Carboxyamidotriazole Research Articles

An effective LC-MS method for the simultaneous determination of a potential anti-rheumatoid arthritis drug, carboxyamidotriazole, and its major metabolite in rat plasma.

Carboxyamidotriazole (CAI) was previously recognized as a well-tolerated anticancer drug. It has also demonstrated significant anti-inflammatory effects in various cell and animal model experiments, prompting its investigation as a potential treatment for rheumatoid arthritis. In this study, the potential biotransformation metabolites of CAI were identified both in vitro and in vivo. A sensitive, specific, and accurate LC-MS method was developed for the quantitative analysis of CAI and its major metabolite, CAI-OH, in rat plasma. CAI, CAI-OH, and telmisartan (used as an internal standard) were separated using a Zorbax SB C18 column. The mobile phase consisted of water (phase A, containing 0.1% formic acid) and acetonitrile (phase B, containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The analytes were examined using a high-resolution mass spectrometer, with detected mass-to-charge ratios of m/z 424.01293 for CAI, m/z 440.00785 for CAI-OH, and m/z 515.24415 for telmisartan. Good linearity was observed within the range of 10-5000 ng/mL. Both inter- and intra-batch precision (relative standard deviation, %) were below 6%, and the accuracy ranged from 94.9% to 106.1%. The analytes remained stable throughout the entire experimental period. This method was successfully applied in a pharmacokinetic study of CAI following oral administration in rats.

Carboxyamidotriazole alleviates pannus formation and cartilage erosion in rats with adjuvant arthritis

Carboxyamidotriazole (CAI) was initially considered a non-cytotoxic anticancer agent. However, recently, pronounced anti-inflammatory properties of CAI have been reported. Rheumatoid arthritis (RA) is an autoimmune inflammatory disease characterized by aberrant activation of signaling pathways. Therefore, this study explored the therapeutic effects and potential mechanism of action of CAI on RA in the adjuvant arthritis (AA) model. The results showed that CAI reduced the severity of arthritis in AA rats as demonstrated by inhibited hind paw swelling, reduced body weight, and decreased infiltration of joint pathological inflammatory cells. Importantly, pathological scoring of new blood vessels and immunohistochemical assays revealed that CAI inhibited pannus formation. CAI decreased the expression of pro-angiogenic growth factors, such as vascular epidermal growth factor, basic fibroblast growth factor, and metalloproteinases (MMPs), namely, MMP-1 and MMP-3 in the synovium of AA rats. Furthermore, CAI significantly reduced the increased levels of phosphorylated p38, c-Jun N-terminal kinase (JNK)1/2, and extracellular signal-regulated kinase (ERK)1/2 proteins in AA rats. In addition, the proliferation of fibroblast-like synoviocytes (FLS) was downregulated by CAI both in vivo and in vitro. In conclusion, this investigation illustrates the therapeutic effect of CAI on synovitis and erosion of articular cartilage in RA. Furthermore, the mechanism might involve inhibition of aberrantly activated mitogen-activated protein kinase signaling, as well as a decrease in pro-angiogenic factors, MMP expression, and FLS proliferation.

AIM2 and NLRC4-driven inflammasome activation in adult-onset Still's disease and the preliminary therapeutic effect exploration of carboxyamidotriazole.

This study aimed to explore the changes of four major inflammasomes in adult-onset Still's disease (AOSD) and preliminarily evaluate the therapeutic effect of carboxyamidotriazole (CAI), which has previously been reported to have the significant anti-inflammatory activity. The mRNA expressions of proinflammatory cytokines and inflammasome components in peripheral blood mononuclear cells (PBMCs) from AOSD patients and healthy controls (HC) were determined by reverse transcription-quantitative PCR. Poly(dA:dT)-induced AIM2 inflammasome and flagellin-induced NLRC4 inflammasome activation models were established in bone marrow-derived macrophages (BMDMs). The levels of cytokines in serum and culture supernatants were measured by ELISA method. The serum levels of IL-1β, IL-6, and TNF-α in AOSD patients were significantly higher than those in HC. However, the mRNA expressions of IL-1β, IL-6, IL-18, and TNF-α in PBMCs did not differ markedly in AOSD patients in comparison with HC. Significantly increased mRNA levels of AIM2, NLRC4, ASC, and caspase-1 were observed in patients with AOSD when compared with HC, while NLRP1 and NLRP3 showed no change in AOSD samples. In addition, CAI treatment could significantly reduce the levels of IL-1β, IL-6, and TNF-α secreted by AOSD PBMCs and inhibit AIM2 and NLRC4 inflammasomes activation in BMDMs. Increased levels of proinflammatory cytokines in AOSD might be associated with NLRC4 and AIM2 inflammasomes activation. CAI is likely to have the therapeutic potential for AOSD by inhibiting NLRC4 and AIM2 inflammasomes activation and reducing the proinflammatory cytokines and worthy of further investigation. These results provide new ideas for elucidating the pathogenesis of AOSD and providing specific targeted therapy. Key points • Significantly higher mRNA levels of AIM2 and NLRC4 inflammsome signaling were observed in AOSD patients compared with health controls, indicating that AIM2 and NLRC4 inflammsome activation might be related to the increased proinflammatory cytokines in AOSD. • CAI treatment markedly reduced the secretion levels of cytokines IL-1β, IL-6, and TNF-α in AOSD PBMCs and inhibited AIM2 and NLRC4 inflammasome activation.

