Somatostatin receptor profiling in hepatic metastases from small intestinal and pancreatic neuroendocrine neoplasms: immunohistochemical approach with potential clinical utility.

BACKGROUND: The expression of somatostatin receptors (SSTRs) on endocrine tumor (ET) cells forms the basis for somatostatin analog treatment of patients with SSTR-positive, hormonally active ETs. In patients with SSTR-negative ETs, the clinical response is generally absent or suboptimal, while nonfunctioning ETs with SSTR positivity show a variable response to such therapy. METHODS: We retrospectively studied SSTR subtype expression in hepatic metastases from 14 adult patients with primary endocrine carcinomas (ECAs) of the small intestine and pancreas and compared SSTR subtype expression among the primary and metastatic ECAs. Polyclonal antibodies against the 5 SSTR subtypes were used on formalin-fixed, paraffin sections from each primary and metastatic ECA. Both qualitative and semiquantitative evaluation of the stained ECA sections was carried out. RESULTS: Eleven (61%) of 18 hepatic metastases from small intestinal and pancreatic ECAs were positive for SSTR-1, 15 (83%) for SSTR-2, 13 (72%) for SSTR-3, 10 (56%) for SSTR-4, and 15 (83%) for SSTR-5. Among 11 hepatic ECA metastases from small intestinal ECAs (carcinoids), 7 (63%) expressed SSTR-1, 9 (81%) expressed SSTR-2, 8 (72%) expressed SSTR-3, 6 (54%) expressed SSTR-4, and 10 (91%) expressed SSTR-5. Of 7 hepatic ECA metastases from pancreatic ECAs, 4 expressed SSTR-1, 6 expressed SSTR-2, and 5 expressed SSTR-3 and SSTR-5 each. We also observed the immunohistochemical evidence of heterogeneity of expression of various SSTR subtypes in the primary enteropancreatic ECAs and their hepatic metastases. CONCLUSIONS: SSTR subtype expression needs to be correlated to somatostatin analog therapy. Immunohistochemical profiling of various SSTR subtypes as a part of routine surgical pathologic analysis of enteropancreatic ETs may become a useful predictor of responsiveness of ETs to various SSTR analogs.     

Comparative studies on the expression of somatostatin receptor subtypes, outcome of octreotide scintigraphy and response to octreotide treatment in patients with carcinoid tumours.

We have compared the expression of somatostatin receptor (sstr) subtypes with the outcome of somatostatin receptor scintigraphy and the effect of somatostatin receptor activation in patients with disseminated carcinoid tumours. Tumour tissues from nine patients with midgut carcinoids (ileal) and three patients with foregut carcinoids (gastric, thymic) were analysed using Northern blotting. Expression of somatostatin receptors was demonstrated in all tumours (12 out of 12), with all five receptor subtypes present in 9 out of 12 tumours. Somatostatin receptor scintigraphy using [111In]DTPA-D-Phe1-octreotide visualized tumours in all patients (12 out of 12). The 111In activity concentrations in tumour tissue (T) and blood (B) were determined in three tumours 1-7 days after injection of the radionuclide. The T/B 111In activity concentration ratios ranged between 32 and 651. Clinically, treatment with the long-acting somatostatin analogue octreotide resulted in marked symptom relief accompanied by a significant reduction in tumour markers, for example urinary-5-HIAA levels (28-71% reduction). Incubation of midgut carcinoid tumours in primary culture with octreotide (10 microM) resulted in a reduction in spontaneously secreted serotonin (45-71% reduction) and 5-HIAA (41-94% reduction). The results demonstrate that carcinoid tumours possess multiple somatostatin receptor subtypes and that somatostatin analogues such as octreotide, which preferentially bind to somatostatin receptor subtype 2 and 5, can be used in the diagnosis and medical treatment of these tumours. In the future, novel somatostatin analogues with subtype specific receptor profiles may prove to be of value for individualizing the treatment of disseminated carcinoid tumour disease.     

