Neurotensin counteracts apoptosis in breast cancer cells

Neurotensin and Its Involvement in Female Hormone-Sensitive Cancers

Neurotensin (NT) is a peptide involved in digestion, neuromodulation, and cancer progression. NT and its receptors (NTR1 and SORT1 mainly) have been widely studied in oncology. Data show that NT expression is under the control of sex steroid hormones, in particular estradiol. We focused on its involvement in three main female hormone-sensitive cancers, breast, ovarian, and endometrial cancer, in a narrative review. NT, NTR1, and SORT1 are mostly expressed in these three cancers, and their involvement in oncologic processes such as proliferation and invasion seems to match, as does their impact on prognosis for most. The development of NT receptor-targeted therapies, including theranostics and radioligand treatments, presents a promising avenue for personalized cancer treatment.

IL-4, IL-7, IL-9, NT, NRP1 May Be Useful Markers in the Diagnosis of Endometrial Cancer

The search for novel endometrial cancer diagnostic biomarkers is pertinent. The purpose of this study was to determine if IL-4, IL-7, IL-9, IL-10, NT, TSP-2, and NRP1 could be used as novel, helpful markers for the detection of endometrial cancer. Ninety-three women diagnosed with endometrial cancer (EC) and sixty-six patients with noncancerous endometrial lesions (NCEL) were included in this study. ELISA was used to measure the concentrations of the proteins tested. Median serum levels of IL-4, IL-7, IL-9, NT, and NRP1 were significantly higher in the EC group compared with NCEL. The cut-off level of IL-4 was set at 802.26 pg/mL with a sensitivity of 83.87% and a specificity of 50% (AUC = 0.7, p = 0.000023). The cut-off level of IL-7 was set at 133.63 ng/L with a sensitivity of 96.77% and a specificity of 75.76% (AUC = 0.91, p < 0.000001). The cut-off level of IL-9 was set at 228.79 pg/mL with a sensitivity of 69.89% and a specificity of 81.82% (AUC = 0.8, p < 0.000001). The cut-off level of NT was set at 275.43 pmol/L with a sensitivity of 94.62% and a specificity of 59.09% (AUC = 0.83, p < 0.000001). The cut-off level of NRP1 was set at 30.37 ng/mL with a sensitivity of 81.72% and a specificity of 57.58% (AUC = 0.71, p = 0.000004). This study suggests the clinical utility of IL-4, IL-7, IL-9, NT, and NRP1 in the diagnosis of endometrial cancer. Nevertheless, these biomarkers may also have prognostic or predictive value, which should be tested in future studies.

The molecular mechanism of chronic stress affecting the occurrence and development of breast cancer and potential drug therapy

According to the 2020 data released by the International Agency for Research on Cancer, breast cancer has surpassed lung cancer as the world's most newly diagnosed first-time cancer. Compared with patients with other types of cancer, those with breast cancer experience greater mental stress and more severe psychological impacts because of the life-threatening diagnosis, physical changes, treatment side effects, and family and social life dysfunctions. These usually manifest as anxiety, depression, nervousness, and insomnia, all of which elicit stress responses. Particularly under chronic stress, the continuous release of neurotransmitters from the neuroendocrine system can have a highly profound impact on the occurrence and prognosis of breast cancer. However, because of the complex mechanisms underlying chronic stress and the variability in individual tolerance, evidence of the role of chronic stress in the occurrence and evolution of breast cancer remains unclear. This article reviewed previous research on the correlation between chronic stress and the occurrence and development of breast cancer, particularly the molecular mechanism through which chronic stress promotes breast cancer via neurotransmitters secreted by the nervous system. We also review the progress in the development of potential drugs or blockers for the treatment of breast cancer by targeting the neuroendocrine system.

Ru(ii)-Peptide bioconjugates with the cppH linker (cppH = 2-(2'-pyridyl)pyrimidine-4-carboxylic acid): synthesis, structural characterization, and different stereochemical features between organic and aqueous solvents

Three new Ru(ii) bioconjugates with the C-terminal hexapeptide sequence of neurotensin, RRPYIL, namely trans,cis-RuCl2(CO)2(cppH-RRPYIL-κNp) (7), [Ru([9]aneS3)(cppH-RRPYIL-κNp)(PTA)](Cl)2 (8), and [Ru([9]aneS3)Cl(cppH-RRPYIL-κNp)]Cl (11), where cppH is the asymmetric linker 2-(2'-pyridyl)pyrimidine-4-carboxylic acid, were prepared in pure form and structurally characterized in solution. The cppH linker is capable of forming stereoisomers (i.e. linkage isomers), depending on whether the nitrogen atom ortho (No) or para (Np) to the carboxylate on C4 in the pyrimidine ring binds the metal ion. Thus, one of the aims of this work was to obtain pairs of stereoisomeric conjugates and investigate their biological (anticancer, antibacterial) activity. A thorough NMR characterization clearly indicated that in all cases exclusively Np conjugates were obtained in pure form. In addition, the NMR studies showed that, whereas in DMSO-d6 each conjugate exists as a single species, in D2O two (7) or even three if not four (8 and 11) very similar stable species form (each one corresponding to an individual compound). Similar results were observed for the cppH-RRPYIL ligand alone. Overall, the NMR findings are consistent with the occurrence of a strong intramolecular stacking interaction between the phenol ring of tyrosine and the pyridyl ring of cppH. Such stacking interactions between aromatic rings are expected to be stronger in water. This interaction leads to two stereoisomeric species in the free cppH-RRPYIL ligand and in the bioconjugate 7, and is somehow modulated by the less symmetrical Ru coordination environments in 8 and 11, affording three to four very similar species.

