• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.11a
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• pp.153-159
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• 1996

${\alpha}$-Melanotropin (Ac-Ser-Tyr- Ser-Met-Glu$\^$5/-His-Phe-Arg-Trp-Gly$\^$10/-Lys-Pro-Val-NH$_2$) is one of the first peptide hormones to be isolated and have its structure determined. It was early recognized to have essentially the same N-terminal tridecapeptide sequence as adrenocorticotropic hormone (ACTH) except that the N-terminal was acetylated in the case of ${\alpha}$-MSH but not in the case of ACTH, indicating that their biosyntheses were different (Figure 1). Subsequently it was discovered that ${\alpha}$-MSH and ACTH were derived from the same gene, currently referred to as proopiomelanocortin (POMC). Its original bioactivity was pigmentation, but it also was recognized that it may have activity in the central nervous system, though the precise nature of these central activities have been controversial. The recent cloning and expression of five melanocortin receptors, with the MC3 and MC4 receptors found primarily in the brain and the MC5 receptor (MC5-R) found throughout the body, has provided new impetus to understand the structure-activity relationships of ${\alpha}$-MSH at these receptors. The effects of ${\alpha}$-MSH on pigmentation are mediated by the MC1-R expressed specifically on the surface of melanocytes. Similarly the MC2-R is involved in the regulation of adrenal steroidogenesis by ACTH. However, given the complexity of expression of the MC3, MC4, and MC5 receptors, it has not been possible to identify any simple correlations between these receptors and the reported biological activities of the melanocortin peptides. Consequently, potent and receptor specific agonists and especially antagonists would be extremely valuable tools for the determination of the physiological roles of the MC3, MC4, and MC5 receptors. Though the extensive structure-activity relationships have provided much information on agonist activity related to pigmentary effects, only recently has it been possible to begin to systematically develop potent and selective antagonists.

• Journal of Gastric Cancer
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• v.13 no.3
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• pp.172-178
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• 2013

Purpose: The aims of this study were as follow: 1) to de scribe the expression status of estrogen receptor-${\alpha}$ and -${\beta}$ mRNAs in five gastric carcinoma cell lines; 2) to evaluate in vitro the effects of $17{\beta}$-estradiol and estrogen receptor antagonists on the proliferation of the cell lines. Materials and Methods: Detection of estrogen receptor-${\alpha}$ and estrogen receptor-${\beta}$ mRNA in five human gastric cancer cell lines (AGS, KATO III, MKN28, MKN45 and MKN74) was made by the reverse transcription-polymerase chain reaction system. To evaluate the effect of $17{\beta}$-estradiol and estrogen receptor antagonists on the proliferation of gastric cancer cell line, the cell lines which expressed both es trogen receptors were chosen and treated with $17{\beta}$-estradiol and estrogen receptor antagonists (methyl-piperidino-pyrazole and pyrazolo [1,5-a] pyrimidine). Cell proliferation was assessed with the methylthiazol tetrazolium test. Results: Estrogen receptor-${\alpha}$ and estrogen receptor-${\beta}$ mRNAs were expressed in three (KATO III, MKN28 and MKN45) and all of the five gastric cancer cell lines, respectively. At higher concentrations, $17{\beta}$-estradiol inhibited cell growth of MKN28, MKN45 and KATO III cell lines. Neither estrogen receptor-${\alpha}$ nor estrogen receptor-${\beta}$ antagonist blocked the anti-proliferative effect of $17{\beta}$-estradiol. Conclusions: Our results indicate that estrogen receptor-${\beta}$ mRNAs are preferentially expressed in gastric cancers and also imply that hormone therapy rather than estrogen receptor blockers may be a useful strategy for the treatment of estrogen receptor-${\beta}$ positive gastric cancer. Its therapeutic significance in gastric cancer are, however, limited until more evidence of the roles of estrogen receptors in the gastric cancer are accumulated.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7001-7010
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• 2014

