Neurokinin-1 receptors located in human retinoblastoma cell lines: antitumor action of its antagonist, L-732,138

Chronic pruritus: from pathophysiology to drug design

Pruritus, the most common symptom in dermatology, is an innate response capable of protecting skin against irritants. Nonetheless, when it lasts more than six weeks it is assumed to be a chronic pathology having a negative impact on people's lives. Chronic pruritus (CP) can occur in common and rare skin diseases, having a high prevalence in global population. The existing therapies are unable to counteract CP or are associated with adverse effects, so the development of effective treatments is a pressing issue. The pathophysiological mechanisms underlying CP are not yet completely dissected but, based on current knowledge, involve a wide range of receptors, namely neurokinin 1 receptor (NK1R), Janus kinase (JAK), and transient receptor potential (TRP) ion channels, especially transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1). This review will address the relevance of these molecular targets for the treatment of CP and molecules capable of modulating these receptors that have already been studied clinically or have the potential to possibly alleviate this pathology. According to scientific and clinical literature, there is an increase in the expression of these molecular targets in the lesioned skin of patients experiencing CP when compared with non-lesioned skin, highlighting their importance for the development of potential efficacious drugs through the design of antagonists/inhibitors.

NK1 receptor antagonistic effect of 17-trifluoromethyl phenyl trinor prostaglandin F2α on the growth of human breast cancer cell line

BACKGROUND

A growing number of genetic and cancer biology investigations have found that the tachykinin NK1 Receptor plays an important role in cancer cell proliferation and survival. In this study. The present study was designed to evaluate the inhibition of cell growth by 17-trifluoromethyl phenyl trinor prostaglandin F2α with NK1 receptor in breast cancer cell lines.

MATERIALS AND METHODS

MDB-MB-468 and MCF-7 breast cancer cell lines were used in the experiment were blocked with PGF2a. Cell proliferation and apoptosis were analyzed to evaluate the cytotoxic effect. Cell cycle distribution, Caspase-3 enzyme activity, Bad and Bax protein expression through flow cytometry and molecular docking were carried out to analyze the NK1 receptor activity.

RESULTS

We found that PGF2a has a high binding affinity towards NK1 Receptor from molecular docking studies. It exerted cytotoxic and antiproliferative effects against MDB-MB-468 and MCF-7 breast cancer cell lines. Our data found that treatment of cells with 17-TPGF2 resulted in cell death and showed that increased expression of Caspase-3, Bad, and Bax protein and further induces G2 cell cycle arrest.

CONCLUSION

Overall this study investigates the NK1 receptor antagonistic effect of PGF2 against breast cancer cell lines. However, further studies are needed to better characterize the application of NK1 receptor inhibition in clinical cancer treatment and cytotoxicity effect.

A Substance P (SP)/Neurokinin-1 Receptor Axis Promotes Perineural Invasion of Pancreatic Cancer and Is Affected by lncRNA LOC389641

Perineural invasion (PNI) is considered to be a main reason for the poor prognosis of pancreatic cancer. In the present study, we analyzed the roles of substance P (SP)/neurokinin-1 receptor (NK-1R) and lncRNA LOC389641 in pancreatic cancer PNI. Pancreatic cancer cell lines BxPC-3 and MIAPaCa-2 were cocultured with SH-SY5Y cells and then stimulated with SP to simulate the in vivo influence of ganglia on pancreatic cancer. The BxPC-3 and MIAPaCa-2 cells were transfected with a neurokinin-1 receptor (NK-1R) overexpression vector, NK-1R silencing vector, LOC389641 overexpression vector, or LOC389641 silencing vector, respectively. The proliferative abilities of BxPC-3 and MIAPaCa-2 cells were assessed using the cell counting kit-8 and 5-ethynyl-2'-deoxyuridine (EdU) assays. Wound-healing and Transwell assays were performed to determine the migration and invasion abilities of the cells. When SP was added to the coculture system, it positively regulated cancer cell proliferation, migration, and PNI and significantly activated the NK-1R/Akt/NF-κB signaling pathway. Incubation with 100 nmol/L SP for 24 h was selected as the optimal condition for treatment. The activated NK-1R positively regulated the proliferation, migration, and invasion of pancreatic cancer cells. However, the levels of lncRNA LOC389641 and tumor necrosis factor receptor SF10A (TNFRSF10A) mRNA in BxPC-3 and MIAPaCa-2 cells were not affected by SP treatment. Overexpression or silencing of LOC389641 changed the effect of SP stimulation on pancreatic cancer PNI. When taken together, these results revealed that SP/NK-1R and LOC389641 promoted the progression of pancreatic cancer PNI. Moreover, we found that pancreatic cancer PNI promoted by the SP/NK-1R axis could be blocked by the TNFRSF10A/NF-κB pathway mediated by LOC389641.

Pain May Promote Tumor Progression via Substance P-Dependent Modulation of Toll-like Receptor-4

BACKGROUND

In a previous study, persistent pain was suggested to be a risk factor for tumor patients. However, the mechanism underlying this phenomenon is still unclear. Substance P (SP), a pain-related neuropeptide secreted by the neural system and the immune system, plays an important role in the induction and maintenance of persistent pain.

METHODS

In this study, in order to explore whether SP participates in the influence of pain on tumor progression, the serum samples of lung cancer and breast cancer patients were collected and tested. An elevated expression of SP was found in patients with pain.

RESULTS

Cell pharmacological experiments revealed that SP can upregulate the expression of Toll-like receptor-4 (TLR-4) in tumor cells and increase the proliferation, migration, and invasive activity of tumor cells. As high expression of TLR-4 has the ability to enhance the biological activity of tumor cells, TLR-4 is thought to be involved in SP-induced tumor proliferation, migration, and invasion. Treatment of tumor cells with Aprepitant, a specific blocker of the NK-1 receptor, could reduce the expression of TLR-4 and reduce the proliferation, invasion, and migration activities of tumor cells; further proof of the influence of SP on TLR-4 expression depends on the NK-1 receptor located in tumor cells.

CONCLUSIONS

Based on the results above, we proposed a possible mechanism underlying pain affecting tumor progression: The presence of pain increases the content of SP in patients' blood, and elevated SP increases the expression of tumor TLR-4 by acting on the NK-1 receptor, which ultimately affects the biological activity of the tumor.

