• 대한의생명과학회지
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• 제20권2호
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• pp.85-95
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• 2014

Activation of the epidermal growth factor receptor (EGFR) and downstream signaling pathways have been implicated in causing resistance to EGFR-targeted therapy in solid tumors, including the head and neck tumors. To investigate the mechanism of antiproliferation to EGFR inhibition in oral cancer, we compared EGFR tyrosine kinase inhibitor (Gefitinib, Iressa, ZD1839) with respect to its inhibitory effects on three kinases situated downstream of EGFR: MAPK, Akt, and glycogen synthase kinase-$3{\beta}$ (GSK-$3{\beta}$). We have demonstrated that ZD1839 induces growth arrest and apotosis in oral cancer cell lines by independent of EGFR-mediated signaling. An exposure of oral cancer cells to ZD1839 resulted in a dose dependent up-regulation of the cyclin-dependent kinase inhibitor p21 and p27, down regulation of cyclin D1, inactivation of GSK-$3{\beta}$ and of active MAPK. In resistant cells, GSK-$3{\beta}$ is constitutively active and its activity is negatively regulated primarily through Ser 9 phosphorylation and further enhanced by Tyr216 phosphorylation. These results showed that the resistance to the antiproliferative effects of ZD1839, in vitro was associated with uncoupling between EGFR and MAPK inhibition, and that GSK-$3{\beta}$ activation and degradation of its target cyclin D1 were indicators of high cell sensitivity to ZD1839. In conclusion, our data show that the uncoupling of EGFR with mitogenic pathways can cause resistance to EGFR inhibition in oral cancer.

• Molecules and Cells
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• 제28권1호
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• pp.67-71
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• 2009

Estrogen receptor ${\alpha}$ ($ER{\alpha}$) mediates the mitogenic effects of estrogen. $ER{\alpha}$ signaling regulates the normal growth and differentiation of mammary tissue, but uncontrolled $ER{\alpha}$ activation increases the risk to breast cancer. Estrogen binding induces ligand-dependent $ER{\alpha}$ activation, thereby facilitating $ER{\alpha}$ dimerization, promoter binding and coactivator recruitment. $ER{\alpha}$ can also be activated in a ligand-independent manner by many signaling pathways, including protein kinase A (PKA) signaling. However, in several $ER{\alpha}$-positive breast cancer cells, PKA inhibits estrogen-dependent cell growth. FoxH1 represses the transcriptional activities of estrogen receptors and androgen receptors (AR). Interestingly, FoxH1 has been found to inhibit the PKA-induced and ligand-induced activation of AR. In the present study, we examined the effects of PKA activation on the ability of FoxH1 to represses $ER{\alpha}$ transcriptional activity. We found that PKA increases the protein stability of FoxH1, and that FoxH1 inhibits PKA-induced and estradiol-induced activation of an estrogen response element (ERE). Furthermore, in MCF7 cells, FoxH1 knockdown increased the PKA-induced and estradiol-induced activation of the ERE. These results suggest that PKA can negatively regulate $ER{\alpha}$, at least in part, through FoxH1.

• Journal of Ginseng Research
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• 제22권2호
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• pp.126-132
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• 1998

In the present study, we examined effects of ginseng saponins (ginsenosides) on pp60c-src protein tyrosine kinase (PTK) activity, intracellular calcium concentration ([$Ca^{2+}$]i), and cell proliferation in NIH3T3 cells. Eight different ginsenosides [ginsenoside-Rb1 (G-$Rb_1$), -$Rb_2$, -Rc, -Rd, -Re, -Rf, -$Rg_1$, -$Rg_2$) and ginseng total saponin (GTS) were used for these experiments. All ginsenosides and GTS tested stimulated the activation of $pp60^{c-src}$ kinase, and especially G-$Rb_1$,-Rd,-$Rg_1$, and -$Rg_1$ showed a higher stimulatory effect than others at 16.7 $\mu\textrm{g}$/ml of ginsenosides with a 18 hr-incubation, increasing the activity by 4.5, 3.5, 3.5, and 3.0-fold, respectively, over that of untreated control. In addition, both G-Rd and -$Rg_2$)Rg2 increased ($Ca^{2+}$), to 202 and 334 nM, respectively, about 2-3-fold above the basal level within 7min at 250 $\mu\textrm{g}$/yml of ginsenosides. The increases of ($Ca^{2+}$), were eliminated by Pretreatment of EGTA, an extracellular calcium chelator, suggtasting that they result from an influx of calcium ion from extracellular medium rather than an efflux from intracellular calcium store, endoplasmic reticulum (ER). All ginsenosides studied enhanced cell proliferation to 1.2-1.4-fold over that of untreated control at 5~250 $\mu\textrm{g}$/ml of concentrations. Interestingly the promotion of cell proliferation by ginsenosides corresponded with the activation of c-src kinase, which is an early step in the mitogenic signaling cascade. Taken together, we suggest that some ginsenosides may lead to cellProliferation via the activation of cellular signal transduction Pathway involving $pp60^{c-src}$ kinase.

