TRPV1 analgesics disturb core body temperature via a biased allosteric mechanism involving conformations distinct from that for nociception.

Efforts on developing transient receptor potential vanilloid 1 (TRPV1) drugs for pain management have been hampered by deleterious hypo- or hyperthermia caused by TRPV1 agonists/antagonists. Here, we compared the effects of four antagonists on TRPV1 polymodal gating and core body temperature (CBT) in Trpv1+/+, Trpv1-/-, and Trpv1T634A/T634A. Neither the effect on proton gating nor drug administration route, hair coverage, CBT rhythmic fluctuations, or inflammation had any influence on the differential actions of TRPV1 drugs on CBT. We identified the S4-S5 linker region exposed to the vanilloid pocket of TRPV1 to be critical for hyperthermia associated with certain TRPV1 antagonists. PSFL2874, a TRPV1 antagonist we discovered, is effective against inflammatory pain but devoid of binding to the S4-S5 linker and inducing CBT changes. These findings implicate that biased allosteric mechanisms exist for TRPV1 coupling to nociception and CBT regulation, opening avenues for the development of non-opioid analgesics without affecting CBT.

A shared mechanism for TNP-ATP recognition by members of the P2X receptor family.

P2X receptors (P2X1-7) are non-selective cation channels involved in many physiological activities such as synaptic transmission, immunological modulation, and cardiovascular function. These receptors share a conserved mechanism to sense extracellular ATP. TNP-ATP is an ATP derivative acting as a nonselective competitive P2X antagonist. Understanding how it occupies the orthosteric site in the absence of agonism may help reveal the key allostery during P2X gating. However, TNP-ATP/P2X complexes (TNP-ATP/human P2X3 (hP2X3) and TNP-ATP/chicken P2X7 (ckP2X7)) with distinct conformations and different mechanisms of action have been proposed. Whether these represent species and subtype variations or experimental differences remains unclear. Here, we show that a common mechanism of TNP-ATP recognition exists for the P2X family members by combining enhanced conformation sampling, engineered disulfide bond analysis, and covalent occupancy. In this model, the polar triphosphate moiety of TNP-ATP interacts with the orthosteric site, while its TNP-moiety is deeply embedded in the head and dorsal fin (DF) interface, creating a restrictive allostery in these two domains that results in a partly enlarged yet ion-impermeable pore. Similar results were obtained from multiple P2X subtypes of different species, including ckP2X7, hP2X3, rat P2X2 (rP2X2), and human P2X1 (hP2X1). Thus, TNP-ATP uses a common mechanism for P2X recognition and modulation by restricting the movements of the head and DF domains which are essential for P2X activation. This knowledge is applicable to the development of new P2X inhibitors.

Chronic cough relief by allosteric modulation of P2X3 without taste disturbance.

P2X receptors are cation channels that sense extracellular ATP. Many therapeutic candidates targeting P2X receptors have begun clinical trials or acquired approval for the treatment of refractory chronic cough (RCC) and other disorders. However, the present negative allosteric modulation of P2X receptors is primarily limited to the central pocket or the site below the left flipper domain. Here, we uncover a mechanism of allosteric regulation of P2X3 in the inner pocket of the head domain (IP-HD), and show that the antitussive effects of quercetin and PSFL2915 (our nM-affinity P2X3 inhibitor optimized based on quercetin) on male mice and guinea pigs were achieved by preventing allosteric changes of IP-HD in P2X3. While being therapeutically comparable to the newly licensed P2X3 RCC drug gefapixant, quercetin and PSFL2915 do not have an adverse effect on taste as gefapixant does. Thus, allosteric modulation of P2X3 via IP-HD may be a druggable strategy to alleviate RCC.

Altered Membrane Expression and Function of CD11b Play a Role in the Immunosuppressive Effects of Morphine on Macrophages at the Nanomolar Level.

