Rafael Coveñas

The NK-1 Receptor Is Expressed in Human Primary Gastric and Colon Adenocarcinomas and Is Involved in the Antitumor Action of L-733,060 and the Mitogenic Action of Substance P on Human Gastrointestinal Cancer Cell Lines

Background/Aims: It has been demonstrated that substance P (SP) and neurokinin-1 (NK-1) receptor antagonist L-733,060 induces cell proliferation and inhibition, respectively, in several human cancer cell lines. At present, it is unknown whether such actions are exerted on human gastric and colon adenocarcinomas. We carried out an in vitro study of the growth-inhibitory capacity of L-733,060 against human gastric and colon adenocarcinomas. Methods: A coulter counter was used to determine viable cell numbers followed by application of the tetrazolium compound MTS. Immunoblot analysis was used to determine the NK-1 receptors and the DAPI method was applied to demonstrate apoptosis. Immunohistochemistry was used to demonstrate NK-1 receptors in primary human gastric and colon adenocarcinomas. Results: We observed the presence of several NK-1 receptor isoforms in human gastric and colon adenocarcinomas. Nanomolar concentrations of SP increased the growth of both cell lines and micromolar concentrations of L-733,060 inhibited the growth of such cell lines, with and without previous administration of SP. L-733,060 inhibited the growth of the 23132/87 and SW-403 cell lines in a dose-dependent manner. After administration of L-733,060, apoptosis was observed in both cell lines. In both human primary gastric and colon adenocarcinomas, a high density of NK-1 receptors was observed. Immunoreactivity, showing a diffuse cytoplasmic staining, was observed in the epithelial cells of normal and tumor glands and in numerous stromal elements. Conclusions: We demonstrated that NK-1 receptors were expressed in 23132/37 and SW-403 cell lines and in human primary gastric and colon adenocarcinomas, that SP is a mitogen and that the antitumor action of L-733,060 on both human cell lines occurs through the NK-1 receptor. Data also indicate that the cell death observed is produced by apoptosis. These data suggest that the NK-1 receptor is a new and promising target in the treatment of human gastrointestinal adenocarcinomas.

The NK1 receptor is involved in the antitumoural action of L-733,060 and in the mitogenic action of substance P on neuroblastoma and glioma cell lines ☆

We have carried out an in vitro study to investigate the ability of substance P to activate cell growth and the NK1 receptor antagonist L-733,060 to inhibit cell growth in the SKN-BE(2) neuroblastoma and GAMG glioma cell lines. A coulter counter was used to determine viable cell numbers, followed by application of the tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)2-(4-sulfophenyl)-2H-tetrazolium], inner salt, colorimetric method to evaluate cell viability in this cytotoxicity assay. Nanomolar concentrations of substance P increased, and micromolar concentrations of L-733,060 inhibited the growth of both cell lines studied, with and without previous administration of substance P. In addition, we have demonstrated by immunoblot analysis that NK1 receptors are present in both cancer cell lines studied here. Thus, this study demonstrates that substance P acts as a mitogen in the SKN-BE(2) neuroblastoma and GAMG glioma cell lines, and that the antitumoural action of L-733,060 on both human cell lines occurs through the NK1 receptor. This action suggests that the NK1 receptor is a new and promising target in the treatment of human neuroblastoma and glioma.

The NK-1 receptor is expressed in human melanoma and is involved in the antitumor action of the NK-1 receptor antagonist aprepitant on melanoma cell lines

Melanoma, the most deadly form of skin cancer, is aggressive and resistant to current therapies. It has been previously reported that the substance P and neurokinin-1 (NK-1) receptor antagonists induce cell proliferation and cell inhibition, respectively, in human melanoma cell lines. Aprepitant is a selective high-affinity antagonist of the human NK-1 receptor. Until now, this drug has been used as an anxiolytic, antidepressant and antiemetic. Moreover, the antitumor action of aprepitant has been previously reported. However, the presence of NK-1 receptors in human melanomas and whether the antitumor action of the NK-1 receptor antagonist aprepitant is exerted on human malignant melanomas have not been previously described. The aims of this study are to show the presence of NK-1 receptors in human malignant melanomas and the antitumoral action of aprepitant against several human melanoma cell lines. Immunoblot analysis was used to determine the presence of NK-1 receptors in human melanoma cell lines, and immunohistochemistry was used to demonstrate NK-1 receptors in human melanoma samples. We performed an in vitro study of the cytotoxicity of the NK-1 receptor antagonist aprepitant on human melanoma cell lines. A coulter counter was used to determine viable cell numbers, followed by application of the tetrazolium compound MTS. The DAPI method was applied to demonstrate apoptosis. We observed that NK-1 receptors were present in all the melanoma samples studied as well as in human melanoma cell lines. We also showed that melanoma cell lines expressed mRNA for the NK-1 receptor. Moreover, after using a knockdown method, we showed that NK-1 receptors are involved in the viability of tumor cells. In this study, we also report that aprepitant, at 10–60 μM concentrations, elicits cell growth inhibition in a concentration-dependent manner in all melanoma cell lines studied, that the specific antitumor action of aprepitant occurs through the NK-1 receptor and that melanoma cell death is due to apoptosis. These findings show for the first time that the NK-1 receptor may be a promising new target and that the NK-1 receptor antagonist aprepitant could be a candidate as a new antitumor drug in the treatment of human melanoma.