人类乳腺良恶性病变的SSTR2mRNA表达及其与类固醇受体相关性研究

目的了解人类良、恶性乳腺病变组织中生长抑素受体亚型2(SSTR2)mRNA的表达情况,并探讨其与雌激素受体(ER)、孕激素受体(PR)的相关性.方法收集23例乳腺癌、16例乳腺增生病和9例乳腺纤维腺瘤手术标本,采用多相寡核苷酸探针原位杂交法检测SSTR2mRNA表达,免疫组化法检测ER、PR状况,并用图像分析仪进行SSTR2mRNA相对含量测定.结果SSTR2mRNA在乳腺癌表达的阳性率(87%)和相对含量(0.47)均明显高于乳腺良性病变(64%,0.26)(P＜0.05).乳腺良性病变中SSTR2mRNA表达与ER呈正相关(P＜0.05);在乳腺癌中SSTR2mRNA表达与ER、PR均呈正相关(P＜0.05).结论SSTR2mRNA在乳腺良、恶性病变组织中普遍表达,恶性高于良性;SSTR2mRNA表达与ER、PR具有相关性,提示对ER阳性乳腺癌采用抗雌激素与SST类似物联合治疗的可行性.     

Preclinical evaluation of new and highly potent analogues of octreotide for predictive imaging and targeted radiotherapy.

PURPOSE: Molecular imaging and targeted radiotherapy are emerging fields in nuclear oncology. Five human somatostatin receptors (hsstr1-hsstr5) are known to be overexpressed to some degree on various tumors, sstr2 being the most important one. Clinically used somatostatin based radiopeptides target exclusively sstr2. The aim of this study was to develop novel analogues with a broader sstr profile for diagnostic (positron emission tomography and single-photon emission computed tomography) and radiotherapeutic applications. EXPERIMENTAL DESIGN: The following promising structures emerged from a parallel synthetic approach: [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA(0)),1-Nal(3),Thr(8)]-octreotide (1, DOTA-NOC-ATE) and [DOTA(0),BzThi(3),Thr(8)]-octreotide (2, DOTA-BOC-ATE). The conjugates were labeled with cold and radioactive (111)In. Pharmacologic properties were compared with [(111)In-DOTA,Tyr(3)]-octreotide ([(111)In-DOTA]-TOC). RESULTS: The receptor affinity profile showed high affinity of both peptides to hsstr2, hsstr3, and hsstr5 and some intermediate affinity to hsstr4, whereas [(111)In-DOTA]-TOC shows affinity only to sstr2. The internalization is fast in sstr2 expressing AR4-2J and in transfected sstr3 expressing human embryonic kidney 293 cells. Both radiopeptides internalize much more efficiently than [(111)In-DOTA]-TOC. Animal biodistribution studies showed very high and specific uptake of [(111)In]-1 and [(111)In]-2 in s.c. implanted AR4-2J tumors (Lewis rats) and in somatostatin receptor expressing normal tissues. The uptake was at least 2-fold higher in these tissues and in the tumor compared with [(111)In-DOTA]-TOC. In addition, the kidney uptake was significantly lower for both radiopeptides. CONCLUSIONS: These data suggest that the novel radiopeptides are superior to [(111)In/(90)Y-DOTA]-TOC and show great promise for the clinical application in the imaging of somatostatin receptor-positive tumors and their targeted radiotherapy.     

