Piroxicam and C-phycocyanin mediated apoptosis in 1,2-dimethylhydrazine dihydrochloride induced colon carcinogenesis: exploring the mitochondrial pathway

Apoptosis is a synchronized procedure of cell death that is regulated by caspases and proapoptotic proteins. During apoptosis, translocation of cytochrome c, an electron carrier, from mitochondria into the cytosol is regulated by Bcl-2 family members. Cytochrome c in association with an apoptotic protease activating factor (Apaf), a proapoptotic protein essential for cell differentiation and procaspase-9 form the apoptosome complex, which consecutively activates effector caspase, caspase-3, and coordinate the implementation of apoptosis. In the current study, an attempt has been made to gain insight into piroxicam, a traditional nonsteroidal antiinflammatory drug and c-phycocyanin, a biliprotein from Spirulina platensis (cyanobacterium) mediated apoptosis in DMH-induced colon cancer. Male Sprague-Dawley rats were segregated into 5 groups: control, DMH, DMH + piroxicam, DMH + c-phycocyanin, and DMH + piroxicam + c-phycocyanin. Results illustrated that piroxicam and c-phycocyanin treatments stimulate cytochrome c release by downregulating the Bcl-2 (an antiapoptotic protein) expression significantly, while promoting the level of Bax (a proapoptotic protein), thereby activating caspases (caspases-9 and -3) and Apaf-1. The outcomes of the present study clearly signify that piroxicam and c-phycocyanin may mediate mitochondrial-dependent apoptosis in DMH-induced colon cancer. Moreover, apoptosis induction was more apparent in the combination regimen of piroxicam and c-phycocyanin than the individual drugs alone.

Role of Sulindac and Celecoxib in the regulation of angiogenesis during the early neoplasm of colon: exploring PI3-K/PTEN/Akt pathway to the canonical Wnt/β-catenin signaling

Angiogenesis refers to the generation of new blood vasculature from the nearby pre-existing one and is regulated by a balance between the pro- and anti-angiogenic factors. During carcinogenesis, pro-angiogenic factors dominate and initialize the growth of new blood capillaries to provide nutrition, growth factors and overcome hypoxia inside the tumor microenvironment. In the present study, we have observed the role of Phosphatidylinositol-3-kinase (PI3-K)/Phophatase and tensin homolog deleted on chromosome ten (PTEN)/Akt (Protein kinase B) pathway and canonical Wnt/β-catenin downstream signaling in the regulation of various pro-angiogenic molecules including the vascular endocrine growth factor-A (VEGF-A), matix metalloproteinases (MMPs), inducible nitric oxide synthase (iNOS) and chemokines for the progression of experimental colorectal cancer with 1,2-dimethylhydrazine dihydrochloride (DMH) and anti-angiogenic effects of two non-steroidal anti-inflammatory drugs (NSAIDs) viz. Sulindac and Celecoxib. Morphological and histopathological studies were performed to analyze the tumorigenic modifications while flow cytometry for the relative quantification of apoptotic events. Transcriptional and translational modifications of biomolecules were analyzed via Reverse Transcriptase-and quantitative Real Time PCR, Western immoblotting and immunoflurescence, respectively. In vitro phosphorylation, gelatin zymography and nitric oxide (NO) assay were performed to observe the activation states of Akt, MMPs and iNOS enzyme, respectively. Dysregultion in Akt activation, and thereby, aberrant signaling of β-catenin along with the production of NO could positively regulate tumor angiogenesis. NSAIDs can overcome these carcinogenic effects by controlling various key check points including higher PTEN and glycogen synthase kinase-3β (GSK-3β) expression and repressing Akt, MMPs and iNOS activation while inducing apoptosis among the cancer cells.

Effect of cationic ionophore monensin on the lipid composition and fluidity of rat epididymal spermatozoal membrane

The present study was aimed at exploring the effect of monensin, an antibiotic carboxylic polyether ionophore specific for Na(+), on the structural, chemical, and physiological changes of the epididymal sperm of Wistar rats. Animals received monensin at the dose of 3.5 mg/kg body weight daily orally for 70 days, a treatment duration that corresponds to the spermatogenic cycle in rats. At the end of the treatment regime, three regions of the epididymis were separated and the spermatozoa were collected. The plasma membranes of the spermatozoa were isolated and lipid composition, such total lipid, phospholipid, cholesterol, and ganglioside-sialic acid, was studied. Membrane dynamic behavior was investigated by lipid translational fluidity by pyrene excimer formation and rotational diffusion by diphenyl hexatriene polarization and anisotropy parameter. Structural changes in membrane were also evaluated by the dye-binding study with anilino naphthalene sulphonic acid. The results showed marked changes in lipid compositions, fluidity parameters, and kinetics of fluorescent dye binding in the epididymis, and it can be concluded that monensin, by interfering with normal physiological changes in spermatozoal maturation, may provide the basis of certain molecular intervention in the fertilizing capability of the epididymal spermatozoa and thereby may induce antifertility properties in male rats.