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)-1β, 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.

Identification of a novel toxicophore in anti-cancer chemotherapeutics that targets mitochondrial respiratory complex I.

Disruption of mitochondrial function selectively targets tumour cells that are dependent on oxidative phosphorylation. However, due to their high energy demands, cardiac cells are disproportionately targeted by mitochondrial toxins resulting in a loss of cardiac function. An analysis of the effects of mubritinib on cardiac cells showed that this drug did not inhibit HER2 as reported, but directly inhibits mitochondrial respiratory complex I, reducing cardiac-cell beat rate, with prolonged exposure resulting in cell death. We used a library of chemical variants of mubritinib and showed that modifying the 1H-1,2,3-triazole altered complex I inhibition, identifying the heterocyclic 1,3-nitrogen motif as the toxicophore. The same toxicophore is present in a second anti-cancer therapeutic carboxyamidotriazole (CAI) and we demonstrate that CAI also functions through complex I inhibition, mediated by the toxicophore. Complex I inhibition is directly linked to anti-cancer cell activity, with toxicophore modification ablating the desired effects of these compounds on cancer cell proliferation and apoptosis.

A phase III, randomized, double-blind, controlled trial of carboxyamidotriazole plus chemotherapy for the treatment of advanced non-small cell lung cancer.

Background:Carboxyamidotriazole (CAI), a calcium channel blocker, inhibits tumor cell proliferation, metastasis, and angiogenesis. This trial aimed to determine whether CAI combined with conventional chemotherapy could prolong progression-free survival (PFS) in non-small cell lung cancer (NSCLC) patients.Methods:Patients were assigned into groups (3:1 ratio) to receive either chemotherapy + CAI or chemotherapy alone. Cisplatin (25 mg/m2) was administered by intravenous infusion on days 1, 2, and 3, and vinorelbine (25 mg/m2) on days 1 and 8 of each 3-week cycle for four cycles. CAI was administered at 100 mg daily with concomitant chemotherapy; this treatment was continued after chemotherapy was ceased until serious toxicity or disease progression had occurred. PFS was the primary endpoint, and the secondary endpoints were objective response rate (ORR), disease control rate, overall survival (OS), and quality of life.Results:In total, 495 patients were enrolled in the trial: 378 in the chemotherapy + CAI group and 117 in the chemotherapy + placebo group. PFS was significantly greater in the chemotherapy + CAI [median, 134 days; 95% confidence interval (CI) 127–139] than in the chemotherapy + placebo (median, 98 days; 95% CI: 88–125) group, with a hazard ratio of 0.690 (95% CI: 0.539–0.883; p = 0.003). There was no difference in the OS rates of both groups. The ORR was greater in the chemotherapy + CAI group than in the chemotherapy + placebo group (34.6% versus 25.0%, p = 0.042). Adverse events of ⩾grade 3 occurred more frequently in the CAI group [256 (68.1%) versus 64 (55.2%); p = 0.014].Conclusion:CAI + platinum-based chemotherapy prolonged PFS and could be a useful therapeutic option to treat NSCLC.Clinical Trial Registration:chinadrugtrials.org.cn identifier: CTR20160395

Inhibition of store-operated channels by carboxyamidotriazole sensitizes ovarian carcinoma cells to anti-BclxL strategies through Mcl-1 down-regulation.