Isoflavones are phytoestrogens and natural plant compounds which are similar to 17-${\beta}$-estradiol in chemical structure. It is known that they can act as estrogen agonists or antagonists, depending on endocrine estrogenic levels, but actions of isoflavones are rather complex due to large number of variables such as chemical structures and mechanisms. Some hypotheses on biological mechanisms have not satisfactorily been confirmed to date and human epidemiological and experimental studies have been relatively limited. Nevertheless, isoflavones and isoflavone rich foods have become a focus onf interest due to positive health benefits on many diseases, especially prevention of hormone-related cancers, cardiovascular disease, osteoporosis, and adverse postmenopausal symptoms, and improvement of physiological condition such as maintaining cognitive function. This review provides an overview of chemistry, analytical techniques (focused on human biospecimens), functions including biological mechanisms, and effects of isoflavones, on the basis of the available meta-analysis and review articles and some original articles, on health and cancer.

• YAKHAK HOEJI
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• v.58 no.1
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• pp.21-27
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• 2014

We have developed 8 peptide derivatives as potential MC1R antagonists and their inhibitory effects on ${\alpha}$-MSH induced cell growth in cultured normal human melanocytes (NHM) were investigated. From these experiments, the two most potent peptide derivatives, 5-phenylvaleric acid-(D)His-Arg-Trp-$(Lys)_6NH_2$ (P 6) and 5-phenylvaleric acid-(D)His-Arg-Trp-$(Lys)_9NH_2$ (P 7) were selected for further studies. In ${\alpha}$-MSH depleted NHM cells, we have found that the treatment with 1 ${\mu}M$ of these two peptide derivatives, P 6 and P 7, inhibited the cell proliferation induced by the addition of 1 nM ${\alpha}$- MSH by 70% and 72%, respectively. In NHM cells without previous ${\alpha}$-MSH depletion, 1 ${\mu}M$ treatment in the presence of 10 nM ${\alpha}$-MSH resulted in 70% (P 6) and 80% (P 7) decrease in cell growth and 64% (P 6) and 71% (P 7) reduction in melanin synthesis, respectively. The peptide derivatives P 6 and P 7 were proved to have no apparent cytotoxicity and inhibited the elevation of intracellular cAMP concentration triggered by ${\alpha}$-MSH. In conclusion, our data suggest that the peptide derivatives reported in this study, 5-phenylvaleric acid-(D)His-Arg-Trp-$(Lys)_6NH_2$ (P 6) and 5-phenylvaleric acid-(D)His- Arg-Trp-$(Lys)_9NH_2$ (P 7) strongly antagonize ${\alpha}$-MSH, inhibit cell proliferation and melanin synthesis, and lower the intracellular cAMP concentration, hence have a promising potential as a novel skin lightening agent.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.493-501
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• 1998

The most significant direct role of estrogen in vivo is its ability to elicit receptor-mediated cellular proliferation in mammalian target tissues. However, the mechanism by which exogenously added estrogen causes the neoplastic transformation of renal cortical cells is yet to be uncovered. The present study was designed to evaluate interaction of $17{\beta}-estradiol\;(E_2)$ with epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) on proliferation and $P_i$ uptake in primary cultured rabbit renal proximal tubular cells in phenol red-free, hormonally defined-medium. $[^3H]-thymidine$ incorporation increased markedly by about 133% and 141% more in the presence of $10^{-9}\;and\;10^{-6}\;M\;E_2$, respectively, than that of control. Cell count was 162% and 143% greater in the presence of $10^{-9}\;and\;10^{-6}\;M\;E_2$ , respectively, compared with control. Among all time points examined, there was an increase in $[^3H]-thymidine$ incorporation in the presence of $10^{-9}\;M\;E_2$ at day 9 or 13, respectively. However, $E_2$ ($10^{-9}\;M$) significantly drove up cell count to 160% of that of control at day 13, while it had a slight but statistically insignificant effect at day 9. $E_2-induced$ stimulation of $[^3H]-thymidine$ incorporation was completely reversed by $E_2$ antagonists (progesterone or tamoxifen). $E_2$ ($10^{-9}\;M$) or EGF ($10^{-8}\;M$) significantly stimulated $[^3H]-thymidine$ incorporation by 144% and 154% of control. $E_2$ plus EGF was synergistic on $[^3H]-thymidine$ incorporation (204% of control), while $E_2$ plus IGF-I showed a slight but no significant synergistic effect. Cell number also displayed similar pattern. $E_2$ ($10^{-9}\;M$) significantly stimulated $P_i$ uptake to 134% of control. $E_2$-induced stimulation of $P_i$ uptake was partially reversed by $E_2$ antagonists. EGF or IGF-I ($10^{-8}\;M$) significantly also increased $P_i$ uptake to 132% or 129% of control. $E_2$ plus EGF had synergistic effect on $P_i$ uptake, while $E_2$ plus IGF-I did not. In conclusion, $E_2$ may act not only directly interaction with its receptors but also indirectly as a modulator of EGF in proliferation and $P_i$ uptake of primary cultured rabbit renal proximal tubular cells.