Morphine, one of the most efficacious analgesics, is effective in severe pain, especially in patients with concomitant painful cancers. The clinical use of morphine may be accompanied by increased immunosuppression, susceptibility to infection and postoperative tumor metastatic recurrence, and the specific mechanisms and clinical strategies to alleviate this suppression remain to be investigated. Expression of CD11b is closely associated with the macrophage phagocytosis of xenobiotic particles, bacteria or tumor cells. Here, we find that morphine at 0.1-10 nM levels inhibited CD11b expression and function on macrophages via a µ-opioid receptor (MOR)-dependent mechanism, thereby reducing macrophage phagocytosis of tumor cells, a process that can be reversed by thymopentin (TP5), a commonly used immune-enhancing adjuvant in clinical practice. By knocking down or overexpressing MOR on macrophages and using naloxone, an antagonist of the MOR receptor, and LA1, a molecule that promotes macrophage CD11b activation, we suggest that morphine may regulate macrophage phagocytosis by inhibiting the surface expression and function of macrophage CD11b through the membrane expression and activation of MOR. The CD47/SIRPα axis, which is engaged in macrophage-tumor immune escape, was not significantly affected by morphine. Notably, TP5, when combined with morphine, reversed the inhibition of macrophage phagocytosis by morphine through mechanisms that promote membrane expression of CD11b and modulate its downstream signaling (e.g., NOS2, IFNG, IL1B and TNFA, as well as AGR1, PDGFB, IL6, STAT3, and MYC). Thus, altered membrane expression and function of CD11b may mediate the inhibition of macrophage phagocytosis by therapeutic doses of morphine, and the reversal of this process by TP5 may provide an effective palliative option for clinical immunosuppression by morphine.

Vanilloid agonist-mediated activation of TRPV1 channels requires coordinated movement of the S1-S4 bundle rather than a quiescent state.

Transient receptor potential vanilloid1 (TRPV1) channel plays an important role in a wide range of physiological and pathological processes, and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention. Recent incredible advances in cryo-electron microscopy (cryo-EM) have yielded high-resolution structures of all TRPV subtypes (TRPV1-6) and all of them share highly conserved six transmembrane (TM) domains (S1-S6). As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist (capsaicin or resiniferatoxin), TM helicesS1 to S4 form a bundle that remains quiescent during channel activation, highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels. Here, however, we argue that the structural dynamics rather than quiescence of S1-S4 domains is necessary for capsaicin-mediated activation of TRPV1. Using fluorescent unnatural amino acid (flUAA) incorporation and voltage-clamp fluorometry (VCF) analysis, we directly observed allostery of the S1-S4 bundle upon capsaicin binding. Covalent occupation of VCF-identified sites, single-channel recording, cell apoptosis analysis, and exploration of the role of PSFL828, a novel non-vanilloid agonist we identified, have collectively confirmed the essential role of this coordinated S1-S4 motility in capsaicin-mediated activation of TRPV1. This study concludes that, in contrast to cryo-EM structural studies, vanilloid agonists are also required for S1-S4 movement during TRPV1 activation. Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.

Dynamic recognition of naloxone, morphine and endomorphin1 in the same pocket of µ-opioid receptors.

Morphine, the most widely used analgesic, relieves severe pain by activating the µ-opioid receptor (MOR), whereas naloxone, with only slight structural changes compared to morphine, exhibits inhibitory effect, and is used to treat opioid abuse. The mechanism by which the MOR distinguishes between the two is unclear. Molecular dynamics (MD) simulations on a 1-µs time scale and metadynamics-enhanced conformational sampling are used here to determine the different interactions of these two ligands with MOR: morphine adjusted its pose by continuously flipping deeper into the pocket, whereas naloxone failed to penetrate deeper because its allyl group conflicts with several residues of MOR. The endogenous peptide ligand endomorphin-1 (EM-1) underwent almost no significant conformational changes during the MD simulations. To validate these processes, we employed GIRK4S143T, a MOR-activated Gßγ-protein effector, in combination with mutagenesis and electrophysiological recordings. We verified the role of some key residues in the dynamic recognition of naloxone and morphine and identified the key residue I322, which leads to differential recognition of morphine and naloxone while assisting EM-1 in activating MOR. Reducing the side chain size of I322 (MORI322A) transformed naloxone from an inhibitor directly into an agonist of MOR, and I322A also significantly attenuated the potency of MOR on EM-1, confirming that binding deep in the pocket is critical for the agonistic effect of MOR. This finding reveals a dynamic mechanism for the response of MOR to different ligands and provides a basis for the discovery of new ligands for MOR at the atomic level.