The anti-apoptotic proteins Bcl-xL and Mcl-1 have been identified to play a pivotal role in apoptosis resistance in ovarian cancer and constitute key targets for innovative therapeutic strategies. Although BH3-mimetics (i.e. ABT-737) potently inhibit Bcl-xL activity, targeting Mcl-1 remains a hurdle to the success of these strategies. Calcium signaling is profoundly remodeled during carcinogenesis and was reported to activate the signaling pathway controlling Mcl-1 expression. In this context, we investigated the effect of carboxyamidotriazole (CAI), a calcium channel inhibitor used in clinical trials, on Mcl-1 expression. CAI had an anti-proliferative effect on ovarian carcinoma cell lines and strongly down-regulated Mcl-1 expression. It inhibited store-operated calcium entry (SOCE) and Mcl-1 translation through mTORC1 deactivation. Moreover, it sensitized ovarian carcinoma cells to anti-Bcl-xL strategies as their combination elicited massive apoptosis. Its effect on mTORC1 and Mcl-1 was mimicked by the potent SOCE inhibitor, YM58483, which also triggered apoptosis when combined with ABT-737. As a whole, this study suggests that CAI sensitizes to anti-Bcl-xL strategies via its action on Mcl-1 translation and that modulation of SOCE could extend the therapeutic arsenal for treatment of ovarian carcinoma.

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.

Therapeutic effect and mechanism of carboxyamidotriazole on the pulmonary fibrosis of mice induced by bleomycin

Objective: To investigate the treatment effect of carboxyamidotriazole (CAI) on bleomycin induced lung fibrosis in mice, and the potential mechanism involved. Methods: A total of 45 mice were divided into three groups randomly. Blank control group (blank group): after a one-time tail vein injection of saline solution 0.2 ml, mice were given polyethylene glycol 400 (PEG-400) 0.1 ml/10 g by gavage once daily for 14 days; the bleomycin group (BLM group): after a one-time tail vein injection of bleomycin 150 mg/kg, mice were given PEG-400 solution 0.1 ml/10 g by gavage once daily for 14 days; CAI group: after a one-time tail vein injection of bleomycin 150 mg/kg, mice were given CAI solution 40 mg/kg by gavage once daily for 14 days. All mice were sacrificed on day 28. Observation index: lung coefficient, survival analysis, pathological section and collagen staining of lung tissue, lung hydroxyproline, Transformation growth factor-β(1)(TGF-β(1)), γ-interferon(IFN-γ), matrix metalloproteinase 9(MMP-9) and tissue inhibitor of matrix metalloproteinasese 1(TIMP-1) content determination in lung homogenate. Results: On day 28 the lung coefficient of mice in BLM group and CAI group was significantly higher than the blank group, and the BLM group was with the highest (all P<0.05). Degree of pulmonary fibrosis in lung tissue pathological specimens (HE staining) was, from heavy to light, BLM group, CAI group, blank group. The content of hydroxyproline in mice lung homogenate was (0.406±0.020) μg/mg in blank group, (0.722±0.118) μg/mg in BLM group, (0.537±0.071) μg/mg CAI group, respectively (all P<0.05). The content of TGF-β(1) in three groups was (15±5), (60±10), (41±10) ng/ml respectively (all P<0.05). The content of IFN-γ in three groups was (47±5), (126±24), (194±34) pg/ml respectively (all P<0.05). The content of TIMP-1 in three groups was (73±6), (369±58), (246±51) ng/ml respectively (all P<0.05). Comparisons of the content of MMP-9 between each group had no significant difference (P>0.05). Conclusions: CAI can reduce lung injury induced by bleomycin in mice. The mechanism of action is related to the effects of CAI on cytokines such as TGF-β(1), IFN-γ, MMP-9 and TIMP-1.

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)-1β, 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.

Therapeutic Effect of Carboxyamidotriazole on Adjuvant Arthritis in Rats.

To study the effect of carboxyamidotriazole (CAI) on adjuvant arthritis (AA) in rats. 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)-1β, and IL-6 in the inflamed paw tissues were measured. 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-1β, and IL-6 levels in the inflamed paw tissues (P<0.05, P<0.01). CAI has therapeutic effect on AA rats, which may be achieved by decreasing the pro-inflammatory cytokines at the site of inflammation.

Continuous manufacturing of carboxyamidotriazoleencapsulated nanoemulsions using adaptive focused acoustics: Potential green technology for the pharmaceutical industry

Nanoemulsions containing hydrophobic drugs have a great potential in the pharmaceutical industries to improve thebioavailability of the drug. However, currently there is no cost-effective way of producing nanoemulsions in large scale.The need of subjecting emulsions to an extreme pressure of 50 MPa demands a large excess of energy for themanufacturing process, while low-energy method requires large amount of solvents. Here, nanoemulsions containing awell-characterized hydrophobic drug, carboxyamidotriazole (CAI), are produced in both batch and continuous modes todemonstrate the scalability of nanoemulsion production using Covaris’ Adaptive Focused Acoustics™ (AFA) technology.To move from batch scale to continuous flow, the acoustic and thermal energy inputs can be manipulated to adjust particlesize, while the composition and temperature of starting materials can be altered to achieve complete dissolution ofhydrophobic drugs, thus providing 100% encapsulation efficiency. Furthermore, using two AFA systems in series candrastically enhance the production flow rates, making AFA a competitive means for producing nanoemulsions in thepharmaceutical industry.