• Korean Journal of Veterinary Research
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• v.32 no.2
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• pp.165-173
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• 1992

The present study was carried out to investigate the effects of dopaminergic drugs and the role of specific dopamine(DA) receptors on the release of TSH, $T_4$ and $T_3$. Serum TSH levels (cold-induced, $4{^{\circ}C}$) were determined using RIA(radioimmunoassay) at 30 min after administration of dopamine agonists and antagonists. Serum $T_4$ and $T_3$ levels were detected after these dopaminergic drugs were administered subcutaneously twice a day for a week. The results of the study are summarized as follows : Apomorphine, a nonspecific DA receptor agonist, produced a dose-depedent decrease in serum TSH, $T_4$ and $T_3$ levels. However, only low doses (0.3, 1.0mg/kg) of SKF38393, a specific $D_1$-receptor agonist, produced a decrease in serum lelvels of TSH. I,Y171555, a specific $D_2$-receptor agonist, produced a dose dependent decrease in serum TSH, $T_4$ and $T_3$ levels. However, SCH23390, a specific $D_1$-receptor antagonist, produced a decrease except in serum T levels which were increased dose dependently. High doses (1.0, 3.0mg/kg) of sulpiride, a specific $D_2$-receptor antagonist, made a increase in the serum levels of TSH and $T_3$. The effects of dopaminergic drugs in serum TSH and $T_4$ levels was potentiated by the pretreatment of apomorphine. The overall results of this study suggest that the regulation of TSH, $T_4$ and $T_3$ secretion were mediated via specific $D_1$ and $D_2$ receptor.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.905-911
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• 2001

Phytoestrogens, especially soy-derived isoflavones, are receiving great scrutiny as a food supplement for preventing hormone dependent diseases such as cardiovascular diseases, cancer, and osteoporosis. These beneficial effects of phytoestrogens are caused by functioning as partial agonists or antagonists of estrogens. In contrast to the common usage of soy bean, Yak-kong(Rhynchosia Molubilis ; ) has been used as supplements of estrogen fir preventing postmenopausal osteoporosis in Oriental medicine. To investigate estrogenic effects of Yak-kong and soy bean on the proliferation of MG-63 osteoblastic cells, each bean was extracted with 70% methanol and dried by freeze-drying. Yak-kong treatment of MG-63 cells resulted in an increase of cell proliferation to a maximum of 76% compared to 68% of soy bean treatment. Treatment of MG-63 cells with Yak-kong extract also resulted in an increase of transactivation of an ERE(estrogen response element)-luciferase reporter plasmid and IGF-I expression selectively. Despite increased effects of both bean treatments on the expression of estrogen receptor $\alpha$(ER$\alpha$) and $\beta$(ER$\beta$), soy bean treatment decreased transactivation of an ERE-luciferase reporter plasmid and did not further enhance IGF-I expression. Together, our data demonstrates that the greater estrogenic response of Yak-kong extract for MG-63 cell proliferation is mediated by ER derived transactivation of ERE and selective induction of IGF-I expression.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.4
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• pp.413-421
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• 2014

