Neurokinin receptor antagonism: a patent review (2014-present)

Post-treatment with maropitant reduces oxidative stress, endoplasmic reticulum stress and neuroinflammation on peripheral nerve injury in rats

OBJECTIVE

To determine the effective dose and therapeutic potential of maropitant using through expression of mediators of oxidative stress, inflammatory and of the unfolded protein response (UPR) (bio) markers on spinal cord using a model of neuropathic pain induced through chronic constriction injury (CCI) in rats.

STUDY DESIGN

Randomized, blinded, prospective experimental study.

ANIMALS

98 male Wistar rats.

METHODS

Rats were anesthetized with sevoflurane and after CCI, they were randomly assigned to the following groups that received: vehicle, 3, 6, 15, 30 e 50 mg/kg/24q of maropitant. The effect on inflammatory mediators (IL10, TNFα), oxidative stress (GPx, CAT, SOD), microglial (IBA-1) and neuronal (NeuN, TACR1) markers was evaluated though immunohistochemistry and expression levels of markers of hypoxia (HIF1α, Nrf2), antioxidant enzymes (Catalse, Sod1 and GPx1), and endoplasmic reticulum stress mediators (GRP78, CHOP and PERK) through qRT-PCR.

RESULTS

Intraperitoneal injection (IP) of maropitant inhibited nociception with ID50 values of 4,1 mg/kg (5,85-19,36) in a neuropathic pain model through CCI. A dose of 30 mg/kg/24q was significantly effective in reducing mechanical allodynia 1 to 4h after treatment with nociception inhibition (145,83%). A reduction in the expression of hypoxia factors (HIF1α, Nrf2) was observed, along with an increase in antioxidant activity (CAT, SOD and GPX). Additionally, there was a reduction in inflammatory markes (IL10, TNFα), microglial (IBA-1), and neuronal markers (NeuN, TACR1).

CONCLUSION AND CLINICAL RELEVANCE

These findings demonstrate that the determined dose, administered daily for seven days, had an antinociceptive effect, as well as anti-inflammatory and antioxidant activity.

The combined anti-tumor effects of 5-fluorouracil and neurokinin receptor inhibitor, aprepitant, against colorectal cancer: In vitro and in vivo study

BACKGROUND

Colorectal cancer (CRC) is one of the world's largest health concerns with growing global incidence and mortality. The potential value of the neurokinin-1 receptor as a therapeutic target has been reported in several tumor types, including CRC. Here we examined the potential anti-tumor effects of a clinically approved neurokinin-1 receptor antagonist, aprepitant, alone and its combination with 5-Fluorouracil (5-FU) as a first choice CRC chemotherapeutic drug, in both in vitro and in vivo models of CRC.

METHODS

MTT assay was employed for assessing cell proliferation. mRNA expression levels were determined by quantitative real-time PCR (qRT-PCR). Flow cytometric analysis of apoptosis was performed using an Annexin-V/propidium iodide assay kit. We finally conducted an in vivo experiment in a mouse model of CRC to confirm the in vitro antiproliferative activity of aprepitant and 5-FU.

RESULTS

We found that aprepitant and 5-FU significantly reduced CRC cell viability. The combination of drugs exhibited potent synergistic growth inhibitory effects on CRC cells. Moreover, aprepitant and 5-FU induced apoptosis and altered the levels of apoptotic genes (up-regulation of Bax, and p53 along with downregulation of Bcl-2). Importantly, the aprepitant and 5-FU combination showed a more pronounced impact on apoptosis and associated genes than either of the agents alone. Furthermore, aprepitant reduced tumor growth in vivo and led to significantly longer survival time, and this effect was more prominent when using the aprepitant and 5-FU combination.

CONCLUSIONS

Collectively, combinatory treatment with aprepitant and 5-FU potentially exerts synergistic growth inhibition and apoptosis induction in CRC, deserving further consideration as a novel strategy for CRC patients.

