G protein-coupled receptors in neurodegenerative diseases and psychiatric disorders.

Neuropsychiatric disorders are multifactorial disorders with diverse aetiological factors. Identifying treatment targets is challenging because the diseases are resulting from heterogeneous biological, genetic, and environmental factors. Nevertheless, the increasing understanding of G protein-coupled receptor (GPCR) opens a new possibility in drug discovery. Harnessing our knowledge of molecular mechanisms and structural information of GPCRs will be advantageous for developing effective drugs. This review provides an overview of the role of GPCRs in various neurodegenerative and psychiatric diseases. Besides, we highlight the emerging opportunities of novel GPCR targets and address recent progress in GPCR drug development.

Cryo-EM structure of orphan G protein-coupled receptor GPR21.

GPR21 belongs to class A orphan G protein-coupled receptor (GPCR). The endogenous ligands for human GPR21 remain unidentified. GPR21 expression is associated with developing type 2 diabetes (T2DM), a multifactorial metabolic disease caused by pancreatic ß-cell dysfunction, decreasing insulin production, insulin resistance, and obesity. Animal studies suggested that GPR21 is a potential therapeutic target for T2DM treatment. The underlying mechanisms leading to GPR21 self-activation remain unknown. In our co-expression analysis, we noted that GPR21 could also form a stable complex with an unreported Gα protein subtype, Gαs. To gain further insights into the structural mechanisms of GPR21 activation, we employed cryo-electron microscopy (cryo-EM) and single-particle analysis to resolve the high-resolution structure of GPR21-Gαs complexes. The clear electron density map of the GPR21-Gαs provided direct evidence that GPR21 could couple to Gαs protein at physiological conditions. Thus, GPR21 might mediate previously unexplored pathways in normal or pathological conditions, which warrants further investigation. Structure-guided mutagenesis and biochemical analysis revealed that extracellular loop 2 (ECL2) of GPR21 is essential for the receptor transducing intracellular signal via cAMP. Together, the new structure data reveal a novel signaling cascade of human GPR21 mediated by ECL2 and provide fundamental information for future structure-based drug development.

Cryo-EM structure of G-protein-coupled receptor GPR17 in complex with inhibitory G protein.

GPR17 is a class A orphan G protein-coupled receptor (GPCR) expressed in neurons and oligodendrocyte progenitors of the central nervous system (CNS). The signalling of GPR17 occurs through the heterotrimeric Gi, but its activation mechanism is unclear. Here, we employed cryo-electron microscopy (cryo-EM) technology to elucidate the structure of activated GPR17-Gi complex. The 3.02 Å resolution structure, together with mutagenesis studies, revealed that the extracellular loop2 of GPR17 occupied the orthosteric binding pocket to promote its self-activation. The active GPR17 carried several typical microswitches like other class A GPCRs. Moreover, the Gi interacted with the key residues of transmembrane helix 3 (TM3), the amphipathic helix 8 (Helix8), and intracellular loops 3 (ICL3) in GPR17 to engage in the receptor core. In summary, our results highlight the activation mechanism of GPR17 from the structural basis. Elucidating the structural and activation mechanism of GPR17 may facilitate the pharmacological intervention for acute/chronic CNS injury.

Mitochondrial DHODH regulates hypoxia-inducible factor 1 expression in OTSCC.

Oral tongue squamous cell carcinoma (OTSCC) was one of the most hypoxic tumors with unfavorable outcomes. Hypoxia-inducible factor-1 (HIF-1) signaling was associated with cancer proliferation, lymph node metastasis, angiogenesis and poor prognosis of OTSCC. Dihydroorotate dehydrogenase (DHODH) catalyzed the rate-limiting step in the de novo pyrimidine biosynthesis. The aim of the study was to explore the biological function of DHODH and investigate whether DHODH regulated HIF-1 signaling in OTSCC. Proliferation, migration and anoikis resistance were used to determine the function of DHODH. Western blot and luciferase activity assays were used to determine the regulatory role of DHODH on HIF-1. We found that increased DHODH expression was associated with advanced tumor stage and poorly differentiated tumor in head and neck cancer patients in The Cancer Genome Atlas (TCGA). DHODH enhanced the proliferation and aggressiveness of OTSCC. Moreover, DHODH prompted tumor growth and metastasis in vivo. DHODH promoted transcription, protein stability, and transactivation activity of HIF1A. DHODH-induced HIF1A upregulation in OTSCC can be reversed by reactive oxygen species (ROS) scavenger, indicating that DHODH enhanced HIF1A expression via ROS production. DHODH inhibitor suppressed DHODH-mediated ROS generation and HIF1A upregulation. Targeting DHODH using clinically available inhibitor, atovaquone, might provide a new strategy to treat OTSCC.