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.

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. 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. CAI decreased the arthritis index, improved radiological and histological changes, and reduced synovial IL-1β, 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. 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.

Store-operated Ca2+ entry does not control proliferation in primary cultures of human metastatic renal cellular carcinoma.

Store-operated Ca2+ entry (SOCE) is activated following depletion of the inositol-1,4,5-trisphosphate (InsP3)-sensitive Ca2+ pool to regulate proliferation in immortalized cell lines established from either primary or metastatic lesions. The molecular nature of SOCE may involve both Stim1, which senses Ca2+ levels within the endoplasmic reticulum (ER) Ca2+ reservoir, and a number of a Ca2+-permeable channels on the plasma membrane, including Orai1, Orai3, and members of the canonical transient receptor (TRPC1–7) family of ion channels. The present study was undertaken to assess whether SOCE is expressed and controls proliferation in primary cultures isolated from secondary lesions of heavily pretreated metastatic renal cell carcinoma (mRCC) patients. SOCE was induced following pharmacological depletion of the ER Ca2+ store, but not by InsP3-dependent Ca2+ release. Metastatic RCC cells express Stim1-2, Orai1–3, and TRPC1–7 transcripts and proteins. In these cells, SOCE was insensitive to BTP-2, 10 µM Gd3+ and Pyr6, while it was inhibited by 100 µM Gd3+, 2-APB, and carboxyamidotriazole (CAI). Neither Gd3+ nor 2-APB or CAI impaired mRCC cell proliferation. Consistently, no detectable Ca2+ signal was elicited by growth factor stimulation. Therefore, a functional SOCE is expressed but does not control proliferation of mRCC cells isolated from patients resistant to multikinase inhibitors.

A phase I study of carboxyamidotriazole orotate (CTO) in of advanced solid tumors.

2518 Background: CTO is an orotate salt of carboxyamidotriazole (CAI), which is an inhibitor of calcium-dependent intracellular and extracellular signal transduction pathways (presumably affecting VEGF and PI3K) and has tumor anti-proliferative and anti-invasive properties. The activity of CTO alone and in combination with temozolomide or 5Efluorouracil was demonstrated in human glioblastoma, melanoma, and colon tumor xenografts. Methods: This study assessed the maximum tolerated dose (MTD), safety, pharmacokinetics and activity of CTO monotherapy in 34 patients (pts) with advanced solid tumors meeting eligibility criteria with adequate organ function. The CTO study NCT01107522 enrolled pts in 8 cohorts receiving continuous daily oral CTO capsules at doses ranging from 50mg- 555mg/m2/day. The MTD has not been determined. Pharmacokinetic (PK) sampling was performed during cycle 1 at each dose level. CT scans were performed at baseline and after 8 weeks to assess anti-tumor effect. Patients remained on study if they achieved stable disease (SD) or tumor response and did not experience dose limiting toxicities (DLT). Results: The most frequently recorded adverse events (Grade 1 and 2) were fatigue, nausea, vomiting, and dizziness. DLTs of grade 3 fatigue (219 mg/m2) and grade 3 creatine kinase elevation (555 mg/m2) occurred in one pt each. No cardiac QTc prolongations have been recorded. PK data demonstrated therapeutically relevant CAI levels beginning at the 219mg/m2 dose. Nine pts continued CTO dosing beyond 2 cycles. Tumor assessments demonstrated SD at different doses of CTO: i) 75mg/m2 renal carcinoma (1, 12 cycles); ii) 219 mg/m2-small cell lung cancer (1, 4 cycles), squamous cell lung cancer with PIK3CA mutation (1, 10 cycles and continuing), and lung adenocarcinoma with EGFR mutation (1, 10 cycles and, continuing); iii) 285 mg/m2-1 colon cancer with BRAFV600E mutation (1, 6 cycles), and squamous cell carcinoma (tonsil) with PI3KCA and NRAS mutations (1, 9 cycles, and continuing). Conclusions: CTO given as monotherapy up to 555mg/m2/day is safe and tolerable and without MTD. Six patients with different malignancies and genomic markers achieved SD; combinatorial investigations in malignant gliomas have started. Clinical trial information: NCT01107522.