Immunolocalization of full-length NK1 tachykinin receptors in human tumors

Carcinogenesis and Metastasis: Focus on TRPV1-Positive Neurons and Immune Cells

Both sensory neurons and immune cells, albeit at markedly different levels, express the vanilloid (capsaicin) receptor, Transient Receptor Potential, Vanilloid-1 (TRPV1). Activation of TRPV1 channels in sensory afferent nerve fibers induces local effector functions by releasing neuropeptides (most notably, substance P) which, in turn, trigger neurogenic inflammation. There is good evidence that chronic activation or inactivation of this inflammatory pathway can modify tumor growth and metastasis. TRPV1 expression was also demonstrated in a variety of mammalian immune cells, including lymphocytes, dendritic cells, macrophages and neutrophils. Therefore, the effects of TRPV1 agonists and antagonists may vary depending on the prominent cell type(s) activated and/or inhibited. Therefore, a comprehensive understanding of TRPV1 activity on immune cells and nerve endings in distinct locations is necessary to predict the outcome of therapies targeting TRPV1 channels. Here, we review the neuro-immune modulation of cancer growth and metastasis, with focus on the consequences of TRPV1 activation in nerve fibers and immune cells. Lastly, the potential use of TRPV1 modulators in cancer therapy is discussed.

Detection of neurokinin-1 receptor by immunohistochemistry in canine mammary gland tumours

Canine mammary gland tumour (cMGT) is the most common tumour in intact female dogs. Surgery is the only effective treatment for cMGT, and dogs with metastasis at the time of diagnosis or those diagnosed at an advanced stage have poorer prognosis. Thus, novel diagnostic biomarkers and therapeutic targets are needed. Neurokinin‐1 receptor (NK‐1 receptor) is involved in cancer progression and has been detected in various malignant tumours including breast cancer in humans. Furthermore, NK‐1 receptor antagonists inhibit cancer progression. We evaluated NK‐1 receptor expression in malignant and benign cMGT compared with that in normal mammary gland tissues and analysed the relationship between the expression of NK‐1 receptor and histopathological type or malignancy grade. Specimens from 34 malignant MGT and 35 benign MGT cases were used for immunohistochemistry and scored according to intensity and percentage. Healthy margins from each tumour were used as internal controls. The scores for NK‐1 receptor intensity, percentage of positive cells and overall immunohistochemistry were higher in malignant MGT than in benign MGT and normal tissue (p < .000). NK‐1 receptor expression was not correlated with either malignancy grade or histopathological type. Expression of the NK‐1 receptor in malignant MGT was higher than that in benign MGT and normal tissues. Thus, NK‐1 receptor could be considered a novel therapeutic target for cMGT. Further studies using other quantitative tests such as western blotting or PCR and the evaluation of substance P in patient tumour tissue or serum are needed.

The Added Value of Diagnostic and Theranostic PET Imaging for the Treatment of CNS Tumors

This review highlights the added value of PET imaging in Central Nervous System (CNS) tumors, which is a tool that has rapidly evolved from a merely diagnostic setting to multimodal molecular diagnostics and the guidance of targeted therapy. PET is the method of choice for studying target expression and target binding behind the assumedly intact blood-brain barrier. Today, a variety of diagnostic PET tracers can be used for the primary staging of CNS tumors and to determine the effect of therapy. Additionally, theranostic PET tracers are increasingly used in the context of pharmaceutical and radiopharmaceutical drug development and application. In this approach, a single targeted drug is used for PET diagnosis, upon the coupling of a PET radionuclide, as well as for targeted (nuclide) therapy. Theranostic PET tracers have the potential to serve as a non-invasive whole body navigator in the selection of the most effective drug candidates and their most optimal dose and administration route, together with the potential to serve as a predictive biomarker in the selection of patients who are most likely to benefit from treatment. PET imaging supports the transition from trial and error medicine to predictive, preventive, and personalized medicine, hopefully leading to improved quality of life for patients and more cost-effective care.

