFbeta1 system may mediate, in part, the growth-inhibitory action of dopamine on lactotropes.

Intrapituitary regulatory system of mammotrophs in the mouse.

Estrogen stimulates the proliferation of pituitary cells, in particular mammotrophs. The present study was designed to clarify involvement of transforming growth factor alpha (TGF-alpha) in the estrogen-induced growth of mouse pituitary cells in vitro. Anterior pituitary cells obtained from ICR male mice were cultured in a primary, serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of a thymidine analogue, bromodeoxyuridine. Secretory cell types were immunocytochemically determined. Treatment with TGF-alpha (0.1 and 1 ng/ml) for 5 days stimulated cell proliferation. Since TGF-alpha binds to the epidermal growth factor (EGF)-receptor, this action may be exerted through this receptor. Estradiol-17beta (E2, 10(-9) M) stimulated proliferation of mammotrophs. RG-13022, an EGF receptor inhibitor, reduced the cell proliferation induced by EGF or E2, showing that the EGF receptor was involved in this induction of mammotroph growth. Treatment with TGF-alpha antisense oligodeoxynucleotide (ODN) inhibited the cell proliferation induced by E2, but treatment with EGF antisense ODN did not. Dual detection of TGF-alpha mRNA and growth hormone by in situ hybridization and fluorescence-immunocytochemistry demonstrated that TGF-alpha mRNA was detected in most somatotrophs. Our recent RT-PCR analysis revealed that E2 stimulated TGF-alpha-mRNA and EGF-receptor mRNA expression. These results indicate that TGF-alpha produced in somatotrophs mediates the stimulatory effect of estrogen on pituitary cell proliferation in a paracrine manner, and that EGF-receptor expression is stimulated by estrogen. These findings indicate that intrapituitary cell-to-cell interaction plays an important role in the control of pituitary secretory cells.

Kdap, a novel gene associated with the stratification of the epithelium.

The skin develops and differentiates during embryogenesis, which is concertedly regulated by a variety of genes. The present study isolated from the rat embryonic skin a novel differentiation-associated gene named Kdap (keratinocyte differentiation-associated protein) by suppression subtractive hybridization between the skin of 14day postcoitus (dpc) embryo (the prehair-germ stage) and that of 17dpc embryo (the hair-germ stage). Its mRNA contained four spliced forms in these tissues. The gene encoded a protein of total 98 amino acids with a calculated molecular mass of 11kDa and an isoelectric point of 6.1 as an unspliced form. The two splicing zones were well conserved among rat, mouse, and human. This protein had a high hydrophobic N-terminal region, a possible signal sequence, and contained two putative N-myristoylation sites and two casein kinase II phosphorylation sites. In situ hybridization experiments detected Kdap transcripts exclusively in the suprabasal cell layers of the embryonic epidermis. Intense expression was also seen in suprabasal cells in regions of infundibulum of the hair follicle. These results indicated that Kdap provides a new insight into the mechanism of differentiation and the maintenance of stratified epithelia.

Transforming growth factor-alpha stimulates proliferation of mammotrophs and corticotrophs in the mouse pituitary.

Oestrogen stimulates the proliferation of pituitary cells. The present study was designed to clarify the involvement of transforming growth factor-alpha (TGF-alpha) in the oestrogen-induced growth of mouse pituitary cells in vitro. Anterior pituitary cells obtained from ICR male mice were cultured in a primary serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of bromodeoxyuridine. Secretory cell types were immunocytochemically determined. Treatment with TGF-alpha (0.1 and 1 ng/ml) for 5 days stimulated cell proliferation. Since TGF-alpha binds to the epidermal growth factor (EGF) receptor, this action may be exerted through the EGF receptor. Oestradiol-17beta (OE(2), 10(-)(9) M) stimulated mammotrophic and corticotrophic cell proliferation. RG-13022, an EGF receptor inhibitor, inhibited the cell proliferation induced by EGF or OE(2), showing that the EGF receptor was involved in the growth response in mammotrophs and corticotrophs. Treatment with antisense TGF-alpha oligodeoxynucleotide (ODN) inhibited the cell proliferation induced by OE(2), but treatment with antisense EGF ODN did not. RT-PCR analysis revealed that OE(2) stimulated TGF-alpha mRNA and EGF receptor mRNA expression. These results indicate that TGF-alpha mediates the stimulatory effect of oestrogen on the pituitary cell proliferation in a paracrine or autocrine manner, and that EGF receptor expression is stimulated by oestrogen.