Homology modeling, virtual screening, molecular docking, and ADME approaches to identify a potent agent targeting NK2R protein

Neurokinin/tachykinin receptors are classified as the G-protein coupled receptor superfamily. The neurokinin 2 receptor (NK2R) is widely expressed in different tissues. NK2R is associated with a range of biological events, such as inflammation, smooth muscle contraction, intestinal motor functions, and asthma. Despite these diverse activities, no approved drugs targeting NK2R have been developed yet. Our study focuses on finding potential inhibitors for NK2R using virtual screening, molecular docking, and ADME (absorption, distribution, metabolism, and excretion) approaches. We used a homology modeling approach and AlphaFold DB to obtain the three-dimensional structure of mouse and human NK2R proteins, respectively. The homology model of NK2R was predicted using MODELLER v10.3 and further refined and validated using the 3Drefine tool and RAMPAGE server, respectively. Molecular docking was performed using a library of 910 structurally similar molecules to four NK1R antagonists: aprepitant, casopitant, fosaprepitant, and rolapitant. Molecular docking revealed six small molecules that displayed high Chemscore fitness scores, and binding energies with desirable ligand-NK2R interactions. The evaluation of the in silico ADME profile, solubility, and permeability of the ligand molecules has revealed that the small molecules are potentially nontoxic and have the chance of exhibiting biological activity after oral administration. Further experimental studies (in vitro and in vivo assays) are required to evaluate the effectiveness of these inhibitors as therapeutic targets.

Diterpenes of Pinus pinaster aiton with anti-inflammatory, analgesic, and antibacterial activities

ETHNO-PHARMACOLOGICAL RELEVANCE

The P. pinaster species, known as 'Pino nigral or rodeno', is used in the treatment of colds, asthma, flu, and tuberculosis.

AIM OF THE STUDY

This study determined the anti-inflammatory, analgesic, and antibacterial activities of the P. pinaster resin, identifying the compounds with higher biological activity.

MATERIALS AND METHODS

A bio-guided isolation of the compounds of P. pinaster was carried out by selecting the most active extracts with anti-inflammatory and analgesic effects in the HBEC3-KT, MRC-5, and THP-1 cell lines. The antibacterial activity was determined against the S. aureus, S. pneumoniae, K. pneumoniae and P. aeruginosa strains.

RESULTS

The following compounds were identified by NMR: dehydroabietic acid (1), ( + )-cis-abienol (2), pimaric acid (3), isopimaric acid (4), 7α-hydroxy-dehydroabietic acid (5), 7-oxo-dehydroabietic acid (6), 15-hydroxy-abietic acid (7), 7-oxo-15-hydroxy-dehydroabietic acid (8), 13-oxo-8 (14)-podocarpen-18-oic acid (9), and pinyunin A (10). Regarding their anti-inflammatory activity, all compounds inhibited NF-κB. Compound 9 was the most active (IC50 = 3.90-12.06 μM). Concerning the analgesic activity, all the compounds inhibited NK-1, yet compound 9 was the most active (IC50 = 0.28-0.33 μM). Finally, compounds 6 (MIC = 12.80-25.55 μM) and 9 (MIC = 9.80-24.31 μM) were the most promising antibacterial compounds in all strains.

CONCLUSION

This study managed to identify, for the first time, six diterpenes from the resin of P. pinaster, with anti-inflammatory, analgesic, and antibacterial activity. Among the identified compounds, compound 9 was the most active, being considered a promising candidate as an antagonist of the tachykinin NK-1 receptor and as an analgesic agent against inflammation and neuropathic pain. It also had an antibacterial effect against Gram negative bacteria.

The In Vitro Pro-inflammatory Functions of the SP/NK1R System in Prostate Cancer: a Focus on Nuclear Factor-Kappa B (NF-κB) and Its Pro-inflammatory Target Genes

Prostate cancer is one of the main global health threats for men which is in close association with chronic inflammation. Neuropeptide substance P (SP), acting through neurokinin receptor (NK-1R), induces various pro-inflammatory responses which are strongly involved in the pathogenesis of several diseases as well as cancer. Therefore, we aimed to investigate the pro-inflammatory functions of the SP/NK1R complex in prostate cancer and the therapeutic effects of its inhibition by NK-1R antagonist, aprepitant, in vitro. MTT assay was conducted for the cytotoxicity assessment of aprepitant in prostate cancer cells. The protein expression levels were evaluated by Western blot assay. Quantitative real-time PCR (qRT-PCR) was applied to measure mRNA expression levels of pro-inflammatory cytokines. Concurrently, the protein concentrations of pro-inflammatory cytokines were also analyzed by enzyme-linked immunosorbent assay. We observed that SP increased the levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), while treatment with aprepitant reduced the effects of SP. We also indicated that SP increased the protein levels of nuclear factor-kappa B (NF-κB), as the main regulator of inflammatory processes, and also an NF-κB target gene, cyclooxygenase 2 (COX-2) in prostate cancer cells, while treatment with aprepitant reversed these effects. Taken together, our findings highlight the importance of the SP/NK1R system in the modulation of pro-inflammatory responses in prostate cancer cells and suggest that aprepitant may be developed as a novel anti-inflammatory agent for the management of cancer-associated inflammation.