The dorsal and the ventral side of hypoglossal motor nucleus showed different response to chronic intermittent hypoxia in rats.

PURPOSE: To study neurochemical reactions to chronic intermittent hypoxia (CIH) in the hypoglossal nucleus (HN) of rats. METHODS: Adult male Sprague-Dawley rats (n = 12) were randomly divided into two groups (the CIH and the control group). The CIH rats were housed in a hypoxic chamber with the fraction of oxygen volume alternating between 21% and 5% by providing air for 60 s and then providing nitrogen for 60 s from 8:30 am to 16:30 pm each day for 35 days. The control group was housed in a cabin with normal oxygen levels. We studied the expression of c-fos protein, 5-hydroxytryptamine (5-HT) positive terminals, and its 2A receptors in hypoglossal nuclei by immunohistochemistry. RESULTS: The expression of c-fos, 5-HT positive terminals, and accordingly 5-HT 2A receptors in the CIH group were significantly higher than that in the controls (p < 0.05). The ventral side of the HN showed a clearly higher expression of 5-HT and its 2A receptors than the dorsal side (p < 0.05). CONCLUSION: There were 2 responses of the HN to CIH. First, CIH induced a higher expression of 5-HT positive terminals and its 2A receptors, and second, this reaction was much more evident in ventral side than in the dorsal side. We postulate that these responses may serve to be a protective and compensatory mechanism for CIH.

Robot-assisted real-time sentinel lymph node mapping in oral cavity cancer: preliminary experience.

This study aims to assess the feasibility of using indocyanine green and robotic near infra-red fluorescent imaging (Firefly®) for sentinel lymph node biopsy in cN0 oral cavity cancer. Ten patients with early squamous cell carcinoma of the tongue (n = 8) and buccal mucosa (n = 2) were included. Peritumoral injection of 10 mg indocyanine green and real-time mapping of sentinel lymph nodes in the neck was performed using Firefly® via a retro-auricular trans-hairline incision. Sentinel lymph node was detected in all patients at 1.2 sentinel lymph node per person. Majority were situated in level II (91.7%). Mean time to detection of sentinel lymph node was 171.0 (68.0-312.0)s. Mean signal-to-background ratio was 5.62 (3.51-7.91). Frozen section of one sentinel lymph node was positive for malignancy, paraffin section of which confirmed the presence of metastatic disease. Modified radical neck dissection was performed for that particular patient, paraffin section of which did not show any tumor deposit. Frozen section and paraffin section of all other sentinel lymph nodes (n = 11) and neck dissection specimens yielded no malignancy. All resection margins were clear. Three patients completed adjuvant radiotherapy for pT2N0 (n = 2) and pT2N1 (n = 1) carcinoma of the tongue. Mean follow-up was 12.0 (4.0-18.0) months. All patients were alive at last follow-up with no disease recurrence. There were no adverse outcomes associated with the use of indocyanine green and robot-assisted neck dissection. Indocyanine green and Firefly® for sentinel lymph node biopsy in cN0 oral cavity cancer is feasible with no adverse effects.

CD38 triggers inflammasome-mediated pyroptotic cell death in head and neck squamous cell carcinoma.

