Immunohistochemical expression of somatostatin type 2A receptor in neuroendocrine tumors.

Somatostatin (SS) and SS analogues inhibit the growth of various kinds of endocrine and exocrine cells via the SS receptor (SSTR). Carcinoid tumor is representative of the tumors treatable by SS analogues. We examined the expression of SSTR2A by immunohistochemical and in situ hybridization methods with a specific antibody against a synthesized 20-amino acid peptide of the COOH terminus of human SSTR2A and oligonucleotide probes in 62 endocrine tumors of various kinds: pancreatic endocrine tumor; carcinoid; neuroendocrine carcinoma; medullary thyroid carcinoma; pheochromocytoma; and small cell carcinoma of the lung, neuroblastoma, and ganglioneuroma. SSTR2A was expressed in 87% of these tumors and at both primary and metastatic sites. The immunohistochemical reactivity of SSTR2A was strong on the cell membrane and less intense in the cytoplasm of the tumor cells. SSTR2A mRNA was also detected in the tumor cells. The results indicate the usefulness of SSTR2A analogues for the treatment of neuroendocrine tumors, even metastatic ones: metastatic carcinoids, metastatic pheochromocytomas, tumors that adhered to large vessels, and neuroendocrine carcinomas.     

生长抑素及其2型受体与胰腺癌

生长抑素在体内有着广泛的生物学活性。研究表明,生长抑索及其类似物可以和生长抑素2型受体（SSTR2）结合发挥直接抗肿瘤细胞增殖的作用。少部分胰腺癌组织中存在着SSTR2的表达,大多数不表达SSTR2的胰腺癌则通过在细胞表面的再表达也可发挥抑制肿瘤生长的作用。现就胰腺癌中生长抑素及SSTR2的研究进展作一综述。     

Subtype selective interactions of somatostatin and somatostatin analogs with sst1, sst2, and sst5 in BON-1 cells

Somatostatin is a polypeptide hormone acting as an inhibitor of pituitary, pancreatic, and gastrointestinal secretion through specific membrane receptors of which five subtypes have been cloned (sst_1–5). Somatostatin analogs are used in the clinic to treat patients with excessive hormone production due to a neuroendocrine tumor. The aim of this study was to investigate the biological activity of three new somatostatin receptor subtype selective analogs (BIM-23926, sst₁-selective; BIM-23120, sst₂-selective; and BIM-23206, sst₅-selective) in the human neuroendocrine tumor cell line, BON-1, which expresses sst₁, sst₂, and sst₅ natively. Somatostatin-14 and octreotide were used as reference substances. Forskolin-induced cAMP accumulation and chromogranin A (CgA) secretion were inhibited by BIM-23120, BIM-23206, and somatostatin-14 in a dose-dependent manner. Cholecystokinin (CCK-8) stimulated activation of mitogen-activated protein (MAP) kinase was inhibited by BIM-23120 and BIM-23206, while BIM-23926 stimulated the activity. Selective BIM analogs showed a more efficient inhibitory effect on cAMP accumulation, CgA secretion, and MAP kinase activity than octreotide in BON-1 cells. This may be explained by the differences in affinity of the ligand to the receptor or by interaction between different sst subtypes. We conclude that increasing knowledge about sst physiology and expression in malignant disease indicates a need for new analogs that can be incorporated into the therapeutic arsenal.     

Anti-angiogenic effects of somatostatin receptor subtype 2 on human pancreatic cancer xenografts.

