Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Camptothecin (CPT) was conjugated to the N-terminal of a somatostatin analog (SSA) directly via a carbamate group and a basic N-terminal linking motif, D-Lys-D-Tyr-Lys-D-Tyr-D-Lys. This new CPT-SSA conjugate termed JF-10-81 was evaluated as a receptor-specific delivery system for its anti-invasive and anti-angiogenic activities. It was found that, in addition to blocking migration and invasion of highly invasive prostate cancer PC-3 cells, this conjugate also inhibited in vitro capillary-like tube formation of endothelial cells and in vivo angiogenesis in C57B1/6N female mice. JF-10-81 was found to block PC-3 cell attachment to various extracellular matrix components, mainly to vitronectin, the ligand of cell surface receptors integrin alphaVbeta3 and alphaVbeta5. Additionally, JF-10-81 reduced expression of integrins alphaVbeta3 and alphaVbeta5 on PC-3 cell surfaces, without effects on beta1 or any alphabeta1 heterodimers. This conjugate also inactivated phosphorylation of protein kinase B (PKB/Akt), down-regulated the expression of latent matrix metalloproteinase (MMP) -2 and MMP-9, but had little effect on MMP-3/-10. Meanwhile, membrane type-1 matrix metalloproteinase (MT1-MMP) and the tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) were not detectable in PC-3 cells. alphaVbeta3/alphaVbeta5 and MMP-2/-9 are known to be highly expressed in many tumor cells and play an important role in tumor progression. Our results support that this conjugate could possibly inhibit prostate cancer PC-3 cell invasion through a signaling pathway involving PI3K/Akt, alphaVbeta3/alphaVbeta5 and MMP-2/-9, and this SSA could be used as an efficient vector to deliver CPT or other cytotoxic agents to target sites for cancer therapy.
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PMID:A conjugate of camptothecin and a somatostatin analog against prostate cancer cell invasion via a possible signaling pathway involving PI3K/Akt, alphaVbeta3/alphaVbeta5 and MMP-2/-9. 1664 5

The development of resistance to anticancer therapies is a major hurdle in preventing long-lasting clinical responses to conventional therapies in hormone-refractory prostate cancer. Herein, the molecular evidence documenting that bone metastasis microenvironment survival factors (mainly the paracrine growth hormone-independent, urokinase-type plasminogen activator-mediated increase of IGF-1 and the endocrine production of growth hormone-dependent IGF-1, mainly liver-derived IGF-1 production) produce an epigenetic form of prostate cancer cells that are resistant to proapoptotic therapies is reviewed. Consequently, the authors present the conceptual framework of a novel antibone microenvironment survival factor, mainly an anti-IGF-1 hormonal manipulation for androgen ablation refractory prostate cancer (a combination of conventional androgen ablation therapy [luteinising hormone-releasing hormone agonist-A or orchiectomy]) with dexamethasone plus somatostatin analogue, which yielded durable objective responses and major improvement of bone pain and performance status in stage D3 prostate cancer patients.
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PMID:Combination therapy using LHRH and somatostatin analogues plus dexamethasone in androgen ablation refractory prostate cancer patients with bone involvement: a bench to bedside approach. 1678 42

Early clinical trials in Mexico with analogs of luteinizing hormone-releasing hormone (LH-RH) also known as gonadotropin releasing hormone (Gn-RH), were reviewed. Extensive clinical studies were carried out at IMSS with agonists of LH-RH, both in men and woman. All subjects responded to LH-RH agonists with a release of LH and FSH, but repeated administration of these analogs, initially aimed at stimulation of fertility (thought to stimulate fertility), was later shown to result in inhibition due to desensitization of pituitary gland and downregulation of LH-RH receptors. Various clinical investigations with LH-RH antagonists were also carried out. This included the first demonstration that LH-RHantagonists can suppress LH and FSH and sex steroid secretion in men and women. Various studies in Mexico with early LH-RH antagonists aimed at the development of new contraceptive methods were reviewed. Modern LH-RH antagonist Cetrorelix was shown to be effective in men and women and useful in treatment of uterine leiomyomas and benign prostatic hyperplasia. Major oncological studies were also carried out with agonist D-Trp6-LH-RH and antagonist Cetrorelix in men with prostate cancer, which demonstrated therapeutic efficacy of both types of analogs. Some endocrine studies with early analogs of somatostatin were also cited and a clinical trial with somatostatin analog vapreotide in patients with relapsed prostate cancer was reviewed. All these studies played a major role in introducing analogs of hypothalamic-releasing hormones into clinical medicine.
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PMID:[History of clinical studies on hypothalamic hormone analogs in Mexico]. 1702 7