Significance of the Overexpression of Substance P and Its Receptor NK-1R in Head and Neck Carcinogenesis: A Systematic Review and Meta-Analysis

The objective of our study has been, through a systematic review and meta-analysis, to increase the scientific evidence on the implications of SP and its receptor NK-1R in head and neck carcinogenesis. We searched studies published before May-2020 without date and publication language restrictions (PubMed, Embase, Web of Science, Scopus). We evaluated the quality of the studies included (QUIPS tool). We performed heterogeneity, sensitivity, small-study effects, and subgroup analyses. A total 16 studies and 1308 cases met inclusion criteria. Qualitative evaluation demonstrated that not all studies were performed with the same scientific rigor, finding the greatest risk of bias in the study confounding and prognostic factors measurement domains. Quantitative evaluation showed a greater SP/NK-1R overexpression in malignant head and neck lesions compared to benign lesions (p = 0.02), and that expression was observed in malignant salivary gland pathology. Likewise, we found a higher overexpression of NK-1R compared to SP (p = 0.02). In conclusion, the results of this systematic review and meta-analysis show evidence that the upregulation of SP and NK-1R are oncogenic events involved in head and neck carcinogenesis, probably acting in the early stages of malignization. In addition, there is evidence of a greater relevance of the upregulation of the NK-1R receptor compared to SP, which highlights the interest in deepening the development of targeted therapies on the receptor. Future studies assessing the relationships between SP/NK-1R among subjects with head and neck tumors could consider the recommendations given in this systematic review and meta-analysis to improve and standardize future research.

Evaluation of the antileukemic effects of neurokinin-1 receptor antagonists, aprepitant, and L-733,060, in chronic and acute myeloid leukemic cells

Neurokinin-1 receptor (NK1R) antagonists are known for their anxiolytic, antiemetic, anticancer, and anti-inflammatory effects. Aprepitant is used in vomiting and nausea, which are the most common side-effects of patients undergoing chemotherapy for cancer. L-733,060 has been shown to have anxiolytic and antidepressant effects in animal studies and anticancer effect in in-vitro studies. Previous anticancer activity studies with NK1R antagonists have reported that NK-1 antagonists have an antitumoral activity on gastric carcinoma, larynx carcinoma, retinoblastoma, hepatocarcinoma, glioma, neuroblastoma, and osteoblastoma cells. In this study, we have aimed to show and compare the antileukemic effects of aprepitant and L-733,060 on acute and chronic myeloid leukemic cells by using in-vitro experiments, such as WST-1, cell imaging, annexin-V binding, soft agar colony formation, and Hoescht staining. As a result, we have determined that both aprepitant and L-733,060 had strong antiproliferative effects on K562 and HL-60 cells. Moreover, the two drugs caused significant apoptosis and decreased colony forming depending on concentration increase. These findings suggested that NK1R antagonists exhibited antileukemic activities and may be considered to have a novel therapeutic potential for acute and chronic myeloid leukemia.

New insight into the role of substance P/neurokinin-1 receptor system in breast cancer progression and its crosstalk with microRNAs

The neuropeptide substance P (SP) triggers a variety of tumor-promoting signaling pathways through the activation of neurokinin-1receptor (NK1R), a class of neurokinin G protein-coupled receptors superfamily. Recent researches in our and other laboratories have shown the overexpression of both SP and NK1R in breast cancer (BC) patients. SP/NK1R signaling is strongly implicated in the pathogenesis of BC through affecting cell proliferation, migration, metastasis, angiogenesis, and resistance. Therefore, SP/NK1R signaling responses must be rigorously regulated; otherwise, they would contribute to a more aggressive BC phenotype. Recently, microRNAs (miRNAs) as a specific class of epigenetic regulators have been shown to regulate NK1R and thus, controlling SP/NK1R signaling responses in BC. This review summarizes the current knowledge of the role of SP/NK1R signaling and its therapeutic potentials in BC. We also provide an overview regarding the effects of miRNA-mediated NK1R regulatory mechanisms in controlling BC tumorigenesis to gain a clearer view and thus better management of cancer.

miR-206 Promotes Cancer Progression by Targeting Full-Length Neurokinin-1 Receptor in Breast Cancer

Substance P plays a pivotal role in human cancer development and progression by binding to its receptor, neurokinin-1. Neurokinin-1 has 2 isoforms: full-length neurokinin-1 and truncated neurokinin-1, the latter lacking the cytoplasmic terminal 96-amino acid residues of the full-length protein. We have identified 3 candidate miR-206 target sites within the 3′-untranslated region of the full-length neurokinin-1 gene from bioinformatics database searches. In the present study, real-time quantitative polymerase chain reaction was performed to quantify the expression of miR-206, and the expression of neurokinin-1 and full-length neurokinin-1 was detected by immunohistochemistry in 82 clinical cases of breast cancer and paired adjacent normal tissues. The miR-206 target gene was demonstrated by using a dual-luciferase reporter assay, quantitative real-time polymerase chain reaction, and Western blotting. Transwell migration and invasion, colony formation, and proliferation assays were performed to evaluate the effects of miR-206 expression on various aspects of breast cancer cell behavior in vitro. We showed that miR-206 expression is upregulated in breast cancer cell lines and breast cancer tissues when compared to that in adjacent normal tissues, and full-length neurokinin-1 expression inversely correlates with Tumor Lymph Node Metastasis (TNM) stage and lymph node metastasis. Western blotting, quantitative real-time polymerase chain reaction, and dual-luciferase reporter assays demonstrated that miR-206 binds the 3′-untranslated region of full-length neurokinin-1 messenger RNA, regulating protein expression. We showed that the overexpression of miR-206 promotes breast cancer cell invasion, migration, proliferation, and colony formation in vitro. The present study furthers the current understanding of the mechanisms underlying breast cancer pathogenesis and may be useful for the development of novel targeted therapies.

Neurokinin-1 Receptor Antagonists as Anticancer Drugs

Background::

Human tumor cells lines and tumor samples overexpress the neurokinin-1 receptor (NK-1R). Substance P (SP), after binding to NK-1Rs, induces tumor cell proliferation, an antiapoptotic effect and promotes angiogenesis and the migration of cancer cells for invasion and metastasis.