Somatostatin receptor subtypes, especially subtype 2 (SSTR2), exert their antitumor (cytostatic and/or cytotoxic) and anti-angiogenic effects. Here we aimed to investigate the anti-angiogenic effect of SSTR2 gene transfer into pancreatic cancer cell line PC-3, and the mechanisms involved in this effect. The full-length human SSTR2 complementary DNA was introduced into pancreatic cancer cell line PC-3 by lipofectamine-mediated transfection, and stable expression of SSTR2 was detected by immunohistochemistry and RT-PCR. Athymic mice were separately xenografted with SSTR2-expressing cells (experimental group), vector control and mock control cells. Intratumoral microvessel density (MVD) was assessed by immunohistochemistry. Immunohistochemistry and RT-PCR were used to determine the expression of angiogenic factors vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and matrix metalloproteinase (MMP)-2 in xenograft tumors. MVD was significantly lower in the experimental group (5.16 +/- 1.34) than that in the vector control (16.52 +/- 2.25) and mock control (15.32 +/- 2.53) (P < 0.05). The immunohistochemical assay showed a significant decrease in the expression of VEGF, bFGF and MMP-2 protein in the experimental group compared with the vector control and mock control, considering both the integral optical density and area of staining (P < 0.05). RT-PCR showed a significant reduction of VEGF, bFGF and MMP-2 mRNA expression in the experimental group compared with the vector control and mock control (P < 0.05). Thus, introduction of the SSTR2 gene, the expression of which is frequently lost in human pancreatic adenocarcinoma, exerts its anti-angiogenic effects by down-regulating the expression of the factors, which are involved in tumor angiogenesis and metastasis, suggesting SSTR2 gene transfer as a promising strategy of gene therapy for pancreatic cancer.     

Somatostatin receptor subtype 2 is expressed by supratentorial primitive neuroectodermal tumors of childhood and can be targeted for somatostatin receptor imaging.

PURPOSE: Although gliomas predominate among central nervous system (CNS) neoplasms in adulthood, embryonal tumors are the most common malignant brain tumors in children. Despite novel treatment approaches, including improved radiotherapy and high-dose chemotherapy, survival rates remain unsatisfactory. The timely diagnosis of residual or recurrent embryonal CNS tumors and thus the earliest possible time point for intervention is often hampered by inaccuracies of conventional imaging techniques. Novel and refined imaging methodologies are urgently needed. EXPERIMENTAL DESIGN: We have previously demonstrated the use of somatostatin receptor imaging (SRI) in the diagnosis of recurrent and residual medulloblastomas. Here, we evaluated somatostatin receptor type 2 (sst(2)) expression using an antibody in an array of CNS tumors of childhood. Eight high-grade gliomas, 4 atypical teratoid/rhabdoid tumors, 7 supratentorial primitive neuroectodermal tumors (stPNET), 1 medulloepithelioma (ME), and 8 ependymomas were screened. Tumors positive in vitro were additionally analyzed in vivo using SRI. RESULTS: Abundant expression of somatostatin receptor type 2 in stPNET, a ME, and ependymomas warranted in vivo imaging of 7 stPNET, 1 rhabdomyosarcoma, 3 ependymomas, 1 ME, and 1 glioblastoma. Although SRI was positive in 6/7 stPNET, 1 rhabdomyosarcoma, and 1 ME, none of the ependymomas nor the glioblastoma could be imaged using SRI. In selected cases SRI was more sensitive in the detection of relapse than conventional imaging by magnetic resonance imaging and computed tomography. CONCLUSIONS: SRI should be considered in the evaluation of residual or recurrent embryonal CNS tumors, especially stPNET. The strengths of SRI lie in the differentiation of reactive tissue changes versus residual or recurrent tumor, the detection of small lesions, and possibly in the distinction of stPNET from gliomas.     

Immunohistochemical determination of androgen receptors in relation to oestrogen and progesterone receptors in female breast cancer.

The expression of oestrogen (ER), progesterone (PR) and androgen (AR) receptors in female breast cancer was investigated by immunohistochemistry on snap-frozen tissue specimens of a series of 100 breast cancers. For detection of the AR we used a recently developed mouse monoclonal antibody specific for the N-terminal domain of the human AR. Expression of AR was compared with that of ER and PR as well as with tumour grade and age. Of the breast cancers investigated, 76% were AR-positive. This high percentage corresponds well with previous data on AR expression in breast cancer determined with ligand-binding assays. In 53% of the tumours AR, ER and PR were present, while 9% of the tumours were positive for AR and negative for ER and PR. In 13% of the tumours no ER, PR or AR expression was seen; these were all grade-III tumours. A positive correlation was found between age and ER expression, but no correlation was seen between age and PR or AR. Future studies should establish the prognostic value of the combination ER, PR and AR determinations on female breast cancer with regard to biological behaviour and response rate to hormonal therapy.     