BACKGROUND: Pyroptosis is a form of inflammatory cell death. Although it is recognized that NLRP3 (nucleotide-binding domain, leucine-rich repeat-containing family, pyrin domain-containing 3) inflammasome is involved in pyroptosis activation, the mechanism by which head and neck squamous cell carcinoma (HNSCC) inhibits pyroptotic cell death remains undefined. This study aims to delineate the role of calcium regulator CD38 in NLRP3 inflammasome-dependent pyroptosis in HNSCC. METHODS: CD38 overexpressing HNSCC cell lines (SAS, CAL27, SNU899) were generated using lentiviral vectors. NLRP3 and gasdermin D (GSDMD) quantity were detected using Western blot. Caspase-1 activity changes were measured using the Caspase-Glo® 1 inflammasome assay. Cell death proportion was determined by flow cytometry analysis. Proliferation assay was performed using xCELLigence RTCA system. Mouse xenotransplantation was performed to evaluate the potential oncogenic or tumor-suppressive function of CD38. ChIP assay was conducted to verify whether transcription factor NFAT1-mediated NLRP3 expression. RESULTS: Exogenous calcium treatment can lead to a significant increase in caspase-1 activity in HNSCC. This feature was also observed in HNSCC cells with stable CD38 overexpression. CD38-overexpressing cell lines showed a significant reduction in proliferation. Further, expression of NLRP3 protein level was significantly increased in CD38-overexpressing cell lines. The N-terminal effector domain of GSDMD was remarkably increased in the CD38-overexpressing HNSCC. ChIP assay indicated that calcium-sensitive transcription factor NFAT1 was possibly involved in the transcriptional upregulation of NLRP3 observed in CD38-overexpressing HNSCC. The pre-clinical xenograft model revealed that CD38 expression had an inhibiting function on HNSCC progression. CONCLUSION: In conclusion, our results suggested that activation of pyroptosis in HNSCC is a calcium-dependent process. Reduced expression of calcium ion regulator CD38 functions could prevent inflammasome-induced pyroptosis in HNSCC. CD38 may function as a tumor suppressor in HNSCC progression.

NADPH oxidase 5α promotes the formation of CD271 tumor-initiating cells in oral cancer.

Oral tongue squamous cell carcinoma (OTSCC) has a distinctive cell sub-population known as tumor-initiating cells (TICs). CD271 is a functional TIC receptor in head and neck cancers. The molecular mechanisms governing CD271 up-regulation remains unclear. Oxidative stress is a contributing factor in TIC development. Here, we explored the potential role of NADPH oxidase 5 (NOX5) and its regulatory mechanism on the development of CD271-expressing OTSCC. Our results showed that the splice variant NOX5α is the most prevalent form expressed in head and neck cancers. NOX5α enhanced OTSCC proliferation, migration, and invasion. Overexpression of NOX5α increased the size of OTSCC xenograft significantly in vivo. The tumor-promoting functions of NOX5α were mediated through the reactive oxygen species (ROS)-generating property. NOX5α activated ERK singling and increased CD271 expression at the transcription level. Also, NOX5α reduces the sensitivity of OTSCC to cisplatin and natural killer cells. The findings indicate that NOX5α plays an important part in the development of TIC in OTSCC.

Curcumin enhances cisplatin sensitivity by suppressing NADPH oxidase 5 expression in human epithelial cancer.

Cisplatin-based chemotherapy regimens serve a pivotal role in human cancer treatment. Nevertheless, treatment failure may occur if the cancer is inherently resistant to cisplatin or acquires a resistant phenotype during the course of treatment. Although cisplatin resistance can hinder the efficacy of cisplatin treatment for human cancer, the underlying mechanism remains poorly understood. The current study established a cisplatin-resistant human epithelial cancer cell line. Notably, differential upregulation of NADPH oxidase 5 (NOX5) was identified in this resistant cell line. Furthermore, cisplatin treatment induced cancer cells to express NOX5 and cells that overexpressed NOX5 exhibited greater resistance to cisplatin via the activation of Akt. Treatment with curcumin may suppress NOX5 expression in cancer cells and enhance sensitivity to cisplatin treatment. In a xenograft model, a combined regimen of cisplatin with low-dose curcumin significantly reduced malignant tumor growth. These data demonstrate that curcumin has a chemosensitizing effect on cisplatin-resistant epithelial cancer types. Therefore, the use of curcumin in addition to a cisplatin-based treatment regimen may improve treatment outcomes in human patients with epithelial cancer.

Detection of Epstein-Barr virus (EBV)-encoded microRNAs in plasma of patients with nasopharyngeal carcinoma.