Effect of exogenous surfactant on phosphatidylinositol 3-kinase-Akt pathway and peroxisome proliferator activated receptor-γ during endotoxin induced acute respiratory distress syndrome

Lipopolysaccharide induced acute respiratory distress syndrome (ARDS) leads to an unacceptably high mortality. In this regard, the anti-inflammatory properties of surfactant may provide a therapeutic option. Phosphoinositide 3-kinase (PI3-K) and the downstream serine/threonine kinase Akt/protein kinase B have a central role in modulating neutrophil function, including respiratory burst, chemotaxis, and apoptosis. This study explores the mechanisms of surfactant dependent protection by regulating PPAR-γ in a rat model of ARDS. Sprague-Dawley male rats were divided into four groups: buffer controls; rats challenged with LPS (055:B5 E. coli); challenged with LPS and treated with porcine surfactant; and challenged with LPS and treated with synthetic surfactant. Expression of PI3-K, Akt, GSK3-β, and PPAR-γ were studied by western immunoblot, immunofluorescence and by immunohistochemistry. In vivo endotoxin administration to rat resulted in activation of PI3-K and Akt in the lungs. The severity of endotoxemia-induced ALI was significantly diminished in rat with surfactant administration. Similar results were also seen in PPAR-γ expression. These results show that PI3-K occupies a central position in regulating endotoxin-induced ALI involving inflammatory responses. Surfactant treatment conferred protection in rat model dependent on PPAR-γ and inhibition of PI3-K/Akt pathway.

Exogenous surfactant protects against endotoxin induced acute respiratory distress syndrome in rodents via vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor which is abundantly expressed in the normal lung and is released by numerous cell types. Using a bacteria-induced lung injury model and surfactant therapy in rats, VEGF expression in lung was investigated. Sprague Dawley male rats were divided into four groups: buffer controls; rats challenged with LPS (055:B5 E. coli); challenged with LPS and treated with porcine surfactant (P-SF); and challenged with LPS and treated with synthetic surfactant (S-SF). The expressions of VEGF, PCNA, and BrdU were studied. VEGF protein expression was decreased in comparison to the control rats, as seen by both Western immunoblot and immunohistochemistry. Protein expression of PCNA and proliferation index as determined by both PCNA and BrdU immunostaining were also seen to be decreased in the LPS-treated animals, and with the surfactant treatment the expression was increased. The downregulation of VEGF in the alveolar space may reflect the recovery from acute lung injury, which leads to the limited endothelial permeability, and may participate in the decrease in capillary number, as observed during acute respiratory distress syndrome with potentially significant clinical consequences.

Non steroidal anti-inflammatory drugs modulate the physicochemical properties of plasma membrane in experimental colorectal cancer: a fluorescence spectroscopic study

According to "fluid-mosaic model," plasma membrane is a bilayer constituted by phospholipids which regulates the various cellular activities governed by many proteins and enzymes. Any chemical, biochemical, or physical factor has to interact with the bilayer in order to regulate the cellular metabolism where various physicochemical properties of membrane, i.e., polarization, fluidity, electrostatic potential, and phase state may get affected. In this study, we have observed the in vivo effects of a pro-carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) and the two non steroidal anti-inflammatory drugs (NSAIDs); sulindac and celecoxib on various properties of the plasma membrane of colonocytes, i.e., electric potential, fluidity, anisotropy, microviscosity, lateral diffusion, and phase state in the experimentally induced colorectal cancer. A number of fluorescence probes were utilized like membrane fluidity and anisotropy by 1,6-diphenyl-1,3,5-hexatriene, membrane microviscosity by Pyrene, membrane electric potential by merocyanine 540, lateral diffusion by N-NBD-PE, and phase state by Laurdan. It is observed that membrane phospholipids are less densely packed and therefore, the membrane is more fluid in case of carcinogenesis produced by DMH than control. But NSAIDs are effective in reverting back the membrane toward normal state when co-administered with DMH. The membrane becomes less fluid, composed of low electric potential phospholipids whose lateral diffusion is being prohibited and the membrane stays mostly in relative gel phase. It may be stated that sulindac and celecoxib, the two NSAIDs may exert their anti-neoplastic role in colorectal cancer via modifying the physicochemical properties of the membranes.

