Anti-inflammatory agents as cancer therapeutics

The Potential Preventive and Therapeutic Roles of NSAIDs in Prostate Cancer

Prostate cancer (PC) is the second most common type of cancer and the leading cause of death among men worldwide. Preventing the progression of cancer after treatments such as radical prostatectomy, radiation therapy, and hormone therapy is a major concern faced by prostate cancer patients. Inflammation, which can be caused by various factors such as infections, the microbiome, obesity and a high-fat diet, is considered to be the main cause of PC. Inflammatory cells are believed to play a crucial role in tumor progression. Therefore, nonsteroidal anti-inflammatory drugs along with their effects on the treatment of inflammation-related diseases, can prevent cancer and its progression by suppressing various inflammatory pathways. Recent evidence shows that nonsteroidal anti-inflammatory drugs are effective in the prevention and treatment of prostate cancer. In this review, we discuss the different pathways through which these drugs exert their potential preventive and therapeutic effects on prostate cancer.

Etoricoxib-Cannabidiol Combo: Potential Role in Glioblastoma Treatment and Development of PLGA-Based Nanoparticles

BACKGROUND

Glioblastoma (GBM) is the most frequently occurring primary malignant central nervous system tumor, with a poor prognosis and median survival below two years. Administration of a combination of non-steroidal anti-inflammatory drugs and natural compounds that exhibit a curative or prophylactic effect in cancer is a new approach to GBM treatment. This study aimed to investigate the synergistic antitumor activity of etoricoxib (ETO) and cannabidiol (CBD) in a GBM cell line model, and to develop poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs) for these two substances.

METHODS

The activity of ETO+CBD was determined using the MTT test, cell-cycle distribution assay, and apoptosis analysis using two GBM cell lines, namely, T98G and U-138 MG. The PLGA-based NPs were developed using the emulsification and solvent evaporation method. Their physicochemical properties, such as shape, size, entrapment efficiency (EE%), in vitro drug release, and quality attributes, were determined using scanning electron microscopy, diffraction light scattering, high-performance liquid chromatography, infrared spectroscopy, and differential scanning calorimetry.

RESULTS

The combination of ETO and CBD reduced the viability of cells in a dose-dependent manner and induced apoptosis in both tested GBM cell lines. The developed method allowed for the preparation of ETO+CBD-NPs with a spherical shape, mean particle size (MPS) below 400 nm, zeta potential (ZP) values from -11 to -17.4 mV, polydispersity index (PDI) values in the range from 0.029 to 0.256, and sufficient EE% of both drugs (78.43% for CBD, 10.94% for ETO).

CONCLUSIONS

The combination of ETO and CBD is a promising adjuvant therapeutic in the treatment of GBM, and the prepared ETO+CBD-NPs exhibit a high potential for further pharmaceutical formulation development.

Anti-inflammatory strategies for photothermal therapy of cancer

High temperature generated by photothermal therapy (PTT) can trigger an inflammatory response at the tumor site, which not only limits the efficacy of PTT but also increases the risk of tumor metastasis and recurrence. In light of the current limitations posed by inflammation in PTT, several studies have revealed that inhibiting PTT-induced inflammation can significantly improve the efficacy of cancer treatment. In this review, we summarize the research progress made in combining anti-inflammatory strategies to enhance the effectiveness of PTT. The goal is to offer valuable insights for developing better-designed photothermal agents in clinical cancer therapy.

NSAIDs and Cancer Resolution: New Paradigms beyond Cyclooxygenase

Acute inflammation or resolved inflammation is an adaptive host defense mechanism and is self-limiting, which returns the body to a state of homeostasis. However, unresolved, uncontrolled, or chronic inflammation may lead to various maladies, including cancer. Important evidence that links inflammation and cancer is that nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, reduce the risk and mortality from many cancers. The fact that NSAIDs inhibit the eicosanoid pathway prompted mechanistic drug developmental work focusing on cyclooxygenase (COX) and its products. The increased prostaglandin E2 levels and the overexpression of COX-2 in the colon and many other cancers provided the rationale for clinical trials with COX-2 inhibitors for cancer prevention or treatment. However, NSAIDs do not require the presence of COX-2 to prevent cancer. In this review, we highlight the effects of NSAIDs and selective COX-2 inhibitors (COXIBs) on targets beyond COX-2 that have shown to be important against many cancers. Finally, we hone in on specialized pro-resolving mediators (SPMs) that are biosynthesized locally and, in a time, -dependent manner to promote the resolution of inflammation and subsequent tissue healing. Different classes of SPMs are reviewed, highlighting aspirin's potential in triggering the production of these resolution-promoting mediators (resolvins, lipoxins, protectins, and maresins), which show promise in inhibiting cancer growth and metastasis.

H2S Donors and Their Use in Medicinal Chemistry

Hydrogen sulfide (H2S) is a ubiquitous gaseous signaling molecule that has an important role in many physiological and pathological processes in mammalian tissues, with the same importance as two others endogenous gasotransmitters such as NO (nitric oxide) and CO (carbon monoxide). Endogenous H2S is involved in a broad gamut of processes in mammalian tissues including inflammation, vascular tone, hypertension, gastric mucosal integrity, neuromodulation, and defense mechanisms against viral infections as well as SARS-CoV-2 infection. These results suggest that the modulation of H2S levels has a potential therapeutic value. Consequently, synthetic H2S-releasing agents represent not only important research tools, but also potent therapeutic agents. This review has been designed in order to summarize the currently available H2S donors; furthermore, herein we discuss their preparation, the H2S-releasing mechanisms, and their -biological applications.

Macrophage Reprogramming and Cancer Therapeutics: Role of iNOS-Derived NO

Nitric oxide and its production by iNOS is an established mechanism critical to tumor promotion or suppression. Macrophages have important roles in immunity, development, and progression of cancer and have a controversial role in pro- and antitumoral effects. The tumor microenvironment consists of tumor-associated macrophages (TAM), among other cell types that influence the fate of the growing tumor. Depending on the microenvironment and various cues, macrophages polarize into a continuum represented by the M1-like pro-inflammatory phenotype or the anti-inflammatory M2-like phenotype; these two are predominant, while there are subsets and intermediates. Manipulating their plasticity through programming or reprogramming of M2-like to M1-like phenotypes presents the opportunity to maximize tumoricidal defenses. The dual role of iNOS-derived NO also influences TAM activity by repolarization to tumoricidal M1-type phenotype. Regulatory pathways and immunomodulation achieve this through miRNA that may inhibit the immunosuppressive tumor microenvironment. This review summarizes the classical physiology of macrophages and polarization, iNOS activities, and evidence towards TAM reprogramming with current information in glioblastoma and melanoma models, and the immunomodulatory and therapeutic options using iNOS or NO-dependent strategies.