BACKGROUND: Nasopharyngeal carcinoma (NPC) latently infected by Epstein-Barr virus (EBV) expresses 40 EBV BART microRNAs (miRNAs). Difference in diagnostic efficacy of these miRNAs on NPC detection was observed. Here, we performed a comprehensive evaluation on the efficacy of these miRNAs. METHODS: Quantitative polymerase chain reaction was performed on plasma nucleic acid isolated from patients with NPC and noncancer donors. RESULTS: For primary NPC, BART2-5P, BART6-3P, BART7-3P, BART7-5P, BART9-5P, BART11-3P, BART17-5P, and BART19-5P were significantly elevated. For recurrent NPC, plasma levels of BART2-3P, BART2-5P, BART5-3P, BART5-5P, BART6-3P, BART8-3P, BART9-5P, BART17-5P, BART19-3P, and BART20-3P were significantly increased. Area under curve (AUC) analysis showed that BART19-5P had the best performance to identify NPC which was serologically EBV DNA undetectable. For recurrent NPC, BART8-3P and BART10-3P had highest AUC value for identifying cancer in EBV DNA undetectable plasma. CONCLUSION: Our data supported the use of circulating EBV miRNAs in NPC and recurrent NPC detection.

Epstein-Barr virus-encoded microRNA BART7 downregulates major histocompatibility complex class I chain-related peptide A and reduces the cytotoxicity of natural killer cells to nasopharyngeal carcinoma.

Evasion from natural killer (NK) cell surveillance enables cancer to proliferate and spread at the early stages. NK cells mediate specific cytolysis by activation of the triggering receptors on their cell surface, of which the communication between natural killer group 2, member D (NKG2D) and major histocompatibility complex class I chain-related peptide A (MICA) is a key regulatory axis. It has been indicated that cancer cells can reduce the surface expression of MICA, which thereby reduces the cytotoxicity of NK cells. In nasopharyngeal carcinoma (NPC), however, the underlying mechanism remains unclear. The present study indicated that MICA expression in NPC was regulated by TGFß1. Furthermore, the human MICA gene was demonstrated to contain the c-Myc binding site in the promoter region. Notably, the results suggested that TGFß1 upregulated MICA expression by promoting c-Myc expression. Additionally, the findings demosntrated that TGFß1 expression in NPC was negatively controlled by Epstein-Barr virus-encoded microRNA BART7 (ebv-miR-BART7). In ebv-miR-BART7-expressing NPC, the TGFß1/c-Myc/MICA regulatory axis was significantly inhibited. Notably, functional analysis indicated that NPC cells expressing ebv-miR-BART7 were less sensitive to the cytolysis mediated by NK cells. In conclusion, the present results revealed that ebv-miR-BART7-expressing NPC may impair NK cells recognition and activity, which suggests that targeting ebv-miR-BART7 may be a useful therapeutic strategy in NPC immunotherapy.

Functional significance of the long non-coding RNA RP11-169D4.1 as a metastasis suppressor in laryngeal squamous cell carcinoma by regulating CDH1.

The present study investigated the expression profile and the function of RP11-169D4.1 and explored its potential mechanisms in laryngeal squamous cell carcinoma. The biological function of RP11-169D4.1 was examined using the MTT assay, flow cytometric analysis, wound healing and transwell assays. The relationship between RP11-169D4.1 and miR-205-5p was discovered by Argonaute 2 protein immunoprecipitation. The target gene of RP11-169D4.1 was CDH1 which was assessed by Pearson's correlation analysis, RT-PCR and western blot assay. We demonstrated that RP11-169D4.1 expression was markedly decreased in LSCC tissues and cell lines. The overexpression of RP11-169D4.1 inhibited the proliferation, migration and invasion of LSCC cell lines as well as promoted apoptosis. We further verified that miR-205-5p had binding sites with RP11­169D4.1 and that RP11-169D4.1 could regulate the expression of CDH1. Ectopic transfection of RP11-169D4.1 led to a significant reduction in the downstream signaling molecule AKT in LSCC cells. The long non-coding RNA RP11-169D4.1 may serve as a tumor suppressor and a promising therapeutic target in laryngeal cancer, which could inhibit the process of EMT by regulating CDH1.

