Effects of Superfine Tricalcium Silicate Powder on the Physicochemical and Mechanical Properties of Its Premixed Cement as a Root Canal Filling Material.

Calcium silicate-based cement is a promising material for filling root canals. However, it has several drawbacks to its clinical application, including difficult operation and low curing strength. In this study, we successfully prepared an ultrafine tricalcium silicate powder and investigated the effects of this ultrafine powder on the performance of the premixed tricalcium silicate cement, including the curing process, setting time, hydration products, microstructure, injectivity, fluidity, and compressive strength. The results demonstrate that the addition of ultrafine tricalcium silicate powder alters the hydration product content and product morphology of the premixed cement. By increasing the content of the ultrafine powder, the injectable property of the cement can be increased to more than 95%, the fluidity can be increased from 18 mm to 35 mm, and the curing time can be shortened from 13 h to 11 h. Notably, the addition of the ultrafine powder greatly enhances the compressive strength of the hardened cement, which increases from 20.6 MPa to 51.0 MPa. These results indicate that altering the particle size distribution of the powder is an effective method for enhancing the physicochemical and mechanical properties of tricalcium silicate cement as a root canal filling material.

Targeting glutamine utilization to block metabolic adaptation of tumor cells under the stress of carboxyamidotriazole-induced nutrients unavailability.

Tumor cells have unique metabolic programming that is biologically distinct from that of corresponding normal cells. Resetting tumor metabolic programming is a promising strategy to ameliorate drug resistance and improve the tumor microenvironment. Here, we show that carboxyamidotriazole (CAI), an anticancer drug, can function as a metabolic modulator that decreases glucose and lipid metabolism and increases the dependency of colon cancer cells on glutamine metabolism. CAI suppressed glucose and lipid metabolism utilization, causing inhibition of mitochondrial respiratory chain complex I, thus producing reactive oxygen species (ROS). In parallel, activation of the aryl hydrocarbon receptor (AhR) increased glutamine uptake via the transporter SLC1A5, which could activate the ROS-scavenging enzyme glutathione peroxidase. As a result, combined use of inhibitors of GLS/GDH1, CAI could effectively restrict colorectal cancer (CRC) energy metabolism. These data illuminate a new antitumor mechanism of CAI, suggesting a new strategy for CRC metabolic reprogramming treatment.

Carboxyamidotriazole exerts anti-inflammatory activity in lipopolysaccharide-induced RAW264.7 macrophages by inhibiting NF-κB and MAPKs pathways.

Carboxyamidotriazole (CAI), originally developed as a non-cytotoxic anti-cancer drug, was shown to have anti-inflammatory activity according to recent studies in a number of animal models of inflammation. However, its mechanism of action has not been characterized. Therefore, the present study was performed to identify the anti-inflammatory action of CAI in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and to identify the signal transduction pathways involved. The in vitro results revealed that CAI had no direct effect on the activity of cyclooxygenase (COX), suggesting a different anti-inflammatory mechanism compared with that of COX-inhibiting non-steroidal anti-inflammatory drugs. Further investigation in RAW264.7 macrophages revealed that CAI decreased the production of nitric oxide via decreasing the LPS-stimulated expression of inducible nitric oxide synthase, and downregulated both mRNA and protein expression levels of the cytokines tumor necrosis factor-α, interleukin (IL)-1ß, and IL-6. CAI also significantly reduced the increased DNA-binding activity of nuclear factor (NF)-κB induced by LPS stimulation. With respect to the mechanisms involved on NF-κB activity, CAI exhibited suppression of the phosphorylation and degradation of the inhibitor of nuclear factor-κBα (IκB), and decreased the phosphorylation levels of the p65 subunit and its subsequent nuclear translocation. In addition, CAI significantly decreased the phosphorylated forms of p38, JNK and ERK, which were increased following LPS stimulation, while the total expression levels of p38, JNK and ERK remained unaltered. The results in the present study indicate that CAI alleviates the inflammatory responses of RAW 264.7 macrophages in response to LPS stimulation via attenuating the activation of NF-κB and MAPK signaling pathways and decreasing the levels of pro-inflammatory mediators. This offers a novel perspective for understanding the anti-inflammatory mechanism of CAI and suggests its potential use as a therapeutic treatment in inflammatory diseases with excessive macrophage activation.