Dimeric Prodrug Self-Delivery Nanoparticles with Enhanced Drug Loading and Bioreduction Responsiveness for Targeted Cancer Therapy

Efficient drug accumulation in tumor cells is essential for cancer therapy. Herein, we developed dimeric prodrug self-delivery nanoparticles (NPs) with enhanced drug loading and bioreduction responsiveness for triple negative breast cancer (TNBC) therapy. Specially designed camptothecin dimeric prodrug (CPTD) containing a disulfide bond was constructed to realize intracellular redox potential controlled drug release. Direct conjugation of hydrophobic CPTD to poly(ethylene glycol) PEG₅₀₀₀, a prodrug-based amphiphilic CPTD-PEG₅₀₀₀ co-polymer was synthesized, which could encapsulate parental CPTD prodrug spontaneously and form ultrastable NPs due to the highly analogous structure. Such dimeric prodrug self-delivery nanoparticles showed ultrahigh stability with critical micelle concentration as low as 0.75 μg/mL and remained intact during endocytosis. In addition, neurotensin (NT), a 13 amino acid ligand, was further modified on the nanoparticles for triple negative breast cancer (TNBC) targeting. Optimized NT-CPTD NPs showed improved pharmacokinetics profile and increased drug accumulation in TNBC lesions than free CPT, which largely reduced the systemic toxicity and presented an improved anticancer efficacy in vivo. In summary, with advantages of extremely high drug loading capacity, tumor microenvironmental redox responsiveness, and targeted TNBC accumulation, NT-CPTD NPs showed their potential for effective triple negative breast cancer therapy.

Oncogenic role of neurotensin and neurotensin receptors in various cancers

Neurotensin (NTS) has long been recognized as a neurotransmitter or neuromodulator in the central nervous system and as an endocrine agent in the periphery via actions mediated through neurotensin receptors (NTSRs). Many studies support a role for NTS in the endocrine, autocrine and paracrine growth stimulation of cancer, with oncogenic actions described for NTS in different types of cancers and cancer cell lines at each step of cancer progression, ranging from tumour growth and survival to metastatic spread. The mechanisms underlying the effects of the NTS/NTSR system in cell proliferation, migration and invasion, as well as the anti-apoptotic effects of this system, have been elucidated in different types of cancers, and include mitogen-activated protein kinases, phosphatidylinositol 3-kinase and RhoGTPases. The present mini review summarizes recent findings relating to the oncogenic function of the NTS/NTSR system.

NTS/NTR1 co-expression enhances epithelial-to-mesenchymal transition and promotes tumor metastasis by activating the Wnt/β-catenin signaling pathway in hepatocellular carcinoma

Neurotensin (NTS) is a neuropeptide distributed in central nervous and digestive systems. In this study, the significant association between ectopic NTS expression and tumor invasion was confirmed in hepatocellular carcinoma (HCC). In primary HCC tissues, the NTS and neurotensin receptor 1 (NTR1) co-expression (NTS⁺NTR1⁺) is a poor prognostic factor correlated with aggressive biological behaviors and poor clinical prognosis. Enhanced epithelial-to-mesenchymal transition (EMT) features, including decreased E-cadherin, increased β-catenin translocation and N-cadherin expression, were identified in NTS⁺NTR1⁺ HCC tissues. Varied NTS-responsible HCC cell lines were established using NTR1 genetically modified Hep3B and HepG2 cells which were used to elucidate the molecular mechanisms regulating NTS-induced EMT and tumor invasion in vitro. Results revealed that inducing exogenous NTS stimulation and enhancing NTR1 expression promoted tumor invasion rather than proliferation by accelerating EMT in HCC cells. The NTS-induced EMT was correlated with the remarkable increase in Wnt1, Wnt3, Wnt5, Axin, and p-GSK3β expression and was significantly reversed by blocking the NTS signaling via the NTR1 antagonist SR48692 or by inhibiting the activation of the Wnt/β-catenin pathway via specific inhibitors, such as TSW119 and DKK-1. SR48692 also inhibited the metastases of NTR1-overexpressing HCC xenografts in the lungs in vivo. This finding implied that NTS may be an important stimulus to promote HCC invasion and metastasis both in vitro and in vivo, and NTS signaling enhanced the tumor EMT and invasion potentials by activating the canonical Wnt/β-catenin signaling pathway. Therefore, NTS may be a valuable therapeutic target to prevent tumor progression in HCC.

New extracellular factors in glioblastoma multiforme development: neurotensin, growth differentiation factor-15, sphingosine-1-phosphate and cytomegalovirus infection

Recent years have seen considerable progress in understanding the biochemistry of cancer. For example, more significance is now assigned to the tumor microenvironment, especially with regard to intercellular signaling in the tumor niche which depends on many factors secreted by tumor cells. In addition, great progress has been made in understanding the influence of factors such as neurotensin, growth differentiation factor-15 (GDF-15), sphingosine-1-phosphate (S1P), and infection with cytomegalovirus (CMV) on the 'hallmarks of cancer' in glioblastoma multiforme. Therefore, in the present work we describe the influence of these factors on the proliferation and apoptosis of neoplastic cells, cancer stem cells, angiogenesis, migration and invasion, and cancer immune evasion in a glioblastoma multiforme tumor. In particular, we discuss the effect of neurotensin, GDF-15, S1P (including the drug FTY720), and infection with CMV on tumor-associated macrophages (TAM), microglial cells, neutrophil and regulatory T cells (T_reg), on the tumor microenvironment. In order to better understand the role of the aforementioned factors in tumoral processes, we outline the latest models of intratumoral heterogeneity in glioblastoma multiforme. Based on the most recent reports, we discuss the problems of multi-drug therapy in treating glioblastoma multiforme.

Neurotensin receptor type 2 protects B-cell chronic lymphocytic leukemia cells from apoptosis

B-cell chronic lymphocytic leukemia (B-CLL) cells are resistant to apoptosis, and consequently accumulate to the detriment of normal B cells and patient immunity. Because current therapies fail to eradicate these apoptosis-resistant cells, it is essential to identify alternative survival pathways as novel targets for anticancer therapies. Overexpression of cell-surface G protein-coupled receptors drives cell transformation, and thus plays a critical role in malignancies. In this study, we identified neurotensin receptor 2 (NTSR2) as an essential driver of apoptosis resistance in B-CLL. NTSR2 was highly expressed in B-CLL cells, whereas expression of its natural ligand, neurotensin (NTS), was minimal in both B-CLL cells and patient plasma. Surprisingly, NTSR2 remained in a constitutively active phosphorylated state, caused not by a mutation-induced gain-of-function but rather by an interaction with the oncogenic tyrosine kinase receptor TrkB. Functional and biochemical characterization revealed that the NTSR2-TrkB interaction acts as a conditional oncogenic driver requiring the TrkB ligand brain-derived neurotrophic factor (BDNF), which unlike NTS is highly expressed in B-CLL cells. Together, NTSR2, TrkB and BDNF induce autocrine and/or paracrine survival pathways that are independent of mutation status and indolent or progressive disease course. The NTSR2-TrkB interaction activates survival signaling pathways, including the Src and AKT kinase pathways, as well as expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL. When NTSR2 was downregulated, TrkB failed to protect B-CLL cells from a drastic decrease in viability via typical apoptotic cell death, reflected by DNA fragmentation and Annexin V presentation. Together, our findings demonstrate that the NTSR2-TrkB interaction plays a crucial role in B-CLL cell survival, suggesting that inhibition of NTSR2 represents a promising targeted strategy for treating B-CLL malignancy.