Somatostatin receptor (SSTR) scintigraphy in patients with osteosarcoma

To investigate somatostatin receptors (SSTRs) in primary or metastatic high-grade osteosarcoma, 18 patients (12 without metastases, 4 with synchronous lung, and 2 with metachronous bone metastases) underwent SSTR scintigraphy. After intravenous (i.v.) injection of 200-250 MPq of 111In-pentreotide, images were recorded at 4 and 24 hours. All patients underwent 99mTc-methylene diphosphonate (MDP) bone scan (BS). Scans were interpreted both with qualitative evaluation and with semiquantitative image processing, by means of tumor-to-background ratio modification over time. Primary tumor: SSTR scintigraphy was positive in 12 (75%) patients: 10 (83%) of the 12 nonmetastatic patients, and 2 (50%) of those with synchronous metastases. Metastases: SSTR scintigraphy was positive only in one (17%) of the six patients with metastatic disease. No relation was found between SSTR scintigraphy results and gender, histologic subtype, site, and size of the tumor. After primary chemotherapy, 15 patients underwent surgery of primary tumor; a good histologic response was found in 7 (64%) of the 11 patients with positive SSTR scintigraphy versus 1 (25%) of the 4 patients with negative SSTR scintigraphy. High-grade osteosarcoma exhibits somatostatin receptors, usually detectable in the primary tumor, but not in the metastatic lesions. The different expression of somatostatin receptors observed in primary and metastatic lesions, and in patients with tumors having different chemosensitivity, could indicate a possible relation between somatostatin receptors and biological behavior of the tumor.     

胰腺癌生长抑素受体报告基因表达与其靶向显像的相关性研究

目的探讨荷胰腺癌裸鼠模型肿瘤组织生长抑素受体(SSTR)报告基因的mRNA表达水平与99mTc-sandostatin显像对肿瘤的靶向诊断价值及二者的相关性。方法建立荷胰腺癌动物模型,对18只荷胰腺癌裸鼠模型行99mTc-sandostatin显像,勾画感兴趣区,计算瘤体与对侧正常组织的放射性比值(T/NT),用RT-PCR方法检测肿瘤组织SSTR1、SSTR2、SSTR5 mRNA的表达水平,对各SSTR亚型表达水平与T/NT比值进行相关性分析。结果13只荷胰腺癌裸鼠肿瘤清晰显影,瘤组织有较高的局灶性放射性浓聚;6 h T/NT比值达2.53±0.84。5只荷胰腺癌裸鼠显像弱阳性或阴性,6 hT/NT比值为1.04±0.06。肿瘤组织有SSTR1、SSTR2、SSTR5 mRNA表达,SSTR1、SSTR2的表达水平与肿瘤显像阳性裸鼠T/NT比值呈正相关,r分别为0.597(P<0.05)和0.807(P<0.01)。结论荷胰腺癌裸鼠肿瘤组织有SSTR表达,SSTR2尤为显著9。9mTc-sandostatin受体显像对荷胰腺癌动物模型有很好的靶向诊断价值;肿瘤99mTc-sandostatin摄取程度同SSTR1、SSTR2表达水平正相关。     

Neuroendocrine tumor targeting: study of novel gallium-labeled somatostatin radiopeptides in a rat pancreatic tumor model

Somatostatin analogs labeled with radionuclides are of considerable interest in the diagnosis and therapy of SSTR-expressing tumors, such as gastroenteropancreatic, small cell lung, breast and frequently nervous system tumors. In view of the favorable physical characteristics of the Ga isotopes (67)Ga and (68)Ga, enabling conventional tumor scintigraphy, PET and possibly internal radiotherapy, we focused on the development of a Ga-labeled somatostatin analog suitable for targeting SSTR-expressing tumors. For this purpose, 3 somatostatin analogs, OC, TOC and TATE were conjugated to the metal chelator DOTA and labeled with the radiometals (111)In, (90)Y and (67)Ga. They were then evaluated for their performance in the AR4-2J pancreatic tumor model by testing SSTR2-binding affinity, internalization/externalization in isolated cells and biodistribution in tumor-bearing nude mice. Surprisingly, we found that, compared to (111)In or (90)Y, labeling with (67)Ga considerably improved the biologic performance of the tested somatostatin analogs with respect to SSTR2 affinity and tissue distribution. (67)Ga-labeled DOTA-somatostatin analogs were rapidly excreted from nontarget tissues, leading to excellent tumor-to-nontarget tissue uptake ratios. Of interest for radiotherapeutic application, [(67)Ga]DOTATOC was strongly internalized by AR4-2J cells. Furthermore, our results suggest a link between the radioligand charge and its kidney retention. The excellent tumor selectivity of Ga-DOTA somatostatin analogs together with the different applications of Ga in nuclear oncology suggests that Ga-DOTA somatostatin analogs will become an important tool in the management of SSTR-positive tumors.     