Design, Synthesis, and Evaluation of a Neurokinin-1 Receptor-Targeted Near-IR Dye for Fluorescence-Guided Surgery of Neuroendocrine Cancers

The neurokinin-1 receptor (NK1R) is implicated in the growth and metastasis of many tumors, including cancers of the brain (e.g., gliomas, glioblastomas, and astrocytomas), skin (e.g., melanomas), and neuroendocrine tissues (cancers of the breast, stomach, pancreas, larynx, and colon). Because overexpression of NK1R has been reported in most of these malignancies, we have undertaken designing an NK1R-targeted near-infrared (NIR) fluorescent dye for fluorescence-guided surgeries of these cancers. We demonstrate here that an NK1R-binding ligand linked to the NIR dye LS288 selectively accumulates in NK1R-expressing tumor xenografts with high affinity (Kd = 13 nM), allowing intraoperative imaging of these cancers in live mice. Because tumor accumulation is nearly quantitatively blocked by excess unlabeled ligand, and because NK1R-negative tumors and normal tissues display virtually no uptake, we conclude that the observed tumor retention is NK1R-mediated. Results on the synthesis, in vitro characterization, and animal testing of NK1R-targeted NIR dye are presented.

High expression of substance P and its receptor neurokinin-1 receptor in colorectal cancer is associated with tumor progression and prognosis

Background

Epidemiologic evidence suggests that chronic inflammation and/or chronic infection is associated with cancer development, and the inflammatory process may play a crucial role in the carcinogenesis and prognosis of colorectal cancer (CRC). Substance P (SP) belongs to the family of tachykinins and acts as an immunomodulator, binding to the neurokinin-1 receptor (NK1R) to initiate tumor cell proliferation, angiogenesis, and migration, steps that are critical for tumor cell invasion and metastasis. It is suggested that SP/NK1R signaling may play an important role in cancer progression and metastasis. However, the exact involvement and significance of SP and NK1R in CRC pathologies remain to be adequately deciphered.

Patients and methods

We performed immunohistochemistry staining on tissue microarrays containing 267 pairs of CRC and adjacent normal tissues to evaluate the clinical significance of SP or NK1R in the progression and prognosis of CRC. We also explored the potential correlation between SP and NK1R in CRC development.

Results

Expression levels of SP and NK1R were upregulated in CRC compared with their expressions in adjacent normal tissues (P<0.001). High expression of SP in CRC was significantly associated with lymph node metastasis (P<0.001). We also found that high expression of NK1R in CRC was significantly related to TNM (tumor node metastasis) stage (P=0.010) and lymph node metastasis (P=0.019). A high correlation between SP and NK1R expression was also observed (r=0.419, P<0.001). Survival analysis showed that CRC patients with high expression of SP or NK1R have a poor prognosis when compared to patients with low SP or NK1R expression (log rank test, P<0.05). Multivariate analysis using Cox regression model showed that survival was independently correlated with lymph node metastasis, distant metastasis, and SP expression (P<0.05).

Conclusion

Upregulation of SP-NK1R may play a crucial role in CRC progression. Moreover, SP-NK1R expression may also be used as a predictor for CRC prognosis.

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.

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.

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.