Epstein-Barr virus encoded microRNA BART7 regulates radiation sensitivity of nasopharyngeal carcinoma.

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is very sensitive to radiotherapy. To date, the underlying mechanism remains poorly understood. Here, we demonstrated that expression of EBV-encoded microRNA BART7 (ebv-miR-BART7) increases responsiveness of NPC to radiation treatment by targeting GFPT1/TGFß1 signaling. GFPT1 is the the key rate-limiting enzyme of the hexosamine signaling pathway and governs TGFß1 production. TGFß1, a pleotropic cytokine with the potency to trigger self-renewal and damage-repair machinery in somatic cells. TGFß1 can protect zebrafish embryo from the lethal effects of radiation treatment. In silico analysis showed that ebv-miR-BART7 could target GFPT1 transcript. Correlation analysis on primary NPC tissues suggested that ebv-miR-BART7 and GFPT1 have negative expression correlation. Expression of GFPT1 and TGFß1 were inducible by radiation in NPC cell with ebv-miR-BART7 expression. Further, suppressing endogenous GFPT1 expression inhibited TGFß1 which subsequently increased the responsiveness of NPC to radiation treatment. Taken together, our results demonstrated that ebv-miR-BART7 controls TGFß1 production by targeting GFPT1. Detection of ebv-miR-BART7 may provide useful indicator for monitoring NPC progression and predict therapeutic outcomes.

BEX3 contributes to cisplatin chemoresistance in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) can develop cisplatin-resistant phenotype. Research has revealed that enriched in cancer stem cell population is involved in developing cisplatin-resistant phenotype. CD271 is a candidate stem cell maker in head and neck cancers. The CD receptor does not possess any enzymatic property. Signal transduction function of CD271 is mediated by the cellular receptor-associated protein. Our data showed that Brain-expressed X-linked 3 (BEX3), a CD271 receptor-associated protein, was overexpressed in NPC. BEX3 overexpression was a unique event in cancer developed in the head and neck regions, especially NPC. BEX3 expression was inducible by cisplatin in NPC. In cisplatin-resistant NPC xenograft, treatment with nontoxic level of cisplatin led to a remarkable increase in BEX3 level. High BEX3 expression was accompanied with high octamer-binding transcription factor 4 (OCT4) expression in cisplatin-resistant NPC. To confirm the inducing role of BEX3 on OCT4 expression, we knockdown BEX3 using siRNA and compared the expression of OCT4 with mock transfectants. Suppressing BEX3 transcripts led to a significant reduction in OCT4. In addition, targeting BEX3 using shRNA could increase the sensitivity of NPC cells to cisplatin. In summary, our results indicated a unique functional role of BEX3 in mediating the sensitivity of NPC cells to cisplatin. Targeting or blocking BEX3 activity might be useful in reversing the cisplatin-resistant phenotype in NPC.

MicroRNA-138-5p controls sensitivity of nasopharyngeal carcinoma to radiation by targeting EIF4EBP1.

Radiation therapy is the standard treatment for primary nasopharyngeal carcinoma (NPC). MicroRNA regulates cancer responsiveness to radiation therapy by controlling the genes involved in radiation responses. Recent studies suggested that downregulation of microRNA-138-5p was clinically significant in NPC. Here, we evaluated the effect of miR-138-5p on radiosensitivity of NPC cells and explored the underlying mechanisms by identifying its target gene that impacted sensitivity to radiation. Our results revealed that overexpression of miR-138-5p reduced the ability to form colonies, inhibited proliferation, and enhanced radiation-induced DNA damage and autophagy in NPC cells upon radiation treatment. By integrating predicted targets with the transcripts downregulated by miR-138-5p, EIF4EBP1 was identified to be a target gene of miR-138-5p. Results from luciferase reporter assay demonstrated that miR-138-5p downregulated the expression of EIF4EBP1 by binding to the 3'-UTR. Silence of EIF4EBP1 enhanced radiosensitivity of NPC cells as evidenced by reduced ability to form colonies after radiation exposure. In summary, our results indicated that miR-138-5p enhanced radiosensitivity of NPC cells by targeting EIF4EBP1. Further studies are warranted to investigate the potential use of miR-138-5p in the clinical management and treatment prediction of NPC patients.