Classical Neurotransmitters and Neuropeptides Involved in Major Depression: a Review

ABSTRACT We propose several pathways that could be involved in major depression. According to our proposal, noradrenaline hypoactivity could occur through a strong presynaptic GABAergic inhibition, via GABAB receptors, and serotonin hypoactivity through a strong glutaminergic inhibition via subreceptor 5 of the metabotropic glutaminergic receptor. In this sense, it is important to know whether the antagonists of such receptors might be able to improve the symptoms observed in major depression. Some neuropeptides are also altered in such states (corticotropin-releasing hormone, neuropeptide Y, galanin). It is also important to know whether in addition to current antidepressants the administration of neuropeptides and their agonists/antagonists could ameliorate depressive symptoms.

Involvement of substance P and the NK-1 receptor in human pathology.

The peptide substance P (SP) shows a widespread distribution in both the central and peripheral nervous systems, but it is also present in cells not belonging to the nervous system (immune cells, liver, lung, placenta, etc.). SP is located in all body fluids, such as blood, cerebrospinal fluid, breast milk, etc. i.e. it is ubiquitous in human body. After binding to the neurokinin-1 (NK-1) receptor, SP regulates many pathophysiological functions in the central nervous system, such as emotional behavior, stress, depression, anxiety, emesis, vomiting, migraine, alcohol addiction, seizures and neurodegeneration. SP has been also implicated in pain, inflammation, hepatitis, hepatotoxicity, cholestasis, pruritus, myocarditis, bronchiolitis, abortus, bacteria and viral infection (e.g., HIV infection) and it plays an important role in cancer (e.g., tumor cell proliferation, antiapoptotic effects in tumor cells, angiogenesis, migration of tumor cells for invasion, infiltration and metastasis). This means that the SP/NK-1 receptor system is involved in the molecular bases of many human pathologies. Thus, knowledge of this system is the key for a better understanding and hence a better management of many human diseases. In this review, we update the involvement of the SP/NK-1 receptor system in the physiopathology of the above-mentioned pathologies and we suggest valuable future therapeutic interventions involving the use of NK-1 receptor antagonists, particularly in the treatment of emesis, depression, cancer, neural degeneration, inflammatory bowel disease, viral infection and pruritus, in which that system is upregulated.

A new frontier in the treatment of cancer: NK-1 receptor antagonists.

The past two decades have witnessed an exponential increase in research into cancer. This effort, however, has not been translated into better perspectives as regards the problem, although several fields of research have certainly been promising (the human genome project, gene therapy, the search for new cytostatic agents and stem cell research). New pathways must be opened up to offer future hope to oncologic patients. Thus, there is a need to explore other research initiatives in cancer ways to improve this chronic global problem. Substance P (SP) has a widespread distribution in both the central and peripheral nervous systems. It is known that after binding to the specific neurokinin-1 (NK-1) receptor, SP regulates biological functions related to cancer, such as tumour cell proliferation, angiogenesis, and migration of the tumour cells for invasion and metastasis. By contrast, it is also known that after binding to NK-1 receptors, the NK-1 receptor antagonists specifically inhibit tumour cell proliferation (tumour cells die by apoptosis), angiogenesis and the migration of the tumour cells. It is also known that NK-1 receptors are overexpressed in tumours. All these observations suggest that the SP/NK-1 receptor system could play an important role in the development of cancer and metastasis; that the NK-1 receptor could be a new promising target in the treatment of cancer, and that NK-1 receptor antagonists could improve cancer treatment.