Expression of neurotensin receptor 1 in endometrial adenocarcinoma is correlated with histological grade and clinical outcome

The promalignant effects of neurotensin (NTS) are sustained in many solid tumors, including hormone-dependent cancers. As the endometrium is also subjected to hormonal regulation, we evaluated the contribution of NTS to endometrial carcinogenesis. Neurotensin receptor 1 (NTSR1) expression and NTSR1 promoter methylation (HM450) were analyzed in 385 cases of endometrial carcinoma from The Cancer Genome Atlas (TCGA). Additionally, from a series of 100 endometrial carcinomas, and 66 benign endometrium samples, NTS and NTSR1 labeling was evaluated by immunohistochemistry. Using TCGA series, NTSR1 messenger RNA (mRNA) level was negatively correlated with overall survival (OS) and progression-free survival (PFS) (p = 0.0012 and p = 0.0116, respectively), and positively correlated with the grade (p = 0.0008). When including only endometrioid carcinomas, NTSR1 mRNA level continued to be negatively correlated with OS (log-rank: p < 0.0001) and PFS (log-rank: p = 0.002). A higher NTSR1 mRNA level was significantly associated with a loss of NTSR1 promoter methylation. Immunohistochemical expression of NTS and NTSR1 was significantly increased in adenocarcinoma (n = 100), as compared to benign endometrium (p < 0.001). NTSR1 expression was positively correlated with grade (p = 0.004). High immunohistochemical expression of cytoplasmic NTSR1 was significantly correlated with a shorter OS and PFS (p < 0.001 and p = 0.001, respectively). This correlation remained significant when excluding non-endometrioid subtypes (p = 0.04 and p = 0.02, respectively). In multivariate analysis, the expression of NTSR1 was an independent prognostic factor (p = 0.004). NTSR1 overexpression is a poor prognostic factor in endometrial cancer, highlighting the contribution of NTS in endometrial cancer progression and its uses as a prognostic marker, and as a potential therapeutic target.

Neurotensin Receptor 1 Antagonist SR48692 Improves Response to Carboplatin by Enhancing Apoptosis and Inhibiting Drug Efflux in Ovarian Cancer

Purpose: The high affinity receptor 1 (NTSR1) and its agonist, neurotensin (NTS), are correlated with tumor cell aggressiveness in most solid tumors. As chemoresistance and tumor aggressiveness are often related, we decided to study the role of the NTSR1 complex within platinum-based chemotherapy responses. In an ovarian model, we studied carboplatin because it is the main standard of care for ovarian cancer.Experimental Design: Experimental tumors and in vitro studies were performed using SKOV3 and A2780 cells treated with carboplatin, with or without a very specific NTSR1 antagonist, SR48692. We measured the effects of these treatments on cell apoptosis and apoptosis-related proteins, platinum accumulation in the cell and nucleus, and the expression and localization of platinum transporters. NTS and NTSR1 labeling was measured in patients with ovarian cancer.Results: SR48692 enhanced the response to carboplatin in ovarian cancer cells and experimental tumors. When SR48692 is combined with carboplatin, we noted a major improvement of platinum-induced DNA damage and cell death, as well as a decrease in tumor growth. The relationship of these results to clinical studies was made by the detection of NTS and NTSR1 in 72% and 74% of ovarian cancer, respectively. Furthermore, in a large series of high-grade ovarian cancer, NTSR1 mRNA was shown to correlate with higher stages and platinum resistance.Conclusions: This study strongly suggests that the addition of NTSR1 inhibitor in combination with platinum salt-based therapy will improve the response to the drug. Clin Cancer Res; 23(21); 6516-28. ©2017 AACR.

The Internalization of Neurotensin by the Low-Affinity Neurotensin Receptors (NTSR2 and vNTSR2) Activates ERK 1/2 in Glioma Cells and Allows Neurotensin-Polyplex Transfection of tGAS1

Glioblastoma is the most malignant primary brain tumor and is very resistant to treatment; hence, it has a poor prognosis. Neurotensin receptor type 1 (NTSR1) plays a key role in cancer malignancy and has potential therapeutic applications. However, the presence and function of neurotensin (NTS) receptors in glioblastoma is not clearly established. RT-PCR assays showed that healthy (non-tumor) astroglial cells and C6 glioma cells express NTSR2 and its isoform (vNTSR2) rather than NTSR1. In glioma cells, NTS promotes the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK 1/2), an effect that was completely abolished by blocking the internalization of the NTS/NTSR complex. We demonstrated pharmacologically that the internalization is dependent on the activation of NTSR2 receptors and it was prevented by levocabastine, a NTSR2 receptor antagonist. The internalization of NTSR2 and vNTSR2 was further demonstrated by its ability to mediate gene transfer (transfection) via the NTS-polyplex system. Expression of reporter transgenes and of the pro-apoptotic soluble form of growth arrest specific 1 (tGAS1) was observed in glioma cells. A significant reduction on the viability of C6 cells was determined when tGAS1 was transfected into glioma cells. Conversely, astroglial cells could neither internalize NTS nor activate ERK 1/2 and could not be transfected by the NTS-polyplex. These results demonstrate that the internalization process of NTSR2 receptors is a key regulator necessary to trigger the activation of the ERK 1/2. Our data support a new internalization pathway in glioma C6 cells that involve NTSR2/vNTSR2, which can be used to selectively transfer therapeutic genes using the NTS-polyplex system.