Lessons learned in translating pain knowledge into practice

Introduction

During the past 2 decades, basic research deciphering the underlying mechanisms of nociception and chronic pain was thought to finally step beyond opioids and nonsteroidals and provide patients with new analgesics. But apart from calcitonin gene-related peptide antagonists, nothing arrived in hands of clinicians.

Objectives

To present existing evidence of 3 representative target molecules in the development of novel pain treatment that, so far, did not result in approved drugs.

Methods

This Clinical Update aligns with the 2022 IASP Global Year Translating Pain Knowledge into Practice and selectively reviews best available evidence and practice.

Results

We highlight 3 targets: a ion channel, a neuronal growth factor, and a neuropeptide to explore why these drug targets have been dropped in clinical phase II-III trials. Antibodies to nerve growth factor had very good effects in musculoskeletal pain but resulted into more patients requiring joint replacements. Blockers of NaV1.7 were often not effective enough-at least if patients were not stratified. Blockers of neurokinin receptor were similarly not successful enough. In general, failure was most often to the result of a lack of effect and to a lesser extend because of unexpected severe side effects. However, all studies and trials lead to an enormous move in the scientific community to better preclinical models and testing as well as revised methods to molecularly phenotype and stratify patients.

Conclusion

All stakeholders in the process can help in the future: better preclinical studies, phenotyping and stratifying patients, and participation in clinical trials to move the discovery of analgesics forward.

Moving out of CF3 -Land: Synthesis, Receptor Affinity, and in silico Studies of NK1 Receptor Ligands Containing a Pentafluorosulfanyl (SF5 ) Group

The NK1 receptor (NK1R) is a molecular target for both approved and experimental drugs intended for a variety of conditions, including emesis, pain, and cancers. While contemplating modifications to the typical NK1R pharmacophore, we wondered whether the CF3 groups common for many NK1R ligands, could be replaced with some other moiety. Our attention was drawn by the SF5 group, and so we designed, synthesized, and tested ten novel SF5 -containing compounds for NK1R affinity. All analogues exhibit detectable NK1R binding, with the best of them, compound 5 a, (3-bromo-5-(pentafluoro-λ6 -sulfanyl)benzyl acetyl-L-tryptophanate) binding only slightly worse (IC50 =34.3 nM) than the approved NK1R-targeting drug, aprepitant (IC50 =27.7 nM). Molecular docking provided structural explanation of SAR. According to our analysis, the SF5 group in our compounds occupies a position similar to that of one of the CF3 groups of aprepitant as found in the crystal structure. Additionally, we checked whether the docking scoring function or energies derived from Fragment Molecular Orbital quantum chemical calculations may be helpful in explaining and predicting the experimental receptor affinities for our analogues. Both these methods produce moderately good results. Overall, this is the first demonstration of the utility of the SF5 group in the design of NK1R ligands.

[WITHDRAWN] Neuron-dependent tuft cell expansion initiates sinonasal allergic Type 2 inflammation

The authors have withdrawn this manuscript owing to inaccuracies in the calculation of tuft cell numbers and errors in the selection of immunofluorescence images used to support our claims. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

Neurokinin 1/3 receptor antagonists for menopausal women: A current systematic review and insights into the investigational non-hormonal therapy

BACKGROUND

Over 75% of menopausal women experience vasomotor symptoms (VMS), such as night sweats and hot flashes. Despite the prevalence of these symptoms, there is limited data on non-hormonal therapies to alleviate them.

METHODS

PubMed, Cochrane, Scopus, Ovid, Web of Science, and ClinicalTrials.Gov were searched for relevant studies. The search was performed using the following keywords, which were customized to suit the specific databases/registers: menopause, women, neurokinin 3, and/or Fezolinetant. The search was conducted until December 20, 2022. This systematic review was conducted in compliance with the PRISMA Statement 2020 guidelines.