Methods: :

In contrast, NK-1R antagonists block the previous pathophysiological actions mediated by SP. These antagonists promote the death of tumor cells by apoptosis. Peptide and non-peptide NK-1R antagonists have been reported.

Results: :

Peptide NK-1R antagonists show chemical modifications of the SP molecule (L-amino acids being replaced by D-amino acids), whereas non-peptide NK-1R antagonists include numerous compounds with different chemical compositions while showing similar stereochemical features (affinity for the NK- 1R). Currently, there are more than 300 NK-1R antagonists.

Conclusion::

In combination therapy with classic cytostatics, NK-1R antagonists have additive or synergic effects and minimize the side-effects of cytostatics. The effect of NK-1R antagonists as broad-spectrum anticancer drugs is reviewed and the use of these antagonists for the treatment of cancer is suggested.

Varicella Zoster Virus Induces Nuclear Translocation of the Neurokinin-1 Receptor, Promoting Lamellipodia Formation and Viral Spread in Spinal Astrocytes

Background

Varicella zoster virus (VZV) can present as a myelopathy with spinal astrocyte infection. Recent studies support a role for the neurokinin-1 receptor (NK-1R) in virus infections, as well as for cytoskeletal alterations that may promote viral spread. Thus, we examined the role of NK-1R in VZV-infected primary human spinal astrocytes (HA-sps) to shed light on the pathogenesis of VZV myelopathy.

Methods

Mock- and VZV-infected HA-sps were examined for substance P (subP) production, NK-1R localization, morphological changes, and viral spread in the presence or absence of the NK-1R antagonists aprepitant and rolapitant.

Results

VZV infection of HA-sps induced nuclear localization of full-length and truncated NK-1R in the absence of the endogenous ligand, subP, and was associated with extensive lamellipodia formation and viral spread that was inhibited by NK-1R antagonists.

Conclusions

We have identified a novel, subP-independent, proviral function of nuclear NK-1R associated with lamellipodia formation and viral spread that is distinct from subP-induced NK-1R cell membrane/cytoplasmic localization without lamellipodia formation. These results suggest that binding of a putative viral ligand to NK-1R produces a dramatically different NK-1R downstream effect than binding of subP. Finally, the NK-1R antagonists aprepitant and rolapitant provide promising alternatives to nucleoside analogs in treating VZV infections, including myelopathy.

Neuroendocrine Factors and Head and Neck Squamous Cell Carcinoma: An Affair to Remember

Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignancies. Therefore, the major goal of cancer treatment is inhibition of tumor cell growth and of metastasis development. In order to choose the best management option for HNSCC patients, we need to identify reliable prognostic factors and to develop new molecular techniques in order to obtain a better understanding of therapy resistance. By acting as neurohormones, neurotransmitters, or neuromodulators, the neuroendocrine factors are able to signal the maintenance of physiological homeostasis or progression to malignant disease. Certain neuropeptides possess strong antitumor properties acting as tumor suppressors and immunomodulators, providing additional benefits for future potential therapeutic strategies. In light of the current understanding, cancer starts as a localized disease that can be effectively treated if discovered on proper time. Unfortunately, more than often cancer cells migrate to the surrounding tissues generating distant metastases, thus making the prognosis and survival in this stage much worse. As cellular migration is mandatory for tumor invasion and metastasis development, searching for alternate controllers of these processes, such as the neuroendocrine factors, it is an active tremendous task.

The NK-1 receptor antagonist L-732,138 induces apoptosis in human gastrointestinal cancer cell lines

BACKGROUND

Gastric and colon cancer cells express the neurokinin-1 receptor (NK-1R) and the peptide substance P (SP), after binding to this receptor, elicits the proliferation of gastrointestinal cancer cells and an antiapoptotic effect. In these cells, NK-1R antagonists (L-733,060: a piperidine derivative; aprepitant: a morpholine derivative) block, after binding to the NK-1R, the action of SP and exert an antiproliferative action, both antagonists promote apoptosis and the death of cancer cells. However, it is currently unknown whether tryptophan derivative NK-1R antagonists (e.g., L-732,138) exert an antiproliferative effect against gastrointestinal cancer cells. L-732,138, L-733,060 and aprepitant being structurally unrelated compounds show a high specificity for the NK-1R.

METHODS

To determine the number of viable cells, a Coulter counter was performed. For evaluation of tumor cell viability, an MTS colorimetric method was conducted. For apoptosis, a DAPI stain was carried out.

RESULTS

L-732,138 blocked, in a concentration-dependent manner, the proliferation of gastrointestinal cancer cells (IC₅₀: 75.28 and IC₁₀₀: 127.4 for human SW-403 colon carcinoma cell line; IC₅₀: 76.8 and IC₁₀₀: 157.2 for 23132-87 gastric carcinoma cell line. Level of significance: p≤0.01). The antitumor effect elicited by L-732,138 was via the NK-1R and, in addition, 72.1% and 59.3% apoptotic cells (chromatin condensation and nuclear fragmentation) were respectively found in gastric and colon cancer cell lines when L-732,138 (at IC₁₀₀ concentration) was administered.

CONCLUSION

It seems that the NK-1R is an emerging drug target for the treatment of gastrointestinal cancer and that the tryptophan derivative NK-1R antagonist L-732,138 must be considered as an anticancer drug in gastrointestinal cancer.

An RNA interference screen identifies new avenues for nephroprotection

Acute kidney injury is a major public health problem, which is commonly caused by renal ischemia and is associated with a high risk of mortality and long-term disability. Efforts to develop a treatment for this condition have met with very limited success. We used an RNA interference screen to identify genes (BCL2L14, BLOC1S2, C2ORF42, CPT1A, FBP1, GCNT3, RHOB, SCIN, TACR1, and TNFAIP6) whose suppression improves survival of kidney epithelial cells in in vitro models of oxygen and glucose deprivation. Some of the genes also modulate the toxicity of cisplatin, an anticancer agent whose use is currently limited by nephrotoxicity. Furthermore, pharmacological inhibition of TACR1 product NK1R was protective in a model of mouse renal ischemia, attesting to the in vivo relevance of our findings. These data shed new light on the mechanisms of stress response in mammalian cells, and open new avenues to reduce the morbidity and mortality associated with renal injury.