Piperazine: A Promising Scaffold with Analgesic and Anti-inflammatory Potential

Piperazine, a nitrogen-containing heterocyclic has acquired an inimitable position in medicinal chemistry because of its versatile structure, which has fascinated researchers to design novel piperazine based molecules having various biological actions. The subsistence of various compounds possessing diverse pharmacological activities in the literature further confirms this fact. Currently available analgesics and anti-inflammatory drugs are associated with side effects that limit their use. Moreover, the literature reveals the incredible anti-inflammatory and analgesic potential of piperazine derivatives along with their method of synthesis, therefore; the present review has been designed to collate the development made in this area that will surely be advantageous in designing novel piperazine based candidates with enhanced efficacy and less toxicity. An extensive literature survey was carried by scrutinizing peer reviewed articles from worldwide scientific databases available on GOOGLE, SCOPUS, PUBMED, and only relevant studies published in English were considered.

The Elevated Pre-Treatment C-Reactive Protein Predicts Poor Prognosis in Patients with Locally Advanced Rectal Cancer Treated with Neo-Adjuvant Radiochemotherapy

The aim of the present study was to investigate the association of the pre-treatment C-reactive protein (CRP) plasma level with survival outcomes in a cohort of 423 consecutive patients with locally advanced rectal cancer treated with neo-adjuvant radiochemotherapy followed by surgical resection. To evaluate the prognostic value of the CRP level for clinical endpoints recurrence-free survival (RFS), local-regional control (LC), metastases-free survival (MFS), and overall survival (OS), uni- and multivariate Cox regression analyses were applied, and survival rates were calculated using Kaplan–Meier analysis. The median follow-up time was 73 months. In univariate analyses, the pre-treatment CRP level was a significant predictor of RFS (hazard ratio (HR) 1.015, 95% CI 1.006–1.023; p < 0.001), LC (HR 1.015, 95% CI 1.004–1.027; p = 0.009), MFS (HR 1.014, 95% CI 1.004–1.023; p = 0.004), and OS (HR 1.016, 95% CI 1.007–1.024; p < 0.001). Additionally, univariate analysis identified the MRI circumferential resection margin (mrCRM) and pre-treatment carcinoembryonic antigen (CEA) as significant predictor of RFS (HR 2.082, 95% CI 1.106–3.919; p = 0.023 and HR 1.005, 95% CI 1.002–1.008; p < 0.001). Univariate analysis also revealed a significant association of the mrCRM (HR 2.089, 95% CI 1.052–4.147; p = 0.035) and CEA (HR 1.006, 95% CI 1.003–1.008; p < 0.001) with MFS. Age and CEA were prognostic factors for OS (HR 1.039, 95% CI 1.013–1.066; p = 0.003 and HR 1.005, 95% CI 1.002–1.008; p < 0.001). In multivariate analysis that included parameters with a p-level < 0.20 in univariate analysis, the pre-treatment CRP remained a significant prognostic factor for RFS (HR 1.013, 95%CI 1.001–1.025; p = 0.036), LC (HR 1.014, 95% CI 1.001–1.027; p = 0.031), and MFS (HR 1.013, 95% CI 1.000–1.027; p = 0.046). The results support the hypothesis that an elevated pre-treatment CRP level is a predictor of poor outcome. If confirmed by additional studies, this easily measurable biomarker could contribute to the identification of patients who might be candidates for more aggressive local or systemic treatment approaches or the administration of anti-inflammatory drugs.

The evolving landscape for cellular nitric oxide and hydrogen sulfide delivery systems: A new era of customized medications

Nitric oxide (NO) and hydrogen sulfide (H2S) are industrial toxins or pollutants; however, both are produced endogenously and have important biological roles in most mammalian tissues. The recognition that these gasotransmitters have a role in physiological and pathophysiological processes has presented opportunities to harness their intracellular effects either through inhibition of their production; or more commonly, through inducing their levels and or delivering them by various modalities. In this review article, we have focused on an array of NO and H2S donors, their hybrids with other established classes of drugs, and the various engineered delivery platforms such a fibers, polymers, nanoparticles, hydrogels, and others. In each case, we have reviewed the rationale for their development.

Anti-Inflammatory Drugs as Anticancer Agents

Inflammation is strictly associated with cancer and plays a key role in tumor development and progression. Several epidemiological studies have demonstrated that inflammation can predispose to tumors, therefore targeting inflammation and the molecules involved in the inflammatory process could represent a good strategy for cancer prevention and therapy. In the past, several clinical studies have demonstrated that many anti-inflammatory agents, including non-steroidal anti-inflammatory drugs (NSAIDs), are able to interfere with the tumor microenvironment by reducing cell migration and increasing apoptosis and chemo-sensitivity. This review focuses on the link between inflammation and cancer by describing the anti-inflammatory agents used in cancer therapy, and their mechanisms of action, emphasizing the use of novel anti-inflammatory agents with significant anticancer activity.

The Pre-Treatment C-Reactive Protein Represents a Prognostic Factor in Patients with Oral and Oropharyngeal Cancer Treated with Radiotherapy

The purpose of the present study was to evaluate the prognostic significance of the pre- treatment C-reactive protein (CRP) level in a cohort of 503 patients with oral and oropharyngeal cancer treated at a tertiary academic center between 2000 and 2017. Cancer-specific survival (CSS), overall survival (OS) and loco-regional control (LC) were calculated using Kaplan-Meier analysis. To evaluate the prognostic value of the CRP level for the clinical endpoints, univariate and multivariate Cox regression models were applied. The median follow-up period was 61 months. Patients were divided into elevated CRP (≥5 mg/L) and normal CRP groups, according to pre-treatment plasma levels. An increased CRP level was significantly associated with shorter CSS (p < 0.001, log-rank test), as well as with shorter OS (p < 0.001, log-rank test) and loco-regional control (p = 0.001, log-rank test). In addition, multivariate analysis identified CRP as an independent predictor for CSS (hazard ratio (HR) 1.59, 95% confidence interval (CI) 1.08-2.35; p = 0.020) as well as for OS (HR 1.62, 95%CI 1.17-2.24; p = 0.004) and LC (HR 1.50, 95%CI 1.06-2.14; p = 0.023). In subgroup analysis, Kaplan Meier curves revealed that an elevated pre-treatment CRP level was a consistent prognostic factor for poor CSS (p = 0.003, log-rank test), OS (p = 0.001, log-rank test), and LC (p = 0.028, log-rank test) in patients treated with definitive (chemo-) radiotherapy, whereas a significant association in patients undergoing surgery and postoperative radiotherapy was not detected. The pre-treatment CRP level seems to represent a prognostic factor for CSS, OS, and LC in patients with oral and oropharyngeal cancer, particularly in those treated with definitive (chemo-) radiotherapy. Additional large-scale prospective studies are warranted to confirm and extend our findings.