Activation of EGFR, HER2 and HER3 by neurotensin/neurotensin receptor 1 renders breast tumors aggressive yet highly responsive to lapatinib and metformin in mice

A present challenge in breast oncology research is to identify therapeutical targets which could impact tumor progression. Neurotensin (NTS) and its high affinity receptor (NTSR1) are up regulated in 20% of breast cancers, and NTSR1 overexpression was shown to predict a poor prognosis for 5 year overall survival in invasive breast carcinomas. Interactions between NTS and NTSR1 induce pro-oncogenic biological effects associated with neoplastic processes and tumor progression. Here, we depict the cellular mechanisms activated by NTS, and contributing to breast cancer cell aggressiveness. We show that neurotensin (NTS) and its high affinity receptor (NTSR1) contribute to the enhancement of experimental tumor growth and metastasis emergence in an experimental mice model. This effect ensued following EGFR, HER2, and HER3 over-expression and autocrine activation and was associated with an increase of metalloproteinase MMP9, HB-EGF and Neuregulin 2 in the culture media. EGFR over expression ensued in a more intense response to EGF on cellular migration and invasion. Accordingly, lapatinib, an EGFR/HER2 tyrosine kinase inhibitor, as well as metformin, reduced the tumor growth of cells overexpressing NTS and NTSR1. All cellular effects, such as adherence, migration, invasion, altered by NTS/NTSR1 were abolished by a specific NTSR1 antagonist. A strong statistical correlation between NTS-NTSR1-and HER3 (p< 0.0001) as well as NTS-NTSR1-and HER3- HER2 (p< 0.001) expression was found in human breast tumors. Expression of NTS/NTSR1 on breast tumoral cells creates a cellular context associated with cancer aggressiveness by enhancing epidermal growth factor receptor activity. We propose the use of labeled NTS/NTSR1 complexes to enlarge the population eligible for therapy targeting HERs tyrosine kinase inhibitor or HER2 overexpression.

Neurotensin, a Novel Messenger to Cross-Link Inflammation and Tumor Invasion via Epithelial-Mesenchymal Transition Pathway

Multiple cytokines and growth factors are critical for the prognosis of cancer which has been regarded as a worldwide health problem. Recently, neuropeptides, soluble factors regulating a series of functions in the central nervous system, have also been demonstrated to stimulate the proliferation and migration of tumor cells. Among these signaling peptides, the role of neurotensin (NTS) on malignancy procession has become a hot topic. The effects of NTS on tumor growth and its antiapoptosis role have already been identified. Subsequently, studies demonstrated the impact of NTS on the migration and invasion, but the molecular mechanisms involved are still unclear at present. Recently, some reports indicated that NTS could induce expression and secretion of interleukin-8 (IL-8) to promote local imflammatory response which might participate in epithelial-mesenchymal transition (EMT)-related tumor migration. In present review, we highlight the process of tumor EMT induced by NTS through stimulating IL-8 and the significance of NTS/IL-8 pathway in clinical application prospect.

Suicide HSVtk gene delivery by neurotensin-polyplex nanoparticles via the bloodstream and GCV Treatment specifically inhibit the growth of human MDA-MB-231 triple negative breast cancer tumors xenografted in athymic mice

The human breast adenocarcinoma cell line MDA-MB-231 has the triple-negative breast cancer (TNBC) phenotype, which is an aggressive subtype with no specific treatment. MDA-MB-231 cells express neurotensin receptor type 1 (NTSR1), which makes these cells an attractive target of therapeutic genes that are delivered by the neurotensin (NTS)-polyplex nanocarrier via the bloodstream. We addressed the relevance of this strategy for TNBC treatment using NTS-polyplex nanoparticles harboring the herpes simplex virus thymidine kinase (HSVtk) suicide gene and its complementary prodrug ganciclovir (GCV). The reporter gene encoding green fluorescent protein (GFP) was used as a control. NTS-polyplex successfully transfected both genes in cultured MDA-MB-231 cells. The transfection was demonstrated pharmacologically to be dependent on activation of NTSR1. The expression of HSVtk gene decreased cell viability by 49% (P<0.0001) and induced apoptosis in cultured MDA-MB-231 cells after complementary GCV treatment. In the MDA-MB-231 xenograft model, NTS-polyplex nanoparticles carrying either the HSVtk gene or GFP gene were injected into the tumors or via the bloodstream. Both routes of administration allowed the NTS-polyplex nanoparticles to reach and transfect tumorous cells. HSVtk expression and GCV led to apoptosis, as shown by the presence of cleaved caspase-3 and Apostain immunoreactivity, and significantly inhibited the tumor growth (55-60%) (P<0.001). At the end of the experiment, the weight of tumors transfected with the HSVtk gene was 55% less than that of control tumors (P<0.05). The intravenous transfection did not induce apoptosis in peripheral organs. Our results offer a promising gene therapy for TNBC using the NTS-polyplex nanocarrier.

The anti-apoptotic role of neurotensin

The neuropeptide, neurotensin, exerts numerous biological functions, including an efficient anti-apoptotic role, both in the central nervous system and in the periphery. This review summarizes studies that clearly evidenced the protective effect of neurotensin through its three known receptors. The pivotal involvement of the neurotensin receptor-3, also called sortilin, in the molecular mechanisms of the anti-apoptotic action of neurotensin has been analyzed in neuronal cell death, in cancer cell growth and in pancreatic beta cell protection. The relationships between the anti-apoptotic role of neurotensin and important physiological and pathological contexts are discussed in this review.

Synthesis and in vitro cytotoxicity of cis,cis,trans-diamminedichloridodisuccinatoplatinum(IV)-peptide bioconjugates

The synthesis and characterization of four Pt(IV)-peptide conjugates, containing one or two peptides in the axial position, designed for the purpose of targeted drug delivery to tumor cells, are described. The precursor cis,cis,trans-diamminedichloridodisuccinatoplatinum(IV) was coupled in the last step of standard solid-phase peptide synthesis (SSPS) with an analogue of neurotensin (pseudo-neurotensin = Lys-Lys-Pro-Tyr-Ile-Leu) and with octreotate (D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-OH), an analogue of somatostatin, respectively. For all peptides, the SSPS reactions afforded both mono- and diconjugated Pt-peptide species, which were separated and purified by RP-HPLC. The two couples of conjugates, together with the precursor, were tested as cytotoxic agents towards different cancer cell lines. In general all conjugates are good inhibitors of cellular proliferation when compared to a nontargeting platinum(IV) parent compound, so that its relatively low cytotoxicity is greatly improved by addition of the peptides.