Chemopreventive action of diclofenac in dimethybenzanthracene induced lung cancer in female Wistar rat

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to be effective antineoplastic agents that block prostaglandin formation by inhibiting the enzyme cyclooxygenase (COX), which exists in two isoforms, COX-1 and COX-2. COX-2 is over expressed in lung cancer. The present study evaluates the chemopreventive efficiency of diclofenac, which is a preferentially selective COX-2 inhibitor in lung cancer. Female Wistar rats were divided into 4 groups. Group 1 served as control and received saline intratracheally, once. In group 2 lung cancer was induced by a single intratracheal instillation of dimethybenz(a)anthracene (DMBA) (20 mg/kg body weight). Group 3 was given the intervention of diclofenac (8 mg/kg body weight) daily by oral gavage, in addition to DMBA. Group 4 received diclofenac alone. After 18 weeks of treatment, animals were sacrificed and various studies done. COX-2 expression as seen by western immunoblot and immunohistochemistry (IHC) was increased in the DMBA group, while diclofenac intervention was able to bring down the levels of the enzyme. Apoptosis studies by DNA fragmentation, TUNEL and fluorescent dyes reveal the lowered number of apoptotic cells in group 2. The levels were restored by diclofenac treatment in group 3. There was also a significant reduction in tumor incidence in DMBA+Diclofenac treated animals. All these results indicate that diclofenac acts as an effective chemopreventive agent that mediates its effects by the induction of apoptosis in cancer tissue and suppression of COX-2 enzyme.

Diclofenac, a selective COX-2 inhibitor, inhibits DMH-induced colon tumorigenesis through suppression of MCP-1, MIP-1α and VEGF

Angiogenesis is a physiological process involving growth of new blood vessels from pre-existing ones; however, it also plays a critical role in tumor progression. It favors the transition from hyperplasia to neoplasia, that is, from a state of cellular multiplication to uncontrolled proliferation. Therefore targeting angiogenesis will be profitable as a mechanism to inhibit tumor's lifeline. Further, it is important to understand the cross-communication between vascular endothelial growth factor (VEGF)-master switch in angiogenesis and other molecules in the neoplastic and pro-inflammatory milieu. We studied the role of two important chemokines [monocyte chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-lα] alongwith VEGF and matrix metalloproteinases (MMPs) in non-steroidal anti-inflammatory drugs (NSAIDs)-induced chemopreventive effect in experimental colon cancer in rat. 1,2-Dimethylhydrazine (DMH, 30 mg/kg body weight, subcutaneously (s.c.) once-a-week) for 18 wk was used as pro-carcinogen and diclofenac (8 mg/kg body weight, orally daily) as the preferential cyclooxygenase-2 (COX-2) inhibitor. Expression of COX-2 and VEGF was found to be significantly elevated in the DMH-treated group as compared to the control, which was lowered notably by Diclofenac co-administration with DMH. Gelatin zymography showed prominent MMP-9 activity in the DMH-treated rats, while the activity was nearly absent in all the other groups. Expression of MCP-1 was found to be markedly increased whereas MIP-1α expression was found to be decreased in colonic mucosa from DMH-treated rats, which was reversed in the DMH + Diclofenac group. Our results indicate potential role of chemokines alongwith VEGF in angiogenesis in DMH-induced cancer and its chemoprevention with diclofenac.

PI3-kinase/Wnt association mediates COX-2/PGE(2) pathway to inhibit apoptosis in early stages of colon carcinogenesis: chemoprevention by diclofenac

In addition to having anti-inflammatory properties, non-steroidal anti-inflammatory drugs (NSAIDs) inhibit neoplastic cell proliferation by inducing apoptosis. Inhibition of cyclooxygenase-2 (COX-2) seemed to be the principal target of NSAIDs, as it is overexpressed in several cancers and catalyzes the synthesis of prostaglandin E₂ (PGE₂), the critical pro-inflammatory molecule. A major role for phosphatidylinositol-3 kinase (PI3-kinase) pathway activation in human tumors has been more recently established. The present study explored the role of PI3-kinase and Wnt molecular pathways in COX-2 and PGE₂ production as well as NSAIDs' chemopreventive effect in colon cancer. 1,2-dimethylhydrazine (DMH) was used for experimental colon cancer model in rat and diclofenac as the preferential COX-2 selective chemopreventive agent. Expression of caspase-3 and caspase-9 was checked in the colonic tissue by immunofluorescence. A decrease was seen in their expressions, indicative of inhibition of apoptosis in the present model. COX-2 mRNA expression as well as PGE₂ levels was elevated after DMH treatment; however, COX-1 mRNA expression was unaltered as seen by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. DMH also activated PI3-kinase, Akt, Wnt, and β-catenin expressions but reduced the glycogen synthase kinase-3β (GSK-3β) levels. Co-administration of diclofenac with DMH increased the mRNA expression of GSK-3β while inactivating PI3-kinase, Akt, Wnt, and β-catenin. The study suggests that activation of PI3-kinase and Wnt signaling is associated with COX-2/PGE₂ production and in turn inhibition of apoptosis in colon cancer, while diclofenac targeted these pathways to restore apoptosis in the present system.