NOSH-aspirin (NBS-1120) inhibits pancreatic cancer cell growth in a xenograft mouse model: Modulation of FoxM1, p53, NF-κB, iNOS, caspase-3 and ROS

Pancreatic cancer has poor survival rates and largely ineffective therapies. Aspirin is the prototypical anti-cancer agent but its long-term use is associated with significant side effects. NOSH-aspirin belongs to a new class of anti-inflammatory agents that were designed to be safer alternatives by releasing nitric oxide and hydrogen sulfide. In this study we evaluated the effects of NOSH-aspirin against pancreatic cancer using cell lines and a xenograft mouse model. NOSH-aspirin inhibited growth of MIA PaCa-2 and BxPC-3 pancreatic cancer cells with IC₅₀s of 47 ± 5, and 57 ± 4 nM, respectively, while it did not inhibit growth of a normal pancreatic epithelial cell line at these concentrations. NOSH-aspirin inhibited cell proliferation, caused G₀/G₁ phase cycle arrest, leading to increased apoptosis. Treated cells displayed increases in reactive oxygen species (ROS) and caspase-3 activity. In MIA PaCa-2 cell xenografts, NOSH-aspirin significantly reduced tumor growth and tumor mass. Growth inhibition was due to reduced proliferation (decreased PCNA expression) and induction of apoptosis (increased TUNEL positive cells). Expressions of ROS, iNOS, and mutated p53 were increased; while that of NF-κB and FoxM1 that were high in vehicle-treated xenografts were significantly inhibited by NOSH-aspirin. Taken together, these molecular events and signaling pathways contribute to NOSH-aspirin mediated growth inhibition and apoptotic death of pancreatic cancer cells in vitro and in vivo.

Main Inflammatory Cells and Potentials of Anti-Inflammatory Agents in Prostate Cancer

Prostate cancer is the most common type of cancer and the leading cause of cancer deaths among men in many countries. Preventing progression is a major concern for prostate cancer patients on active surveillance, patients with recurrence after radical therapies, and patients who acquired resistance to systemic therapies. Inflammation, which is induced by various factors such as infection, microbiome, obesity, and a high-fat diet, is the major etiology in the development of prostate cancer. Inflammatory cells play important roles in tumor progression. Various immune cells including tumor-associated neutrophils, tumor-infiltrating macrophages, myeloid-derived suppressor cells, and mast cells promote prostate cancer via various intercellular signaling. Further basic studies examining the relationship between the inflammatory process and prostate cancer progression are warranted. Interventions by medications and diets to control systemic and/or local inflammation might be effective therapies for prostate cancer progression. Epidemiological investigations and basic research using human immune cells or mouse models have revealed that non-steroidal anti-inflammatory drugs, metformin, statins, soy isoflavones, and other diets are potential interventions for preventing progression of prostate cancer by suppressing inflammation. It is essential to evaluate appropriate indications and doses of each drug and diet.

The dichotomous role of H2S in cancer cell biology? Déjà vu all over again

Nitric oxide (NO) a gaseous free radical is one of the ten smallest molecules found in nature, while hydrogen sulfide (H2S) is a gas that bears the pungent smell of rotten eggs. Both are toxic yet they are gasotransmitters of physiological relevance. There appears to be an uncanny resemblance between the general actions of these two gasotransmitters in health and disease. The role of NO and H2S in cancer has been quite perplexing, as both tumor promotion and inflammatory activities as well as anti-tumor and antiinflammatory properties have been described. These paradoxes have been explained for both gasotransmitters in terms of each having a dual or biphasic effect that is dependent on the local flux of each gas. In this review/commentary, I have discussed the major roles of NO and H2S in carcinogenesis, evaluating their dual nature, focusing on the enzymes that contribute to this paradox and evaluate the pros and cons of inhibiting or inducing each of these enzymes.

Multiple target-centric strategy to tame inflammation

Single-target inhibition is an unsatisfactory therapeutic option to treat multifactorial pathologies, brought into limelight 'paradox of inflammation' beside dearth of innovation, rationalizes a shift toward 'multiple-target' design concept in anti-inflammatory research field. To improvise, two platform strategies, drugs mixture or multitarget drugs, are plausible. Dual cyclooxygenase/lipoxygenase inhibitor 'licofelone' developed after the backfire of rofecoxib due to safety concerns has fetched first light of triumph of the latter strategy. As hitting multiple targets in restraint is perhaps more viable strategy rather than single target, this review, outlines the most germane multiple target agents of synthetic and natural origin placing clear advantage in favors of multitarget strategy as real therapeutic solution for inflammation.

Effect of natural and semi-synthetic cadinanes from Heterotheca inuloides on NF-κB, Nrf2 and STAT3 signaling pathways and evaluation of their in vitro cytotoxicity in human cancer cell lines

The effects of ten natural cadinane sesquiterpenoids isolated from Heterotheca inuloides on the pathways of the NF-κB, Nrf2 and STAT3 transcription factors were studied for the first time. The main constituent in this species, 7-hydroxy-3,4-dihydrocadalene (1), showed anti-NF-κB activity and activated the antioxidant Nrf2 pathway, which may explain the properties reported for the traditional use of the plant. In addition to the main metabolite, a structurally similar compound, 7-hydroxy-cadalene (2), also displayed anti-NF-κB activity. Thus, both natural compounds were used as templates for the preparation of a novel semi-synthetic derivative set, including esters and carbamates, which were evaluated for their potential in vitro antiproliferative activities against six human cancer cell lines. Carbamate derivatives 32 and 33 were found to exhibit potent activity against human colorectal adenocarcinoma and showed important selectivity in cancer cells. Among ester derivatives, compound 13 was determined to be a more potent NF-κB inhibitor and Nrf2 activator than its parent, 7-hydroxy-3,4-dihydrocadalene (1). Furthermore, this compound decreases levels of phospho-IκBα, a protein complex involved in the NF-κB activation pathway. Molecular simulations suggest that all active compounds interact with the activation loop of the IKKβ subunit in the IKK complex, which is the responsible of IκBα phosphorylation. Thus, we identified two natural, and one semi-synthetic, NF-κB and Nrf2 modulators and two new promising cytotoxic compounds.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Quinoline-based imidazole-fused heterocycles as new inhibitors of 15-lipoxygenase

A series of 2-chloro-quinoline-based imidazopyridines 6a-l and imidazothiazoles 6m-o bearing a bulky alkylamine side chain were synthesized as soybean 15-LOX inhibitors. The target compounds 6a-o were prepared via one-pot reaction of 2-chloroquinoline-3-carbaldehyde (3), heteroaromatic amidine 4, and alkyl isocyanides 5, in the presence of NH4Cl. All compounds showed significant anti-15-LOX activity (IC50 values ≤40 μM). Among the title compounds, the imidazo[2,1-b]thiazole derivative 6n bearing a tert-butylamine moiety showed the highest activity against soybean 15-LOX enzyme.