Neurotensin and its high affinity receptor 1 as a potential pharmacological target in cancer therapy

Cancer is a worldwide health problem. Personalized treatment represents a future advancement for cancer treatment, in part due to the development of targeted therapeutic drugs. These molecules are expected to be more effective than current treatments and less harmful to normal cells. The discovery and validation of new targets are the foundation and the source of these new therapies. The neurotensinergic system has been shown to enhance cancer progression in various cancers such as pancreatic, prostate, lung, breast, and colon cancer. It also triggers multiple oncogenic signaling pathways, such as the PKC/ERK and AKT pathways. In this review, we discuss the contribution of the neurotensinergic system to cancer progression, as well as the regulation and mechanisms of the system in order to highlight its potential as a therapeutic target, and its prospect for its use as a treatment in certain cancers.

Inhibition of neurotensin receptor 1 selectively sensitizes prostate cancer to ionizing radiation

Radiotherapy combined with androgen depletion is generally successful for treating locally advanced prostate cancer. However, radioresistance that contributes to recurrence remains a major therapeutic problem in many patients. In this study, we define the high-affinity neurotensin receptor 1 (NTR1) as a tractable new molecular target to radiosensitize prostate cancers. The selective NTR1 antagonist SR48692 sensitized prostate cancer cells in a dose- and time-dependent manner, increasing apoptotic cell death and decreasing clonogenic survival. The observed cancer selectivity for combinations of SR48692 and radiation reflected differential expression of NTR1, which is highly expressed in prostate cancer cells but not in normal prostate epithelial cells. Radiosensitization was not affected by androgen dependence or androgen receptor expression status. NTR1 inhibition in cancer cell-attenuated epidermal growth factor receptor activation and downstream signaling, whether induced by neurotensin or ionizing radiation, establish a molecular mechanism for sensitization. Most notably, SR48692 efficiently radiosensitized PC-3M orthotopic human tumor xenografts in mice, and significantly reduced tumor burden. Taken together, our findings offer preclinical proof of concept for targeting the NTR1 receptor as a strategy to improve efficacy and outcomes of prostate cancer treatments using radiotherapy.

The potential use of the neurotensin high affinity receptor 1 as a biomarker for cancer progression and as a component of personalized medicine in selective cancers

A growing challenge in medicine today, is the need to improve the suitability of drug treatments for cancer patients. In this field, biomarkers have become the "flags" to provide additional information in tumor biology. They are a relay between the patient and practitioner and consequently, aid in the diagnosis, providing information for prognosis, or in some cases predicting the response to specific therapies. In addition to being markers, these tumor "flags" can also be major participants in the process of carcinogenesis. Neurotensin receptor 1 (NTSR1) was recently identified as a prognosis marker in breast, lung, and head and neck squamous carcinomas. Neurotensin (NTS) was also shown to exert numerous oncogenic effects involved in tumor growth and metastatic spread. These effects were mostly mediated by NTSR1, making the NTS/NTSR1 complex an actor in cancer progression. In this review, we gather information on the oncogenic effects of the NTS/NTSR1 complex and its associated signaling pathways in order to illuminate its significant role in tumor progression and its potential as a biomarker and a therapeutic target in some tumors.

Neurotensin receptor 1 determines the outcome of non-small cell lung cancer

PURPOSE

This study aimed to investigate the role of the neurotensin/neurotensin receptor I (NTSR1) complex in non-small cell lung cancer (NSCLC) progression.

EXPERIMENTAL DESIGN

The expression of neurotensin and NTSR1 was studied by transcriptome analysis and immunohistochemistry in two series of 74 and 139 consecutive patients with pathologic stage I NSCLC adenocarcinoma. The findings were correlated with clinic-pathologic features. Experimental tumors were generated from the malignant human lung carcinoma cell line A459, and a subclone of LNM35, LNM-R. The role of the neurotensin signaling system on tumor growth and metastasis was investigated by small hairpin RNA-mediated silencing of NTSR1 and neurotensin.

RESULTS

Transcriptome analysis carried out in a series of 74 patients showed that the positive regulation of NTSR1 put it within the top 50 genes related with relapse-free survival. Immunohistochemistry revealed neurotensin- and NTSR1-positive staining in 60.4% and 59.7% of lung adenocarcinomas, respectively. At univariate analysis, NTSR1 expression was strongly associated with worse 5-year overall survival rate (P = 0.0081) and relapse-free survival (P = 0.0024). Multivariate analysis showed that patients over 65 years of age (P = 0.0018) and NTSR1 expression (P = 0.0034) were independent negative prognostic factors. Experimental tumor xenografts generated by neurotensin- and NTSR1-silenced human lung cancer cells revealed that neurotensin enhanced primary tumor growth and production of massive nodal metastasis via autocrine and paracrine regulation loops.

CONCLUSION

NTSR1 expression was identified as a potential new prognostic biomarker for surgically resected stage I lung adenocarcinomas, as NTSR1 activation was shown to participate in lung cancer progression.

Neurotensin(8-13) analogue: radiolabeling and biological evaluation using different chelators

INTRODUCTION

Several strategies on the development of radiopharmaceuticals have been employed. Bifunctional chelators seem to be a promising approach since high radiochemical yields as well as good in vitro and in vivo stability have been achieved. To date, neurotensin analogs have been radiolabeled using the (99m)Tc-carbonyl approach and none was described employing the bifunctional chelating agent technique.

AIM

The purpose of this study was to evaluate the radiochemical and biological behaviour of NT(8-13) analogue radiolabeled with (99m)Tc, using HYNIC and NHS-S-acetyl-MAG(3) as chelator agents.

METHODS

Radiolabeling, in vitro stability toward cysteine and glutathione, partition coefficient and plasma protein binding were assessed for both radioconjugates. Biodistribution in healthy Swiss mice were carried out in order to evaluate the biological behaviour of the radiocomplexes.

RESULTS

Radiochemical yields were higher than 97% and no apparent instability toward transchelant agents was observed for both radioconjugates. A higher lipophilic character was observed for the radioconjugate labeled via MAG(3). The chelators seem to have no effect on the percentage of the radioconjugate bound to plasma proteins. A similar biological pattern was observed for both radioconjugates. Total blood, bone and muscle values revealed a slightly slower clearance for the radiocomplex labeled via MAG(3). Moreover, a remarkable liver and intestinal uptake was observed for the radiocomplex labeled via MAG(3) even at the later time points studied.