The clinical association of programmed cell death protein 4 (PDCD4) with solid tumors and its prognostic significance: a meta-analysis.

BACKGROUND: Programmed cell death protein 4 (PDCD4) is a novel tumor suppressor protein involved in programmed cell death. Its association with cancer progression has been observed in multiple tumor models, but evidence supporting its association with solid tumors in humans remains controversial. This study aimed to determine the clinical significance and prognostic value of PDCD4 in solid tumors. METHODS: A systematic literature review was performed to retrieve publications with available clinical information and survival data. The eligibility of the selected articles was based on the criteria of the Dutch Cochrane Centre proposed by the Meta-analysis Of Observational Studies in Epidemiology group. Pooled odds ratios (ORs), hazard ratios (HRs), and 95% confidence intervals (CIs) for survival analysis were calculated. Publication bias was examined by Begg's and Egger's tests. RESULTS: Clinical data of 2227 cancer patients with solid tumors from 23 studies were evaluated. PDCD4 expression was significantly associated with the differentiation status of head and neck cancer (OR 4.25, 95% CI 1.87-9.66) and digestive system cancer (OR 2.87, 95% CI 1.84-4.48). Down-regulation of PDCD4 was significantly associated with short overall survival of patients with head and neck (HR: 3.44, 95% CI 2.38-4.98), breast (HR: 1.86, 95% CI 1.36-2.54), digestive system (HR: 2.12, 95% CI 1.75-2.56), and urinary system cancers (HR: 3.16, 95% CI 1.06-9.41). CONCLUSIONS: The current evidence suggests that PDCD4 down-regulation is involved in the progression of several types of solid tumor and is a potential marker for solid tumor prognoses. Its clinical usefulness should be confirmed by large-scale prospective studies.

MicroRNA 744-3p promotes MMP-9-mediated metastasis by simultaneously suppressing PDCD4 and PTEN in laryngeal squamous cell carcinoma.

MicroRNA controls cancer invasion by governing the expression of gene regulating migration and invasion. Here, we reported a novel regulatory pathway controlled by miR-744-3p, which enhanced expression of matrix metallopeptidase 9 (MMP-9) in laryngeal squamous cell carcinoma (LSCC). We profiled the differential micoRNA expression pattern in LSCC cell lines and normal epithelial cultures derived from the head and neck mucosa using microRNA microarray. MiR-7-1-3p, miR-196a/b and miR-744-3p were expressed differentially in the LSCC cell lines. Subsequent validation using real-time PCR revealed that high miR-744-3p level was positively correlated with regional lymph node metastasis of LSCC. Real-time cellular kinetic analysis showed that suppressing miR-744-3p could inhibit migration and invasion of LSCC cell lines and reduce the number of lung metastatic nodules in nude mice modules. In silico analysis revealed that miR-744-3p targeted 2 distinct signaling cascades which eventually upregulated MMP-9 expression in LSCC. First, miR-744-3p could suppress programmed cell death 4 (PDCD4), a direct suppressor of NF-κB (p65). PDCD4 could also prevent AKT activation and suppress MMP-9 expression. Further, suppressing miR-744-3p expression could restore phosphatase and tensin homolog (PTEN) expression. PTEN could inhibit AKT activation and inhibit MMP-9 expression in LSCC cells. The results revealed that suppressing miR-744-3p was effective to inhibit LSCC metastasis by inactivating AKT/mTOR and NF-κB (p65) signaling cascade. Targeting miR-744-3p could be a valuable therapeutic intervention to suppress the aggressiveness of LSCC.

Decreased brain-expressed X-linked 4 (BEX4) expression promotes growth of oral squamous cell carcinoma.