Carboxyamidotriazole combined with IDO1-Kyn-AhR pathway inhibitors profoundly enhances cancer immunotherapy.

BACKGROUND: Cancer immunotherapy has generated significant excitement, mainly as a result of the development of immune checkpoint inhibitors. The blockade of PD-1 or its ligand with antibodies has resulted in impressive clinical efficacy. However, a subset of patients does not respond to biologic therapeutics, and another subset suffers from severe immune-related adverse events in certain cases. The modulation of the immune system with small molecules might yield surprising benefits. METHODS: CD8+ cells were obtained through a magnetic cell sorting system (MACS), and their capabilities for IFN-γ release and PD-1 expression were analyzed. The in vitro effects of drugs were studied in a coculture system of tumor cells and activated CD8+ cells. We further isolated the primary tumor cells in tumor-bearing mice treated with CAI, DMF, 1-MT or a combination (CAI and DMF/CAI and 1-MT) and analyzed the percentages of CD8+ T cells and PD-1+CD8+ T cells among TILs. The selective anti-tumor immune reactions of the two drug combinations were confirmed in a coculture system consisting of B16-OVA cells and OVA-specific CTLs derived from OT-1 transgenic mice. The anti-tumor effects of the single drugs or combined therapies were assessed according to their capability to slow tumor growth and extend the life span of tumor-bearing mice, and they were compared with the effects of PD-1 antibody. RESULTS: CAI increased IFN-γ release from activated T cells, which might strengthen the anti-proliferative and anti-metastatic effects on cancer cells. However, CAI also stimulated IDO1-Kyn metabolic circuitry in the tumor microenvironment and facilitated tumor cell immune evasion. Combining CAI with 1-MT or DMF disrupted PD-1 expression and promoted IFN-γ production in CD8+ T cells, and it also increased T lymphocyte infiltration in the tumor microenvironment, inhibited tumor growth and prolonged the life spans of tumor-bearing mice. CONCLUSION: Inhibitors of the IDO1-Kyn-AhR pathway could abolish the negative effects of CAI on CD8+ T cells and result in complementary and beneficial anti-tumor immune effects. The combination of CAI with 1-MT or DMF greatly augmented the ability of CD8+ T cells to kill malignant cells and showed a strong anti-cancer capability that was superior to that of either of the single agents was is comparable with that of anti-PD-1 antibody. The combinations of small molecules utilized in this study may serve as valuable new immunotherapy strategies for cancer treatment.

Metabolic Mechanisms and a Rational Combinational Application of Carboxyamidotriazole in Fighting Pancreatic Cancer Progression after Chemotherapy.

The anticancer and anti-inflammatory effects of carboxyamidotriazole (CAI) have been demonstrated in several studies, but the underlying mechanisms remain to be elucidated. This study showed that CAI caused metabolic reprogramming of pancreatic cancer cells. The inhibition of mitochondrial oxidative metabolism by CAI led to increased glutamine-dependent reductive carboxylation and enhanced glycolytic metabolism. The presence of environmental substances that affect cellular metabolism, such as glutamine and pyruvate, attenuated the anticancer efficacy of CAI. Based on the action of CAI: 1) when glutamine was removed, the NAD+/NADH ratio was decreased, the synthesis of cellular aspartate was reduced, and autophagy flux was blocked; and 2) when glycolysis was pharmacologically inhibited, the ATP level was significantly decreased, the cell viability was greatly inhibited, and the compensatory rescue effect of glutamine was eliminated. When combined with chemotherapy, cotreatment with CAI and the glycolysis inhibitor 2-deoxyglucose (2-DG) inhibited the pancreatic cancer progression after chemotherapy. As the inhibition of mitochondrial oxidative metabolism can explain several anticancer activities of CAI reported previously, including inhibition of calcium entry and induction of reactive oxygen species, we demonstrate that inhibition of mitochondrial oxidative phosphorylation may be the fundamental mechanism of CAI. The combination of CAI and 2-DG causes energy depletion in cancer cells, eliminating the rescue effect of the metabolic environment. Inhibiting pancreatic cancer progression after chemotherapy is a rational application of this metabolism-disturbing combination strategy.

Carboxyamidotriazole Synergizes with Sorafenib to Combat Non-Small Cell Lung Cancer through Inhibition of NANOG and Aggravation of Apoptosis.