Effect of Cocoa and Its Flavonoids on Biomarkers of Inflammation: Studies of Cell Culture, Animals and Humans

Chronic inflammation has been identified as a necessary step to mediate atherosclerosis and cardiovascular disease and as a relevant stage in the onset and progression of several types of cancer. Considerable attention has recently been focused on the identification of dietary bioactive compounds with anti-inflammatory activities as an alternative natural source for prevention of inflammation-associated diseases. The remarkable capacity of cocoa flavanols as antioxidants, as well as to modulate signaling pathways involved in cellular processes, such as inflammation, metabolism and proliferation, has encouraged research on this type of polyphenols as useful bioactive compounds for nutritional prevention of cardiovascular disease and cancer. Data from numerous studies suggest that cocoa and cocoa-derived flavanols can effectively modify the inflammatory process, and thus potentially provide a benefit to individuals with elevated risk factors for atherosclerosis/cardiovascular pathology and cancer. The present overview will focus on the most recent findings about the effects of cocoa, its main constituents and cocoa derivatives on selected biomarkers of the inflammatory process in cell culture, animal models and human cohorts.

Gastrointestinal safety, chemotherapeutic potential, and classic pharmacological profile of NOSH-naproxen (AVT-219) a dual NO- and H2S-releasing hybrid

Naproxen (NAP) is a potent nonsteroidal anti-inflammatory drug (NSAID) with a favorable cardiovascular profile. However, its long-term use may lead to serious gastrointestinal and renal side effects. NOSH- (nitric oxide and hydrogen sulfide) releasing naproxen (NOSH-NAP, AVT-219) belongs to a new class of anti-inflammatory agents designed to overcome these limitations. We compared the gastrointestinal safety, anti-inflammatory, analgesic, antipyretic, and antiplatelet properties of AVT-219 to that of NAP in preclinical animal models. We also evaluated its anticancer effects in 11 human cancer cell (HCC) lines of six different tissue origins and in a chemotherapeutic xenograft mouse model of colon cancer. AVT-219: (1) was orders of magnitude more potent than NAP in inhibiting the growth of cultured HCC; (2) was safe to the stomach, whereas NAP caused significant ulceration; (3) showed strong anti-inflammatory, analgesic, antipyretic, and antiplatelet properties comparable to NAP; and (4) NAP caused a significant rise in plasma tumor necrosis factor-alpha (TNFα), whereas in the AVT-219-treated rats this rise was significantly less. Mechanistically, AVT-219 was a strong antioxidant, inhibited cyclooxygenase (COX)-1 and -2, thus reducing prostaglandin (PG) E2. In xenografts, AVT-219 significantly reduced tumor growth and tumor mass with no sign of GI toxicity, whereas NAP-treated mice died due to GI bleeding. AVT-219 displayed considerable safety and potency in inhibiting HCC growth; was an effective analgesic, antipyretic, antiplatelet, and anti-inflammatory; and was significantly more efficacious than NAP in reducing the growth of established tumors in a xenograft mouse model.

Synthesis and antitumor activity of ATB-429 derivatives containing a nitric oxide-releasing moiety

A series of novel ATB-429 (an anti-inflammatory candidate) derivatives containing a nitric oxide (NO)-releasing moiety were designed, synthesized and evaluated for their in vitro activity against six human cancer cell lines. Our results reveal that phenylsulfonylfuroxan-based derivatives have considerable antitumor activity, and compounds 7-9 (IC50s: 0.256-3.024 μM) against HT-29 and PANC-1, 8a,b (IC50s: 2.677-3.051 μM) against MCF-7 and 8a (IC50: 1.270 μM) against DU145 are more active than Vandetanib (IC50s: 1.925-4.107 μM).

Synthesis of p-O-Alkyl Salicylanilide Derivatives as Novel EGFR Inhibitors

Preclinical Research Epidermal growth factor receptor (EGFR), a validated target for anticancer drugs, plays a critical role in tumorigenesis and tumor development. A series of p-O-alkyl salicylanilide derivatives were designed and synthesized as novel EGFR inhibitors using a salicylic acid scaffold. A simulated six-membered ring strategy formed through intramolecular hydrogen bonds was employed to mimic the planar quinazoline of the EGFR antagonist, gefitinib. The derived compounds with hydroxyl at the ortho position were more potent than ones with methoxyl group. In particular, compounds 5d and 5b displayed significant EGFR inhibitory (IC50 values = 0.30 and 0.45 μM, respectively) activity as well as potent antiproliferative activity in A431 and HCT-116 tumor cells. These salicylanilides could be considered as promising lead compounds for developing novel EGFR inhibitors.

Phytochemical characterization and bioactive properties of Osyris quadripartita Salzm. ex Decne. leaves from Algeria

Medicinal plants are sources of bioactive compounds with recognized beneficial effects on human health.

NOSH-aspirin (NBS-1120), a novel nitric oxide- and hydrogen sulfide-releasing hybrid has enhanced chemo-preventive properties compared to aspirin, is gastrointestinal safe with all the classic therapeutic indications

Aspirin is chemopreventive; however, side effects preclude its long-term use. NOSH-aspirin (NBS-1120), a novel hybrid that releases nitric oxide and hydrogen sulfide, was designed to be a safer alternative. Here we compare the gastrointestinal safety, anti-inflammatory, analgesic, anti-pyretic, anti-platelet, and chemopreventive properties of aspirin and NBS-1120 administered orally to rats at equimolar doses. Gastrointestinal safety: 6h post-administration, the number and size of hemorrhagic lesions in stomachs were counted; tissue samples were frozen for PGE2, SOD, and MDA determination. Anti-inflammatory: 1h after drug administration, the volume of carrageenan-induced rat paw edemas was measured for 5h. Anti-pyretic: fever was induced by LPS (ip) an hour before administration of the test drugs, core body temperature was measured hourly for 5h. Analgesic: time-dependent analgesic effects were evaluated by carrageenan-induced hyperalgesia. Antiplatelet: anti-aggregatory effects were studied on collagen-induced platelet aggregation of human platelet-rich plasma. Chemoprevention: nude mice were gavaged daily for 25 days with vehicle, aspirin or NBS-1120. After one week, each mouse was inoculated subcutaneously in the right flank with HT-29 human colon cancer cells. Both agents reduced PGE2 levels in stomach tissue; however, NBS-1120 did not cause any stomach ulcers, whereas aspirin caused significant bleeding. Lipid peroxidation induced by aspirin was higher than that exerted by NBS-1120. SOD activity was significantly inhibited by aspirin but increased by NBS-1120. Both agents showed similar anti-inflammatory, analgesic, anti-pyretic, and anti-platelet activities. Aspirin increased plasma TNFα more than NBS-1120-treated animals. NBS-1120 was better than aspirin as a chemopreventive agent; it dose-dependently inhibited tumor growth and tumor mass.