CONCLUSION

The high radiochemical yields achieved and the similar in vivo pattern found for both radioconjugates make them potential candidates for imaging tumors using nuclear medicine techniques.

Cancer, chemistry, and the cell: molecules that interact with the neurotensin receptors

The literature covering neurotensin (NT) and its signalling pathways, receptors, and biological profile is complicated by the fact that the discovery of three NT receptor subtypes has come to light only in recent years. Moreover, a lot of this literature explores NT in the context of the central nervous system and behavioral studies. However, there is now good evidence that the up-regulation of NT is intimately involved in cancer development and progression. This Review aims to summarize the isolation, cloning, localization, and binding properties of the accepted receptor subtypes (NTR1, NTR2, and NTR3) and the molecules known to bind at these receptors. The growing role these targets are playing in cancer research is also discussed. We hope this Review will provide a useful overview and a one-stop resource for new researchers engaged in this field at the chemistry-biology interface.

Nanoliposomal short-chain ceramide inhibits agonist-dependent translocation of neurotensin receptor 1 to structured membrane microdomains in breast cancer cells

Neurotensin (NTS) receptor 1 (NTSR1) is a G protein-coupled receptor that has been recently identified as a mediator of tumorigenicity and metastasis. NTSR1, as well as its endogenous ligand, NTS, are coexpressed in several breast cancer cell lines and breast cancer tumor samples but not in normal breast tissue. We have previously published that ceramide mimetics could inhibit breast cancer growth in vitro and in vivo. Thus, understanding the biochemical and biophysical regulation of NTSR1 by ceramide can help further define NTSR1 as a novel target in breast cancer. Our results show that nanoliposomal formulations of ceramide inhibit NTSR1-mediated MDA-MB-231 breast cancer progression (mitogenesis, migration, and matrix metalloproteinase-9 activity). In addition, liposomal ceramide inhibited NTSR1-mediated, but not phorbol 12-myristate 13-acetate-mediated, activation of the mitogen-activated protein kinase pathway. Mechanistically, nanoliposomal short-chain ceramide reduces NTSR1 interaction with Galphaq/11 subunits within structured membrane microdomains, consistent with diminished NTS-induced translocation of NTSR1 into membrane microdomains. Collectively, our findings suggest that exogenous short-chain ceramide has the potential to be used as an adjuvant therapy to inhibit NTS-dependent breast cancer progression.

Selection of a biotin protein ligase by phage display using a combination of in vitro selection and in vivo enzymatic activity

We report the development of a phage display-based method for the direct selection of enzymatic activity by a combination of selection in vitro and an assay of enzymatic activity in vivo. We describe the selection of a biotin protein ligase (BPL) that specifically recognizes neurotensin as a substrate, as an example of the utility of our method. We constructed an enzyme library with a diversity of 8.8 x 10(6) by insertion of four randomized regions into a BPL backbone and used it for the selection of variant BPLs. We obtained an active BPL, which was identical to wild-type BPL, using the combination of selection in vitro and an assay of enzymatic activity in vivo. Our results indicate that our method is suitable for the selection of enzymes with specific functions of interest.

The neurotensin receptor-1 pathway contributes to human ductal breast cancer progression

Background

The neurotensin (NTS) and its specific high affinity G protein coupled receptor, the NT1 receptor (NTSR1), are considered to be a good candidate for one of the factors implicated in neoplastic progression. In breast cancer cells, functionally expressed NT1 receptor coordinates a series of transforming functions including cellular migration and invasion.

Methods and Results

we investigated the expression of NTS and NTSR1 in normal human breast tissue and in invasive ductal breast carcinomas (IDCs) by immunohistochemistry and RT-PCR. NTS is expressed and up-regulated by estrogen in normal epithelial breast cells. NTS is also found expressed in the ductal and invasive components of IDCs. The high expression of NTSR1 is associated with the SBR grade, the size of the tumor, and the number of metastatic lymph nodes. Furthermore, the NTSR1 high expression is an independent factor of prognosis associated with the death of patients.

Conclusion

these data support the activation of neurotensinergic deleterious pathways in breast cancer progression.

Increased neurotensin receptor-1 expression during progression of colonic adenocarcinoma

The high affinity neurotensin receptor (NTSR1) mediates most of the biologic effects of neurotensin (NT), a 13-amino acid peptide that stimulates growth in certain cell types. NT is expressed in fetal but not differentiated colonic epithelium and is re-expressed in colonic adenocarcinoma. The cognate receptor, NTSR1, is also not expressed or is present at a low level in adult colonic epithelial cells but is expressed in most colon cancer cell lines. These observations suggest that altered NT-NTSR1 signaling may be associated with malignant transformation in the colon. To further understand the possible role of NTSR1 expression in colonic tumorigenesis and progression, we examined NTSR1 mRNA by in situ hybridization in normal colonic mucosa, adenomas, and colonic adenocarcinomas. NTSR1 mRNA expression was undetectable or weak in superficial differentiated epithelial cells of normal colonic epithelium, but adenomas and adenocarcinomas showed moderate to strong expression (p<0.05). Adenocarcinomas showed a higher level of expression compared to adenomas (p<0.05). Furthermore, adenocarcinomas that infiltrated into and beyond the muscularis propria showed a higher intensity of NTSR1 expression compared with tumors that were localized to the mucosa or submucosa. In some cases, infiltrating margins and foci of lymphovascular invasion showed a higher intensity of expression than the main mass of the tumor. These results suggest that increased NTSR1 expression may be an early event during colonic tumorigenesis and also contribute to tumor progression and aggressive behavior in colonic adenocarcinomas. NTSR1 may thus be a potential target for preventive or therapeutic strategies in colon cancer.