The neurokinin-1 receptor antagonist aprepitant is a promising candidate for the treatment of breast cancer

The substance P (SP)/neurokinin (NK)-1 receptor system plays an important role in the development of cancer. No in-depth studies of the involvement of this system in breast cancer (BC) have been carried out, and the action exerted by the drug aprepitant on BC cells is currently unknown. We show the involvement of this system in human BC cell lines: i) these cells express mRNA for the NK-1 receptor; ii) they overexpress NK-1 receptors; iii) the NK-1 receptor is involved in their viability; iv) SP induces their proliferation; v) NK-1 receptor antagonists block SP-induced mitogen stimulation of these cells; vi) the specific antitumor action of such antagonists on these cells occurs through the NK-1 receptor; and vii) BC cell death is due to apoptosis. We also found NK-1 receptors and SP in all human BC samples studied. The NK-1 receptor may be a promising target in the treatment of BC and NK-1 receptor antagonists could be candidates as a new antitumor drug in the treatment of BC.

Neurokinin-1 receptor expression and antagonism by the NK-1R antagonist maropitant in canine melanoma cell lines and primary tumour tissues

We interrogated the neurokinin-1 receptor (NK-1R)/substance P (SP) pathway in canine melanoma tumour tissues and cell lines. NK-1R messenger RNA (mRNA) and protein expression were observed in the majority of tumour tissues. Immunohistochemical assessment of archived tissue sections revealed NK-1R immunoreactivity in 11 of 15 tumours, which may have diagnostic, prognostic and therapeutic utility. However, we were unable to identify a preclinical in vitro cell line or in vivo xenograft model that recapitulates NK-1R mRNA and protein expression documented in primary tumours. While maropitant inhibited proliferation and enhanced apoptosis in cell lines, in the absence of documented NK-1R expression, this may represent off-target effects. Furthermore, maropitant failed to suppress tumour growth in a canine mouse xenograft model derived from a cell line expressing mRNA but not protein. While NK-1R represents a novel target, in the absence of preclinical models, in-species clinical trials will be necessary to investigate the therapeutic potential for antagonists such as maropitant.

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.

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

Pancreatic cancer is the fourth leading cause of cancer related-death for both men and women and the 1- and 5-year relative survival rates are 25% and 6%, respectively. Thus, it is urgent to investigate new antitumor drugs to improve the survival of pancreatic cancer patients. The peptide substance P (SP) has a widespread distribution throughout the body. After binding to the neurokinin-1 (NK-1) receptor, SP regulates biological functions related to cancer, such as tumor cell proliferation, neoangiogenesis, the migration of tumor cells for invasion, infiltration and metastasis, and it exerts an antiapoptotic effects on tumor cells. It is known that the SP/NK-1 receptor system is involved in pancreatic cancer progression: (1) pancreatic cancer cells and samples express NK-1 receptors; (2) the NK-1 receptor is overexpressed in pancreatic cancer cells in comparison with non-tumor cells; (3) nanomolar concentrations of SP induce pancreatic cancer cell proliferation; (4) NK-1 receptor antagonists inhibit pancreatic cell proliferation in a concentration-dependent manner, at a certain concentration, these antagonists inhibit 100% of tumor cells; (5) this antitumor action is mediated through the NK-1 receptor, and tumor cells die by apoptosis; and (6) NK-1 receptor antagonists inhibit angiogenesis in pancreatic cancer xenografts. All these data suggest that the SP/NK-1 receptor system could play an important role in the development of pancreatic cancer; that the NK-1 receptor could be a new promising therapeutic target in pancreatic cancer, and that NK-1 receptor antagonists could improve the treatment of pancreatic cancer.

Tachykinins and their receptors: contributions to physiological control and the mechanisms of disease

The tachykinins, exemplified by substance P, are one of the most intensively studied neuropeptide families. They comprise a series of structurally related peptides that derive from alternate processing of three Tac genes and are expressed throughout the nervous and immune systems. Tachykinins interact with three neurokinin G protein-coupled receptors. The signaling, trafficking, and regulation of neurokinin receptors have also been topics of intense study. Tachykinins participate in important physiological processes in the nervous, immune, gastrointestinal, respiratory, urogenital, and dermal systems, including inflammation, nociception, smooth muscle contractility, epithelial secretion, and proliferation. They contribute to multiple diseases processes, including acute and chronic inflammation and pain, fibrosis, affective and addictive disorders, functional disorders of the intestine and urinary bladder, infection, and cancer. Neurokinin receptor antagonists are selective, potent, and show efficacy in models of disease. In clinical trials there is a singular success: neurokinin 1 receptor antagonists to treat nausea and vomiting. New information about the involvement of tachykinins in infection, fibrosis, and pruritus justifies further trials. A deeper understanding of disease mechanisms is required for the development of more predictive experimental models, and for the design and interpretation of clinical trials. Knowledge of neurokinin receptor structure, and the development of targeting strategies to disrupt disease-relevant subcellular signaling of neurokinin receptors, may refine the next generation of neurokinin receptor antagonists.

Antitumor activity of neurokinin-1 receptor antagonists in MG-63 human osteosarcoma xenografts

Osteosarcoma is a highly malignant bone tumor in children and adolescents. Aprepitant is a selective high‑affinity antagonist of the human neurokinin‑1 (NK‑1) receptor (NK1R) with robust antitumor activity. No data exist on the presence of NK1R in osteosarcoma and whether this tumor responds to NK1R antagonists. Here, we analyzed the expression of NK1R in the human osteosarcoma cell line MG-63 with western blot analysis and PCR and found significant expression both at the protein and mRNA levels. We further studied the growth inhibitory capacity of aprepitant and other NK1R antagonists on MG-63 in vitro using an MTS cytotoxicity assay and DAPI staining. All antagonists induced tumor growth inhibition and apoptosis. Synergism was observed for the combination of L-733,060 with common cytostatic drugs in MG-63, but not in non-malignant HEK293 cells. Pretreatment of HEK293 with L-733,060 prior to exposure to cytostatic drugs partially protected HEK293 cells from inhibition by these drugs. Furthermore, nanomolar concentrations of substance P (SP), the natural ligand of the NK1R, increased the growth rate of MG‑63 cells and micromolar concentrations of aprepitant inhibited SP-induced growth in a dose‑dependent manner. In vivo, a xenograft for MG-63 was created in nude mice and treated with peritumoral s.c. injections of fosaprepitant, which resulted in a significant reduction of tumor volume. Collectively, we demonstrated for the first time that the NK1R is expressed in human osteosarcoma cell line MG‑63 and that this receptor can be targeted with NK1R antagonists both in vitro as well as in vivo.