P2X3-selective mechanism of Gefapixant, a drug candidate for the treatment of refractory chronic cough.

Gefapixant/AF-219, a selective inhibitor of the P2X3 receptor, is the first new drug other than dextromethorphan to be approved for the treatment of refractory chronic cough (RCC) in nearly 60 years. To date, seven P2X subtypes (P2X1-7) activated by extracellular ATP have been cloned, and subtype selectivity of P2X inhibitors is a prerequisite for reducing side effects. We previously identified the site and mechanism of action of Gefapixant/AF-219 on the P2X3 receptor, which occupies a pocket consisting of the left flipper (LF) and lower body (LB) domains. However, the mechanism by which AF-219 selectively acts on the P2X3 receptor is unknown. Here, we combined mutagenesis, chimera construction, molecular simulations, covalent occupation and chemical synthesis, and find that the negative allosteric site of AF-219 at P2X3 is also present in other P2X subtypes, at least for P2X1, P2X2 and P2X4. By constructing each chimera of AF-219 sensitive P2X3 and insensitive P2X2 subtypes, the insensitive P2X2 subtype was made to acquire the inhibitory properties of AF-219 and AF-353, an analog of AF-219 with higher affinity. Our results suggest that the selectivity of AF-219/AF-353 for P2X3 over the other P2X subtypes is determined by a combination of the accessibility of P2X3 binding site and the internal shape of this pocket, a finding that could provide new perspectives for drug design against P2X3-mediated diseases such as RCC, idiopathic pulmonary fibrosis, hypertension and overactive bladder disorder.

Thymopentin-Mediated Inhibition of Cancer Stem Cell Stemness Enhances the Cytotoxic Effect of Oxaliplatin on Colon Cancer Cells.

Thymopentin (TP5) is an immunomodulatory pentapeptide that has been widely used in malignancy patients with immunodeficiency due to radiotherapy and chemotherapy. Here, we propose that TP5 directly inhibits the stemness of colon cancer cells HCT116 and therefore enhances the cytotoxicity of oxaliplatin (OXA) in HCT116 cells. In the absence of serum, TP5 was able to induce cancer stemness reduction in cultured HCT116 cells and significantly reduced stemness-related signals, such as the expression of surface molecular markers (CD133, CD44 and CD24) and stemness-related genes (ALDH1, SOX2, Oct-4 and Nanog), and resulted in altered Wnt/ß-catenin signaling. Acetylcholine receptors (AchRs) are implicated in this process. OXA is a common chemotherapeutic agent with therapeutic effects in various cancers. Although TP5 had no direct effect on the proliferation of HCT116, this pentapeptide significantly increased the sensitivity of HCT116 to OXA, where the effect of TP5 on the stemness of colon cancer cells through stimulation of AchRs may contribute to this process. Our results provide a promising strategy for increasing the sensitivity of colon cancer cells to chemotherapeutic agents by incorporating immunomodulatory peptides.

Knockout of interleukin-17A diminishes ventricular arrhythmia susceptibility in diabetic mice via inhibiting NF-κB-mediated electrical remodeling.

Interleukin-17A (IL-17), a potent proinflammatory cytokine, has been shown to participate in cardiac electrical disorders. Diabetes mellitus is an independent risk factor for ventricular arrhythmia. In this study, we investigated the role of IL-17 in ventricular arrhythmia of diabetic mice. Diabetes was induced in both wild-type and IL-17 knockout mice by intraperitoneal injection of streptozotocin (STZ). High-frequency electrical stimuli were delivered into the right ventricle to induce ventricular arrhythmias. We showed that the occurrence rate of ventricular tachycardia was significantly increased in diabetic mice, which was attenuated by IL-17 knockout. We conducted optical mapping on perfused mouse hearts and found that cardiac conduction velocity (CV) was significantly decreased, and action potential duration (APD) was prolonged in diabetic mice, which were mitigated by IL-17 knockout. We performed whole-cell patch clamp recordings from isolated ventricular myocytes, and found that the densities of Ito, INa and ICa,L were reduced, the APDs at 50% and 90% repolarization were increased, and early afterdepolarization (EAD) was markedly increased in diabetic mice. These alterations were alleviated by the knockout of IL-17. Moreover, knockout of IL-17 alleviated the downregulation of Nav1.5 (the pore forming subunit of INa), Cav1.2 (the main component subunit of ICa,L) and KChIP2 (potassium voltage-gated channel interacting protein 2, the regulatory subunit of Ito) in the hearts of diabetic mice. The expression of NF-κB was significantly upregulated in the hearts of diabetic mice, which was suppressed by IL-17 knockout. In neonatal mouse ventricular myocytes, knockdown of NF-κB significantly increased the expression of Nav1.5, Cav1.2 and KChIP2. These results imply that IL-17 may represent a potential target for the development of agents against diabetes-related ventricular arrhythmias.