Positional isomerism markedly affects the growth inhibition of colon cancer cells by NOSH-aspirin: COX inhibition and modeling

We recently reported the synthesis of NOSH-aspirin, a novel hybrid that releases both nitric oxide (NO) and hydrogen sulfide (H₂S). In NOSH-aspirin, the two moieties that release NO and H₂S are covalently linked at the 1, 2 positions of acetyl salicylic acid, i.e. ortho-NOSH-aspirin (o-NOSH-aspirin). In the present study, we compared the effects of the positional isomers of NOSH-ASA (o-NOSH-aspirin, m-NOSH-aspirin and p-NOSH-aspirin) to that of aspirin on growth of HT-29 and HCT 15 colon cancer cells, belonging to the same histological subtype, but with different expression of cyclooxygenase (COX) enzymes; HT-29 express both COX-1 and COX-2, whereas HCT 15 is COX-null. We also analyzed the effect of these compounds on proliferation and apoptosis in HT-29 cells. Since the parent compound aspirin, inhibits both COX-1 and COX-2, we also evaluated the effects of these compounds on COX-1 and COX-2 enzyme activities and also performed modeling of the interactions between the positional isomers of NOSH-aspirin and COX-1 and COX-2 enzymes. We observed that the three positional isomers of NOSH aspirin inhibited the growth of both colon cancer cell lines with IC₅₀s in the nano-molar range. In particular in HT-29 cells the IC₅₀s for growth inhibition were: o-NOSH-ASA, 0.04±0.011 µM; m-NOSH-ASA, 0.24±0.11 µM; p-NOSH-ASA, 0.46±0.17 µM; and in HCT 15 cells the IC₅₀s for o-NOSH-ASA, m-NOSH-ASA, and p-NOSH-ASA were 0.062 ±0.006 µM, 0.092±0.004 µM, and 0.37±0.04 µM, respectively. The IC₅₀ for aspirin in both cell lines was >5 mM at 24 h. The reduction of cell growth appeared to be mediated through inhibition of proliferation, and induction of apoptosis. All 3 positional isomers of NOSH-aspirin preferentially inhibited COX-1 over COX-2. These results suggest that the three positional isomers of NOSH-aspirin have the same biological actions, but that o-NOSH-ASA displayed the strongest anti-neoplastic potential.

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NOSH-aspirin is a hybrid compound, releasing nitric oxide and hydrogen sulfide.

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Positional isomers of NOSH-aspirin effectively inhibit colon cancer cell growth.

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In colon cancer cells, NOSH-aspirin inhibits proliferation and induces apoptosis.

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NOSH-aspirin preferentially inhibits COX-1 enzyme activity over COX-2.

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Potency order is o-NOSH-aspirin>m-NOSH-aspirin>p-NOSH-aspirin.

Codelivery of SH-aspirin and curcumin by mPEG-PLGA nanoparticles enhanced antitumor activity by inducing mitochondrial apoptosis

Natural product curcumin (Cur) and H₂S-releasing prodrug SH-aspirin (SH-ASA) are potential anticancer agents with diverse mechanisms, but their clinical application prospects are restricted by hydrophobicity and limited efficiency. In this work, we coencapsulated SH-ASA and Cur into methoxy poly(ethylene glycol)-poly (lactide-coglycolide) (mPEG-PLGA) nanoparticles through a modified oil-in-water single-emulsion solvent evaporation process. The prepared SH-ASA/Cur-coloaded mPEG-PLGA nanoparticles had a mean particle size of 122.3±6.8 nm and were monodispersed (polydispersity index =0.179±0.016) in water, with high drug-loading capacity and stability. Intriguingly, by treating with SH-ASA/Cur-coloaded mPEG-PLGA nanoparticles, obvious synergistic anticancer effects on ES-2 and SKOV3 human ovarian carcinoma cells were observed in vitro, and activation of the mitochondrial apoptosis pathway was indicated. Our results demonstrated that SH-ASA/Cur-coloaded mPEG-PLGA nanoparticles could have potential clinical advantages for the treatment of ovarian cancer.

NOSH-sulindac (AVT-18A) is a novel nitric oxide- and hydrogen sulfide-releasing hybrid that is gastrointestinal safe and has potent anti-inflammatory, analgesic, antipyretic, anti-platelet, and anti-cancer properties

Sulindac is chemopreventive and has utility in patients with familial adenomatous polyposis; however, side effects preclude its long-term use. NOSH-sulindac (AVT-18A) releases nitric oxide and hydrogen sulfide, was designed to be a safer alternative. Here we compare the gastrointestinal safety, anti-inflammatory, analgesic, anti-pyretic, anti-platelet, and anti-cancer properties of sulindac and NOSH-sulindac administered orally to rats at equimolar doses. Gastrointestinal safety: 6h post-administration, number/size of hemorrhagic lesions in stomachs were counted. Tissue samples were frozen for PGE2, SOD, and MDA determination. Anti-inflammatory: 1h after drug administration, the volume of carrageenan-induced rat paw edemas was measured for 5h. Anti-pyretic: fever was induced by LPS (ip) an hour before administration of the test drugs, core body temperature was measured hourly for 5h. Analgesic: time-dependent analgesic effects were evaluated by carrageenan-induced hyperalgesia. Antiplatelet: anti-aggregatory effects were studied on collagen-induced platelet aggregation of human platelet-rich plasma. Anti-cancer: We examined the effects of NOSH-sulindac on the growth properties of 12 human cancer cell lines of six different tissue origins. Both agents reduced PGE2 levels in stomach tissue; however, NOSH-sulindac did not cause any stomach ulcers, whereas sulindac caused significant bleeding. Lipid peroxidation induced by sulindac was higher than that from NOSH-sulindac. SOD activity was significantly lowered by sulindac but increased by NOSH-sulindac. Both agents showed similar anti-inflammatory, analgesic, anti-pyretic, and anti-platelet activities. Sulindac increased plasma TNFα whereas this rise was lower in the NOSH-sulindac-treated animals. NOSH-sulindac inhibited the growth of all cancer cell lines studied, with potencies of 1000- to 9000-fold greater than that of sulindac. NOSH-sulindac inhibited cell proliferation, induced apoptosis, and caused G2/M cell cycle block. These results demonstrate that NOSH-sulindac is gastrointestinal safe, and maintains the anti-inflammatory, analgesic, antipyretic, and antiplatelet properties of its parent compound sulinsac, with anti-growth activity against a wide variety of human cancer cells.