Lung cancer is currently the leading cause of cancer-related deaths worldwide. In this study, we investigated the combination of carboxyamidotriazole (CAI) and sorafenib in non-small cell lung cancer (NSCLC) in vitro and in vivo to test whether CAI enhances the antitumor effects of sorafenib and reduces its side effects. The combination index (CI) showed that coadministration of CAI and sorafenib synergistically inhibited the proliferation of NSCLC cells (Lewis lung carcinoma, A549, and NCI-H1975 cells). Cell death as a result of the combination treatment was attributed to apoptosis, which was accompanied by activation of caspase-3 and poly(ADP-ribose) polymerase. In addition, combination therapy induced the accumulation of mitochondrial-associated reactive oxygen species, as well as depolarization of mitochondrial and reduced NANOG (homeobox protein NANOG) mRNA and protein expression. Basic fibroblast growth factor, a stimulator of NANOG, was applied to identify the possible mechanism. The addition of basic fibroblast growth factor followed by combined treatment may stimulate NANOG expression and synchronously rescue the accumulation of reactive oxygen species. C57BL/6J mice bearing Lewis lung carcinoma were randomized to receive vehicle (polyethylene glycol 400), CAI (30 mg/kg), low-dose sorafenib (SFB-L; 10 mg/kg), high-dose sorafenib (SFB-H; 30 mg/kg), or a CAI and SFB-L combination. Tumor growth was significantly suppressed in the combination group, and the efficacy of combination treatment was equivalent to that of the SFB-H monotherapy group. Furthermore, the combination group had reduced side effects compared with the SFB-H group, as indicated by weight preservation in mice. Our study illustrates that CAI enhances the antitumor activity of sorafenib in NSCLC and provides a novel strategy for NSCLC treatment.

Therapeutic efficacy of carboxyamidotriazole on 2,4,6-trinitrobenzene sulfonic acid-induced colitis model is associated with the inhibition of NLRP3 inflammasome and NF-κB activation.

Excess proinflammatory cytokines owing to the activation of NF-κB and NLRP3 inflammasome play the key role in inflammatory bowel disease (IBD). Previously, we reported the anti-inflammatory activity of carboxyamidotriazole (CAI) resulting from decreasing cytokines. Therefore, we investigated the therapeutic effects of CAI in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rat colitis and the involvement of CAI action with NLRP3 inflammasome and NF-κB pathway. CAI was orally administered to TNBS-induced colitis rat. The severity of colitis was assessed, and NLRP3 inflammasome, NF-κB pathway and cytokines were determined. Our results showed that CAI significantly reduced weight loss and disease activity index (DAI) scores in colitis rats and alleviated the colonic macroscopic signs and pathological damage. In addition, the intestinal inflammatory markers and permeability index were markedly ameliorated by CAI treatment. The decreased levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, IL-6, IL-18 were also detected in the colon tissues of CAI-treated colitis rats. Moreover, the activation of NLRP3 inflammasome in inflamed colon was significantly suppressed by showing an obvious reduction in the NLRP3 and activated caspase-1 levels. Furthermore, CAI reduced NF-κB p65 expression and IκBα phosphorylation and degradation in colitis rats. Therefore, CAI attenuates TNBS-induced colitis, which may be attributed to its inhibition of NLRP3 inflammasome and NF-κB activation, and down-regulation of proinflammatory cytokines. These results provide further understanding of the intestinal anti-inflammatory effect of CAI and highlight it as a potential drug for the treatment of IBD.

Carboxyamidotriazole alleviates muscle atrophy in tumor-bearing mice by inhibiting NF-κB and activating SIRT1.

Cancer cachexia is a complex disorder characterized by inflammatory responses, and it is associated with poor performance status and high mortality rate of cancer patients. Carboxyamidotriazole (CAI), a noncytotoxic chemotherapy agent, shows anti-inflammatory features in the treatment of many diseases. Here, we investigated the preventive and therapeutic effects of CAI on muscle loss that occurred in mice with advanced Lewis lung carcinoma (LLC). The carcass weights of CAI-treated mice were significantly higher than that of mice in the vehicle group from Day 19 to the end of the study. The gastrocnemius and epididymal adipose tissue weights were also increased by CAI treatment. The protective mechanisms might be attributed to the following points: CAI treatment inhibited the proteolysis in muscles by decreasing expressions of muscle-specific FoxO3 transcription factor and ubiquitin E3 ligases (MuRF1 and atrogin1). Moreover, CAI restricted the NF-κB signaling, downregulated the level of TNF-α in muscle and both TNF-α and IL-6 levels in serum, directly stimulated SIRT1 activity in vitro, and increased SIRT1 content in muscle. These results indicate that CAI can alleviate muscle wasting and is a promising drug against lung cancer cachexia.