Expression of neurotensin and its receptors in pituitary adenomas

The neurotensin (NT) produced in the hypothalamus and in pituitary gonadotrophs and thyrotrophs participates in neuroendocrine regulation. Recently, the involvement of this peptide in normal and neoplastic cell proliferation has been postulated. In the present study, we evaluated the expression of NT and its receptors (NTR1, 2 and 3) in a series of 50 pituitary adenomas [11 growth hormone (GH)-, eight prolactin (PRL)-, four adrenocorticotrophic hormone (ACTH)- and 27 nonfunctioning adenomas]. NT mRNA expression was significantly higher in functioning compared to nonfunctioning adenomas and with normal pituitary. Nonfunctioning pituitary adenomas showed lower expression of NT mRNA than normal pituitary. In the immunohistochemical study of functioning adenomas, NT was colocalised with GH, PRL and ACTH secreting cells. In nonfunctioning adenomas, the NT immunoreactivity intensity was variable among the samples. NTR3 mRNA expression was observed in all examined samples and was higher in the adenomas, both functioning and nonfunctioning, compared to normal pituitary. By contrast, NTR1 and NTR2 mRNA were not detected in either pituitary adenomas or normal tissue. The higher expression of NTR3, as well as the expression of NT by tumoural corticotrophs, lactotrophs and somatotrophs, which are cells types that do not express this peptide in the normal pituitary, suggests that NT autocrine and/or paracrine stimulation mediated by NTR3 may be a mechanism associated with the tumourigenesis of functioning adenomas.

Molecular profile of the BCL2 family of the apoptosis related genes in breast cancer cells after treatment with cytotoxic/cytostatic drugs

BCL2 (bcl-2) gene family members are important regulators of apoptosis. Increasing evidence supports their modulated expression in breast cancer cells and in many cases their relation to chemotherapy response, outcome, and overall prognosis, as well as their value as important potent therapeutic targets. Investigation and increased understanding of their transcriptional regulation and their specific roles in cancer progression and therapy response will be useful for focusing research on the development of novel therapies targeted against this gene family members' expression status. In the present review, we describe current knowledge of the molecular profile of the classical and novel members of the BCL2 family of genes as a response of breast cancer cells to cytotoxic/cytostatic drugs.

Chromosomal changes associated with clinical outcome in lymph node-negative breast cancer

Breast cancer is the most common malignancy among women and accounts for over one million new cases worldwide per year. Lymph node-negative breast cancer patients are reputed as having a better prognosis than lymph node-positive ones. Around 20% of the lymph node-negative patients die within 10 years after diagnosis. To improve the prognostics of node-negative breast cancer, it is important to understand the underlying biologic mechanisms promoting survival, such as specific genetic changes in the tumor genome. In this study, CGH was applied to analyze 64 tumors from node-negative breast cancer patients to identify DNA copy number changes in chromosomes and chromosome regions that may be correlated to survival. The main findings show gains at 4q, 5q31 approximately qter, 6q12 approximately q16, and 12q14 approximately q22, as well as losses of 17p, 18p, and Xq, which were significantly more recurrent in tumors from deceased patients than in tumors from survivors. The average number of chromosomal changes was higher in the tumors from deceased compared to the survivor tumors. Our findings suggest that tumors with specific chromosomal aberrations at 4q, 5q31 approximately qter, 6q12 approximately q16, 12q14 approximately q22, 17p, 18p, and Xq result in an aggressive form of breast cancer and that these patients are predisposed to succumb to breast cancer.

Neurotensin and growth of normal and neoplastic tissues

Neurotensin (NT) is a brain-gut tridecapeptide that functions as a neurotransmitter/neuromodulator in the central nervous system (CNS) and as an endocrine agent in the periphery. NT has numerous physiologic effects on multiple organs. This review will focus on the effects of NT as a trophic factor for normal and neoplastic tissues. In this regard, NT may act as an endocrine agent or, in some instances, in a paracrine and/or autocrine fashion. These effects appear to be mediated predominantly through the G protein-coupled high-affinity NT receptor. However, some of the trophic effects may also be through the other two receptor subtypes, particularly the NT receptor type 3, which belongs to a recently identified family of sorting receptors. The signaling pathways mediating the effects of NT are multiple but most appear to activate the ERK signaling pathway, which then activates downstream transcription factors, ultimately leading to proliferation. NT may be a useful agent to enhance the growth of normal tissues such as the small bowel mucosa during periods of gut disuse or disease and, finally, the selective targeting of NT receptor subtypes on certain cancers may offer a novel strategy in the armamentarium of cancer chemotherapeutics.

Involvement of neurotensin in cancer growth: evidence, mechanisms and development of diagnostic tools

Focusing on the literature of the past 15 years, we evaluate the evidence that neurotensin and neurotensin receptors participate in cancer growth and we describe possible mechanisms. In addition, we review the progress achieved in the use of neurotensin analogs to image tumors in animals and humans. These exciting advances encourage us to pursue further research and stimulate us to consider novel ideas regarding the multiple inputs to cancer growth that neurotensin might influence.

Expression of Neurotensin and NT1 Receptor in Human Breast Cancer: A Potential Role in Tumor Progression

Emerging evidence supports neurotensin as a trophic and antiapoptotic factor, mediating its control via the high-affinity neurotensin receptor (NT1 receptor) in several human solid tumors. In a series of 51 patients with invasive ductal breast cancers, 34% of all tumors were positive for neurotensin and 91% positive for NT1 receptor. We found a coexpression of neurotensin and NT1 receptor in a large proportion (30%) of ductal breast tumors, suggesting a contribution of the neurotensinergic signaling cascade within breast cancer progression. Functionally expressed NT1 receptor, in the highly malignant MDA-MB-231 human breast cancer cell line, coordinated a series of transforming functions, including cellular migration, invasion, induction of the matrix metalloproteinase (MMP)-9 transcripts, and MMP-9 gelatinase activity. Disruption of NT1 receptor signaling by silencing RNA or use of a specific NT1 receptor antagonist, SR48692, caused the reversion of these transforming functions and tumor growth of MDA-MB-231 cells xenografted in nude mice. Our findings support the contribution of neurotensin in human breast cancer progression and point out the utility to develop therapeutic molecules targeting neurotensin or NT1 receptor signaling cascade. These strategies would increase the range of therapeutic approaches and be beneficial for specific patients.