Identification of epidermal growth factor mRNA-expressing cells in the mouse anterior pituitary.

Epidermal growth factor (EGF) produced within the pituitary gland is associated with the growth of pituitary cells in rats. The aim of the present study was to localize EGF- and EGF receptor-expressing cells, and to clarify the involvement of EGF in DNA replication in 2-month-old male mouse pituitary cells. In situ hybridization of the pituitaries of these mice demonstrated that EGF mRNA was expressed in the anterior and intermediate lobes. Within the anterior pituitary, EGF mRNA-expressing cells were medium-sized and round, and made up 40% of the total number of secretory cells. EGF receptor mRNA was only detected in anterior pituitary cells. Forty-seven percent anterior pituitary cells expressed EGF receptor mRNA. An immunocytochemical study showed that most somatotropes and some mammotropes expressed EGF mRNA. When anterior pituitary cells were enzymatically dissociated and cultured in serum-free medium, RT-PCR demonstrated both EGF mRNA and EGF receptor mRNA expression. Treatment with EGF (1 and 10 ng/ml) for 5 days stimulated DNA replication in mammotropes and corticotropes. These results indicate that the DNA replication in mammotropes and corticotropes is regulated by the paracrine and/or autocrine activity of EGF produced at least in part by these cell types themselves.

Stimulatory effect of insulin-like growth factor I on proliferation of mouse pituitary cells in serum-free culture.

IGF-I is synthesized in the human and rat anterior pituitary glands. The present study was designed to clarify the growth-promoting action of IGF-I on mouse pituitary cells in a primary serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of bromodeoxyuridine (BrdU). BrdU labelling in the nucleus was found in all types of secretory cells: corticotrophs, thyrotrophs, gonadotrophs (LH cells and FSH cells), somatotrophs and mammotrophs. IGF-I (75 ng/ml) stimulated the proliferation of corticotrophs and mammotrophs among the pituitary secretory cells. IGF-I receptor mRNA was detected in the cultured pituitary cells using reverse transcription (RT)-PCR, indicating that mouse pituitary cells expressed IGF-I receptors. Insulin (100 ng/ml) or IGF-I (7.5 ng/ml) failed to increase the percentage of BrdU-labelled cells. However, treatment with insulin (100 ng/ml) plus IGF-I (7.5 ng/ml) increased the percentage of BrdU-labelled cells in a synergistic-like manner. Genistein, a tyrosine kinase specific inhibitor, decreased the IGF-I-induced cell proliferation, indicating that IGF-I acts through IGF-I receptors. IGF-I mRNA was also detected in the cultured pituitary cells by RT-PCR, and its peptides were immunocytochemically detected. The present results demonstrate that all types of pituitary secretory cells have the ability to proliferate in our serum-free culture system. IGF-I synthesized in the pituitary gland may stimulate the growth of pituitary cells, in particular corticotrophs and mammotrophs, by an autocrine or paracrine mechanism.

Augmentation of Prolactin Release by alpha-Melanocyte Stimulating Hormone Is Possibly Mediated by Melanocortin 3-Receptors in the Mouse Anterior Pituitary Cells.

Suckling- and estrogen-induced prolactin release from the anterior pituitary is mediated by alpha-melanocyte stimulating hormone (alpha-MSH) secreted by the intermediate lobe of the pituitary in the rat. Melanocortin 5-receptors are expressed in the anterior pituitary and probably mediate the alpha-MSH function. In contrast, the mouse anterior pituitary does not express the receptor. To examine whether or not alpha-MSH regulates prolactin release in mice, we performed cell immunoblot assay using anterior pituitary cells from adult female mice. We found that alpha-MSH acted on mammotrophs (prolactin-secreting cells) and stimulated prolactin release in a dose dependent manner. A series of RT-PCR using oligonucleotide primer pairs specific for each subtypes of melanocortin receptors revealed that the melanocortin 3-receptor is the sole receptor expressed in the mouse anterior pituitary. These results suggest that alpha-MSH-induced prolactin release is mediated by melanocortin 3-receptors in female mice.