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.

NK1 receptor antagonists and dexamethasone as anticancer agents in vitro and in a model of brain tumours secondary to breast cancer

Emend, an NK1 antagonist, and dexamethasone are used to treat complications associated with metastatic brain tumours and their treatment. It has been suggested that these agents exert anticancer effects apart from their current use. The effects of the NK1 antagonists, Emend and N-acetyl-L-tryptophan, and dexamethasone on tumour growth were investigated in vitro and in vivo at clinically relevant doses. For animal experiments, a stereotaxic injection model of Walker 256 rat breast carcinoma cells into the striatum of Wistar rats was used. Emend treatment led to a decrease in tumour cell viability in vitro, although this effect was not replicated by N-acetyl-L-tryptophan. Dexamethasone did not decrease tumour cell viability in vitro but decreased tumour volume in vivo, likely to be through a reduction in tumour oedema, as indicated by the increase in tumour cell density. None of the agents investigated altered tumour cell replication or apoptosis in vivo. Inoculated animals showed increased glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 immunoreactivity indicative of astrocytes and microglia in the peritumoral area, whereas treatment with Emend and dexamethasone reduced the labelling for both glial cells. These results do not support the hypothesis that NK1 antagonists or dexamethasone exert a cytotoxic action on tumour cells, although these conclusions may be specific to this model and cell line.

Safety of neurokinin-1 receptor antagonists

INTRODUCTION

The substance P (SP)/neurokinin (NK)-1 receptor system is involved in many pathological processes. NK-1 receptor antagonists have many promising therapeutic indications. However, the only NK-1 receptor antagonist used in clinical practice is the drug aprepitant and its intravenously administered prodrug, fosaprepitant. In general, NK-1 receptor antagonists are safe and well tolerated.

AREAS COVERED

A search was carried out in Medline using the following terms: adverse events, aprepitant, casopitant, clinical trials, CP-122,721, ezlopitant, fosaprepitant, NK-1 receptor antagonists, randomized, safety, side effects, tolerability and vofopitant.

EXPERT OPINION

Most clinical trials have focused on the antiemetic action of aprepitant in cancer patients treated with chemotherapy. However, the efficacy and safety of aprepitant have not been fully tested in other diseases in which the SP/NK-1 receptor system is involved (e.g., cancer, HIV, alcoholism); thus, clinical trials are required. The use of NK-1 receptor antagonists in oncology therapy is quite promising, but to date pharmacological therapy has not exploited the many possible therapies offered by such antagonists.

The substance P/neurokinin-1 receptor system in lung cancer: focus on the antitumor action of neurokinin-1 receptor antagonists

The last decades have seen no significant progress in extending the survival of lung cancer patients and there is an urgent need to improve current therapies. The substance P (SP)/neurokinin-1 receptor (NK-1R) system plays an important role in the development of cancer: SP and NK-1R antagonists respectively induce cell proliferation and inhibition in human cancer cell lines. No study of the involvement of this system in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) cells has been carried out in depth. Here, we demonstrate the involvement of the SP/NK-1R system in human H-69 (SCLC) and COR-L23 (NSCLC) cell lines: (1) they express isoforms of the NK-1R and mRNA for the NK-1R; (2) they overexpress the tachykinin 1 gene; (3) the NK-1R is involved in their viability; (4) SP induces their proliferation; (5) NK-1R antagonists (Aprepitant (Emend), L-733,060, L-732,138) inhibit the growth of both cell lines in a concentration-dependent manner; (6) the specific antitumor action of these antagonists against such cells occurs through the NK-1R; and (7) lung cancer cell death is due to apoptosis. We also demonstrate the presence of NK-1Rs and SP in all the human SCLC and NSCLC samples studied. Our findings indicate that the NK-1R may be a promising new target in the treatment of lung cancer and that NK-1R antagonists could be new candidate antitumor drugs in the treatment of SCLC and NSCLC.

Activation of neurokinin-1 receptor by substance P inhibits melanogenesis in B16-F10 melanoma cells

Skin pigmentation plays a number of valuable roles and its regulation is a complex process that is controlled by different factors. Substance P (SP) regulates many biological functions, including neurogenic inflammation, pain, and stress. However, to date, the regulatory role of SP in the control of melanogenesis has not been elucidated. The present study was designed to investigate the effects of SP on melanogenesis and to elucidate its underlying mechanism(s). After treatment for 48 h in mouse B16-F10 melanoma cells, SP (1 and 10nM) significantly down-regulated tyrosinase activity and melanin content. Importantly, western blot analysis revealed the presence of neurokinin-1 receptor (NK-1 R) in B16-F10 cells and the activation of it after SP treatment. It was also found that preincubation with NK-1 receptor antagonist Spantide I could partially reversed SP-induced down-regulations of tyrosinase activity, melanin content and the expression of tyrosinase and tyrosinase-related protein 1. Furthermore, SP could remarkably inhibit the expressions of microphtalmia-associated transcription factor (MITF) and p-p38 MAPK and stimulated p-p70 S6K1. These effects could also be partially reversed by the pretreatment with Spantide I. These results collectively suggested that SP inhibited melanogenesis in B16-F10 cells, which might be attributed to the fact that SP induces the activation of NK-1 receptor, stimulates the phosphorylation of p70 S6K1 and inhibits that of p38 MAPK, decreases the tyrosinase and tyrosinase-related protein 1 expression through MITF, finally resulting in the suppression of melanogenesis. These observations in vitro indicated that the regulation of the SP/NK-1 receptor system might be a useful novel management for skin pigmentation.