生长抑素受体亚型在人鼻咽癌细胞株CNE2中表达

背景与目的：生长抑素受体（somatostatin receptor SSTR）在许多肿瘤组织均有表达，为生长抑素类似物如奥曲肽用于这些肿瘤的治疗提供了生物学基础，但对生长抑素受体在鼻咽癌中表达情况的研究甚少。本研究旨在了解生长抑素受体基因在鼻咽癌细胞中的表达情况，为生长抑素类似物用于鼻咽癌治疗的进一步研究提供试验基础。方法：采用RT—PCR法和SP免疫组化法联合检测体外培养的人鼻咽癌细胞株CNE2的SSTRs表达，并对PCR mRNA产物测序以鉴定结果。结果：RT—PCR提示人鼻咽癌细胞株CNE2分别表达生长抑素受体亚型SSTR1、SSTR2、SSTR4；免疫组化结果：人鼻咽癌细胞株CNE2表达SSTR1、SSTR2A为强阳性（〉60％），表达SSTR4为弱阳性、SSTR2介于两者之间、SSTR3和SSTR5则无表达。结论：我们的研究证实人鼻咽癌细胞株CNE2有多种生长抑素受体亚型基因表达，且以表达SSTR1、SSTR2较多。     

Pre-clinical evaluation of [(111)In-DTPA-Pro(1), Tyr(4)]bombesin, a new radioligand for bombesin-receptor scintigraphy.

Bombesin (BN) is a 14-amino-acid neuropeptide with a high affinity for the gastrin-releasing peptide receptor. This receptor has been found to be expressed in a variety of tumours, including lung, breast, prostate and pancreas. A newly synthesized BN analogue, [DTPA-Pro(1),Tyr(4)]BN, was shown to be a high-affinity BN-receptor (BNR) agonist, stimulating prolactin secretion from 7315b cells with an IC(50) of 8 nM. The (111)In-labelled analogue was found to bind with high affinity to rat BNR in vitro and in vivo. The radioligand is internalized by BNR-expressing cells, in contrast to DTPA-conjugated BN antagonists. Therefore, we further studied the biodistribution of i.v. injected [(111)In-DTPA-Pro(1),Tyr(4)]BN in rats. High and specific uptake was found in tissues of the gastrointestinal tract, notably pancreas. Uptake of radioactivity was blocked by pre- or co-injection of 100 microgram [Tyr(4)]BN, but not when this was administered 30 min after the radioligand. This suggests BNR-mediated internalization of the radioligand within 30 min. The percentage injected dose (ID) taken up by BNR-positive tissues was a bell-shaped function of the amount (0.01-0.1 microgram) of injected ligand. Next to the pancreas, highest uptake was observed in the kidneys, which was not blocked by excess [Tyr(4)]BN. Dynamic gamma camera studies showed rapid clearance of radioactivity from the blood compartment. Urinary excretion amounted to about 35% ID after 1 hr and to 70% ID after 24 hr, with a total body retention of 10% ID. Specific uptake was found in the BNR-positive CA20948 pancreas tumour and CC531 colon carcinoma in tumour-bearing rats. The CA20948 tumour, inoculated in the hindleg, was also visualized scintigraphically. [(111)In-DTPA-Pro(1), Tyr(4)]BN appears to be a promising radioligand for scintigraphy of BNR-expressing tumours.     