Corticotropin-releasing factor (CRF) is involved in the stress response and there is increasing evidence that stress influences skin disease such as hair loss. In cultured human hair follicles, CRF inhibits hair shaft elongation, induces premature regression and promotes the apoptosis of hair matrix keratinocytes. We investigated whether CRF influences the dermal papilla cells (DPC) that play pivotal roles in hair growth and cycling. Human DPCs were treated with CRF, adrenocorticotropic hormone (ACTH) and cortisol, key stress hormones along the hypothalamic-pituitary -adrenal (HPA) axis for 1-24 h. Interestingly, CRF modulated the expression of cytokines related to hair growth (KGF, Wnt5a, $TGF{\beta}-2$, Nexin) and increased cAMP production in cultured DPCs. CRF receptors were down-regulated by negative feedback systems. Pretreatment of CRF receptor antagonists or protein kinase A (PKA) inhibitor prevented the CRF-induced modulation. Since the CRF induces proopiomelanocortin (POMC) expression through the cAMP/PKA pathway, we analyzed POMC mRNA. CRF stimulated POMC expression in cultured human DPCs, yet we were unable to detect ACTH levels by western blot. These results indicate that CRF operates within DPCs through CRF receptors along the classical CRF signaling pathway and CRF receptor antagonists could serve as potential therapeutic and cosmetic agents for stress-induced hair loss.

• Archives of Plastic Surgery
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• v.45 no.5
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• pp.432-440
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• 2018

Background Adjuvant therapy after breast surgery, including tamoxifen or aromatase inhibitors, improves the postoperative outcomes and long-term survival of breast cancer patients. The aim of this study was to determine whether volume changes occurred in the contralateral breast during hormonal or other adjuvant therapies. Methods This study reviewed 90 patients who underwent unilateral breast reconstruction between September 2012 and April 2018 using tissue expanders and a permanent implant after the surgical removal of breast cancer. The volume of the contralateral breast was measured using a cast before the first (tissue expander insertion) and second (permanent implant change) stages of surgery. Changes in breast volume were evaluated to determine whether adjuvant therapy such as hormonal therapy, chemotherapy, and radiation therapy influenced the volume of the contralateral breast. Results The group receiving tamoxifen therapy demonstrated a significant decrease in volume compared with the group without tamoxifen (-7.8% vs. 1.0%; P=0.028). The aromatase inhibitor-treated group showed a significant increase in volume compared with those who did not receive therapy (-6.2% vs. 4.5%; P=0.023). There were no significant differences between groups treated with other hormonal therapy, chemotherapy, or radiation therapy. Conclusions Patients who received tamoxifen therapy showed a significant decrease in volume in the contralateral breast, while no significant change in weight or body mass index was found. Our findings suggest that we should choose smaller implants for premenopausal patients, who have a high likelihood of receiving tamoxifen therapy.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.4
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• pp.275-281
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• 2000

Cholecystokinin (CCK) is a gastrointestinal hormone which plays an important role in satiety and gastric motility. It is also widely distributed throughout the central nervous system, where it appears to be involved in the central control of anxiety, feeding behavior and nociception. Two distinct CCK receptor types, $CCK_A$ and $CCK_B,$ have been found in the brain. Both CCK receptors coexist in the rat nucleus tractus solitarius (NTS), which is the primary center for the coordination of peripheral and central activities related to gastrointestinal, cardiovascular and respiratory functions. In order to study ionic actions of CCK on each type of receptor, we investigated the effects of CCK-8S on neurons located in the NTS of the rat using whole-cell patch-clamp recordings in brainstem slices. Application of CCK-8S, under current clamp, produced a membrane depolarization accompanied by action potential firing. This CCK-evoked excitation was dose-dependent $(10\;nM{\sim}10\;{\mu}M)$ and observed in more than 60% of NTS neurons. Under voltage clamp conditions, CCK-8S induced an inward current with a notably increased spontaneous excitatory synaptic activity. However, CCK-8S did not significantly change the amplitude of pharmacologically isolated and evoked EPSP(C)s. Using selective $CCK_A$ and $CCK_B$ receptor antagonists, we observed two different effects of CCK-8S, which suggest $CCK_A$ receptor-mediated inhibitory and $CCK_B$ receptor-mediated excitatory effects in the NTS. These results may help to explain the ability of CCK to modulate gastrointestinal and other reflex systems in the NTS.