NK-1 receptor antagonists as antitumor drugs: a survey of the literature from 2000 to 2011

INTRODUCTION

After binding to the neurokinin (NK-1) receptor, substance P (SP) induces tumor cell proliferation, the migration of tumor cells (invasion and metastasis) and angiogenesis. By contrast, NK-1 receptor antagonists inhibit tumor cell proliferation (tumor cells die by apoptosis), block the migratory activity of tumor cells and exert antiangiogenic properties.

AREAS COVERED

This review offers a 12-year overview of the underlying mechanism of the action of the SP/NK-1 receptor system and NK-1 receptor antagonists in cancer, providing a new approach to the treatment of tumors.

EXPERT OPINION

Chemically diverse NK-1 receptor antagonists have been identified. The antitumor action of these compounds is independent of their chemical structures and such action is associated with their affinity for the NK-1 receptor and with the dose of the antagonist administered. The NK-1 receptor can be considered as a target in cancer treatment and NK-1 receptor antagonists could be considered as new antitumor drugs. The NK-1 receptor antagonist aprepitant is used in clinical practice and exerts an antitumor action against tumor cells in vitro. In the future, such antitumor action should be tested in human clinical trials.

Walker 256 tumour cells increase substance P immunoreactivity locally and modify the properties of the blood-brain barrier during extravasation and brain invasion

It is not yet known how tumour cells traverse the blood-brain barrier (BBB) to form brain metastases. Substance P (SP) release is a key component of neurogenic inflammation which has been recently shown to increase the permeability of the BBB following CNS insults, making it a possible candidate as a mediator of tumour cell extravasation into the brain. This study investigated the properties of the BBB in the early stages of tumour cell invasion into the brain, and the possible involvement of SP. Male Wistar rats were injected with Walker 256 breast carcinoma cells via the internal carotid artery and euthanised at 1, 3, 6 and 9 days post tumour inoculation. Culture medium-injected animals served as controls at 1 and 9 days. Evidence of tumour cell extravasation across the BBB was first observed at 3 days post-inoculation, which corresponded with significantly increased albumin (p < 0.05) and SP immunoreactivity (p < 0.01) and significantly reduced endothelial barrier antigen labelling of microvessels when compared to culture medium control animals (p < 0.001). By day 9 after tumour cell inoculation, 100 % of animals developed large intracranial neoplasms that had significantly increased albumin in the peri-tumoral area (p < 0.001). The increased SP immunoreactivity and altered BBB properties at 3 days post-inoculation that coincided with early tumour invasion may be indicative of a mechanism for tumour cell extravasation into the brain. Thus, extravasation of tumour cells into the brain to form cerebral metastases may be a SP-mediated process.

The role of neurokinin-1 receptor in the microenvironment of inflammation and cancer

The recent years have witnessed an exponential increase in cancer research, leading to a considerable investment in the field. However, with few exceptions, this effort has not yet translated into a better overall prognosis for patients with cancer, and the search for new drug targets continues. 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, triggers a wide variety of functions. Antagonists against the NK-1 receptor are safe clinical drugs that are known to have anti-inflammatory, analgesic, anxiolytic, antidepressant, and antiemetic effects. Recently, it has become apparent that SP can induce tumor cell proliferation, angiogenesis, and migration via the NK-1 receptor, and that the SP/NK-1 receptor complex is an integral part of the microenvironment of inflammation and cancer. Therefore, the use of NK-1 receptor antagonists as a novel and promising approach for treating patients with cancer is currently under intense investigation. In this paper, we evaluate the recent scientific developments regarding this receptor system, its role in the microenvironment of inflammation and cancer, and its potentials and pitfalls for the usage as part of modern anticancer strategies.

Substance P immunoreactive nerve fibres are related to gastric cancer differentiation status and could promote proliferation and migration of gastric cancer cells

Tachykinins such as SP (substance P) may be involved in the progression of gastric adenocarcinoma through binding to NK-1 receptor. However, the existence and relationship between SP and gastric cancer progression and differentiation remained unknown. We have studied the NK-1 receptor in human gastric cancer tissue and MKN45 cell line and found SP-containing nerve fibres in human gastric cancer and found that the amounts of SP-positive nerves were related to gastric cancer differentiation. SP could promote proliferation, adhesion, migration and invasion of MKN45 cells in vitro. In addition, the intracellular calcium level of MKN45 cells was elevated after SP stimulation, and administration of CRACs (calcium release-activated calcium channels) inhibitor SKF-96365 could partially abolish these effects induced by SP. These results demonstrated that NK-1 receptor and SP-containing nerves existed in human gastric cancer; SP positive nerves may play an important role in human gastric cancer progression, and calcium is critically significant among SP-induced biological effects.

Neurotransmitters, more than meets the eye--neurotransmitters and their perspectives in cancer development and therapy

The neurotransmitter/receptor system has been shown to modulate various aspects of tumor development including cell proliferation, angiogenesis, invasion, migration and metastasis. It has been found that tumor tissues can not only synthesize and release a wide range of neurotransmitters but also produce different biological effects via respective receptors. These tissues are also innervated by nerve fibers but the biological significance is unknown. Nevertheless neurotransmitters can produce either stimulatory or inhibitory effect in normal and tumor tissues. These effects are dependent on the types of tissues and the kinds of neurotransmitter as well as the subtypes of corresponding receptors being involved. These findings clearly extend the conventional role of neurotransmitters in nervous system to the actions in oncogenesis. In this regard, intervention or stimulation of these neuronal pathways in different cancer diseases would have significant clinical implications in cancer treatments. Here, we summarize the influences of various well-characterized neurotransmitters and their receptors on tumor growth and further discuss the respective possible strategies and perspectives for cancer therapy in the future.

NK-1 as a melanoma target

INTRODUCTION

Melanoma expresses both neurokinin-1 (NK-1) receptors and substance P (SP). After binding to the NK-1 receptor, SP induces tumor cell proliferation in melanoma cells, whereas after binding to the same NK-1 receptor, antagonists inhibit melanoma cell proliferation and cause tumor cell death by apoptosis. Thus, the NK-1 receptor could be a new and promising target in melanoma therapy.

AREAS COVERED

This review provides an overview of the underlying mechanism of action of the SP/NK-1 receptor system, and NK-1 receptor antagonists in human melanoma, over the last 7 years.