RESULTS

A total of 326 records were found, with 10 studies (enrolling 1993 women) selected for inclusion. The women received 40-mg doses of NK1/3 receptor antagonists twice daily, with follow-ups at 1 to 3 weeks. Moderately strong evidence was found suggesting that NK1/3 receptor antagonists can help limit the frequency and severity of hot flashes in menopausal women.

CONCLUSION

While the results should be interpreted with caution until further clinical trials validate the efficacy and safety of NK1/3 receptor antagonists among menopausal women, these findings suggest that they are promising targets for future pharmacological and clinical studies in addressing vasomotor symptoms.

Orexin antagonism and substance-P: Effects and interactions on polycystic ovary syndrome in the wistar rats

BACKGROUND

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder without definitive treatments. Orexin and Substance-P (SP) neuropeptides can affect the ovarian steroidogenesis. Moreover, there are limited studies about the role of these neuropeptides in PCOS. We aimed here to clarify the effects of orexins and SP in PCOS as well as any possible interactions between them.

METHODS

For this purpose, the animals (n = five rats per group) received intraperitoneally a single dose of SB-334,867-A (orexin-1 receptor antagonist; OX1Ra), JNJ-10,397,049 (orexin-2 receptor antagonist; OX2Ra), and CP-96,345 (neurokinin-1 receptor antagonist; NK1Ra), alone or in combination with each other after two months of PCOS induction. The blocking of orexin and SP receptors was studied in terms of ovarian histology, hormonal changes, and gene expression of ovarian steroidogenic enzymes.

RESULTS

The antagonists' treatment did not significantly affect the formation of ovarian cysts. In the PCOS groups, the co-administration of OX1Ra and OX2Ra as well as their simultaneous injections with NK1Ra significantly reversed testosterone levels and Cyp19a1 gene expression when compared to the PCOS control group. There were no significant interactions between the PCOS groups that received NK1Ra together with one or both OX1R- and OX2R-antagonists.

CONCLUSION

The blocking of the orexin receptors modulates abnormal ovarian steroidogenesis in the PCOS model of rats. This suggests that the binding of orexin-A and -B to their receptors reduces Cyp19a1 gene expression while increasing testosterone levels.

The Potential In Vitro Inhibitory Effects of Neurokinin-1 Receptor (NK-1R) Antagonist, Aprepitant, in Osteosarcoma Cell Migration and Metastasis

Background

Osteosarcoma, the most frequent osteogenic malignancy, has become a serious public health challenge due to its high morbidity rates and metastatic potential. Recently, the neurokinin-1 receptor (NK-1R) is proved to be a promising target in cancer therapy. This study is aimed at determining the effect of aprepitant, a safe and Food and Drug Administration (FDA) approved NK-1R antagonist, on osteosarcoma cell migration and metastasis, and to explore its underlying mechanism of action.

Methods

Colorimetric MTT assay was employed to assess cell viability and cytotoxicity. A wound-healing assay was used to examine migration ability. The desired genes' protein and mRNA expression levels were measured by western blot assay and quantitative real-time PCR (qRT-PCR), respectively. Gelatinase activity was also measured by zymography.

Results

We found that aprepitant inhibited MG-63 osteosarcoma cell viability in a dose-dependent manner. We also observed that aprepitant inhibited the migrative phenotype of osteosarcoma cells and reduced the expression levels and activities of matrix metalloproteinases (MMP-2 and MMP-9). Aprepitant also reduced the expression of an angiogenic factor, VEGF protein, and NF-κB as an important transcriptional regulator of metastasis-related genes.

Conclusion

Collectively, our observations indicate that aprepitant modulates the metastatic behavior of human osteosarcoma cells, which may be applied to an effective therapeutic approach for patients with metastatic osteosarcoma.

The redox modulatory effects of SP/NK1R system: Implications for oxidative stress-associated disorders

Oxidative stress which refers to redox imbalance with increased generation of reactive oxygen species (ROS) has been associated with the pathophysiology of diverse disease conditions. Recently, a close, yet not fully understood, relation between oxidative stress and neuropeptides, in particular, substance P (SP), has been reported in certain conditions. SP has been shown to affect the cellular redox environment through activation of neurokinin-1receptor (NK1R). It seems that SP/NK1R system and oxidative stress can act either synergistically or antagonistically in a context-dependent manner, thereby, influencing the pathology of various clinical disorders either destructively or protectively. Importantly, the interactions between oxidative stress and SP/NK1R system can be pharmacologically targeted. Therefore, a better understanding of the redox modulatory properties of SP/NK1R signaling will pave the way for identifying new therapeutic possibilities for attenuating oxidative stress-mediated damage. Towards this end, we performed a comprehensive search through PubMed/Medline and Scopus databases and discussed all related existing literature regarding the interplay between oxidative stress and SP/NK1R system as well as their implication in various clinical disorders, to provide a clear view and hence better management of oxidative damage.