BACKGROUND: Brain-expressed X-linked (BEX) 4 is a member of BEX family. The functional role of BEX4 in oral squamous cell carcinoma (OSCC) remains unknown. METHODS: Expression level of BEX family members (BEX1-5) in OSCC tissues and the paired normal epithelial were examined. Functions of epigenetic changes (DNA methylation and histone modifications) on BEX4 suppression in OSCC were examined by zebularine and trichostatin A (TSA) treatment on OSCC cell lines. Lentivector containing full-length BEX4 was used to generate OSCC cell lines with stable BEX4 expression. Effects of BEX4 expression on OSCC proliferation were monitored with xCELLigence RTCA real-time cell analyzer. BEX4-overexpressing CAL27 was implanted into nude mice to evaluate the effects on tumor growth in vivo. The signaling pathways regulated by BEX4 in OSCC was explored using human whole-transcript expression microarray. RESULTS: Among the 5 BEX family members, BEX1 and BEX4 showed significant down-regulation in OSCC (P < 0.001). BEX3, in comparison, was overexpressed in the primary tumor. BEX4 expression in OSCC cell lines was re-activated after zebularine and TSA treatment. High BEX4 expression could suppress proliferation of OSCC in vitro. Subcutaneous tumor volume of BEX4-overexpressing CAL27 was remarkably reduced in nude mice. Microarray experiment showed that S100A family members (S100A7, S100A7A, S100A8, S100A9 & S100A12) might be the downstream targets of BEX4 in OSCC. CONCLUSIONS: BEX4 functions as tumor suppressor by inhibiting proliferation and growth of oral cancer. Decreased BEX4 contributes to the increased proliferative propensity of OSCC.

Blockade of MCP-1/CCR4 signaling-induced recruitment of activated regulatory cells evokes an antitumor immune response in head and neck squamous cell carcinoma.

FoxP3+ regulatory T (Treg) cells have diverse functions in the suppression of antitumor immunity. We show that FoxP3hiCD45RA-CD4+ Treg cells [activated Treg (aTreg) cells] are the predominant cell population among tumor-infiltrating FoxP3+ T cells, and that high aTreg cell-infiltrating content is associated with reduced survival in patients with head and neck squamous cell carcinoma (HNSCC). In vitro studies have demonstrated that aTreg cells can suppress tumor-associated antigen (TAA) effector T cell immune responses in HNSCC. Moreover, C-C chemokine receptor 4 (CCR4) was specifically expressed by aTreg cells in the peripheral blood of HNSCC patients. Using a RayBiotech human chemokine antibody array, we showed that monocyte chemoattractant protein-1 (MCP-1), an endogenous CCR4-binding ligand, was specifically upregulated in the HNSCC microenvironment compared to the other four CCR4-binding ligands. Blocking MCP-1/CCR4 signaling-induced aTreg cell recruitment using a CCR4 antagonist evoked antitumor immunity in mice, and lead to inhibition of tumor growth and prolonged survival. Therefore, blocking aTreg cell trafficking in tumors using CCR4-binding agents may be an effective immunotherapy for HNSCC.

Eliciting cytotoxic T lymphocytes against human laryngeal cancer-derived antigens: evaluation of dendritic cells pulsed with a heat-treated tumor lysate and other antigen-loading strategies for dendritic-cell-based vaccination.

BACKGROUND: Dendritic cells (DCs) have been used successfully in clinical pilot studies. However, tumor-specific immunity and clinical responses were only induced in certain cancer patients. It has been well documented that immunotherapy efficacy can be optimized for responses using antigen pulsing. METHODS: The human laryngeal squamous cell cancer (LSCC) cell line SNU899 was used to evaluate the in vitro anti-tumor efficacy of three different preparations of dendritic cell (DC) vaccines consisting of either whole tumor cells or their derivatives including: i) DCs pulsed with a tumor cell supernatant (DC-TCS), ii) DCs pulsed with whole-cell tumor stressed lysate (DC-TSL), and iii) DCs pulsed with irradiated tumor cells (DC-ITC). RESULTS: Our results showed that DC-TSL is an effective source of tumor-associated antigens (TAAs) for pulsing DCs. DC-TSL induced the highest expansion of TAA-specific T cells, the strongest Th1 cytokine response, and the most potent cytotoxic T lymphocyte (CTL) activity. DC-TCS and DC-ITC inhibited T cell activation but induced a certain extent of CTL activity. CONCLUSIONS: These data suggest that DC-TSL is a more potent inducer of antitumor immunity against laryngeal cancer than other antigen-loading strategies using whole tumor cell materials. This strategy provides an alternative approach for DC-based immunotherapy for laryngeal cancer.