EXPERT OPINION

In stages III - IV, no effective treatment exists for melanoma and hence there is an urgent need to improve therapy in melanoma patients. The NK-1 receptor is a promising new target in human melanoma treatment, since preclinical assays (most of them in vitro assays) have reported that NK-1 receptor antagonists exert an antitumor action against melanoma. The NK-1 receptor antagonist aprepitant is used in clinical practice and exerts an antitumor action against human melanoma in vitro. In the future, such antitumor action should be tested in human clinical trials. This should be faster compared with less investigated NK-1 receptor antagonists, because a great part of the required safety and characterization studies for aprepitant have already been carried out.

The NK-1 receptor is expressed in human leukemia and is involved in the antitumor action of aprepitant and other NK-1 receptor antagonists on acute lymphoblastic leukemia cell lines

Substance P and neurokinin-1 (NK-1) receptor antagonists respectively induce cell proliferation and cell inhibition in human cancer cell lines. In acute lymphoblastic leukemia (ALL), substance P is expressed in human blast cells. However, the possible presence of NK-1 receptors in human ALL and the issue of whether the antitumor action of NK-1 receptor antagonists is exerted or not on human ALL (T-ALL BE-13 and B-ALL SD-1 cell lines) remain unknown. An immunoblot analysis was performed and an in vitro study of the cytotoxicity of three NK-1 receptor antagonists (L-733,060, L-732,138, aprepitant) was carried out on both cell lines. NK-1 receptors were found in those cell lines, and both expressed mRNA for this receptor. Using a knockdown method, we demonstrate that NK-1 receptors are involved in the viability of tumor cells. TAC1R cDNA was detected in the ALL cell lines by real-time quantitative RT-PCR. We also observed that the three NK-1 receptor antagonists elicited the inhibition of ALL cell growth; that the specific antitumor action of the NK-1 receptor antagonists occurs through the NK-1 receptor, and that ALL cell death is due to apoptosis. These findings suggest that NK-1 receptor antagonists could be considered as new antitumor drugs for the treatment of human ALL.

The broad-spectrum antitumor action of cyclosporin A is due to its tachykinin receptor antagonist pharmacological profile

Cyclosporin A (CsA) is an immunosuppressive drug. In human cancer cells substance P (SP) and neurokinin-1 (NK-1) receptor antagonists, respectively, induce cell proliferation and inhibition. CsA is a tachykinin receptor antagonist that showed selectivity for both NK-1 and NK-2 receptors. CsA exerts antitumor action against gastric (AGS) and colon (HT29) carcinoma cell lines. However, the mechanisms involved in this action remain unknown, and it is unknown whether CsA exerts an antitumor action on other human cancer cell lines or not. To demonstrate that CsA exerts a broad-spectrum antitumor action, we carried out an in vitro study of the growth-inhibitory capacity of CsA against seven human cancer cell lines, namely GAMG glioma, SKN-BE(2) neuroblastoma, WERI-Rb-1 retinoblastoma, HEp-2 larynx carcinoma, CAPAN pancreas carcinoma, 23132/87 gastric carcinoma, and SW-403 colon carcinoma. A Coulter counter was used to determine viable cell numbers followed by application of the MTS colorimetric method. Micromolar concentrations of CsA inhibited the growth of these tumor cells, both with and without previous administration of nanomolar concentrations of SP; the inhibition occurred in a dose-dependent manner. Moreover, CsA blocks SP-induced mitogen stimulation of tumor cells, suggesting that the NK-1 receptor is involved in such action. Following administration of CsA apoptosis was observed in the above seven tumor cell lines. These findings suggest that the antitumor action of CsA is at least due to its NK-1 receptor antagonist pharmacological profile, since the involvement of NK-2 receptors in the mentioned action must not be discarded, and that CsA has a broad-spectrum antitumor action.

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 microM 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.

SR140333 counteracts NK-1 mediated cell proliferation in human breast cancer cell line T47D

Background

It has been demonstrated that certain NK-1 antagonists could reduce proliferation of several cancer cell lines, however, it is unknown whether SR140333 exerts proliferation inhibition in breast cancer cell line.

Methods

Immunohistochemical staining was carried out to investigate the immunolocation of NK-1 in breast cancer tissues and T47D cell line, thereafter, various concentrations of [Sar9, Met(O2)11]substance P and SR140333 were applied alone or combined. MTT assay was applied to detect cytoactivation and coulter counter was to detect growth curve. The Hoechst33258 staining was performed to detect apoptosis.

Results

We found that breast cancer and T47D cells bear positive expression of NK-1. SR140333 inhibited cell growth in a dose dependent manner. Furthermore, SR140333 could counteract [Sar9, Met(O2)11]substance P induced proliferation. Hoechst33258 staining revealed the presence of apoptosis after SR140333 treatment.

Conclusions

Our study demonstrated SR140333 exert proliferation inhibition in breast cancer cell line T47D and indicates NK-1 play a central role in the substance P related cell proliferation in breast cancer.

Immunolocalization of NK-1 receptor and Substance P in human normal placenta

A role for Substance P (SP) in human placenta is not known, although is possible that regulates placental physiology through the Neurokinin (NK)-1 receptor. Ten human normal placenta tissues were studied by immunohistochemistry to demonstrate the localization of NK-1 receptor and SP. An immunostaining pattern for NK-1 receptor and SP was observed in the endothelium and myocytes of fetal blood vessels, decidua and trophoblast. The SP is located in both the cytoplasm and the nucleus whereas NK-1 receptor in cytoplasmic. These findings reported here for the fist time, suggest a role for the SP and NK-1 receptor in the placental physiology.

The NK-1 Receptor Antagonist L-732,138 Induces Apoptosis and Counteracts Substance P-Related Mitogenesis in Human Melanoma Cell Lines

It has been recently demonstrated that substance P (SP) and neurokinin-1 (NK-1) receptor antagonists induce cell proliferation and cell inhibition in human melanoma cells, respectively. However, the antitumor action of the NK-1 receptor antagonist L-732,138 on such cells is unknown. The aim of this study was to demonstrate an antitumor action of L-732,138 against three human melanoma cell lines (COLO 858, MEL HO, COLO 679). We found that L-732,138 elicits cell growth inhibition in a concentration dependent manner in the melanoma cells studied. Moreover, L-732,138 blocks SP mitogen stimulation. The specific antitumor action of L-732,138 occurred through the NK-1 receptor and melanoma cell death was by apoptosis. These findings indicate that the NK-1 receptor antagonist L-732,138 could be a new antitumor agent in the treatment of human melanoma.