Heat shock protein 90 stabilizes nucleolin to increase mRNA stability in mitosis

Most studies on heat shock protein 90 (Hsp90) have focused on the involvement of Hsp90 in the interphase, whereas the role of this protein in the nucleus during mitosis remains largely unclear. In this study, we found that the level of the acetylated form of Hsp90 decreased dramatically during mitosis, which indicates more chaperone activity during mitosis. We thus probed proteins that interacted with Hsp90 by liquid chromatography/mass spectrometry (LC/MS) and found that nucleolin was one of those interacting proteins during mitosis. The nucleolin level decreased upon geldanamycin treatment, and Hsp90 maintained the cyclin-dependent kinase 1 (CDK1) activity to phosphorylate nucleolin at Thr-641/707. Mutation of Thr-641/707 resulted in the destabilization of nucleolin in mitosis. We globally screened the level of mitotic mRNAs and found that 229 mRNAs decreased during mitosis in the presence of geldanamycin. Furthermore, a bioinformatics tool and an RNA immunoprecipitation assay found that 16 mRNAs, including cadherin and Bcl-xl, were stabilized through the recruitment of nucleolin to the 3'-untranslated regions (3'-UTRs) of those genes. Overall, strong correlations exist between the up-regulation of Hsp90, nucleolin, and the mRNAs related to tumorigenesis of the lung. Our findings thus indicate that nucleolin stabilized by Hsp90 contributes to the lung tumorigenesis by increasing the level of many tumor-related mRNAs during mitosis.

Truncated neurokinin-1 receptor is increased in colonic epithelial cells from patients with colitis-associated cancer

Patients with chronic ulcerative colitis (UC) are at high risk for developing colorectal cancer. In this study, archival formalin-fixed paraffin-embedded colonic tissue from patients with UC who developed carcinoma (CA) or high-grade dysplasia (HGD) was examined for changes in expression of the proinflammatory and mitogenic neurokinin-1 receptor (NK-1R). Laser capture microscopy was used to microdissect epithelia from areas of colons that showed histologic evidence of CA, HGD, and epithelia that were not dysplastic or cancerous but did contain evidence of prior inflammation (quiescent colitis). mRNA was extracted from the dissected tissue, and PCR array analysis was performed on extracted mRNA. Two antibodies were necessary to separately estimate the protein levels of the truncated (tr-NK-1R) and full-length (fl-NK-1R) receptors by immunohistochemistry. mRNA expression of tr-NK-1R increased 14-fold (P = 0.02) when comparing the HGD and CA groups. In contrast, the fl-NK-1R transcript showed no significant differences among groups. The protein levels of the total NK-1R increased by 40% (P = 0.02) in HGD and 80% (P = 0.0007) in CA compared with quiescent colitis. There were no significant changes in protein levels of the fl-NK-1R. We conclude that the increase in total NK-1R protein in HGD and CA is attributable to an increase in tr-NK-1R, suggesting there may be a functional role for tr-NK-1R in malignant transformation in colitis-associated cancer. The tr-NK-1R could prove useful as a diagnostic marker to identify patients at risk for neoplasia and may serve as a useful therapeutic target in the treatment of colitis-associated cancer.

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.

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.

Ontogeny of apelin and its receptor in the rodent gastrointestinal tract

Apelin is the endogenous ligand for the APJ receptor and both apelin and APJ are expressed in the gastrointestinal (GI) tract. The aim of this study was to define ontogeny of apelin and APJ in the developing rodent GI tract by measuring expression levels and characterizing abundance and cellular localization at an embryonic stage (E18.5 or E21), two postnatal stages (P4, P16) and in the adult. Apelin and APJ mRNA levels were measured by real time RT-PCR, apelin and APJ-containing cells were identified by immunohistochemical (IHC) staining. Gastric, duodenal and colonic apelin and APJ mRNA levels were highest at birth and declined postnatally. In the postnatal rat stomach, few apelin peptide-containing cells were identified, the density of gastric apelin-containing cells increased progressively after weaning and into adulthood. A robust APJ immunostaining was observed postnatally in the epithelium, intestinal goblet cells and in smooth muscle cells. In the adult rat, APJ immunostaining in the surface epithelium and goblet cells decreased markedly. During the early postnatal period, in an apelin-deficient mouse, APJ expression and immunostaining in the gut were reduced suggesting that apelin regulates APJ. Together, our data support a role for the apelin-APJ system in the regulation of smooth muscle, epithelial and goblet cell function in the GI tract.

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.