Neurotensin receptor 1 gene activation by the Tcf/beta-catenin pathway is an early event in human colonic adenomas

Alterations in the Wnt/APC (adenomatous polyposis coli) signalling pathway, resulting in beta-catenin/T cell factor (Tcf)-dependent transcriptional gene activation, are frequently detected in familial and sporadic colon cancers. The neuropeptide neurotensin (NT) is widely distributed in the gastrointestinal tract. Its proliferative and survival effects are mediated by a G-protein coupled receptor, the NT1 receptor. NT1 receptor is not expressed in normal colon epithelial cells, but is over expressed in a number of cancer cells and tissues suggesting a link to the outgrowth of human colon cancer. Our results demonstrate that the upregulation of NT1 receptor occurring in colon cancer is the result of Wnt/APC signalling pathway activation. We first established the functionality of the Tcf response element within the NT1 receptor promoter. Consequently, we observed the activation of NT1 receptor gene by agents causing beta-catenin cytosolic accumulation, as well as a strong decline of endogenous receptor when wt-APC was restored. At the cellular level, the re-establishment of wt-APC phenotype resulted in the impaired functionality of NT1 receptor, like the breakdown in NT-induced intracellular calcium mobilization and the loss of NT pro-invasive effect. We corroborated the Wnt/APC signalling pathway on the NT1 receptor promoter activation with human colon carcinogenesis, and showed that NT1 receptor gene activation was perfectly correlated with nuclear or cytoplasmic beta-catenin localization while NT1 receptor was absent when beta-catenin was localized at the cell-cell junction in early adenomas of patients with familial adenomatous polyposis, hereditary non-polyposis colorectal cancer and loss of heterozygosity tumours. In this report we establish a novel link in vitro between the Tcf/beta-catenin pathway and NT1 receptor promoter activation.

Gastrointestinal hormone receptors in primary human colorectal carcinomas

BACKGROUND

In this study, the prevalence and identity of the cells expressing functional receptors for the gastrointestinal (GI) peptide hormones: gastrin, bombesin, and neurotensin in dissociated cells from 20 freshly resected human primary colorectal carcinomas were determined.

MATERIALS AND METHODS

GI peptide hormone-induced increases in the concentration of free intracellular Ca(2+) ([Ca(2+)](i)) were used as an assay for the detection of functional receptors. Reverse-transcription polymerase chain reaction (RT-PCR) was performed in a subset of tumor samples. Agonist-responsive cells were identified as either of epithelial or stromal origin by immunocytochemistry with cytokeratin and vimentin antibodies, respectively.

RESULTS

Overall, expression of GI peptide hormone receptors was more frequent in stromal cells when compared to epithelial cells. Of the three receptors, expression of bombesin receptor (95%) was most prevalent in vimentin-positive (stromal) cells; whereas, gastrin receptor expression by cytokeratin-positive (epithelial) cells was more common (39%). A single gastrin receptor splice variant differentially regulates [Ca(2+)](i) in a cell-type specific manner. The gastrin receptor-expression profile in the 11 colon cancer-derived cell lines did not reflect the prevalence of expression in primary human cancers.

CONCLUSIONS

The Ca(2+) assay is a sensitive method for detecting functional GI peptide hormone receptor expression by colon cancer cells. Because this approach utilizes living cells, it is amenable to further functional analyses of signal transduction mechanisms at the single cell level. Importantly, our data provide a rationale for examining of the role of these GI peptide hormones and their cognate receptors in mesenchymal cell biology.

Neurotensin negatively modulates Akt activity in neurotensin receptor-1-transfected AV12 cells

Neurotensin (NT) regulates a variety of biological processes primarily through interaction with neurotensin receptor-1 (NTR1), a heterotrimeric G-protein-coupled receptor (GPCR). Stimulation of NTR1 has been linked to activation of multiple signaling transduction pathways via specific coupling to G(q), G(i/o), or G(s), in various cell systems. However, the function of NT/NTR1 in the regulation of the Akt pathway remains unknown. Here, we report that activation of NTR1 by NT inhibits Akt activity as determined by the dephosphorylation of Akt at both Ser473 and Thr308 in AV12 cells constitutively expressing human NTR1 (NTR1/AV12). The inactivation of Akt by NT was rapid and dose-dependent. This effect of NT was completely blocked by the specific NTR1 antagonist, (S)-(+)-[1-(7-chloro-4-quinolinyl)-5-(2,6-dimethoxyphenyl)pyrazol-3-yl)-carbonylamino] cyclohexylacetic acid (SR 48527), but unaffected by the less active enantiomer ((R)-(-)-[1-(7-chloro-4-quinolinyl)-5-(2,6-dimethoxyphenyl)pyrazol-3-yl)-carbonylamino] cyclohexylacetic acid (SR 49711)), indicating the stereospecificity of NTR1 in the negative regulation of Akt. In addition, NT prevented insulin- and epidermal growth factor (EGF)-mediated Akt activation. Our results provide insight into the role of NT in the modulation of Akt signaling and the potential physiological significance of Akt regulation by NT.

Glucagon-like peptides: regulators of cell proliferation, differentiation, and apoptosis

Peptide hormones are secreted from endocrine cells and neurons and exert their actions through activation of G protein-coupled receptors to regulate a diverse number of physiological systems including control of energy homeostasis, gastrointestinal motility, neuroendocrine circuits, and hormone secretion. The glucagon-like peptides, GLP-1 and GLP-2 are prototype peptide hormones released from gut endocrine cells in response to nutrient ingestion that regulate not only energy absorption and disposal, but also cell proliferation and survival. GLP-1 expands islet mass by stimulating pancreatic beta-cell proliferation and induction of islet neogenesis. GLP-1 also promotes cell differentiation, from exocrine cells or immature islet progenitors, toward a more differentiated beta-cell phenotype. GLP-2 stimulates cell proliferation in the gastrointestinal mucosa, leading to expansion of the normal mucosal epithelium, or attenuation of intestinal injury in experimental models of intestinal disease. Both GLP-1 and GLP-2 exert antiapoptotic actions in vivo, resulting in preservation of beta-cell mass and gut epithelium, respectively. Furthermore, GLP-1 and GLP-2 promote direct resistance to apoptosis in cells expressing GLP-1 or GLP-2 receptors. Moreover, an increasing number of structurally related peptide hormones and neuropeptides exert cytoprotective effects through G protein-coupled receptor activation in diverse cell types. Hence, peptide hormones, as exemplified by GLP-1 and GLP-2, may prove to be useful adjunctive tools for enhancement of cell differentiation, tissue regeneration, and cytoprotection for the treatment of human disease.