原发性肝癌患者肿瘤组织生长抑素受体表达与血AFP水平的相关性

背景与目的:生长抑素类似物(somatostatin analogue,SSTA)对部分原发性肝癌(hepatocellular carcinoma,HCC)患者具有一定疗效,但HCC患者肿瘤组织中生长抑素受体(somatostatin receptor,SSTR)表达状况不详,其与血甲胎蛋白(alphafetoprotein,AFP)的相关性也未见探讨.本研究拟了解肝癌组织中SSTR1、SSTR2、SSTR3、SSTR4及SSTR5亚型的表达状况及其与血AFP的相关性.方法:逆转录-聚合酶链反应及免疫组织化学法分别检测人肝癌及肝硬化组织(各40例)SSTR1、SSTR2、SSTR3、SSTR4及SSTR5亚型的mRNA及蛋白表达:酶联免疫吸附试验检测HCC患者肿瘤组织及外周血AFP水平.结果:肝癌组织中SSTR1、SSTR2、SSTR3、SSTR4及SSTR5蛋白阳性率(分别为47.5%、70.0%、50.0%、65.0%及67.5%)显著高于肝硬化组织(分别为55.0%、67.5%、52.5%、60.0%及47.5%).肝癌组织中SSTR1、SSTR2、SSTR3、SSTR4及SSTR5表达与患者血AFP水平呈二次曲线正相关(r依次为0.882、0.901、0.877、0.854、0.903,P＜0.05).血AFP水平在200～800 μg/L范围时,伴有肝癌组织SSTRs的高表达,过低或过高的血AFP水平伴有SSTR低表达.结论:约60%HCC患者的肿瘤组织表达了SSTRs,其表达量明显高于肝硬化组织;15 AFP水平在200-800μg/L的HCC患者伴有肝癌组织SSTRs的高表达,提示为SSTA治疗的适宜候选者.     

Biodistribution of 177Lu-octreotate and 111In-minigastrin in female nude mice transplanted with human medullary thyroid carcinoma GOT2

To be able to evaluate new radiopharmaceuticals and optimize diagnostic and therapeutic procedures, relevant animal models are required. The aim of this study was to evaluate the medullary thyroid carcinoma GOT2 animal model by analyzing the biodistribution of 177Lu-octreotate and 111In-minigastrin (MG0). BALB/c nude mice, subcutaneously transplanted with GOT2, were intravenously injected with either 177Lu-octreotate or 111In-MG0, with or without excess of unlabeled human minigastrin simultaneously with 111In-MG0. Animals were sacrificed 1-7 days after injection in the 177Lu-octreotate study and 1?h after injection of 111In-MG0. The activity concentrations in organs and tissues were determined and mean absorbed doses from 177Lu were calculated. There was a specific tumor uptake of either 177Lu-octreotate or 111In-MG0. 177Lu-octreotate samples showed high activity concentrations in tissues expressing somatostatin receptors (SSTR). For both radiopharmaceuticals the highest activity concentrations were found in the kidneys. Compared to results from similar studies in mice with another MTC cell line (TT) the biodistribution was favorable (higher tumor uptake) for the GOT2 model, while compared to other animal models expressing SSTR, the tumor uptake of 177Lu-octreotate was modest. In conclusion, the GOT2 animal model is a valuable model for evaluation and optimization of diagnostic and therapeutic procedures using radiolabeled somatostatin, CCK2 and gastrin analogues prior to clinical studies.     

Uptake of radiolabeled somatostatin analog is detectable in patients with metastatic foci of sarcoma.