• The Korean Journal of Physiology
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• 제29권1호
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• pp.1-11
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• 1995

Alveolar macrophages play a pivotal role in the pathogenesis of silicosis since the macrophages may release a wide variety of toxic and inflammatory mediators as well as mitogenic growth factors. In the present study, the effects of in vitro exposure to silica on release of various mediator such as reactive oxygen species, platelet activating factor(PAF), and interleukin-1 (IL-1) by alveolar macrophages were examined. First, hydrogen peroxide release from alveolar macrophages was monitored by measuring the change in fluorescence of scopoletin in the absence or presence of graded concentration of silica. Significantly enhanced release of hydrogen peroxide was observed at 0.5 mg/ml and above. A maximal enhancement of 10 fold above control was observed at 5 mg/ml silica. Similarly, in vitro exposure to silica also significantly stimulated the generation of chemiluminescence from alveolar macrophages at 0.5 mg/ml and above with n maximal enhancement of 8 fold at 5 mg/ml silica. Second, PAF release from alveolar macrophages after 30 min incubation at $37^{\circ}C$ in absence or presence of zymosan and silica was determined by measuring $^{3}H-serotonin$ release ability of the conditioned macrophage supernates from platelets. 5 mg/ml zymosan as a positive control fur the PAF assay increased PAF release by 19 % of total serotonin release. Furthermore, silica also resulted in significant enhancement of the PAF release compared with that in unstimulated (control) cells, i.e., $17.7{\pm}5.8%$ and $24.0{\pm}4.9%$ of total serotonin release at 5 mg/ml and 10 mg/ml silica, respectively, which represents the release of nanomole levels of PAF. Lastly, IL-1 production by alveolar macrophages was analysed following their stimulation with lipopolysaccharide (LPS) and silica by their capacity to stimulate thymocyte proliferation. $10\;{\mu}g/ml$ LPS resulted in an 11 fold increase in IL-1 production. In comparison, $50\;{\mu}g/ml$ silica resulted in a 4 fold increase in IL-1 release. These data indicate that in vitro exposure of alveolar macrophages to silica activates the release of various bioactive mediators such as reactive oxygen species, PAF and IL-1 which thus contribute to amplification of inflammatory reactions and regulation of fibrotic responses by the lung after inhalation of silica.

• Journal of Periodontal and Implant Science
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• 제25권3호
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• pp.720-732
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• 1995