GSK1702934A and M085 directly activate TRPC6 via a mechanism of stimulating the extracellular cavity formed by the pore helix and transmembrane helix S6.

Transient receptor potential canonical (TRPC) channels, as important membrane proteins regulating intracellular calcium (Ca2+i) signaling, are involved in a variety of physiological and pathological processes. Activation and regulation of TRPC are more dependent on membrane or intracellular signals. However, how extracellular signals regulate TRPC6 function remains to be further investigated. Here, we suggest that two distinct small molecules, M085 and GSK1702934A, directly activate TRPC6, both through a mechanism of stimulation of extracellular sites formed by the pore helix (PH) and transmembrane (TM) helix S6. In silico docking scanning of TRPC6 identified three extracellular sites that can bind small molecules, of which only mutations on residues of PH and S6 helix significantly reduced the apparent affinity of M085 and GSK1702934A and attenuated the maximal response of TRPC6 to these two chemicals by altering channel gating of TRPC6. Combing metadynamics, molecular dynamics simulations, and mutagenesis, we revealed that W679, E671, E672, and K675 in the PH and N701 and Y704 in the S6 helix constitute an orthosteric site for the recognition of these two agonists. The importance of this site was further confirmed by covalent modification of amino acid residing at the interface of the PH and S6 helix. Given that three structurally distinct agonists M085, GSK1702934A, and AM-0883, act at this site, as well as the occupancy of lipid molecules at this position found in other TRP subfamilies, it is suggested that the cavity formed by the PH and S6 has an important role in the regulation of TRP channel function by extracellular signals.

Interleukin-17 upregulation participates in the pathogenesis of heart failure in mice via NF-κB-dependent suppression of SERCA2a and Cav1.2 expression.

Interleukin-17 (IL-17), also called IL-17A, is an important regulator of cardiac diseases, but its role in calcium-related cardiac dysfunction remains to be explored. Thus, we investigated the influence of IL-17 on calcium handling process and its contribution to the development of heart failure. Mice were subjected to transaortic constriction (TAC) to induce heart failure. In these mice, the levels of IL-17 in the plasma and cardiac tissue were significantly increased compared with the sham group. In 77 heart failure patients, the plasma level of IL-17 was significantly higher than 49 non-failing subjects, and was negatively correlated with cardiac ejection fraction and fractional shortening. In IL-17 knockout mice, the shortening of isolated ventricular myocytes was increased compared with that in wild-type mice, which was accompanied by significantly increased amplitude of calcium transient and the upregulation of SERCA2a and Cav1.2. In cultured neonatal cardiac myocytes, treatment of with IL-17 (0.1, 1 ng/mL) concentration-dependently suppressed the amplitude of calcium transient and reduced the expression of SERCA2a and Cav1.2. Furthermore, IL-17 treatment increased the expression of the NF-κB subunits p50 and p65, whereas knockdown of p50 reversed the inhibitory effects of IL-17 on SERCA2a and Cav1.2 expression. In mice with TAC-induced mouse heart, IL-17 knockout restored the expression of SERCA2a and Cav1.2, increased the amplitude of calcium transient and cell shortening, and in turn improved cardiac function. In addition, IL-17 knockout attenuated cardiac hypertrophy with inhibition of calcium-related signaling pathway. In conclusion, upregulation of IL-17 impairs cardiac function through NF-κB-mediated disturbance of calcium handling and cardiac remodeling. Inhibition of IL-17 represents a potential therapeutic strategy for the treatment of heart failure.