BACKGROUND: Somatostatin receptors are present on many types of epithelial tumors, and ligands targeting these receptors are used to treat patients with neuroendocrine malignancies. Preclinical studies have demonstrated the presence of somatostatin receptors on a variety of mesenchymal tumors by in vitro receptor autoradiography. The use of radiolabeled somatostatin analogs to assess the presence of somatostatin receptors in vivo has been established, but use of this technique to evaluate human sarcomas has not been reported previously. METHODS: Seventeen patients (13 females and 4 males) with metastatic sarcoma underwent imaging via somatostatin-receptor scintigraphy. Scans were performed using indium -111 pentetreotide. Planar studies and single photon emission computed tomography imaging were performed at 4 and 24 hours, and results of scintigraphy were correlated with computed tomography findings. RESULTS: Twelve of 17 scans showed increased uptake in regions of known metastatic disease. There was no apparent correlation with scan positivity and patient age, histology, site of disease, or duration of diagnosis. CONCLUSIONS: Seventy-one percent of patients with advanced soft-tissue sarcomas had positive scintigraphy scans demonstrating tumor expression of somatostatin receptors subtype 2 in vivo. Imaging with indium-111 pentetreotide could be studied as an adjunct to conventional imaging modalities for assessment of sarcoma patients. Further research is needed to determine the prognostic implications of somatostatin receptor subtype 2 positivity, including larger studies to evaluate any potential correlation with metastatic behavior and other clinical outcomes.     

帕瑞泰在肿瘤诊疗中的转化医学研究

生长抑素类似物帕瑞泰是首个以脑垂体为靶点的新型蛋白.它与靶细胞膜上的生长抑素受体给合后,可阻止促肾上腺皮质激素的释放,并抑制肿瘤细胞的生长.帕瑞泰对生长抑素受体的大部分亚型都具有良好的亲和力,尤其是对生长抑素受体5(SSTR5)有非常高的亲和力.通过转化医学的研究,帕瑞泰将在新一轮肿瘤新靶点个体化诊疗中发挥重要作用.     

New pansomatostatin ligands and their chelated versions: affinity profile, agonist activity, internalization, and tumor targeting.

PURPOSE: Somatostatin receptor (sst) targeting is an established method to image and treat sst-positive tumors. Particularly, neuroendocrine tumors express the receptor subtype 2 in high density, but sst1, sst3, sst4, and sst5 are also expressed to some extent in different human tumors. Currently used targeting peptides mainly have sst2 affinity. We aimed at developing (radio)peptides that bind with high affinity to all receptor subtypes. EXPERIMENTAL DESIGN: Carbocyclic octapeptides were coupled with macrocyclic chelators for radiometal labeling. Affinity, internalization, and agonist potencies were determined on sst1- to sst5-expressing cell lines. Biodistribution was determined on nude mice bearing HEK-sst2 or AR4-2J and HEK-sst3 tumors. RESULTS: High affinity to all receptor subtypes was found. Y(III)-KE88 showed agonistic properties at all five sst receptor subtypes as it inhibits forskolin-stimulated cyclic AMP production. Surprisingly, very low or even absent sst2 receptor internalization was found compared with currently clinically established octapeptides, whereas the sst3 internalization was very efficient. Biodistribution studies of [(111)In]KE88 and [(67)Ga]KE88/[(68)Ga]KE88 reflected the in vitro data. In nude mice with s.c. implanted sst2 (HEK-sst2, AR4-2J)-expressing and sst3 (HEK-sst3)-expressing tumors, high and persistent uptake was found in sst3-expressing tumors, whereas the uptake in the sst2-expressing tumors was lower and showed fast washout. The kidney uptake was high but blockable by coinjection of lysine. CONCLUSION: This peptide family shows pansomatostatin potency. As radiopeptides, they are the first to show a full pansomatostatin profile. Despite some drawback, they should be useful for imaging sst2-expressing tumors with short-lived radiometals, such as (68)Ga, at early time points and for sst3-expressing tumors at later time points with longer-lived radiometals, such as (64)Cu or (86)Y.     

