• 제목/요약/키워드: somatostatin receptor 2

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Development of radiolabeled somatostatin derivatives for neuroendocrine tumors

  • Hee-Kwon Kim
    • 대한방사성의약품학회지
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    • 제7권2호
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    • pp.127-131
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    • 2021
  • Neuroendocrine tumor is one of popular diseases, and somatostatin receptor antagonists have been considered as promising agents for neuroendocrine tumors. Imaging of somatostatin receptor is useful approach on the diagnosis and therapy of neuroendocrine tumors. Thus, several radiolabeled somatostatin derivatives have been developed by scientists, and used for patients with neuroendocrine tumors. In particular, some radiopharmaceuticals for neuroendocrine tumors were approved by FDA. In this highlight review, the development of important radiolabeled somatostatin derivatives is described.

Somatostatin Receptor 2 and 5 Expressions in Gastroenteropancreatic Neuroendocrine Tumors in Turkey

  • Yerci, Omer;Sehitoglu, Ibrahim;Ugras, Nesrin;Cubukcu, Erdem;Yuce, Suleyman;Bedir, Recep;Cure, Erkan
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권10호
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    • pp.4377-4381
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    • 2015
  • Background: Gastroenteropancreatic neuroendocrine tumors (GNs) are slow growing and although their incidence has increased in recent years, they are relatively rarely seen. Somatostatin analogues are used in the treatment of GNs that express somatostatin receptor (SR). We aimed to investigate the expression of SR2 and SR5 in GNs. Materials and Methods: In this study the expression of SR2 and SR5 was investigated immunohistochemically in 49 cases (26 males, 23 females) diagnosed and graded with GN according to the World Health Organization classification 2010. Results: The percentage of SR2 staining was 91.0% in grade 1, 82.8% in grade 2 and 100% in grade 3. On the other hand, the percentage of SR5 staining was 81.8% % in grade 1, 60.0% in grade 2 and 0% in grade 3. According to the tumor localization, the percentages of SR2 expression were as follows: pancreas 85.7%, stomach 100%, small bowel 70%, appendix 85.7% and rectum 100%. The percentages of SR5 expression were: pancreas 61,9%, stomach 37.5%, small bowel 70%, appendix 71.5% and rectum 66.6%. There was a significant negative correlation between ki67 percentage and SR5 expression (r=-0.341, p=0.016). Conclusions: In this study, GNs were found to highly express SR2 and SR5. Although the expression of SR2 and SR5 changed according to tumor localization, the expression of SR2 was higher than the expression of SR5 in GN. There was a significant negative correlation between ki67 and SR5. Accordingly, SR5 may be a prognostic indicator of GN.

Modulation of Pituitary Somatostatin Receptor Subtype (sst1-5) mRNA Levels by Growth Hormone (GH)-Releasing Hormone in Purified Somatotropes

  • Park, Seung-Joon;Park, Hee-Soon;Lee, Mi-Na;Sohn, Sook-Jin;Kim, Eun-Hee;Jung, Jee-Chang;Frohman, Lawrence A.;Kineman, Rhonda D.
    • The Korean Journal of Physiology and Pharmacology
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    • 제7권2호
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    • pp.79-84
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    • 2003
  • We have previously reported that expression of the somatostatin receptor subtypes, sst1-5, is differentially regulated by growth hormone (GH)-releasing hormone (GHRH) and forskolin (FSK), in vitro. GHRH binds to membrane receptors selectively located on pituitary somatotropes, activates adenylyl cyclase (AC) and increases sst1 and sst2 and decreases sst5 mRNA levels, without significantly altering the expression of sst3 and sst4. In contrast FSK directly activates AC in all pituitary cell types and increases sst1 and sst2 mRNA levels and decreases sst3, sst4 and sst5 expression. Two explanations could account for these differential effects: 1) GHRH inhibits sst3 and sst4 expression in somatotropes, but this inhibitory effect is masked by expression of these receptors in unresponsive pituitary cell types, and 2) FSK inhibits sst3 and sst4 expression levels in pituitary cell types other than somatotropes. To differentiate between these two possibilities, somatotropes were sequentially labeled with monkey anti-rat GH antiserum, biotinylated goat anti-human IgG, and streptavidin-PE and subsequently purified by fluorescent-activated cell sorting (FACS). The resultant cell population consisted of 95% somatotropes, as determined by GH immunohistochemistry using a primary GH antiserum different from that used for FACS sorting. Purified somatotropes were cultured for 3 days and treated for 4 h with vehicle, GHRH (10 nM) or FSK ($10{\mu}M$). Total RNA was isolated by column extraction and specific receptor mRNA levels were determined by semi-quantitative multiplex RT-PCR. Under basal conditions, the relative expression levels of the various somatostatin receptor subtypes were sst2>sst5>sst3=sst1> sst4. GHRH treatment increased sst1 and sst2 mRNA levels and decreased sst3, sst4 and sst5 mRNA levels in purified somatotropes, comparable to the effects of FSK on purified somatotropes and mixed pituitary cell cultures. Taken together, these results demonstrate that GHRH acutely modulates the expression of all somatostatin receptor subtypes within GH-producing cells and its actions are likely mediated by activation of AC.