Some clinical results indicate that somatostatin (sms) might be useful in the treatment of advanced prostate cancer (HRPC). Because of its transient in vivo half-life only more stable derivatives of sms are of interest in this context. Recent studies have shown that natural sms can be conjugated to a carbohydrate (smsdx) with preservation of sms-like effects on the prostatic tumor cell proteome. The present study identifies some of the affected proteins in an effort to elucidate pathways and proteins that might be of importance for the potential usefulness of sms treatment in HRPC. After incubating the LNCaP cell-line with sms14/smsdx, comparative proteomics was used for analysing and identifying affected proteins. Protein expression patterns were analysed with two-dimensional polyacrylamide gel electrophoresis and mass spectrometry. Catalytic mitochondrial and mitochondrial-associated proteins were significantly affected (fold change approximately 2 or higher) and they were in general up-regulated. Apoptosis-related proteins were both up-regulated (VDAC1, VDAC2) and down-regulated (PRDX2, TCTP). The fold change was >2 for PRDX2 and <2 for the others. There was a strong agreement between sms and smsdx on the up- and down-regulation of proteins. Sms/smsdx triggered up-regulation of catalytic mitochondrial proteins and seemed to affect apoptosis-related proteins. This could indicate important pathways on which smsdx might be able to curb the progression of HRPC. The results encourage a pending clinical phase II study.
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PMID:Somatostatin effects on the proteome of the LNCaP cell-line. 1739 19

Several monoclonal antibodies that target cell surface receptors have gained approval by the U.S. Food and Drug Administration and are widely used in the treatment of some cancers. These include but are not limited to the anti-CD20 antibody Rituximab, used in lymphoma treatment, as well as anti-HER-2 antibody for breast cancer therapy. The efficacy of this cancer immunotherapy modality is, however, limited by the large size of the antibody (160 kd) and its relatively nonspecific binding to the reticuloendothelial system. This latter property is particularly problematic if the antibody is used as a vehicle to deliver radionuclides, cytotoxic drugs, or toxins to the tumor site. Peptides, peptidomimetic, or small molecules are thus attractive as alternative cell surface targeting agents for cancer imaging and therapy. Cancer cell surface targeting peptides can be derived from known native peptide hormones such as somatostatin and bombesin, or they can be identified through screening combinatorial peptide libraries against unknown cell surface receptor targets. Phage-display peptide library and one-bead one-compound (OBOC) combinatorial library methods have been successfully used to discover peptides that target cancer cells or tumor blood vessel endothelial cells. The phage-display peptide library method, because of its biological nature, can only display l-amino acid peptides. In contrast, the OBOC combinatorial library method allows for bead-surface display of peptides that contain l-amino acids, d-amino acids, unnatural amino acids, or other organic moieties. We have successfully used the OBOC method to discover and optimize ligands against unique cell surface receptors of prostate cancer, T- and B-cell lymphoma, as well as ovarian and lung cancers, and we have used some of these peptides to image xenografts in nude mice with high specificity. Here, we (i) review the literature on the use of phage-display and OBOC combinatorial library methods to discover cancer and tumor blood vessel targeting ligands, and (ii) report on the use of an ovarian cancer targeting ligand, OA02, as an in vivo PET imaging probe in a xenograft model in nude mice.
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PMID:From combinatorial chemistry to cancer-targeting peptides. 1788 Jan 66