Combination of carboxyamidotriazole and 1-Methyl-L-tryptophan has synergistic inhibtory effects on programmed death 1 expression / 中国药理学与毒理学杂志

OBJECTIVE To evaluate whether the IDO1 inhibitor 1- methyl- L- tryptophan (1- MT) combine calcium influx inhibitor carboxyamidotriazole (CAI) could further enhance the suppression of programmed death 1 (PD-1) in CD8 + T cells and investigate the curative effect of the combined use. METHODS CD8 +T cells were isolated from normal mice spleen by negative selection using magnetic cell separation. The isolated CD8 +T cells were cultured in RPMI 1640 medium containing 10% FBS and 100 U·mL- 1 IL-2 and activated by the addition of anti-CD3 and anti-CD28 (1 g·L- 1 each mabs). CD8 + T cells were pretreated for 48 h with drug and the fluo- 3 as a marker of intracellular calcium concentration was detected by flow cytometry. The calcineurin (CaN) levels were assayed with ELISA in CD8+T cells after 48 h incubation with 10 μm CAI. The nuclear translocations of NFAT and AHR were detected by immunofluorescent staining after 48 h of drug treatment. The expression of PD-1 in CD8+T cells was analyzed by flow cytometry. RESULTS Intracellular fluorescent intensity was markedly debase due to CAI treatment(P<0.01). Meanwhile, the changes of CaN content had a resembled correlation (P<0.01). Immunofluorescence experiment showed that after combination therapy the transfer of NFAT and AHR in nuclear substantially reduced. Flow cytometry revealed that after the combination caused a significant decrease in PD-1 expression in CD8+T cells. CONCLUSION CAI and 1-MT could inhibit markedly the expression of PD-1 in CD8 +T cells by inhibiting the nuclear translocation of NFAT and AHR, respectively and the combination of them has synergetic effect.

Therapeutic Effect of Carboxyamidotriazole on Adjuvant Arthritis in Rats.

OBJECTIVE: To study the effect of carboxyamidotriazole (CAI) on adjuvant arthritis (AA) in rats. METHODS: The rats were randomly divided into normal group,two vehicle groups (polyethylene glycol 400 control and normal sodium control group), CAI-treated groups (10, 20, and 40 mg/kg) and positive control dexamethasone group. Freund's completed adjuvant was used to induce AA in rats. The arthritis index (AI) was scored, and X-ray check of the hind limbs and histopathological examination were performed. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 in the inflamed paw tissues were measured. RESULTS: The administration of CAI significantly decreased the AI, restored the body weights, and ameliorated the radiological and histopathological features of joint destruction in AA rats (P<0.05, P<0.01). In addition, CAI reduced the TNF-α, IL-1ß, and IL-6 levels in the inflamed paw tissues (P<0.05, P<0.01). CONCLUSION: CAI has therapeutic effect on AA rats, which may be achieved by decreasing the pro-inflammatory cytokines at the site of inflammation.

Carboxyamidotriazole inhibits oxidative phosphorylation in cancer cells and exerts synergistic anti-cancer effect with glycolysis inhibition.

Targeting cancer cell metabolism is a promising strategy against cancer. Here, we confirmed that the anti-cancer drug carboxyamidotriazole (CAI) inhibited mitochondrial respiration in cancer cells for the first time and found a way to enhance its anti-cancer activity by further disturbing the energy metabolism. CAI promoted glucose uptake and lactate production when incubated with cancer cells. The oxidative phosphorylation (OXPHOS) in cancer cells was inhibited by CAI, and the decrease in the activity of the respiratory chain complex I could be one explanation. The anti-cancer effect of CAI was greatly potentiated when being combined with 2-deoxyglucose (2-DG). The cancer cells treated with the combination of CAI and 2-DG were arrested in G2/M phase. The apoptosis and necrosis rates were also increased. In a mouse xenograft model, this combination was well tolerated and retarded the tumor growth. The impairment of cancer cell survival was associated with significant cellular ATP decrease, suggesting that the combination of CAI and 2-DG could be one of the strategies to cause dual inhibition of energy pathways, which might be an effective therapeutic approach for a broad spectrum of tumors.