Valsartan reduced the vulnerability to atrial fibrillation by preventing action potential prolongation and conduction slowing in castrated male mice.

INTRODUCTION: Deficiency of testosterone was associated with the susceptibility of atrial fibrillation (AF). Angiotensin-II (AngII) receptor antagonists were shown to reduce AF by improving atrial electrical remodeling. This study investigated the effects and mechanism of valsartan, an AngII receptor antagonist, on the susceptibility to AF with testosterone deficiency. METHODS AND RESULTS: Five-week-old male ICR mice were castrated and valsartan was administered orally (50 mg/kg/d). High-frequency electrical stimulation method was used to induce atrial arrhythmia. Patch-clamp technique was used for recording action potential duration (APD), transient outward potassium current ( I to ), sustained outward potassium current ( I ksus ), and late sodium current ( I Na-L ). Optical mapping technique was used to examine atrial conduction velocity (CV). The expression of connexin40 (Cx40) and Cx43 were detected by Western blot analysis. The occurrence rate of AF was significantly increased in castrated mice and APDs measured at 50% and 90% repolarization were markedly prolonged in castrated mice than controls, which were alleviated by the administration of valsartan. Valsartan suppressed the increase of INa-L and rescued the reduction of Ito and Iksus in castrated mice. The left atrial CV in castrated mice was decreased and the expression of Cx43 reduced than controls, which were restored after valsartan treatment. CONCLUSIONS: Valsartan reduced the susceptibility of AF in castrated mice, which may be related to the inhibition of action potential prolongation and improvement of atrial conduction impairment. This study indicates that valsartan may represent a useful agent for the prevention of AF pathogenesis in elderly male patients.

SDF-1/CXCR4 Axis Promotes MSCs to Repair Liver Injury Partially through Trans-Differentiation and Fusion with Hepatocytes.

MSCs have become a popular target for developing end-stage liver therapies. In this study, two models of bone marrow chimeric mice were used to construct the liver failure models. Then it was found that MSCs can transdifferentiate into hepatocyte-like cells and these hepatocyte-like cells can significantly express albumin. Furthermore it was also found that MSCs can fuse with the hepatocytes and these cells had the proliferation activity. However, the percentage of transdifferentiation was significantly higher than fusion. So it was considered that MSCs which transdifferentiated into hepatocyte-likes cells played important roles for repairing the injuring liver function.

Hypolipidemic activity in Sprague-Dawley rats and constituents of a novel natural vegetable oil from Cornus wilsoniana fruits.

UNLABELLED: Cornus wilsoniana Wanger is a woody oil plant distributed in the south region of the Yellow River, China. Its oil has been taken as edible oil for over 100 y, and consumption of such oil is believed to prevent hyperlipidemia in Chinese folk recipe. This study has investigated the hypolipidemic effect of Cornus wilsoniana oil (CWO) in Sprague-Dawley rats. The results demonstrated that CWO could significantly decrease total cholesterol (TC), total triacylglycerol (TG), and low-density lipoprotein cholesterol (HDL-C) in serum, liver weight, hepatic TC, and TG. After analyzing the chemical constituents of CWO, we found that the content of unsaturated fatty acids (UFA) was very high (69.12%). Specially, the n-6 polyunsaturated fatty acids (PUFA), including linoleic acid, γ-linolenic acid, and 11,14-eicosadienoic acid, accounted very great proportion (38.86%). The high hypolipidemic activity of CWO might be attributed to the lipid-lowering functions of these polyunsaturated fatty acids. Molecular docking was further performed to study the binding model of fatty acids (FA) from CWO to a possible hypolipidemic target, peroxisome proliferator-activated receptor δ (PPARδ). The results showed that linoleic acid and γ-linolenic acid could bind PPARδ very well. PRACTICAL APPLICATION: Cornus wilsoniana oil could be used as equilibrated dietary oil, not only having hypolipidemic function, but also helping to overcome essential fatty acids deficiency.

Identification and expression profiles of the WRKY transcription factor family in Ricinus communis.