Genetic validation of neurokinin 3 receptor antagonists for ischemic heart disease prevention in men – A one-sample Mendelian randomization study

Background

Ischemic heart disease (IHD) is a leading cause of mortality, particularly for men. Few interventions have focused on protecting specifically men. Emerging evidence may implicate testosterone. Neurokinin 3 receptor (NK3R) antagonists, an existing class of drugs being considered as treatments for reproductive conditions in women, affect testosterone; this study addresses genetic validation of their use to prevent IHD in men.

Methods

A one-sample Mendelian randomization (MR) study using the UK Biobank cohort study, based on independent (r² < 0.005) genetic variants predicting testosterone in men (n = 157738) at genome wide significance in the target gene for NK3R antagonists (TACR3), was used to assess associations with IHD (cases=15056, non-cases=151964) and positive control outcomes (relative age voice broke, children fathered, hypertension) in men and a negative control outcome (IHD) in women using summary statistics. A two-sample MR study using the PRACTICAL consortium was used for the positive control outcome of prostate cancer.

Findings

Two relevant TACR3 genetic variants (rs116646027 and rs1351623) were identified in men. Genetically mimicked NK3R antagonists were inversely associated with IHD (odds ratio 0.54 per standard deviation lower testosterone, 95% confidence interval 0.31, 0.94) and with control outcomes (older relative age voice broke, fewer children and lower risk of hypertension and prostate cancer) as expected in men and in women (unrelated to IHD).

Interpretation

Genetic validation of a role of NK3R antagonists in IHD suggests their consideration as a new means of preventing IHD in men. Whether they protect against prostate cancer might bear further consideration.

Multi-Omics Prognostic Signatures Based on Lipid Metabolism for Colorectal Cancer

Background: The potential biological processes and laws of the biological components in malignant tumors can be understood more systematically and comprehensively through multi-omics analysis. This study elaborately explored the role of lipid metabolism in the prognosis of colorectal cancer (CRC) from the metabonomics and transcriptomics.

Methods: We performed K-means unsupervised clustering algorithm and t test to identify the differential lipid metabolites determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) in the serum of 236 CRC patients of the First Hospital of Jilin University (JLUFH). Cox regression analysis was used to identify prognosis-associated lipid metabolites and to construct multi-lipid-metabolite prognostic signature. The composite nomogram composed of independent prognostic factors was utilized to individually predict the outcome of CRC patients. Glycerophospholipid metabolism was the most significant enrichment pathway for lipid metabolites in CRC, whose related hub genes (GMRHGs) were distinguished by gene set variation analysis (GSVA) and weighted gene co-expression network analysis (WGCNA). Cox regression and least absolute shrinkage and selection operator (LASSO) regression analysis were utilized to develop the prognostic signature.

Results: Six-lipid-metabolite and five-GMRHG prognostic signatures were developed, indicating favorable survival stratification effects on CRC patients. Using the independent prognostic factors as variables, we established a composite nomogram to individually evaluate the prognosis of CRC patients. The AUCs of one-, three-, and five-year ROC curves were 0.815, 0.815, and 0.805, respectively, showing auspicious prognostic accuracy. Furthermore, we explored the potential relationship between tumor microenvironment (TME) and immune infiltration. Moreover, the mutational frequency of TP53 in the high-risk group was significantly higher than that in the low-risk group (p < 0.001), while in the coordinate mutational status of TP53, the overall survival of CRC patients in the high-risk group was significantly lower than that in low-risk group with statistical differences.

Conclusion: We identified the significance of lipid metabolism for the prognosis of CRC from the aspects of metabonomics and transcriptomics, which can provide a novel perspective for promoting individualized treatment and revealing the potential molecular biological characteristics of CRC. The composite nomogram including a six-lipid-metabolite prognostic signature is a promising predictor of the prognosis of CRC patients.