Activation of NALP1 inflammasomes in rats with adjuvant arthritis; a novel therapeutic target of carboxyamidotriazole in a model of rheumatoid arthritis.

BACKGROUND AND PURPOSE: Pro-inflammatory cytokines are important in rheumatoid arthritis (RA) and their production is mainly regulated by NF-κB and inflammasomes. Carboxyamidotriazole (CAI) exhibits potent anti-inflammatory activities by decreasing cytokines. Here, we have investigated NACHT, LRR and PYD domains-containing protein (NALP) inflammasomes in a rat model of RA and explored the therapeutic effects of CAI in this model and the involvement of NF-κB and inflammasomes in the actions of CAI. EXPERIMENTAL APPROACH: The anti-arthritic effects of CAI were assessed in the adjuvant arthritis (AA) model in rats, using radiological and histological techniques. NALP1 and NALP3 inflammasomes, NF-κB pathway and pro-inflammatory cytokines levels were measured with Western blots, immunohistochemistry and ELISA. KEY RESULTS: CAI decreased the arthritis index, improved radiological and histological changes, and reduced synovial IL-1ß, IL-6, IL-18 and TNF-α levels in rats with AA. Compared with normal rats, the 70 kDa NALP1 isoform was up-regulated, NALP3 was down-regulated, and levels of the 165 kDa NALP1 isoform and the adaptor protein ASC were unchanged in synovial tissue from AA rats. CAI reduced the 70 kDa NALP1 isoform and restored NALP3 levels in AA rats; CAI inhibited caspase-1 activation in AA synovial tissue, but not its enzymic activity in vitro. In addition, CAI reduced expression of p65 NF-κB subunit and IκBα phosphorylation and degradation in AA rats. CONCLUSION AND IMPLICATIONS: NALP1 inflammasomes were activated in synovial tissues from AA rats and appeared to be a novel therapeutic target for RA. CAI could have therapeutic value in RA by inhibiting activation of NF-κB and NALP1 inflammasomes and by decreasing pro-inflammatory cytokines.

Carboxyamidotriazole: a novel inhibitor of both cAMP-phosphodiesterases and cGMP-phosphodiesterases.

Carboxyamidotriazole (CAI) is a non-cytotoxic anti-tumor drug, which also shows considerable anti-inflammatory effects in a variety of animal models of inflammation. The exact target and mechanism of CAI were not clearly understood yet. In the present study, we demonstrate that CAI is a non-selective phosphodiesterase (PDE) inhibitor, which provides comprehensive inhibitions of both adenosine 3',5'-cyclic monophosphate specific PDE (cAMP-PDE) and guanosine 3',5'-cyclic monophosphate specific PDE (cGMP-PDE) isolated from rat brain, mouse pulmonary tissue, primary mouse peritoneal macrophages, RAW264.7 cells, Lewis lung carcinoma (LLC) cells and lymphocytic leukemia cells (L1210) with moderate potencies (IC50≈0.5-30µM). The comprehensive elimination of PDE activities in living LLC cells by CAI results in accumulation of intracellular cAMP and cGMP, which can be visualized by fluorescence resonance energy transfer (FRET)-based cyclic nucleotide sensors. The stimulation by 30µM CAI yielded ~1.5-fold greater cGMP responses compared with 10µM sildenafil citrate, whereas the influence of 30µM CAI on cAMP levels was similar as that of 100µM 3-isobutyl-1-methylxanthine (IBMX). The non-selective inhibitory effect of CAI on cAMP-PDE and cGMP-PDE increases the likelihood for CAI to affect the balance between the levels of intracellular cyclic nucleotides cAMP and cGMP, then a variety of cellular signaling pathways that regulate cell functions and even related disease processes. When examining the widely proven anti-tumor and anti-inflammatory activities of CAI, it is important to affirm its comprehensive inhibitory effect on PDEs, which makes it superior to some selective PDE inhibitors in a way.

Carboxyamidotriazole ameliorates experimental colitis by inhibition of cytokine production, nuclear factor-κB activation, and colonic fibrosis.