The discovery of hypothalamic hormones was briefly reviewed. The development of new hormonal methods for the therapy of various cancers based on analogues of hypothalmic hormones is then presented. My group isolated luteininzing hormone-releasing hormone (LH-RH), also known as Gn-RH, from pig hypothalmi, elucidated its amino acid sequence, and synthesized it in 1971. The interest in medical applications of LH-RH led to the synthesis of LH-RH analogues by various groups. LH-RH agonists substituted in positions 6 or 10 including Decapeptyl, Leuprolide and Zoladex are much more active than LH-RH and on continuous administration produce inhibition of pituitary and gonads. Chronic administration of LH-RH agonists is being utilized for the treatment of prostate and breast cancer. Octapeptide analogues of somatostatin have various applications in Oncology. In 1980 we developed a new endocrine therapy for advanced prostate cancer based on agonists of LH-RH, which is now preferred by 70-90% of prostate cancer patients for primary treatment. LH-RH antagonists such as Cetrorelix can be used for therapy of BPH. On the basis of the presence of specific receptors for hypothalamic peptides on human cancers, we developed targeted cytotoxic analogues of LH-RH, somatostatin, and bombesin/GRP linked to doxorubicin or 2-pyrrolinodoxorubicin. These analogues inhibit the growth of experimental human prostate, breast, ovarian and endometrial cancer, renal cell carcinoma, pancreatic, colorectal and gastric cancers, small cell lung carcinoma (SCLC) and non-SCLC, brain tumors, melanomas, and lymphomas. Cytotoxic LH-RH analogues are now in clinical trials. Recently we demonstrated that growth hormone-releasing hormone (GH-RH) also serves as an autocrine growth factor in many cancers. Antagonistic analogues of GH-RH synthesized in our laboratory inhibit the growth of diverse tumors. The discovery of LH-RH and somatostatin has led to clinical use of their analogues in the field of cancer treatment and GH-RH antagonists also show a great promise.
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PMID:New approaches to the therapy of various tumors based on peptide analogues. 1849 Dec 50

Almost all patients with hormone-refractory prostate cancer under primary androgen deprivation therapy will develop progression, frequently initially marked by an asymptomatic increase of prostate-specific antigen (PSA). Recent data showed that taxane-based chemotherapy offers significant survival benefit to patients with advanced prostate cancer; however, the toxic side effects frequently exert a significant negative impact on the quality of life. At the androgen-independent stage of the cancer, before becoming hormone refractory, progression might still be delayed by secondary manipulation of either androgen or confounding receptors and their signaling pathways. Secondary hormonal manipulations traditionally included antiandrogen withdrawal, second-line antiandrogens, direct adrenal androgen inhibitors, estrogens, and progestins.We discuss the mode of action and application of somatostatin analogs as an emerging secondary hormonal treatment concept in patients with advanced prostate cancer on the basis of the current literature.
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PMID:[Somatostatin analogs for the treatment of advanced, hormone-refractory prostate cancer: a possibility for secondary hormonal ablation?]. 1856 91

Somatostatin (SMS), binds to its specific receptors (SSTRs) and transduces growth inhibitory, anti-secretory and apoptotic signals. Several human cancers express SSTRs, including prostate cancer, and therefore SMS is of interest for anti-cancer therapy. DNA methylation and histone modifications are involved in normal cell development, gene imprinting and human carcinogenesis. Reversing DNA methylation is an attractive therapeutic possibility, since epigenetic modifications change gene expression without changing the gene function. DNA methylation inhibitors such as 5-aza-2'-deoxycytidine (5'-aza, decitabine) have been used to treat several types of haematological malignancies. Histone deacetylase inhibitors such as trichostatin (TSA), are a new class of 'targeted anti-cancer agents'. TSA and decitabine can induce growth arrest, apoptosis or terminal differentiation in a variety of solid and haematological cancers in advanced disease patients. In the present study, the LNCaP cell line (prostate cancer) was incubated with SMS or Somadex (an SMS polymer conjugate) for three days, 1 nM per day, and the untreated cells were the negative control. For DNA demethylation, cells were grown in the presence of 2.5 microM 5-aza for 120 h, and re-fed with 5-aza-containing fresh medium at day 3. The total incubation time with 5-aza was 120 h. TSA at 1.0 microM was added into the cultured cells for 24 h. The combined treatment of 5-aza and TSA was performed by incubating the cells with 5-aza for 120 h followed by a 24-h exposure to TSA. Using cDNA obtained from these cell lines, the difference in the expression level of SSTR mRNA transcripts before and after 5-aza and TSA treatments was analyzed by RT-PCR. An increased induction of mRNA expression of the five SSTR subtypes was observed in the LNCaP cells when incubated with SMS/Somadex (dose-dependent). The inhibition of DNA methylation and histone acetylation resulted in the up-regulation of SSTR5 mRNA expression. The results demonstrate a positive feedback loop between SMS and its receptors. This regulation pathway may enhance the anti-tumor activity of somatostatin. To benefit from this effect in a clinical setting, the dose, dose frequency and pan affinity of the SMS derivative are important factors. The epigenetic manipulation with DNA methylation or histone deacetylase inhibitors, combined with SMS, may offer a novel alternative for the treatment of advanced prostate cancer.
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PMID:Incubation with somatostatin, 5-aza decitabine and trichostatin up-regulates somatostatin receptor expression in prostate cancer cells. 1857 31