Substance P and Neurokinin 1 Receptor in Chronic Inflammation and Cancer of the Head and Neck: A Review of the Literature

Head and neck cancer is a growing worldwide public health problem, accounting for approximately 1,500,000 new cases and 500,000 deaths annually. Substance P (SP) is a peptide of the tachykinin family, which has roles related to a large number of physiological mechanisms in humans. The implications of SP in carcinogenesis have recently been reported through the stimulation of the neurokinin 1 receptor (NK1R), or directly, through the effects derived from the constitutive activation of NK1R. Consequently, SP/NK1R seems to play relevant roles in cancer, upregulating cell proliferation, cell migration and chronic inflammation, among other oncogenic actions. Furthermore, there is growing evidence pointing to a central role for SP in tumour progression, singularly so in laryngeal and oral squamous cell carcinomas. The current narrative review of the literature focuses on the relationship between the SP/NK1R system and chronic inflammation and cancer in the head-and-neck region. We described a role for SP/NK1R in the transition from chronic inflammation of the head and neck mucosa, to preneoplastic and neoplastic transformation and progression.

Potential in vitro therapeutic effects of targeting SP/NK1R system in cervical cancer

BACKGROUND

Cervical cancer, an aggressive gynecological cancer, seriously threatens women's health worldwide. It is recently reported that neuropeptide substance P (SP) regulates many tumor-associated processes through neurokinin-1 receptor (NK1R). Therefore, we used cervical cancer cell line (HeLa) to investigate the functional relevance of the SP/NK1R system in cervical cancer pathogenesis.

METHODS

Cellular proliferation and cytotoxicity were analyzed by colorimetric MTT assay. Quantitative real-time PCR (qRT-PCR) was used to measure mRNA expression levels of desired genes. Cell cycle distribution and apoptosis were evaluated by flow cytometry. A wound-healing assay was employed to assess migration ability.

RESULTS

We found that the truncated isoform of NK1R(NK1R-Tr) is the dominantly expressed form of the receptor in Hela cells. We also indicated that that SP increased HeLa cell proliferation while treatment with NK1R antagonist, aprepitant, inhibited HeLa cell viability in a dose and time-dependent manner. SP also alters the levels of cell cycle regulators (up-regulation of cyclin B1 along with downregulation of p21) and apoptosis-related genes (up-regulation of Bcl-2 along with downregulation of Bax) while aprepitant reversed these effects. Aprepitant also induced arrest within the G2 phase of the cell cycle and subsequent apoptosis. Furthermore, SP promoted the migrative phenotype of HeLa cells and increased MMP-2 and MMP-9 expression while aprepitant exposure significantly reversed these effects.

CONCLUSION

Collectively, our results indicate the importance of the SP / NK1R system in promoting both proliferative and migrative phenotypes of cervical cancer cells and suggest that aprepitant may be developed as a novel treatment for combating cervical cancer.

A Novel Mechanism of Endoplasmic Reticulum Stress- and c-Myc-Degradation-Mediated Therapeutic Benefits of Antineurokinin-1 Receptor Drugs in Colorectal Cancer

The neurokinin-1 receptor (NK-1R) antagonists are approved as treatment for chemotherapy-associated nausea and vomiting in cancer patients. The emerging role of the substance P-NK-1R system in oncogenesis raises the possibility of repurposing well-tolerated NK-1R antagonists for cancer treatment. This study reports that human colorectal cancer (CRC) patients with high NK-1R expression have poor survival, and NK-1R antagonists SR140333 and aprepitant induce apoptotic cell death in CRC cells and inhibit CRC xenograft growth. This cytotoxicity induced by treatment with NK-1R antagonists is mediated by induction of endoplasmic reticulum (ER) stress. ER stress triggers calcium release, resulting in the suppression of prosurvival extracellular signal-regulated kinase (ERK)-c-Myc signaling. Along with ER calcium release, one ER stress pathway mediated by protein kinase RNA-like ER kinase (PERK) is specifically activated, leading to increased expression of proapoptotic C/EBP-homologous protein (CHOP). Moreover, NK-1R antagonists enhance the efficacy of chemotherapy by increasing the sensitivity and overcoming resistance to 5-fluorouracil in CRC cells through the induction of sustained ER stress and the consequent suppression of ERK-c-Myc signaling both in vitro and in vivo. Collectively, the findings provide novel mechanistic insights into the efficacy of NK-1R antagonists either as a single agent or in combination with chemotherapy for cancer treatment.

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.