Carboxyamidotrizole (CAI) has been reported to suppress the production of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1ß and be effective in rats with adjuvant arthritis. The aim of this study was to investigate the role of CAI in inflammatory bowel disease (IBD). We assessed the effect of CAI in dextran sodium sulfate-induced colitis. Inflammation was scored histologically, and potential mediators of IBD were assessed by immunohistochemical and molecular biochemical approaches. CAI-treated colitis animals revealed much fewer signs of colitis with significantly decreased macroscopic and microscopic scores than vehicle-treated animals. CAI inhibited the production of TNF-α, IL-1ß, and IL-6 in serum, supernatant of peritoneal macrophages, and lamina propria. CAI also decreased the expression of intercellular adhesion molecule-1 in colonic tissues. Furthermore, CAI prevented nuclear factor-κB (NF-κB) activation and inhibitor of nuclear factor-κBα phosphorylation and degradation. In addition, CAI showed a beneficial effect on colonic fibrosis, possibly by reducing the production of the fibrogenic cytokine transforming growth factor-ß. The results support that CAI administration is effective in ameliorating experimental colitis and preventing colonic fibrosis. The inhibition of proinflammatory cytokines and adhesion molecules and suppression of NF-κB activation seem to contribute to this effect.

Inhibition of pro-inflammatory cytokines in tumour associated macrophages is a potential anti-cancer mechanism of carboxyamidotriazole.

Carboxyamidotriazole (CAI) has not only direct anti-cancer activities, but also anti-inflammation effects in a variety of inflammatory animal models. In the present study, we investigated whether macrophages, which are important both in cancer and inflammation, could be regulated by CAI. The results showed that CAI could inhibit tumour necrosis factor-α (TNF-α) production in macrophages in various environments, including those isolated from peritoneal cavity of adjuvant-induced arthritis (AA) rats, from Lewis lung carcinoma (LLC) transplanted tumours and those induced by LLC cells in vitro. Dexamethasone (DEX), one of the pro-inflammatory cytokines inhibitors, could enhance CAI's inhibition of LLC cells proliferation and invasion in macrophages and LLC cells co-culture systems, as well as the tumour growth in vivo. However, DEX failed to enhance CAI's inhibition of LLC cells proliferation when LLC cells were cultured alone, suggesting that the combination of CAI and DEX exerted great anti-tumour effects probably by acting on macrophages in the tumour environment. Over all, we found CAI could act on macrophages and regulate the production of TNF-α not only in inflammatory diseases but also in tumour microenvironment, which might be another anti-tumour mechanism of CAI.

[Anti-inflammatory and analgesic potency of carboxyamidotriazole, a tumoristatic agent].

OBJECTIVE: To explore the potential anti-inflammatory and analgesic activities of carboxyamidotriazole (CAI). METHODS: A variety of animal models, including the croton oil-induced ear edema, the cotton-induced granuloma, the rat adjuvant-induced arthritis, were used to evaluate anti-inflammatory effect of CAI. Vascular endothelial growth factor (VEGF)--or histamine-stimulated local vascular permeability in mouse modulated by CAI was also determined. In addition, we assessed the effect of CAI on the levels of proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-beta) at the site of inflammation and in sera. Moreover, antinociceptive effect of CAI on inflammatory pain was assessed using acetic acid-induced writhing model and the formalin test. RESULTS: CAI significantly inhibited acute and chronic phases of inflammation, reduced VEGF or histamine-induced vascular permeability, and showed marked inhibition of proinflammatory cytokines such as TNF-alpha and IL-1 beta. CAI also showed potential therapeutic effect on peripheral inflammatory pain. CONCLUSION: CAI is a promising anti-inflammatory and analgesic agent.

Efficacy of combined inhibition of mTOR and ERK/MAPK pathways in treating a tuberous sclerosis complex cell model.