Somatostatin receptors in primary human breast cancer: quantitative analysis of mRNA for subtypes 1–5 and correlation with receptor protein expression and tumor pathology

Summary Somatostatin receptors (SSTRs) have been identified in most hormone-producing tumors as well as in breast cancer. In the present study, we determined SSTR1–5 expression in primary ductal NOS breast tumors through semi-quantitative RT-PCR and immunocytochemistry. The results from the analysis of 98 samples were correlated with several key histological markers and receptor expression. All five SSTR subtypes are variably expressed at the mRNA level in breast tumors with 91% of samples showing SSTR1, 98% SSTR2, 96% SSTR3, 76% SSTR4, and 54% SSTR5. SSTR1–5 are localized to both tumor cells and the surrounding peritumoral regions as detected by immunocytochemistry. Levels of SSTR mRNA, when corrected for β-actin levels, were highest for SSTR3 followed by SSTR1, SSTR2, SSTR5, and SSTR4. Furthermore, there was good correlation between mRNA and protein expression with 84% for SSTR1, 79% for SSTR2, 89% for SSTR3, 68% for SSTR4, 68% for SSTR5, and 78% for all five receptors. SSTR1, 2 and 4 were correlated with ER levels whereas SSTR2 showed an additional correlation with PR levels. These correlations were independent of patient age and histological grade. Moreover, using immunocytochemistry, blood vessels exhibited receptor-specific localization for SSTR2 and SSTR5. Our results indicate significant correlations between mRNA and protein expression along with receptor-specific correlations with histological markers as well as ER and PR levels. Differential distribution of SSTR subtypes in tumors and receptor-specific expression in vascular structures may be considered as a novel diagnosis for breast tumors with receptor subtype agonists.     

Pre-clinical comparison of [DTPA0] octreotide, [DTPA0,Tyr3] octreotide and [DOTA0,Tyr3] octreotide as carriers for somatostatin receptor-targeted scintigraphy and radionuclide therapy

We have evaluated the potential usefulness of radiolabelled [DTPA⁰,Tyr³]octreotide and [DOTA⁰,Tyr³]octreotide as radiopharmaceuticals for somatostatin receptor–targeted scintigraphy and radiotherapy. In vitro somatostatin receptor binding and in vivo metabolism in rats of the compounds were investigated in comparison with [¹¹¹In-DTPA⁰] octreotide. Comparing different peptide–chelator constructs, [DTPA⁰,Tyr³]octreotide and [DOTA⁰, Tyr³]octreotide were found to have a higher affinity than [DTPA⁰]octreotide for subtype 2 somatostatin receptors (sst₂) in mouse AtT20 pituitary tumour cell membranes (all IC₅₀ values obtained were in the low nanomolar range). In vivo studies in CA20948 tumor-bearing Lewis rats revealed a significantly higher uptake of both ¹¹¹In-labelled [DOTA⁰,Tyr³]octreotide and [DTPA⁰,Tyr³]octreotide in sst₂-expressing tissues than after injection of [¹¹¹In-DTPA⁰]octreotide, showing that substitution of Tyr for Phe at position 3 in octreotide results in an increased affinity for its receptor and in a higher target tissue uptake. Uptake of ¹¹¹In-labelled [DTPA⁰]octreotide, [DTPA⁰,Tyr³]octreotide and [DOTA⁰,Tyr³]octreotide in pituitary, pancreas, adrenals and tumour was decreased to less than 7% of control by pre-treatment with 0.5 mg unlabelled octreotide/rat, indicating specific binding to sst₂. Comparing different radionuclides, [⁹⁰Y-DOTA⁰,Tyr³]octreotide had the highest uptake in sst₂-positive organs, followed by the [¹¹¹In-DOTA⁰,Tyr³]octreotide, whereas [DOTA⁰, ¹²⁵I-Try³]octreotide uptake was low compared to that of the other radiopharmaceuticals, when measured 24 hr after injection. Renal uptake of ¹¹¹In-labelled [DTPA⁰]octreotide, [DTPA⁰, Tyr³]octreotide and [DOTA⁰,Tyr³]octreotide was reduced over 50% by an i.v. injection of 400 mg/kg d-lysine, whereas radioactivity in blood, pancreas and adrenals was not affected. Int. J. Cancer 75:406–411, 1998. © 1998 Wiley-Liss, Inc.     