Induction of apoptosis as a potential chemopreventive effect of dual cycloxygenase inhibitor, diclofenac, in early colon carcinogenesis

We evaluated the role of diclofenac, a dual cycloxygenase inhibitor, in chemoprevention of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rat model. In a six-week long treatment with DMH (initiation stage), colonic mucosa showed a rich presence of preneoplastic lesions, such as multiple plaque lesions (MPL), aberrant crypt foci (ACF), and histologically well-characterized dysplasia. Control animals were free from these features while simultaneous treatment of DMH and diclofenac resulted in a significant reduction of these. The Diclofenac-only group did not show any prominent carcinogenic feature. The colonic tissue showed increased COX-2 expression in the DMH group, immunohistochemically and by western blotting. Apoptosis was quantified in isolated colonocytes by fluorescent staining and by TUNEL assay in tissue sections. The number of apoptotic cells was few in the DMH group, while it was featured prominently in all the other groups. The dose of the diclofenac used in the present study was established at an anti-inflammatory dose by the carrageenan-induced rodent paw oedema test. Because ACF can be accepted as reliable prognostic biomarkers in colon carcinogenesis, its inhibition and also the induction of the apoptosis process may favorably indicate the preclinical promise for chemoprevention of colon cancer as demonstrated in the initiation phase of carcinogenesis.

Immunomodulatory properties of exogenous surfactant in adult rat alveolar macrophages

BACKGROUND AND AIM

The study investigates the immune response of the lung alveolar macrophages in adult rats with intratracheal instillation of surfactant, isolated from porcine, rabbit and rat lung as well as the synthetic surfactant.

MATERIAL AND METHODS

Adult male rats were divided into five groups: Controls were instilled with buffer, similarly P-SF, R-SF, r-SF, and S-SF group of animals were instilled with porcine, rabbit, rat and synthetic surfactant, respectively.

RESULTS

After one month, IL-1beta secretions were found to be elevated in the supernatant of alveolar macrophages. Further, nitric oxide (NO) level was elevated with porcine and synthetic surfactant, while reactive oxygen species (ROS) generation was found to be inhibited significantly in all the treatment groups. Apoptoses were studied by using fluorescence dyes acridine orange/ethidium bromide, where percent of the apoptotic cells were found to be decreased in all the treated groups.

CONCLUSIONS

Exogenous surfactant elevates secretion of pro-inflammatory cytokine IL-1beta and also the NO as signaling molecule. The inhibitory effects of surfactants on ROS generation and on apoptosis may result from the interruption in the cell signaling pathway. In the treatment of respiratory distress syndrome, the anti-inflammatory response of surfactant may thus depend upon the specific preparation of the surfactant.

Alterations in membrane fluidity and dynamics in experimental colon cancer and its chemoprevention by diclofenac

We examined the role of membrane fluidity and dynamics as important early events in the carcinogenic transformation of colonic epithelial cells. 1,2-Dimethylhydrazine dihydrochloride (DMH) was used to induce initial stages of colon cancer and diclofenac was used for chemoprevention. To determine alterations of membrane fluidity of rat colonic epithelial cells, fluidity (inverse of fluorescence polarization) and order parameter were studied with 1,6-diphenylhexatriene (DPH) polarization. Order parameter as well as fluorescence polarization was found to be significantly decreased, thus demonstrating an increase in the fluidity of the membrane. To further confirm the fluidity changes, microviscosity of the cell membrane was studied using pyrene excimer formation, which showed a significant decrease in microviscosity and hence elevated membrane fluidity (translational diffusion). The colonocytes were stained with merocyanine 540 (MC540) to further elaborate the changes in membrane fluidity and lipid packing. The increased number of colonocytes showing high MC540 fluorescence pointed towards the wide spaces and hence, high fluidity in the membrane after DMH treatment. Membrane dynamics studies, i.e., lipid phase separation and membrane phase state were carried out using N-NBD-PE and Laurdan, respectively. We saw a transition from the gel to a more liquid crystalline state of the membrane in the Laurdan experiment. Further more percentage quenching (%Q) value of N-NBD-PE showed less phase separation (or domain formation). Diclofenac co-administration with DMH was successful in reverting the changes observed, confirming the role of these anti-inflammatory drugs in considerable lipid affinity and consequently in the chemoprevention of early stages of colon cancer.