Somatostatin Receptors 3, 4 and 5 Play Important Roles in Gallbladder Cancer

  • Guo, Run-Sheng;Shi, Pei-Dong;Zhou, Jie;Chen, Yue-Yu
    • Asian Pacific Journal of Cancer Prevention
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    • 제14권7호
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    • pp.4071-4075
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    • 2013
  • Expression changes of somatostatin receptor subtypes (SSTRs) including SSTR1, SSTR2, SSTR3, SSTR4 and SSTR5 in the development of gallbladder cancer were assessed with attention to relationships with clinical pathological characteristics. SSTRs in 29 gallbladder cancer and 25 normal gallbladder tissue specimens were examined by immunohistochemical staining. Differences between SSTRs expressions and clinical pathological parameters were analyzed by chi-square test. The five subtypes of SSTR were all expressed in gallbladder cancer tissues and SSTR3 presented the highest expression. SSTR5 expression was increased significantly in gallbladder cancer (P<0.05) compared with that in normal gallbladder tissue. SSTR3 expression in highly and moderately differentiated gallbladder cancer was significantly higher than that in poorly differentiated lesions (P<0.05). SSTR4 expression was lower in gallbladder cancer with lymph node metastasis than that in gallbladder cancer without lymph node metastasis (P<0.05). Therfore, these results indicated that SSRT5, SSTR3 and SSTR4 may play important roles in the formation and development of gallbladder cancer.

신경내분비종양의 방사성핵종 치료 (Review of Radionuclide Treatment for Neuroendocrine Tumors)

  • 정환정
    • Nuclear Medicine and Molecular Imaging
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    • 제40권2호
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    • pp.90-95
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    • 2006
  • Neuroendocrine tumors (NETs) consist of a heterogeneous group of tumors that are able to uptake neuroamine and/or specific receptors, such as somatostatin receptors, which can play important roles of the localization and treatment of these tumors. When considering therapy with radionuclides, the best radioligand should be carefully investigated. $^{131}I$-MIBG and beta-particle emitter labeled somatostatin analogs are well established radionuclide therapy modalities for NETs. $^{111}In,\;^{90}Y\;and\;^{177}Lu$ radiolabeled somatostatin analogues have been used for treatment of NETs. Further, radionuclide therapy modalities, for example, radioimmunotherapy, radiolabeled peptides such as minigastrin are currently under development and in different phases of clinical investigation. for all radionuclides used for therapy, long-term and survival statistics are not yet available and only partial tumour responses have been obtained using $^{131}I$-MIBG and $^{111}In$-octreotide. Experimental results using $^{90}Y$-DOTA-lanreotide as well as $^{90}Y-DOTA-D-Phe1-Tyr^3-octreotide$ and/or $^{177}Lu-DOTA-Tyr^3-octreotate$ have indicated the possible clinical potential of radionuclides receptor-targeted radiotherapy it may be hoped that the efficacy of radionuclide therapy will be improved by co-administration of chemotherapeutic drugs whose antitumoral properties may be synergistic with that of irradiation.