Tuberous sclerosis complex (TSC) is an autosomal dominant tumor syndrome which afflicts multiple organs and for which there is no cure, such that TSC patients may develop severe mental retardation and succumb to renal or respiratory failure. TSC derives from inactivating mutations of either the TSC1 or TSC2 tumor suppressor gene, and the resulting inactivation of the TSC1/TSC2 protein complex causes hyperactivation of the mammalian target of rapamycin (mTOR), leading to uncontrolled cell growth and proliferation. Recent clinical trials of targeted suppression of mTOR have yielded only modest success in TSC patients. It was proposed that abrogation of a newly identified mTOR-mediated negative feedback regulation on extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) signaling pathway and on the well-documented RTK-PI3K-AKT signaling cascade could limit the efficacy of mTOR inhibitors in the treatment of TSC patients. Therefore, we speculate that dual inhibition of mTOR and ERK/MAPK pathways may overcome the disadvantage of single agent therapies and boost the efficacy of mTOR targeted therapies for TSC patients. Investigation of this hypothesis in a TSC cell model revealed that mTOR suppression with an mTOR inhibitor, rapamycin (sirolimus), led to up-regulation of ERK/MAPK signaling in mouse Tsc2 knockout cells and that this augmented signaling was attenuated by concurrent administration of a MEK1/2 inhibitor, PD98059. When compared with monotherapy, combinatorial application of rapamycin and PD98059 had greater inhibitory effects on Tsc2 deficient cell proliferation, suggesting that combined suppression of mTOR and ERK/MAPK signaling pathways may have advantages over single mTOR inhibition in the treatment of TSC patients.

Anti-inflammatory and analgesic potency of carboxyamidotriazole, a tumorostatic agent.

Carboxyamidotriazole (CAI) is a calcium influx inhibitor that is undergoing clinical trials for the treatment of various human cancers following the identification of its antiproliferative and antimetastatic activities. The exact mechanism of its action is not clearly understood, and whether it has other functions besides the established antitumor activity has not been reported either. In the present study, we demonstrate for the first time that CAI possesses anti-inflammatory and analgesic activities using a variety of animal models, including croton oil-induced ear edema, cotton-induced granuloma, rat adjuvant-induced arthritis, acetic acid-induced writhing, and the formalin test. We also show that CAI significantly inhibits local vascular permeability stimulated by vascular endothelial growth factor or histamine and decreases tumor necrosis factor-alpha and interleukin-1beta levels at the site of inflammation and in serums, which may contribute to the anti-inflammatory effect. These data suggest that CAI is a promising anti-inflammatory and analgesic agent, and they provide new insight into the biological activity of the drug.

Regulator of G protein signaling proteins differentially modulate signaling of mu and delta opioid receptors.

Effects of regulator of G protein signaling (RGS) proteins on mu and delta opioid receptors were investigated in HEK293 cells. Co-expression of RGS1, RGS2, RGS4, RGS9, RGS10 or RGS19 (Galpha-interacting protein (GAIP)) significantly reduced [Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol]-Enkephalin (DAMGO)-induced inhibition of adenylyl cyclase (AC) mediated by mu opioid receptor, but only RGS9 decreased the effects of [Tyr-D-Pen-Gly-p-Chloro-Phe-D-Pen]-Enkephalin (DPDPE) mediated by delta opioid receptor. When C-tails of the receptors were exchanged (mu/deltaC and delta/muC chimeras), RGS proteins decreased delta/muC-mediated AC inhibition, but none had significant effects on that via mu/deltaC receptor. Thus, the C-terminal domains of the receptors are critical for the differential effects of RGS proteins, which may be due to differences in receptor-G protein-RGS protein interactions in signaling complexes.

Carboxyamido-triazole inhibits proliferation of human breast cancer cells via G(2)/M cell cycle arrest and apoptosis.

Carboxyamido-triazole (CAI), a voltage-independent calcium channel inhibitor, has been shown to be able to induce growth inhibition and apoptosis in cancer cells. In the present study, we demonstrate that CAI significantly inhibits proliferation of cultured MCF-7 human breast cancer cells in a dose-dependent manner with an IC(50) of approximately 26 microM. Reduced proliferation of MCF-7 cells in the presence of CAI correlated with accumulation of cells in G(2)/M phase and induction of apoptosis. A treatment of MCF-7 cells with 30 microM CAI caused a time-dependent decrease in the levels of proteins that regulate G(2)/M progression, including Cdk1, Cyclin B1, and Cdc25C. A simultaneous increase in the expression of p21 protein was observed. We also demonstrated a concurrent decrease of the mitochondrial membrane potential (DeltaPsi(m)), and down-regulation of anti-apoptotic protein Bcl-2. In conclusion, it seems reasonable to hypothesize that the antitumor effect of CAI in MCF-7 cells is based on G(2)/M cell cycle arrest and inducing apoptosis.