Octreotide and octreotate derivatives radiolabeled with yttrium: pharmacokinetics in rats

Distribution profiles and elimination pathways in rats of two new octreotate derivatives radiolabeled with yttrium, namely Y-DOTAGA-tate and Y-DOTA-t-GA-tate, were compared with those of Y-DOTA-octreotide and Y-DOTA-Tyr(3)-octreotide. All synthetic somatostatin analogues under study were rapidly cleared from the blood and most organs of rats. The main elimination pathway for all peptides under study was urine excretion. High and long-term uptakes of radioactivity in the kidneys and also in organs with high density of somatostatin receptors (the adrenals and pancreas) were found. Radioactivity concentrations in these somatostatin receptor-rich organs were substantially higher for octreotate derivatives in comparison with octreotide analogues; the highest values for Y-DOTAGA-tate were determined. The octreotate derivatives under study appear to be specific ligands for treatment of somatostatin receptor-positive tumors if some mechanism to decrease their kidney retention is provided.     

生长抑素受体亚型与 EGFR在非小细胞肺癌中的表达及其临床意义

目的:探讨联合应用凋亡素(apoptin)基因、新城疫病毒(newcastle disease virus,NDV)血凝素-神经氨酸酶(he-magglutinin-neuramidinase,HN)基因及人白介素18(hIL-18)基因体外对人结肠癌细胞HCT-116的抑制效应。方法:重组质粒pIRApoptinHNIL18通过脂质体介导法体外转染人结肠癌细胞HCT-116,通过Western blotting和RT-PCR检测外源基因表达;采用AO/EB染色法检测pIRApoptinHNIL18对人结肠癌细胞HCT-116抑制作用;利用流式细胞术分析pIRApoptinHNIL18对人结肠癌细胞HCT-116线粒体膜电位(mitochondrial transmembrane potential,△Ψ)和活性氧(reactive oxygen species,ROS)水平;采用3,5-二羟基甲苯法测定唾液酸含量。结果:pIRApoptinHNIL18转染人结肠癌细胞HCT-116后,外源基因能够有效表达;肿瘤细胞生长受到抑制;线粒体△Ψ由(94.41±8.17)%下降到(30.70±8.01)%(P<0.05);唾液酸含量由(0.33±0.06)mmol/L下降到(0.09±0.03)mmol/L(P<0.01);ROS水平由(52.48±6.09)%升高到(68.98±7.26)%(P<0.05)。结论:pIRApoptinHNIL18可通过线粒体途径诱导细胞凋亡,从而抑制人结肠癌细胞HCT-116的生长。     

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

Expression changes of somatostatin receptor subtypes (SSTRs) including SSTR1, SSTR2, SSTR3, SSTR4and SSTR5 in the development of gallbladder cancer were assessed with attention to relationships with clinicalpathological characteristics. SSTRs in 29 gallbladder cancer and 25 normal gallbladder tissue specimens wereexamined by immunohistochemical staining. Differences between SSTRs expressions and clinical pathologicalparameters were analyzed by chi-square test. The five subtypes of SSTR were all expressed in gallbladder cancertissues and SSTR3 presented the highest expression. SSTR5 expression was increased significantly in gallbladdercancer (P<0.05) compared with that in normal gallbladder tissue. SSTR3 expression in highly and moderatelydifferentiated 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 cancerwithout lymph node metastasis (P<0.05). Therfore, these results indicated that SSRT5, SSTR3 and SSTR4 mayplay important roles in the formation and development of gallbladder cancer.