Effects of Somatostatin on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in the Adult Mice

  • Park, Seon-Ah;Yin, Hua;Bhattarai, Janardhan P.;Park, Soo-Joung;Han, Seong-Kyu
    • International Journal of Oral Biology
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    • 제34권4호
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    • pp.191-197
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    • 2009
  • Somatostatin (SST) is a known neuromodulator of the central nervous system. The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) receives many thinmyelinated $A{\delta}$-fiber and unmyelinated C primary afferent fibers and is involved in nociceptive processing. Many studies have demonstrated that SST plays a pivotal role in pain modulation in the spinal cord. However, little is yet known about the direct effects of SST on the SG neurons of the Vc in adult mice. In our present study, we investigated the direct membrane effects of SST and a type 2 SST receptor agonist, seglitide (SEG), on the SG neurons of the Vc using a gramicidin-perforated current clamp in adult mice. The majority (53%, n = 27/51) of the adult SG neurons were hyperpolarized by SST (300 nM) but no differences were found in the hyperpolarization response rate between males and females. When SST was applied successively, the second response was smaller ($76{\pm}9.5%$, n=19), suggesting that SST receptors are desensitized by repeated application. SST-induced hyperpolarization was also maintained under conditions where presynaptic events were blocked ($75{\pm}1.0%$, n=5), suggesting that this neuromodulator exerts direct effects upon postsynaptic SG neurons. SEG was further found to induce membrane hyperpolarization of the SG neurons of the Vc. These results collectively demonstrate that SST inhibits the SG neuronal activities of the Vc in adult mice with no gender bias, and that these effects are mediated via a type 2 SST receptor, suggesting that this is a potential target for orofacial pain modulation.

Up-regulation of NHE8 by somatostatin ameliorates the diarrhea symptom in infectious colitis mice model

  • Lei, Xuelian;Cai, Lin;Li, Xiao;Xu, Hua;Geng, Chong;Wang, Chunhui
    • The Korean Journal of Physiology and Pharmacology
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    • 제22권3호
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    • pp.269-275
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    • 2018
  • $Na^+/H^+$ exchangers (NHEs) have been shown to be involved in regulating cell volume and maintaining fluid and electrolyte homeostasis. Pooled evidences have suggested that loss of $Na^+/H^+$ exchanger isoform 8 (NHE8) impairs intestinal mucosa. Whether NHE8 participates in the pathology of infectious colitis is still unknown. Our previous study demonstrated that somatostatin (SST) could stimulate the expression of intestinal NHE8 so as to facilitate $Na^+$ absorption under normal condition. This study further explored whether NHE8 participates in the pathological processes of infectious colitis and the effects of SST on intestinal NHE8 expression in the setting of infectious colitis. Our data showed that NHE8 expression was reduced in Citrobacter rodentium (CR) infected mice. Up-regulation of NHE8 improved diarrhea symptom and mucosal damage induced by CR. In vitro, a similar observation was also seen in Enteropathogenic E. coli (EPEC) infected Caco-2 cells. Seglitide, a SST receptor (SSTR) 2 agonist, partly reversed the inhibiting action of EPEC on NHE8 expression, but SSTR5 agonist (L-817,818) had no effect on the expression of NHE8. Moreover, SST blocked the phosphorylation of p38 in EPEC-infected Caco-2 cells. Taken together, these results suggest that enhancement of intestinal NHE8 expression by SST could ameliorate the symptoms of mice with infectious colitis.

Current Status of the Diagnosis and Management of Pancreatic Neuroendocrine Tumors in Japan

  • Tetsuhide Ito;Masami Miki;Keijiro Ueda;Lingaku Lee;Ken Kawabe;Hisato Igarashi;Nao Fujimori;Kazuhiko Nakamura;Kohei Yasunaga;Robert T. Jensen;Takao Ohtsuka;Yoshihiro Ogawa
    • Journal of Digestive Cancer Research
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    • 제4권2호
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    • pp.51-57
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    • 2016
  • The epidemiology of pancreatic neuroendocrine neoplasms (PNENs) in Asia has been clarified through epidemiological studies, including one conducted in Japan, and subsequently another in South Korea. As endoscopic ultrasonography (EUS) has become more widely accessible, endoscopic ultrasound-fine needle aspiration (EUS-FNA) has been performed in pancreatic tumors for which the clinical course was only monitored previously. This has enabled accurate diagnosis of pancreatic tumors based on the 2010 WHO classification; as a result, the number of patients with an accurate diagnosis has increased. Although surgery has been the standard therapy for PNENs, new treatment options have become available in Japan for the treatment of advanced or inoperable PNENs; of particular note is the recent introduction of molecular target drugs (such as everolimus and sunitinib) and streptozocin. Treatment for progressive PNENs needs to be selected for each patient with consideration of the performance status, degree of tumor differentiation, tumor mass, and proliferation rate. Somatostatin receptor (SSTR)-2 is expressed in many patients with neuroendocrine tumor. Somatostatin receptor scintigraphy (SRS), which can visualize SSTR-2 expression, has been approved in Japan. The SRS will be a useful diagnostic tool for locating neuroendocrine neoplasms, detecting distant metastasis, and evaluating therapy outcomes. In this manuscript, we review the latest diagnostic methods and treatments for PNENs.