미분화중배엽세포의 분화에 관여한다고 알려진 변형성장인자-${\beta}1$이 초기배양한 치주인대세포와 치은섬유아세포에 각기 다른 농도와 시간에 따라 변형성장인자-${\beta}1$을 주입했을때 두 세포의 세포증식능에 미치는 영향을 알아보고 각 조건에 따른 두 세포간의 증식능을 상호 비교해 보고자 본 실험을 실시하였다. 교정치료를 목적으로 내원한 환자의 제 1 소구치 부위의 정상치은을 절제하고, 건강한 제 1 소구치를 발거하여 치은섬유아세포와 치주인대세포를 분리, 배양하여 변형성장인자-${\beta}1$을 주입시키지 않은 군을 대조군으로 하고, 변형성장인자-${\beta}1$을 각각 0.25, 0.5, 1, 2.5, 5ng/ml로 주입시킨 군을 실험군으로하여 24시간, 48시간, 72시간 동안 배양하였으며, 각 시간별 배양 24시간 전에 $1{\mu}Ci/ml$ $[^3H]-thymidine$을 첨가하여 $[^3H]-thymidine$이 DNA내로 편재되는 속도로써 두세포군의 증식능을 측정하여 다음과 같은 결과를 얻었다. DNA합성능에 미치는 변형성장인자-${\beta}1$의 효과는 치주인대세포와 치은섬유아세포 모두에서 투여한 변형성장인자-${\beta}1$의 효과는 치주인대세포와 치은섬유아세포 모두에서 투여한 변형성장인자에 대하여 농도의존적으로 세포가 증식 하는 것으로 나타났다. 치은섬유아세포에 변형성장인자-${\beta}1$을 투여한 군에서는 24, 48, 72시간 모두에서 각 대조군에 비하여 농도의존적으로 증가하는 경향을 보였다. 24시간 적용시 대조군에 비해 1,2.5, 5 ng/ml투여군에서 통계적으로 유의한 차이(P<0.05)를 나타내었고, 48시간 적용시에는 대조군에 비해 1, 2.5, 5 ng/ml 투여군에서 통계적으로 유의한 차이(P<0.05)를 나타내었다. 48시간 적용시에 가장 높은 증식능을 보였으며 72시간 적용시에는 48시간 적용에 비해 전반적으로 증식능이 감소하는 경향을 보였다. 치주인대세포의 DNA 합성능에 미치는 변형성장인자-${\beta}$의 효과는, 변형성장인자-${\beta}$를 각각 24시간, 48시간 적용하였을�� 각 대조군에 비하여 농도의존적으로 증가하는 경향을 보였으며, 24시간 적용시에 대조군에 비해 1, 2.5, 5ng/ml 투여군에서 통계적으로 유의한 차이(P<0.05)를 나타내었고, 48시간 적용시에 대조군에 비해 2.5, 5ng/ml 투여군에서 통계적으로 유의한 차이(P<0.05)를 나타애었다. 72시간 적용시에는 5ng/ml의 농도에서 증식능이 감소하는 경향을 보였다. 48시간 적용시에 역시 가장 높은 증식능을 보였으며 72시간 적용에서는 48시간 적용에 비해 전반적으로 증식능이 감소되는 경향을 나타내었다. 변형성장인자-${\beta}1$의 적용에 따른 치주인대세포와 농도별 비교에서 치은섬유아세포군이 치주인대세포군보다 더 높은것으로 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제10권4호
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• pp.335-356
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• 1997

Injection of bovine growth hormone (bGH) to lactating dairy cows increases milk yield and yields of milk components including fat. It is generally believed that most of the anabolic effects derived from bGH in animal tissues are primarily mediated by IGF-1. IGF-1 is a strong anabolic peptide in the plasma of animals and exerts mitogenic and metabolic effects on target cells. Contrary to most protein hormones, the majority of IGF-1 in circulation is bound to the binding proteins (IGFBPs) which are known to be responsible for modifying the biological actions of IGF-1, thus making determinations of IGF-1 actions more difficult. On the other hand, fat is a major milk component and the greatest energy source in milk. Currently, the fat content of milk is one of the major criteria used in determining milk prices. It has been known that flavor and texture of dairy products are mainly affected by milk fat and its composition. Acetyl-CoA carboxylase (ACC) is the rate limiting enzyme which catalyzes the conversion of acetyl-CoA to malonyl-CoA for fatty acid synthesis in 1ipogenic tissues of animals including bovine lactating mammary glands. In addition to the short-tenn hormonal regulation of ACC by changes in the catalytic efficiency per enzyme molecule brought about by phosphorylation and dephosphorylation of the enzyme, the long-term hormonal regulation of ACC by changes in the number of enzyme molecules plays an essential role in control of ACC and lipogenesis. Insulin, at supraphysiological concentrations, binds to IGF-1 receptors, thereby mimicking the biological effects of IGF-1. The receptors for insulin and IGF-1 share structural and functional homology. Furthermore, epidermal growth factor increased ACC activity in rat hepatocytes and adipocytes. Therefore, it can be assumed that IGF-1 mediating bGH action may increase milk fat production by stimulation ACC with phosphorylation (short term) and/or increasing amounts of the enzyme proteins (long term). Consequently, the main purpose of this paper is to give the readers not only the galactopoietic effects of bGH, but also the insight of bGH action with regard to stimulating milk fat synthesis from the whole body to the molecular levels.