In plants, WRKY proteins constitute a large family of transcription factors. They are involved in many biological processes, such as plant development, metabolism, and responses to biotic and abiotic stresses. A large number of WRKY transcription factors have been reported from Arabidopsis, rice, and other higher plants. The recent publication of the draft genome sequence of castor bean (Ricinus communis) has allowed a genome-wide search for R. communis WRKY (RcWRKY) transcription factors and the comparison of these positively identified proteins with their homologs in model plants. A total of 47 WRKY genes were identified in the castor bean genome. According to the structural features of the WRKY domain, the RcWRKY are classified into seven main phylogenetic groups. Furthermore, putative orthologs of RcWRKY proteins in Arabidopsis and rice could now be assigned. An analysis of expression profiles of RcWRKY genes indicates that 47 WRKY genes display differential expressions either in their transcript abundance or expression patterns under normal growth conditions.

microRNA-27b suppresses mouse MSC migration to the liver by targeting SDF-1αin vitro.

The SDF-1/CXCR4 axis is critical for inducing stem cell mobilization into the circulation, for homing stem cells to the site of injury, and for stem cell participation in the regeneration of liver tissue. In this study, we have gained insight into the molecular mechanisms involved in regulating the expression of SDF-1α by miRNAs. Using microarray and bioinformatics approaches, we identified six miRNAs with differential expression in damaged liver tissue (21 days after liver injury) compared to normal C57BL/6 murine liver tissue and further confirmed these observations by qPCR; miR-23a, which was identified by other researchers, was also included for comparative purposes. We found that miR-23a, miR-27a and miR-27b expression was significantly lower in the damaged liver than in the normal liver (p<0.05). We further confirmed that miR-27b could directly interact with the 3'UTR of SDF-1α to suppress SDF-1α protein expression using a luciferase reporter assay and Western blot analysis. In addition, we found that the over-expression of miR-27b significantly reduced the directional migration of primary cultured CRCX4-positive murine mesenchymal stem cells (mMSCs) in vitro using a transwell assay. These results suggest that miR-27b may be a unique signature of the stem cell niche in the damaged mouse liver and that mir-27b can suppress the directional migration of mMSCs by down-regulating SDF-1α expression by binding directly to the SDF-1α 3'UTR.

Multiple antigenic peptides based on H-2K(b)-restricted CTL epitopes from murine heparanase induce a potent antitumor immune response in vivo.

Accumulating research suggests that heparanase may be a universal tumor-associated antigen (TAA). Several heparanase T-cell epitopes from humans and mice have already been identified. However, because of low immunogenicity, polypeptide vaccines usually have difficulty inducing effective antitumor immune responses in vivo. In this study, to increase the immunogenicity of polypeptide vaccines, we designed and synthesized two four-branch multiple antigenic peptides (MAP) on the basis of mouse heparanase (mHpa) T-cell epitopes (mHpa398 and mHpa519). The dendritic cells (DC) from mice bone marrow loaded with above MAP vaccines from heparanase were used to evaluate immune response against various tumor cell lines, compared with immune response to their corresponding linear peptides, ex vivo and in vivo. We further assessed IFN-γ release both in CD4(+) T-cell-depleted and nondepleted mice. The results showed that effectors generated from DCs, loaded with MAP-vaccinated mice splenocytes, induced a stronger immune response against target cells expressing both heparanase and H-2K(b) than did effectors generated from mice vaccinated with their corresponding linear peptides. Heparanase-specific CD8(+) T-cell responses induced by MAP and linear peptide vaccination required synergy of CD4(+) T cells. In addition, heparanse-derived MAP vaccines significantly inhibited the growth of B16 murine melanoma in C57BL/6 mice, while also increasing the survival rate of tumor-bearing mice. Our data suggest that MAP vaccines based on T-cell epitopes from heparanase are efficient immunogens for tumor immunotherapy.

Noninvasive and real-time monitoring of the therapeutic response of tumors in vivo with an optimized hTERT promoter.