Antitumor effect of in vivo somatostatin receptor subtype 2 gene transfer in primary and metastatic pancreatic cancer models

Our previous studies conducted in pancreatic cancer models established in nude mice and hamsters revealed that cloned somatostatin receptor subtype 2 (sst2) gene expression induced both antioncogenic and local antitumor bystander effects in vivo. In the present study, in vivo gene transfer of sst2 was investigated in two transplantable models of primary and metastatic pancreatic carcinoma developed in hamsters. LacZ reporter or mouse sst2 genes were expressed by means of two different delivery agents: an adenoviral vector and a synthetic polycationic carrier [linear polyethylenimine (PEI)]. sst2 was injected into either exponentially growing pancreatic primary tumors or hepatic metastases, and then transgene expression and tumor progression were investigated 5-6 days after gene transfer. Molecular mechanisms involved in the inhibition of tumor growth were also analyzed. Both adenovirus- and PEI-mediated in vivo gene transfer in primary pancreatic tumors induced an increase of beta-galactosidase activity and expression of sst2 transgene nRNA (100% and 86% of tumors for adenovirus and PEI vector, respectively). Adenoviral vector-based sst2 gene transfer resulted in significant reduction of pancreatic tumor growth (P < 0.05). Using PEI vector, both pancreatic primary tumor growth and metastatic tumor growth were also significantly slackened as compared with both LacZ-treated and untreated control groups (P < 0.02). Moreover, the proliferative index decreased significantly (P < 0.005), whereas apoptosis increased (P < 0.005) in tumors transferred with sst2 gene. The increase of apoptosis correlated with an activation of the caspase-3 and poly(ADP-ribose) polymerase pathways. We concluded that in both primary and metastatic pancreatic cancer models, the synthetic gene delivery system can achieve in vivo sst2 gene transfer and results in a significant antitumor effect characterized by an increase of apoptosis and an inhibition of cell proliferation. This new strategy of gene therapy allows the restoration of expression of an antioncogenic molecule and could be promising for the treatment of advanced pancreatic cancer.     

Immunohistochemical expression and localization of somatostatin receptor subtypes in androgen ablated prostate cancer

Objective

The aim was to examine the expression and localization of the five somatostatin receptors (termed SSTR1 to 5) in radical prostatectomies (RPs) from patients with prostatic adenocarcinoma (PCa) under complete androgen ablation (CAA) before operation.

Material

The five SSTRs were evaluated in the epithelial, smooth muscle and endothelial cells of normal-looking epithelium (Nep), high-grade prostatic intraepithelial neoplasia (HGPIN) and PCa in 20 RPs with clinically detected PCa from patients under CAA. Twenty RPs with clinically detected PCa from hormonally untreated patients were used as control group.

Results

Concerning the secretory cells (i) Membrane staining was seen for SSTR3 and SSTR4; the mean percentages of positive cells, higher in SSTR3 than in SSTR4, decreased sharply in HGPIN and PCa compared with Nep; the mean percentages in the androgen ablated group were 30% to 90% lower than in the untreated; (ii) Cytoplasmic staining was seen for all five SSTRs; the mean percentages of positive cells in Nep, HGPIN and PCa of the untreated group were similar, and in general as high as 80% or more; in the treated group, the Nep values were similar to those in the untreated, whereas the values in HGPIN and PCa were lower for SSTR1, three and five, with a decrease of 30% for SSTR1; (iii) Nuclear staining was seen with SSTR4 and SSTR5, the mean percentages for the former being much lower than for the latter; treatment affected both HGPIN and PCa, whose proportions of stained cells were 30% to 55% lower than in the untreated group. Cytoplasmic staining in the basal cells was seen for all five SSTRs, both in Nep and HGPIN. The values in the treated group were lower than in the other, the difference between the two group being in general comprised between 10% and 40%. Treatment did not affect SSTR staining in the smooth muscle and endothelial cells.