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단기간의 당섭취 증가가 인슐린 감수성에 미치는 영향 (Effect of Acutely Increased Glucose Uptake on Insulin Sensitivity in Rats)

  • 김용운;마인열;이석강
    • Journal of Yeungnam Medical Science
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    • 제14권1호
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    • pp.53-66
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    • 1997
  • 인슐린 저항성이란 인슐린의 생물학적 효과가 감소하는 상태를 말하며 당뇨병의 중요한 병리기전이다. 인슐린 저항성은 매우 다양한 특성을 가지고 있으며 유전적인 요인이나 후천적인 요인에 의하여 발생한다. 이제까지 가장 잘 알려진 인슐린 저항성의 유발인자로는 고혈당과 고인슐린증이 있다. 장기간의 고혈당이나 고인슐린증은 가장 중요한 인슐린의 작용조직인 골격근에서 인슐린 수용체의 결합능을 감소시키고 당섭취에 필요한 제 4형 당수송체의 발현을 억제하는 것으로 알려져 있다. 그러나 이들 인자는 모두 골격근에서 당섭취를 증가시키는 것으로서 인슐린 저항성은 말초조직이 세포내로의 과도한 영양소 섭취를 방지하기 위하여 작동시키는 조절기전일 가능성을 생각할 수 있다. 본 연구에서는 단기간의 당섭취 증가가 더 이상의 당섭취를 억제할 수 있는지를 평가하고 그 기전을 규명하고자 흰쥐에서 2시간 동안 다양한 조건으로 당섭취를 유도하고 1 시간의 휴식기간을 가진 후 인슐린 예민도를 측정하고 골격근을 분리하여 인슐린 수용체와 제 4 형 당수송체를 분석하여 당섭취량과 인슐린 감수성과의 상관관계를 규명하고 인슐린 수용체 결합능과 제 4형 당수송체량을 비교하였다. 실험군은 hyperinsulinemic glucose clamp 전에 시행한 당섭취의 조건으로써 5개 군으로 구분하였다. 제 I 군은 대조군으로 생리식염수만 주입하여 기초상태의 인슐린 농도와 혈당을 유지하였으며, 제 II 군은 somatostatin과 포도당을 주입하여 정상 인슐린농도와 고혈당을 유지하였으며, 제 III 군은 포도당을 주입하여 고인슐린증과 고혈당을 유지하였고, 제 IV 군은 인슐린(100 mU/kg/min)과 포도당을 주입하여 초고인슐린증(${\sim}4000{\mu}U/ml$)과 정상혈당(~100 mg/dl)으로 유지하였으며, 그리고 제 V 군은 인슐린과 포도당을 주입하여 초고인슐린증과 고혈당(~200 mg/dl)을 유지하였다. 체중, 공복시 혈당 및 인슐린 농도는 각 군 간에 유의한 차이가 없었다. Hyperinsulinemic euglycemic clamp 전에 주입한 포도당의 총량(gm/kg)은 제 II 군이 $1.88{\pm}0.151$, 제 III 군이 $2.69{\pm}0.239$, 제 IV 군이 $3.54{\pm}0.198$, 그리고 제 V 군이 $4.32{\pm}0.621$이었다. Hyperinsulinemic euglycemic clamp의 평형상태 당제거율(mg/kg min)은 제 I 군이 $16.9{\pm}1.74$, 제 II 군이 $13.5{\pm}0.53$, 제 III 군이 $11.2{\pm}0.52$, 제 IV 군이 $13.2{\pm}0.92$, 그리고 제 V 군이 $10.4{\pm}0.41$로 전체 군 간에 유의한 차이가 있었으며(p<0.001) 각 군간의 비교에서 제 II, III, IV, V 군의 값이 제 I 군에 비하여 유의하게 낮았다 (p<0.05). 전체 실험동물에서 포도당 주입량과 당제거율 사이에 역상관관계 (r=-0.701, p<0.001)를 보였다. 인슐린 수용체 결합과 Western blot으로 분석한 제 4형 당수송체량은 각 군 간에 유의한 차이가 없었다. 이상의 결과로 미루어 단기간의 당섭취 증가가 더이상의 당섭취를 억제할 수 있으나 인슐린 수용체 결합과 제 4형 당수송체의 숫적 감소없이 발생하였다.