Synthesis and anti-cancer potential of the positional isomers of NOSH-aspirin (NBS-1120) a dual nitric oxide and hydrogen sulfide releasing hybrid

We recently reported the synthesis of NOSH-aspirin, a novel hybrid compound capable of releasing both nitric oxide (NO) and hydrogen sulfide (H2S). In NOSH-aspirin, the two moieties that release NO and H2S are covalently linked at the 1, 2 positions of acetyl salicylic acid, i.e., ortho-NOSH-aspirin. Here we report on the synthesis of meta- and para-NOSH-aspirins. We also made a head-to-head evaluation of the effects of these three positional isomers of NOSH-aspirin on colon cancer cell kinetics and induction of reactive oxygen species, which in recent years has emerged as a key event in causing cancer cell regression. Electron donating/withdrawing groups incorporated about the benzoate moiety significantly affected the potency of these compounds with respect to colon cancer cell growth inhibition.

Anti-inflammatory activity of copao (Eulychnia acida Phil., Cactaceae) fruits

Copao (Eulychnia acida Phil., Cactaceae) is an endemic species occurring in northern Chile. The edible fruits of this plant are valued for its acidic and refreshing taste. Phenolic-enriched extracts from copao fruit pulp and epicarp, collected in the Elqui and Limari river valleys, were assessed by its in vitro ability to inhibit the pro-inflammatory enzymes lipoxygenase (LOX) and cyclooxygenases (COX-1 and COX-2). At 100 μg/mL, pulp extracts showed better effect towards LOX than epicarp extract, while COX-2 inhibition was observed for both epicarp and pulp samples. In general, the extracts were inactive towards COX-1. A positive correlation was observed between the anti-inflammatory activity and the main phenolic compounds found in this fruit. Copao fruits from the Limari valley, a main place of collection and commercialization, showed major activity, adding evidence on the possible health-beneficial effects of this native Chilean fruit.

NOSH-aspirin (NBS-1120), a dual nitric oxide and hydrogen sulfide-releasing hybrid, reduces inflammatory pain

The development of nitric oxide (NO)- and hydrogen sulfide (H₂S)-releasing nonsteroidal anti-inflammatory drugs (NSAIDs) has generated more potent anti-inflammatory drugs with increased safety profiles. A new hybrid molecule incorporating both NO and H₂S donors into aspirin (NOSH-aspirin) was recently developed. In the present study, the antinociceptive activity of this novel molecule was compared with aspirin in different models of inflammatory pain. It was found that NOSH-aspirin inhibits acetic acid-induced writhing response and carrageenan (Cg)-induced inflammatory hyperalgesia in a dose-dependent (5–150 μmol/kg, v.o.) manner, which was superior to the effect of the same doses of aspirin. NOSH-aspirin’s antinociceptive effect was also greater and longer compared to aspirin upon complete Freund’s adjuvant (CFA)-induced inflammatory hyperalgesia. Mechanistically, NOSH-aspirin, but not aspirin, was able to reduce the production/release of interleukin-1 beta (IL-1β) during Cg-induced paw inflammation. Furthermore, NOSH-aspirin, but not aspirin, reduced prostaglandin E₂-induced hyperalgesia, which was prevented by treatment with a ATP-sensitive potassium channel (K_ATP) blocker (glibenclamide; glib.). Noteworthy, the antinociceptive effect of NOSH-aspirin was not associated with motor impairment. The present results indicate that NOSH-aspirin seems to present greater potency than aspirin to reduce inflammatory pain in several models. The enhanced effects of NOSH-aspirin seems to be due to its ability to reduce the production of pronociceptive cytokines such as IL-1 β and directly block hyperalgesia caused by a directly acting hyperalgesic mediator in a mechanism dependent on modulation of K_ATP channels. In conclusion, we would like to suggest that NOSH-aspirin represents a prototype of a new class of analgesic drugs with more potent effects than the traditional NSAID, aspirin.

Medicinal Chemistry: Insights into the Development of Novel H2S Donors

Hydrogen sulfide (H2S) was traditionally considered as a toxic gas. However, recent studies have demonstrated H2S is an endogenously generated gaseous signaling molecule (gasotransmitter) with importance on par with that of two other well-known endogenous gasotransmitters, nitric oxide (NO) and carbon monoxide (CO). Although H2S's exact mechanisms of action are still under investigation, the production of endogenous H2S and the exogenous administration of H2S have been demonstrated to elicit a wide range of physiological responses including modulation of blood pressure and protection of ischemia reperfusion injury, exertion of anti-inflammatory effects, and reduction of metabolic rate. These results strongly suggest that modulation of H2S levels could have potential therapeutic values. In this regard, synthetic H2S-releasing agents (i.e., H2S donors) are not only important research tools, but also potential therapeutic agents. This chapter summarizes the knowledge of currently available H2S donors. Their preparation, H2S releasing mechanisms, and biological applications are discussed.

Anti-cancer activity of new designer hydrogen sulfide-donating hybrids

SIGNIFICANCE

Hydrogen sulfide (H2S) is likely to join nitric oxide (NO) and carbon monoxide (CO) as the third gaseous transmitter, influencing an array of intracellular signaling cascades. Thus, H2S is implicated in numerous physiological processes and in the pathology of various diseases.

RECENT ADVANCES

H2S-donating agents that liberate H2S slowly either alone or in combination with NO, the so-called NOSH compounds, are being synthesized, and these have been shown to have great potential against cancer.

CRITICAL ISSUES

An accurate determination of H2S levels is challenging. H2S and NO share many similar actions; do these similarities act to potentiate each other? Since many actions of H2S appear to be mediated through inhibition of inflammation and Nuclear factor kappa-light-chain-enhancer of activated B cells is a central player in this scenario, does S-nitrosylation of this transcription factor by NO affect its S-sulfhydration by H2S and vice versa?

FUTURE DIRECTIONS

Deciphering the molecular targets of these novel hybrid agents and having genetically engineered animals should help us move toward targeted therapeutic applications. Human safety data with these new hybrids is essential.

Future directions in the prevention of prostate cancer

The high global incidence of prostate cancer has led to a focus on chemoprevention strategies to reduce the public health impact of the disease. Early studies indicating that selenium and vitamin E might protect against prostate cancer encouraged large-scale studies that produced mixed clinical results. Next-generation prostate cancer prevention trials validated the impact of 5α-reductase inhibitors in hormone-responsive prostate cancer, and these results were confirmed in follow-up studies. Other interventions on the horizon, involving both dietary and pharmacological agents, hold some promise but require further investigation to validate their efficacy. In this Review, we discuss the clinical and preclinical evidence for dietary and pharmacological prevention of prostate cancer and give an overview of future opportunities for chemoprevention.