Conclusions

The present study expands our knowledge on the expression and localization of the five SSTRs in the prostate following CAA.     

Association of breast cancer with meningioma. A report of five cases

Five patients with diagnosed breast cancer who developed meningiomas are reported. The literature contains reports of an additional 25 such patients. Some authors have noted hormonal sensitivity and the presence of hormone receptors in some meningiomas. Because breast cancer is a common tumor of women, it is probable that any association between breast cancer and meningioma is fortuitous. Two patients in this small series each had a sister with breast cancer, one of them also had three other first-degree relations with colon cancer. Three of the patients had other tumors as well as breast cancer. It is important to fully investigate brain lesions in patients with breast cancer so that potentially curable meningiomas are not mistaken for metastases.     

Immunohistochemical evidence of p53 overexpression in gastric epithelial dysplasia.

Molecular abnormalities of the p53 gene in chromosome 17p may be among the most commonly observed in human cancer. Their role in gastric carcinogenesis is suggested by their frequent detection in invasive adenocarcinomas. To investigate the chronology with which these abnormalities appear in the gastric carcinogenesis process, the expression of p53 proteins was investigated in late stages of the process, namely dysplasia, and in superficial carcinomas. A polyclonal antibody, CM-1, against both wild-type and mutant proteins was applied to paraffin-embedded biopsy and gastrectomy specimens previously fixed in buffered formalin. Positive nuclear stain was obtained in 36.4% of 33 cases of gastric epithelial dysplasia, corresponding to 19% of mild, 27.3% of moderate, and 64.3% of severe dysplasias. Eight of 13 (61.5%) invasive carcinomas showed positive stain. The data indicate an increased incidence of p53 abnormalities in the late stages of gastric carcinogenesis.     

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。     

Immunohistochemical evaluation of human epidermal growth factor receptor 2 and estrogen and progesterone receptors in breast carcinoma in Jordan

Introduction  

Although breast carcinoma (BC) is the most common malignancy affecting Jordanian females and the affected population in Jordan is younger than that in the West, no information is available on its biological characteristics. Our aims in this study are to evaluate the expression of estrogen receptor (ER) and progesterone receptor (PR) and Her-2/neu overexpression in BC in Jordan, and to compare the expression of these with other prognostic parameters for BC such as histological type, histological grade, tumor size, patients' age, and number of lymph node metastases.     

Immunohistochemical study of androgen receptors in metastatic prostate cancer. Comparison of receptor content and response to hormonal therapy.

A longstanding goal has been to determine whether androgen receptor (AR) levels could be used to predict the clinical response of metastatic prostate cancer to androgen withdrawal therapy. A major limitation of previous studies was the use of homogenized tissue, which yields an average AR content for all cells. By AR immunohistochemical study using an antibody specific for AR the authors assessed nuclear AR content specifically in the malignant epithelial cells of prostate needle biopsy specimens of 17 patients with Stage D prostate cancer. The authors found that prostate cancer contains AR-positive and AR-negative malignant cells before androgen withdrawal therapy, but the percentage of AR-positive cells did not predict the time to tumor progression after therapy. There was no significant correlation between the percentage of AR-positive malignant cells and the time to tumor progression. When patients were divided into two groups based on the median time to progression, the percentage of AR-positive nuclei was not significantly different in poor responders versus good responders. When patients were divided into two groups based on the median percentage of receptor-positive nuclei, Kaplan-Meier estimates of the progression-free interval revealed no significant difference between the group of patients with AR-poor tumors and patients with AR-rich tumors. Potential explanations for these results are discussed. The authors conclude that the percentage of AR-positive nuclei is not a sufficient criterion to predict tumor behavior.