Immunocytochemical study of enkephalin-like cell bodies in the thalamus of the cat

Using an indirect immunoperoxidase technique, the localization of enkephalin-like cell bodies in the thalamus of the cat was carried out. Enkephalin-like cell bodies are widely distributed in the cat thalamus. However, immunoreactive cells may be regrouped in 4 clusters which do not exactly correlate with the anatomical subdivisions of the thalamus. One is located in the dorsocaudal aspect of the thalamus, another in the midline area, and the others are formed by the nuclei geniculatum mediale and laterale.

The NK-1 Receptor: A New Target in Cancer Therapy

After binding to the specific neurokinin-1 (NK-1) receptor, the peptide substance P (SP), which is widely distributed in both the central and peripheral nervous systems, induces tumor cell proliferation, angiogenesis, and migration of the tumor cells for invasion and metastasis. However, after binding to NK-1 receptors, NK-1 receptor antagonists inhibit the three above mechanisms. In fact, the antiproliferative action exerted by NK-1 receptor antagonists is because they induce cancer cells to die by apoptosis, whereas SP exerts an antiapoptotic effect. Moreover, it is known that NK-1 receptors are overexpressed in tumors and that tumor cells express several isoforms of the NK-1 receptor. All these data suggest that the SP/NK-1 receptor system could play an important role in the development of cancer; that SP may be a universal mitogen in NK-1 receptor-expressing tumor cells, and that NK-1 receptor antagonists could offer a promising therapeutic strategy for the treatment of human cancer, since they act as broad-spectrum antitumor agents. In sum, the NK-1 receptor may be a new and promising target in the treatment of human cancer.

Simultaneous depletion of neurokinin A, substance P and calcitonin gene- related peptide from the caudal trigeminal nucleus of the rat during electrical stimulation of the trigeminal ganglion

Abstract The central terminals of the primary sensory trigeminal ganglion (TG) neurons projecting into the caudal trigeminal nucleus (CTN) of the rat exhibit neurokinin A (NKA)‐, substance P (SP)‐, and calcitonin gene‐related peptide (CGRP)‐immunoreactivities (IRs). We stimulated the TG in the rat to induce some of the alterations which might occur during migraine (neurogenic inflammation). Under a stereotaxic apparatus and by means of a bipolar electrode, one‐side TG of the animals were electrically stimulated (7.5 Hz, 5 ms, 0.8–1.4 mA) with square pulses for 5 min. Then, using immunohistochemical methods, the lower medulla of each rat was studied for NKA‐, SP‐ and CGRP‐IRs. Light microscopic examination of brain‐stem sequencial sections revealed a simultaneous decrease in the immunoreactivities of all neuropeptides (NKA, SP and CGRP) in the CTN ipsilateral to TG stimulation in comparison with the other (not stimulated) side CTN. It is suggested that this decrease in immunoreactivity would be due to the co‐release of neuropeptides following noxious stimuli and that NKA, SP and CGRP might therefore act as co‐transmitters or co‐modulators at the first central synapses of the trigeminal sensory pathway.

Involvement of substance P and the NK-1 receptor in cancer progression

Many data suggest the deep involvement of the substance P (SP)/neurokinin (NK)-1 receptor system in cancer: (1) Tumor cells express SP, NK-1 receptors and mRNA for the tachykinin NK-1 receptor; (2) Several isoforms of the NK-1 receptor are expressed in tumor cells; (3) the NK-1 receptor is involved in the viability of tumor cells; (4) NK-1 receptors are overexpressed in tumor cells in comparison with normal ones and malignant tissues express more NK-1 receptors than benign tissues; (5) Tumor cells expressing the most malignant phenotypes show an increased percentage of NK-1 receptor expression; (6) The expression of preprotachykinin A is increased in tumor cells in comparison with the levels found in normal cells; (7) SP induces the proliferation and migration of tumor cells and stimulates angiogenesis by increasing the proliferation of endothelial cells; (8) NK-1 receptor antagonists elicit the inhibition of tumor cell growth; (9) The specific antitumor action of NK-1 receptor antagonists on tumor cells occurs through the NK-1 receptor; (10) Tumor cell death is due to apoptosis; (11) NK-1 receptor antagonists inhibit the migration of tumor cells and neoangiogenesis. The NK-1 receptor is a therapeutic target in cancer and NK-1 receptor antagonists could be considered as broad-spectrum antitumor drugs for the treatment of cancer. It seems that a common mechanism for cancer cell proliferation mediated by SP and the NK-1 receptor is triggered, as well as a common mechanism exerted by NK-1 receptor antagonists on tumor cells, i.e. apoptosis.