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흰쥐의 시상하부외 지역에서의 Growth Hormone Releasing Hormone (GHRH) 유전자발현;뇌하수체내 국부인자로서 Lactotroph분화에 관여할 가능성에 대하여 (Extrahypothalamic Expression of Rat Growth Hormone Releasing Hormone (GHRH);a possible intrapituitary factor for lactotroph differentiation?)

  • 이성호
    • Clinical and Experimental Reproductive Medicine
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    • 제23권3호
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    • pp.269-275
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    • 1996
  • Biosynthesis and secretion of anterior pituitary hormones are under the control of specific hypothalamic stimulatory and inhibitory factors. Among them, Growth Hormone Releasing Hormone (GHRH) is the major stimulator of pituitary somatotrophs activating GH gene expression and secretion. Human GHRH is a polypeptide of 44 amino acids initially isolated from pancreatic tumors, and the gene for the hypothalamic form of GHRH is organized into 5 exons spanning over 10 kilobases (kb) on genomic DNA and encodes a messenger RNA of 700-750 nucleotides. Several neuropeptides classically associated with the hypothalamus have been found in the extrahypothalamic regions, suggesting the existence of novel sources, targets and functions. GHRH-like immunoreactivity has been found in several peripheral sites, including placenta, testis, and ovary, indicating that GHRH may also have regulatory roles in peripheral reproductive organs. Furthermore, higher molecular weight forms of the GHRH transcripts were identified from these organs (1.75 kb in testis; 1.75 and >3 kb in ovary). These tissue-specific expression of GHRH gene suggest the existence of unique regulatory mechanism of GHRH expression and function in these organs. In fact, placenta-specific and testis-specific promoters for GHRH transcripts which are located in about 10 kb upstream region of hypothalamic promoter were reported. The use of unique promoters in extrahypothalamic sites could be refered in a different control of GHRH gene and different functions of the translated products in these tissues. Somatotrophs and lactotrophs have been thought to be derived from a common bipotential progenitor, the somatolactotrophs, which give origins to either phenotypes. Although the precise mechanism responsible for the lactotroph differentiation in the anterior pituitary gland has not been yet clalified, there are several candidators for the generation of lactotrophs. In human, the presence of GHRH peptides with different size from authentic hypothalamic form in the normal anterior pituitary and several types of adenoma were demonstrated. Recently our group found the existence of immunoreactive GHRH and its transcript from the normal rat anterior pituitary (gonadotroph> somatotroph> lactotroph), and the GHRH treatment evoked the increased proliferation rate of anterior pituitary cells in vitro. The transgenic mouse models clearly shown that GHRH or NGF overexpression by anterior pituitary cells induced development of pituitary hyperplasia and adenomas particularly GH-oma and prolactinoma. Taken together, we hypothesize that the pituitary GHRH could serve not only as a modulator of hormone secretion but as a paracrine or autocrine regulator of anterior pituitary cell proliferation and differentiation. Interestingly enough, the expression of Pit-1 homeobox gene (the POU class transcription factor) was confined to somatotrophs, lactotrophs and somatolactotrophs in which GHRH receptors are expressed commonly. Concerning the mechanism of somatolactotroph and lactotroph differentiation in the anterior pituitary, we have focused following two possibilities; (1) changes in the relative levels or interactions of both hypothalamic and intrapituitary factors such as dopamine, VIP, somatostatin, NGF and GHRH; (2) alterations of GHRH-GHRH receptor signaling and Pit-1 activity may be the cause of lactotroph differentiation or pituitary hyperplasia and adenoma formation. Extensive further studies will be necessary to solve these complicated questions.

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