Hydrogen sulfide-releasing aspirin inhibits the growth of leukemic Jurkat cells and modulates β-catenin expression

Hydrogen sulfide-releasing aspirin (HS-ASA) is a novel compound with potential against cancer. It inhibited the growth of Jurkat T-leukemia cells with an IC₅₀ of 1.9 ± 0.2 μM whereas that of ASA was >5000 μM. It dose-dependently inhibited proliferation and induced apoptosis in these cells, causing a G₀/G₁ cell cycle arrest. HS-ASA down-regulated β-catenin protein levels and reduced mRNA and protein expression of β-catenin/TCF downstream target genes cyclinD1 and c-myc. Aspirin up to 5 mM had no effect on β-catenin expression. HS-ASA also increased caspase-3 protein levels and dose-dependently increased its activity. These effects were substantially blocked by z-VAD-fmk, a pan-caspase inhibitor.

Synthesis and biological activity of NOSH-naproxen (AVT-219) and NOSH-sulindac (AVT-18A) as potent anti-inflammatory agents with chemotherapeutic potential

Nitric oxide- (NO) and hydrogen sulfide- (H₂S) releasing naproxen (NOSH-naproxen) and NO and H₂S-releasing sulindac (NOSH-sulindac) were synthesized and their cell growth inhibitory properties were evaluated in four different human cancer cell lines. These cell lines are of adenomatous (colon, pancreas), epithelial (breast), and lymphocytic (leukemia) origin. Using HT-29 human colon cancer cells, NOSH-naproxen and NOSH-sulindac increased apoptosis, and inhibited proliferation. NOSH-naproxen caused a G₀/G₁ whereas NOSH-sulindac caused a G₂/M block in the cell cycle. Both compounds exhibited significant anti-inflammatory properties, using the carrageenan rat paw edema model. Reconstitution and structure-activity studies representing a fairly close approximation to the intact molecule showed that NOSH-naproxen was approximately 8000-fold more potent than the sum of its parts in inhibiting cell growth. Our data suggest that these compounds merit further investigation as potential anti-cancer agents.

Reaction of pregnenolone with cyanoacetylhydrazine: novel synthesis of hydrazide-hydrazone, pyrazole, pyridine, thiazole, thiophene derivatives and their cytotoxicity evaluations

Pregnenolone (1) was used as a template to develop new anticancer compounds. Ring D modification of 1 through its reaction with cyanoacetylhydrazine (2) gave the hydrazide-hydrazone derivative 3. The latter compound underwent heterocyclization reactions to give the pyrazole, pyridine, thiazole and thiophene derivatives of pregnenolone. The cytotoxicity of the newly synthesized heterocyclic steroids against three human tumor cell lines namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) were studied. Some of tested compounds were found to exhibit much higher inhibitory effects towards the three tumor cell lines than the reference drug, doxorubicin.

Cocoa polyphenols prevent inflammation in the colon of azoxymethane-treated rats and in TNF-α-stimulated Caco-2 cells

Numerous lines of evidence support a relationship between intestinal inflammation and cancer. Therefore, much attention has recently been focused on the identification of natural compounds with anti-inflammatory activities as a strategy to suppress the early stages of colorectal cancer. Because cocoa is a rich source of bioactive compounds, the present study investigated its anti-inflammatory properties in a rat model of azoxymethane (AOM)-induced colon carcinogenesis and in TNF-α-stimulated Caco-2 cells. A total of forty male rats were fed with control or cocoa-enriched diets (12 %) during 8 weeks and injected with saline or AOM (20 mg/kg body weight) during the third and fourth week (n10 rats/group). At the end of the experiment, colon samples were evaluated for markers of inflammation. The anti-inflammatory activity of a cocoa polyphenolic extract (10 μg/ml) was examined in TNF-α-stimulated Caco-2 cells, anin vitromodel of experimentally induced intestinal inflammation. The signalling pathways involved, including NF-κB and the mitogen-activated protein kinase family such as c-Jun NH2-terminal kinases (JNK), extracellular signal-regulated kinases and p38, were also evaluated. The results show that the cocoa-rich diet decreases the nuclear levels of NF-κB and the expression of pro-inflammatory enzymes such as cyclo-oxygenase-2 and inducible NO synthase induced by AOM in the colon. Additionally, the experiments in Caco-2 cells confirm that cocoa polyphenols effectively down-regulate the levels of inflammatory markers induced by TNF-α by inhibiting NF-κB translocation and JNK phosphorylation. We conclude that cocoa polyphenols suppress inflammation-related colon carcinogenesis and could be promising in the dietary prevention of intestinal inflammation and related cancer development.

Biology and therapeutic potential of hydrogen sulfide and hydrogen sulfide-releasing chimeras

Hydrogen sulfide, H2S, is a colorless gas with a strong odor that until recently was only considered to be a toxic environmental pollutant with little or no physiological significance. However, the past few years have demonstrated its role in many biological systems and it is becoming increasingly clear that H2S is likely to join nitric oxide (NO) and carbon monoxide (CO) as a major player in mammalian biology. In this review, we have provided an overview of the chemistry and biology of H2S and have summarized the chemistry and biological activity of some natural and synthetic H2S-donating compounds. The naturally occurring compounds discussed include, garlic, sulforaphane, erucin, and iberin. The synthetic H2S donors reviewed include, GYY4137; cysteine analogs; S-propyl cysteine, S-allyl cysteine, S-propargyl cysteine, and N-acetyl cysteine. Dithiolethione and its NSAID and other chimeras such as, L-DOPA, sildenafil, aspirin, diclofenac, naproxen, ibuprofen, indomethacin, and mesalamine have also been reviewed in detail. The newly reported NOSH-aspirin that releases both NO and H2S has also been discussed.

NOSH-Aspirin: A Novel Nitric Oxide-Hydrogen Sulfide-Releasing Hybrid: A New Class of Anti-inflammatory Pharmaceuticals

A series of new hybrids of aspirin (ASA), bearing both nitric oxide (NO) and hydrogen sulfide (H(2)S)-releasing moieties were synthesized and designated as NOSH compounds (1-4). NOSH-1 (4-(3-thioxo-3H-1,2-dithiol-5-yl) phenyl 2-((4-(nitrooxy)-butanoyl)oxy) benzoate); NOSH-2 (4-(nitrooxy)butyl (2-((4-(3-thioxo-3H-1,2-dithiol-5-yl)phenoxy)carbonyl)phenyl)); NOSH-3 (4-carbamothioylphenyl 2-((4-(nitrooxy)butanoyl)-oxy)benzoate); and NOSH-4 (4-(nitrooxy)butyl 2-(5-((R)-1,2-dithiolan-3-yl)pentanoyloxy)-benzoate). The cell growth inhibitory properties of compounds 1-4 were evaluated in eleven different human cancer cell lines of six different tissue origins. These cell lines are of adenomatous (colon, pancreatic, lung, prostate), epithelial (breast), and lymphocytic (leukemia) origin. All NOSH compounds were extremely effective in inhibiting the growth of these cell lines. NOSH-1 was the most potent, with an IC(50) of 48 ± 3 nM in HT-29 colon cancer cells. This is the first NSAID-based compound with such potency. This compound was also devoid of any cellular toxicity, as determined by LDH release. NOSH-1 was comparable to aspirin in its anti-inflammatory properties, using the carrageenan rat paw edema model.