The NK-1 receptor antagonist aprepitant as a broad spectrum antitumor drug

Aprepitant is a selective high-affinity antagonist of human substance P (SP)/Neurokinin-1 (NK-1) receptors. Until now this drug has been used as anxiolytic, antidepressant and antiemetic. It has been demonstrated that SP induces cell proliferation and NK-1 receptor antagonists different to aprepitant inhibit growth in several human cancer cell lines, where NK-1 receptors are overexpressed. The purpose of this study is to demonstrate the antitumor action of aprepitant. We performed an in vitro study of the growth inhibition capacity of the NK-1 receptor antagonist aprepitant against glioma, neuroblastoma, retinoblastoma and pancreas, larynx, gastric and colon carcinomas cell lines. Coulter counter was used to determine viable cell numbers followed by application of the MTS colorimetric method. Furthermore, a DAPI method was applied to demonstrate apoptosis. We have demonstrated: aprepitant at (5-70 microM) concentration elicits growth cell inhibition in a concentration dependent manner in all tumor cell line studied. Maximum inhibition (100%) was observed when the aprepitant was administered at a concentration of > or = 70 microM in all tumor cell lines studied. The specific antitumor action of aprepitant occurs through the NK-1 receptor and tumor cells death was by apoptosis pathway. These findings reported here for the first time indicate that aprepitant is a new and promising broad spectrum antitumor drug in the treatment of cancer.

A role for the substance P/NK-1 receptor complex in cell proliferation and apoptosis in oral lichen planus

OBJECTIVES

To determine whether substance P (SP) and NK-1 receptor (NK-1R) are expressed in oral lichen planus (OLP) and are related to cell proliferation and apoptosis in this disease.

MATERIAL AND METHODS

Tissue samples from 50 OLP patients and 26 healthy controls were studied. Immunohistochemistry was performed with anti-SP, anti-NK-1R, anti-ki-67 and anti-caspase-3 monoclonal antibodies and the clinical and pathological data of the OLP patients were evaluated.

RESULTS

With the exception of NK-1R expression in epithelial cell membrane and cytoplasm, all markers were more frequently present in OLP patients than in controls (P < 0.05). Higher cytoplasmatic expression of NK-1R was associated with higher epithelial expression of caspase-3 (P < 0.05). Higher epithelial expression of NK-1R and SP was associated with higher suprabasal and basal epithelial expression of ki-67 (P < 0.05 and P < 0.005, respectively).

CONCLUSIONS

Actions of the SP/NK-1R complex may contribute to the immune disorder underlying OLP and trigger stimuli to induce cell proliferation. These results indicate that this complex might play a role in the malignant transformation of OLP.

Cell proliferation associated with actions of the substance P/NK-1 receptor complex in keratocystic odontogenic tumours

The expression of substance P (SP) and its NK-1 receptor (NK-1R) in keratocystic odontogenic tumours (KOTs) was studied to determine whether the intrinsic growth potential of these lesions is related to a cell proliferation stimulus mediated by the SP/NK-1R complex. A total of 65 tissue samples of solitary non-recurrent KOTs, solitary recurrent KOTs, KOTs associated with nevoid basal cell carcinoma syndrome (NBCCS) and KOTs with chondroid wall were studied by immunohistochemistry, using anti-SP, anti-NK-1R and anti-Ki-67 monoclonal antibodies. Expression of these markers was analysed in infiltrating lymphocytes, in fibrous capsule, and in membrane, cytoplasm and nucleus of epithelial cells. SP expression in infiltrating lymphocytes was significantly associated with SP in fibrous capsule and epithelial cells. KOTs associated with NBCCS showed a significantly higher SP expression in all tissues and cell compartments compared with other KOT types. Finally, SP expression in epithelial cells was associated with positive Ki-67 expression in dysplastic epithelium. This first published report on SP and NK-1R expressions in KOTs demonstrates that actions of the SP/NK-1R complex may constitute a mechanism to stimulate epithelial cell proliferation in KOT. This pathway may be of special relevance in the multiple KOTs associated with NBCCS.

NK-1 receptor antagonists induce apoptosis and counteract substance P-related mitogenesis in human laryngeal cancer cell line HEp-2

It has been demonstrated that substance P (SP) induces cell proliferation and neurokinin-1 (NK-1) receptor antagonists inhibit growth in several human cancer cell lines, but it is currently unknown whether such actions are exerted on human laryngeal carcinoma cell line HEp-2. In addition, the presence of NK-1 receptor has not been demonstrated in this cell line. We carried out an in vitro study of the growth inhibitory capacity of the NK-1 receptor antagonists L-733,060 and L-732,138 against human laryngeal carcinoma cell line HEp-2. Coulter counter was used to determine viable cell numbers followed by application of the tetrazolium compound MTS. Furthermore, an immunoblot analysis was used to determine the NK-1 receptor, and the 4',6-diamidino-2-phenylindole (DAPI) method was applied to demonstrate apoptosis of the laryngeal carcinoma cells. We observed the presence of several NK-1 receptors isoforms (34, 46, 58 and 75 kDa). Nanomolar concentrations of SP increased the growth rate of the cell line and micromolar concentrations of L-733,060 and L-732,138 inhibited the growth of the HEp-2 cells in a dose-dependent manner, with and without previous administration of SP. The 50% inhibition concentration values were 21.34 microM and 37.97 (48 h) respectively for HEp-2. NK-1 receptor presence on HEp-2 cells was confirmed by western blotting. DAPI staining revealed the presence of apoptosis following NK-1 receptor antagonists treatment. We demonstrated that NK-1 receptors were present in this laryngeal cancer cell line; these findings demonstrate that SP acts as a mitogen on the human laryngeal carcinoma cell line HEp-2 through the NK-1 receptor, and also indicate that both NK-1 receptors antagonists induced apoptosis of the tumour cells. This new action, reported here for the first time, suggests that the NK-1 receptor is a new and promising target in the treatment of human laryngeal carcinoma.