• 동의생리병리학회지
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• 제18권5호
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• pp.1347-1355
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• 2004

In this study, the immunological effect of a traditional Korea herbal acupuncture, that has been widely used for the treatment of various immunological disorders including inflammation in Korea, was examined in vitro and in vivo. In our previous study demonstrated that BV increased the expression of IFN-γ mRNA, that plays pivotal role in T cell response. This study was designated to evaluate the effect of BV on helper T cell development by monitoring Th1/Th2 specific cytokine secretion patterns in artificially induced Th1/Th2 polarized condition and in vivo. The results demonstrated that BV didn't have mitogenic effects on the unstimulated CD4+ T cell, but increased the CD4+ T cell proliferation upon activation with anti-CD3/CD28 antibody. The Th1 cells were over-populated dramatically in Th1 driven condition with BV treatment, while the Th2 cells were increased slightly in Th2 skewed condition. Furthermore, under Th1-skewed conditions, the level of IFN-γ was considerably increased with BV treatment. Besides, the expression of T-bet, a transcription factor that plays pivotal role in Th1 lineage programming, was increased with BV treatment. The expressions of IFN-γ and T-bet were also significantly increased in vivo. The results that Th1 specific cytokine secretion were considerably increased and Th2 specific cytokine secretion were not significantly changed in vitro and in vivo indicated that BV enhances Th1 lineage development, Therefore, these results suggest that BV might be desirable agent for correction of Th1 dominant pathological disorders.

• Toxicological Research
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• 제16권4호
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• pp.269-274
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• 2000

Epoxidised soya bean oil (ESBO, 1000, 2000 or 4000 mg/kg) was orally administered to BALB/c mice daily for 28 consecutive days, and the control mice were exposed to vehicle (corn oil). Mice were immunized and challenged with sheep red blood cells (SRBC) or bovine serum albumin (BSA). In groups exposed to ESBO, the body weight gains and the relative lymphoid organ weights were not significantly changed as compared with control group. Secondary IgG antibody response to BSA was not significantly changed by ESBO, but plaque-forming cell (PFC) response to SRBC was significantly suppressed in mice treated with 4000 mg ESBO/kg/day. The mitogenic response of splenic B cells induced by LPS was not effected by ESBO in any of the groups. These results indicate that ESBO did not induce significant humoral immune response at a dose less than 2000 mg/kg/day in mice.

• The Korean Journal of Physiology and Pharmacology
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• 제21권3호
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• pp.287-292
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• 2017

Vitiligo is an intriguing depigmentary disorder and is notoriously difficult to be treated. The ultimate goal of vitiligo treatment is to replenish the lost melanocytes by immigration from hair follicle and to restore the normal function of melanogenesis by residual melanocytes. There are two types of topical calcineurin inhibitors called tacrolimus and pimecrolimus, and are recommended as the first-line treatments in vitiligo. Although pimecrolimus is efficacious for the repigmentation of vitiligo, its intrinsic mechanisms have never been investigated in vitro. This research aimed to study the ability of pimecrolimus on stimulating melanogenesis, melanocyte migration and MITF (microphthalmia associated transcription factor) protein expression. Results showed that pimecrolimus at the dosages of 1, 10, $10^2$nM were neither mitogenic nor cytotoxic to melanocytes. The addition of pimecrolimus at 10, $10^2$ and $10^3nM$ significantly increased intracellular tyrosinase activity, which was consistent with the elevated content of melanin content at the same concentrations. The peak effect was seen at 72 h in response to $10^2$nM pimecrolimus. Results of the wound scratch assay and Transwell assays indicate that pimecrolimus is effective in facilitating melanocyte migration on a collagen IV-coated surface. In addition, MITF protein yield reached the highest by pimecrolimus at $10^2nM$. In brief, pimecrolimus enhances melanin synthesis as well as promotes migration of melanocytes directly, possibly via their effects on MITF protein expression.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6595-6599
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• 2013

Leptin and its receptor are involved in breast carcinogenesis as mitogenic factors. Therefore, they could be considered as targets for breast cancer therapy. Expression of the leptin receptor gene could be modulated by leptin secretion. Silibinin and curcumin are herbal compounds with anti-cancer activity against breast cancer. The aim of this study was to assess their potential to inhibit of expression of the leptin gene and its receptor and leptin secretion. Cytotoxic effects of the two agents on combination on T47D breast cancer cells was investigated by MTT assay test after 24h treatment. With different concentrations the levels of leptin, leptin receptor genes expression were measured by reverse-transcription real-time PCR. Amount of secreted leptin in the culture medium was determined by ELISA. Data were statistically analyzed by one-way ANOVA test. The silibinin and curcumin combination inhibited growth of T47D cells in a dose dependent manner. There were also significant difference between control and treated cells in leptin expression and the quantity of secreted leptin with a relative decrease in leptin receptor expression. In conclusion, these herbal compounds inhibit the expression and secretion of leptin and it could probably be used as drug candidates for breast cancer therapy through leptin targeting in the future.