The growth of prostate cancer is controlled by several hormones and growth factors. In cases of metastasized prostate cancer, antigonadotropic therapy is currently considered state-of-the-art treatment. Surgical therapies such as adrenalectomy and hypophysectomy are no longer in use. Nevertheless, hypophysectomy has proven efficacy for palliative pain treatment as well as increasing duration of survival. The authors present the case of a 63-year-old man with metastatic prostate cancer who presented with high serum prostate-specific antigen levels (1216 microg/L) and cavernous sinus syndrome. His disease was progressing despite leuprorelin and docetaxel therapy, and he had severe bone pain despite high-dose pain therapy. He was also anemic. Contrast-enhanced MR imaging showed a pituitary lesion as well as metastatic infiltration of the skull base including the cavernous sinus. The patient's serum level of prolactin was mildly elevated, testosterone was below the detection limit, and insulin-like growth factor-I (IGF-I) was in the upper range for a patient of his age (233 microg/L). Because of the elevated prolactin and high-normal IGF-I levels he was offered a hypophysectomy in addition to pituitary tumor removal. Histological examination of the resected lesion confirmed a nonsecreting pituitary adenoma with infiltration of prostate cancer cells. Postoperatively the patient's prostate-specific antigen levels dropped to 876 microg/L, his bone pain resolved, and the cavernous sinus syndrome improved. Nevertheless, he died of septicemia 4 months after surgery. Older publications as well as this case have shown the benefit of hypophysectomy for pain treatment. A reduction of IGF-I levels even in the final stage metastasized prostate cancer may play a major role. Respectively, clinical studies with somatostatin analogs are currently in progress, which may lead to a "new" way of treatment in these otherwise hopeless patients. On the basis of the pain relief seen after hypophysectomy in this case and similar benefits reported in older publications, the authors raise the question whether this treatment should be offered more frequently, and whether additional medical options of hormone treatment may be beneficial in similar cases.
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PMID:Hypophysectomy for prostate cancer: a revival of old knowledge? 1882 67

Prostate cancer is a common disease affecting males. Despite initial sensitivity to hormone treatment, prostate cancer eventually progresses to a castration-resistant stage (CRPC), which carries an ominous prognosis. Lanreotide is a long-acting somatostatin analog with the same properties with the native peptide. It has been shown to be highly efficacious in treating various hypersecretoty disorders and tumors. Lanreotide has been administered to patients with CRPC within a novel treatment concept, with the aim of targeting not only cancer cells but also various factors secreted in the tumor cell milieu that confer protection from apoptosis. Within this concept, lanreotide has been administered as part of the "antisurvival factor therapy" in combination with dexamethasone and a gonadotropin releasing hormone (GnRH) analog. It has also been given combined with oestrogens in patients with CRPC. The so far published series have documented a clinical response in many patients treated along with significant improvement in parameters related to quality of life. In view of these promising results, large-scale, randomized, controlled trials are warranted to clearly define the exact role of lanreotide and other somatostatin analogs in the treatment of patients with CRPC.
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PMID:Somatostatin analog lanreotide in the treatment of castration-resistant prostate cancer (CRPC). 1919 84


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