BACKGROUND: Telomerase is commonly recognized as an effective anticancer target. The human telomerase reverse transcriptase (hTERT), the rate-limiting component of telomerase, is expressed in most malignant tumors, but it is not found in most normal somatic cells. Here, we report a real-time and noninvasive method to monitor tumor response to a lentivirus-based hTERT-conditional suicidal gene therapy. METHODS: In this study, we constructed a lentivirus system in which an optimized hTERT promoter was used to drive the expression of the cytosine deaminase (CD) gene, one of the suicide genes, and a green fluorescent protein (GFP) reporter gene (pLenti-CD/GFP). The lentivirus was used to infect telomerase-positive or telomerase-negative cell lines. In vitro and in vivo experiments were conducted to analyze the dynamic processes of exogenous gene expression noninvasively in cell culture and living animals in real time via optical imaging. RESULTS: The lentivirus was able to express the CD gene and GFP in telomerase-positive tumor cells and significantly decrease cell proliferation after the use of prodrug 5-flucytosine. However, it could not express GFP and CD in telomerase-negative cell lines, nor could it induce any suicidal effect in those cells. The in vivo study showed that telomerase-positive tumors can be visualized after intratumor injection of the lentivirus in tumor-bearing nude mice via an optical imaging system. Significant tumor growth suppression was observed in telomerase-positive tumors. CONCLUSIONS: Collectively, this technology provides a valuable, noninvasive method to evaluate the real-time therapeutic response of tumors in vivo.

Multiple antigenic peptides of human heparanase elicit a much more potent immune response against tumors.

Peptide vaccination for cancer immunotherapy requires an ideal immune response induced by epitope peptides derived from tumor-associated antigens (TAA). Heparanase is broadly expressed in various advanced tumors. Accumulating evidence suggests that heparanase can serve as a universal TAA for tumor immunotherapy. However, due to the low immunogenicity of peptide vaccines, an ideal immune response against tumors usually cannot be elicited in patients. To increase the immunogenicity of peptide vaccines, we designed three 4-branched multiple antigenic peptides (MAP) on the basis of the human leukocyte antigen (HLA)-A2-restricted cytotoxic T lymphocyte (CTL) epitopes of human heparanase that we identified previously as antigen carriers. Our results show that MAP vaccines based on the HLA-A2-restricted CLT epitopes of human heparanase were capable of inducing HLA-A2-restricted and heparanase-specific CTL in vitro and in mice. Moreover, compared with their corresponding linear peptides, heparanase MAP vaccines elicited much stronger lysis of tumor cells by activating CD8(+) T lymphocytes and increasing the releasing of IFN-γ. However, these heparanase-specific CTLs did not lyse heparanase-expressing autologous lymphocytes and dendritic cells, which confirm the safety of these MAP vaccines. Therefore, our findings indicate that MAP vaccines based on CTL epitopes of human heparanase can be used as potent immunogens for tumor immunotherapy because of advantages such as broad spectrum, high effectiveness, high specificity, and safety.

An optimized telomerase-specific lentivirus for optical imaging of tumors.

Advances in medical imaging techniques, such as ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography, have made great progress in detecting tumors. However, these imaging techniques are unable to differentiate malignant tumors from benign ones. Recently developed optical imaging of tumors in small animals provides a useful method to distinguish malignant tumors from their surrounding normal tissues. Human telomerase reverse transcriptase (hTERT) is normally inactivated in most somatic cells, whereas it is commonly reactivated in many cancer cells. In this study, we constructed a lentiviral vector that expresses green fluorescent protein (GFP) driven by an optimized hTERT promoter to create a noninvasive tumor-specific imaging methodology. The activity of this optimized hTERT promoter was found to be equal to the activity of SV40 and cytomegalovirus promoters. In vitro experiments showed that GFP was only expressed in telomerase-positive tumor cells infected with this lentivirus, whereas there was no GFP expression in telomerase-negative tumor cells or normal somatic cells. We also found that subcutaneous telomerase-positive tumors could be visualized 24 hours after an intratumoral injection with this lentivirus by using a charge-coupled device (CCD) camera. In contrast, telomerase-negative tumors could not be imaged after an intratumoral injection even for 30 days. These results suggest that infection with lentivirus containing this optimized hTERT promoter might be a useful diagnostic tool for the real-time visualization of macroscopically invisible tumor tissues using a highly sensitive CCD imaging system.