NOSH-aspirin (NBS-1120), a novel nitric oxide- and hydrogen sulfide-releasing hybrid is a potent inhibitor of colon cancer cell growth in vitro and in a xenograft mouse model

Nonsteroidal anti-inflammatory drugs (NSAIDs) are prototypical anti-cancer agents. However, their long-term use is associated with adverse gastrointestinal effects. Recognition that endogenous gaseous mediators, nitric oxide (NO) and hydrogen sulfide (H(2)S) can increase mucosal defense mechanisms has led to the development of NO- and H(2)S-releasing NSAIDs with increased safety profiles. Here we report on a new hybrid, NOSH-aspirin, which is an NO- and H(2)S-releasing agent. NOSH-aspirin inhibited HT-29 colon cancer growth with IC(50)s of 45.5 ± 2.5, 19.7 ± 3.3, and 7.7 ± 2.2 nM at 24, 48, and 72 h, respectively. This is the first NSAID based agent with such high degree of potency. NOSH-aspirin inhibited cell proliferation, induced apoptosis, and caused G(0)/G(1) cell cycle block. Reconstitution and structure-activity studies representing a fairly close approximation to the intact molecule showed that NOSH-aspirin was 9000-fold more potent than the sum of its parts towards growth inhibition. NOSH-aspirin inhibited ovine COX-1 more than ovine COX-2. NOSH-ASA treatment of mice bearing a human colon cancer xenograft caused a reduction in volume of 85%. Taken together, these results demonstrate that NOSH-aspirin has strong anti-cancer potential and merits further evaluation.

Nitric Oxide-Releasing Hybrid Drugs Target Cellular Processes Through S-Nitrosylation

Nitric oxide (NO)-releasing agents such as JS-K and NO-releasing hybrids such as NO- and NONO-nonsteroidal anti-inflammatory drugs are novel agents with great potential for controlling cancer. Although studied extensively, a key question pertaining to their molecular targets and mechanism of action remains unclear: the role of NO in the overall biological effect of these agents. It has been shown that NO can directly modify sulfhydryl residues of proteins through S-nitrosylation and induce apoptosis. We showed that 3 structurally diverse NO-nonsteroidal anti-inflammatory drugs S-nitrosylated nuclear factor-κB p65 in vitro and in vivo and also showed that these agents S-nitrosylated caspase-3 in vivo. JS-K reduced nuclear β-catenin and cyclin D1 protein levels without affecting cytosolic β-catenin expression. On the basis of a time course study, S-nitrsolyation of nuclear β-catenin was determined to precede its degradation. These data provide a mechanistic role for NO and a rationale for the chemopreventive effects of these novel agents.

Hydrogen sulfide-releasing aspirin modulates xenobiotic metabolizing enzymes in vitro and in vivo

The balance between phase-I carcinogen-activating and phase-II detoxifying xenobiotic metabolizing enzymes is critical to determining an individual's risk for cancer. We evaluated the effect of Hydrogen sulfide-releasing aspirin (HS-ASA) on xenobiotic metabolizing enzymes in HT-29 human colon and Hepa 1c1c7 mouse liver adenocarcinoma cells and in Wistar rats. HS-ASA inhibited the growth of HT-29 and Hepa 1c1c7 cells, with an IC(50) of 3.2 ± 0.3 μM and 4.2 ± 0.4 μM, respectively. The IC(50) for ASA in both cell lines was greater than 5000 μM at 24h. In these cell lines, HS-ASA caused a dose-dependent increase in activity and expression of the phase-II enzymes glutathione S-transferase (GST) and NAD(P)H:quinoneoxireductase (NQO1). It also caused an increase in UDP-glucuronosyltransferase (UGT) expression. The levels of CYP 1A1 a phase-I enzyme was increased by HS-ASA in both cell lines. Pretreatment of cells with NaF, an esterase inhibitor, abrogated the HS-ASA-mediated increases in NQO1 enzyme activity. HS-ASA increased the protein levels of the transcription factor Nrf2, which is a regulator of the phase-II enzymes. In vivo, HS-ASA at 100mg/kg/day had no effect on rat's weights; it induced a 3.4-fold and 1.4-fold increase in hepatic GST and NQO1 enzyme activities, respectively. GST and NQO1 protein levels were also increased. In contrast to that in cultured cells, CYP 1A1 protein levels were not altered in vivo. Therefore, HS-ASA induces phase-II enzymes, at least in part, through the action of H(2)S and by modulating Nrf2; these effects may be part of its mechanism of action against carcinogenesis.

Synthesis and biological activity of acetyl-protected hydroxybenzyl diethyl phosphates (EHBP) as potential chemotherapeutic agents

Several acetyl-protected hydroxybenzyl diethyl phosphates (EHBPs) that are capable of forming quinone methide intermediates were synthesized and their cell growth inhibitory properties were evaluated in four different human cancer cell lines. Compounds 1, 1a, and 1b, corresponding to (4-acetyloxybenzyl diethylphosphate), (3-methyl-4-acetyloxybenzyl diethylphosphate), and (3-chloro-4-acetyloxybenzyl diethylphosphate), were significantly more potent than compounds 2 and 3, (2-acetyloxybenzyl diethylphosphate) and (3-acetyloxybenzyl diethylphosphate), respectively. Using HT-29 human colon cancer cells, compounds 1 and 3 increased apoptosis, inhibited proliferation, and caused a G(2)/M block in the cell cycle. Our data suggest that these compounds merit further investigation as potential anti-cancer agents.

Curcumin analogues as possible anti-proliferative & anti-inflammatory agents

A series of novel curcumin analogues has been designed, synthesized and tested in vitro/in vivo as potential multi-target agents. Their anti-proliferative and anti-inflammatory activities were studied. Compounds 1b and 2b were stronger inhibitors of soybean lipoxygenase (LOX) than curcumin. Analogue 1b was also the most potent aldose reductase (ALR2) inhibitor. Two compounds, (1a and 1f) exhibited in vivo anti-inflammatory activity comparable to that of indomethacin, whereas derivative 1i exhibited even higher activity. The derivatives were also tested for their anti-proliferative activity using three different human cancer cell lines. Compounds 1a, 1b, 1d and 2b exhibited significant growth inhibitory activity as compared to curcumin, against all three cancer cell lines. Lipophilicity was determined as R(M) values using RPTLC and theoretically. The results are discussed in terms of the structural characteristics of the compounds. Docking simulations were performed on LOX and ALR2 inhibitor 1b and curcumin. Compound 1b is well fitted in the active site of ALR2, binding to the ALR2 enzyme in a similar way to curcumin. Allosteric interactions may govern the LOX-inhibitor binding.