Effect of etoricoxib, a cyclooxygenase-2 selective inhibitor on aberrant crypt formation and apoptosis in 1,2 dimethyl hydrazine induced colon carcinogenesis in rat model

Etoricoxib, a second generation selective cyclooxygenase-2 (COX-2) inhibitor had been studied for the chemopreventive response at its therapeutic anti-inflammatory dose in 1,2-dimethylhydrazine (DMH) induced colon carcinogenesis in rat model. Eight to ten weeks old male rats of Sprague-Dawley strain were divided into four groups. While group 1 served as control and received the vehicle of the drugs, group 2 and 3 were administered freshly prepared DMH in 1mM EDTA-saline (pH 7.0) (30 mg/kg body wt/week, subcutaneously). Group 3 was also given a daily treatment of etoricoxib (0.6 mg/kg body wt orally) while the group 4 received the same amount of etoricoxib only, prepared in 0.5% carboxymethyl cellulose. Animals were sacrificed at the end of 6 weeks, body weight recorded and the colons were subjected to macroscopic and histopathological studies. The maximum number of raised mucosal lesions called the multiple plaque lesions (MPL) were found in the DMH group which significantly reverted back in the DMH + etoricoxib group, while very few MPLs were recorded in the control and etoricoxib only group. Similarly, the number of aberrant crypt foci (ACF), the point of future carcinogenic growth, was recorded more in the DMH group and significantly less in the DMH + etoricoxib group. The histopathological analysis showed the presence of severe hyperplasia, occasional dysplasia and aggregates of lymphoid cells in the localized regions. Etoricoxib group showed near normal histological features with the crypt architecture and the surrounding stromal tissue remaining intact. To ascertain the molecular mechanism of such anti-carcinogenic features the colonocytes were isolated and studied in primary culture for the evidence of apoptosis by fluorescent staining and genotoxic changes by single cell gel electrophoresis assay (comet assay) which shows that the DMH treated animals produced much less apoptotic nuclei but more comet producing cell, while these features were reverted back with the etoricoxib treatment. The cytoplasmic expression of COX-2 protein was studied in paraffin sections of the colon by immunohistochemistry with COX-2 specific antibody which showed a very high presence of this inducible enzyme with the DMH group while in all other groups of animals it was not visible or weekly expressed. The anti-inflammatory effect of the drug, etoricoxib was also validated by a carrageenan-induced inflammation in rat model which showed an extremely high anti-inflammatory response within the dose range used in the present study. Also the growth profile of all the animals remained the same throughout the six week period of the investigation as there was no change in the body weight. It appears that apoptosis remains the dominant anti-proliferative end effect of this drug, mediated by an inhibition of the proinflammatory COX-2 isoform although further molecular probings are needed to arrive at a conclusive agreement in favor of the chemoprotective use of such drugs in colon cancers.

Chemopreventive effect of nonsteroidal anti-inflammatory drugs on 9,10-dimethylbenz[a]anthracene-induced lung carcinogenesis in mice

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, celecoxib, and etoricoxib were studied as chemopreventive agents in lung cancer in mice induced by 9,10-dimethylbenz[a]anthracene (DMBA). The animals were subjected to a single intratracheal instillation of DMBA by surgical intervention, while they were treated with oral NSAIDs daily at their following anti-inflammatory dose: aspirin 25 mg/kg, celicoxib 6 mg/kg, and etoricoxib 0.6 mg/kg body weight, respectively. The animals were sacrificed after 18 weeks of treatment. Results showed a significant incidence of pulmonary tumors, dysplastic changes in histopathology, and signs of inflammatory occurrence in the DMBA-treated animals, which were grossly reversed by the NSAIDs. A greater number of macrophages, neutrophils, and lymphocytes were seen in the bronchoalveolar lavage (BAL) smear while the inflammatory cell counts decreased in DMBA + NSAIDs groups. A significant increase in the drug-metabolizing enzymes viz. cytochrome p450, cytochrome b5, and glutathione-S-transferase was noted in the DMBA group, which was reverted back in the NSAID-treated mice. Similarly, the subcelluler enzymes were elevated in DMBA, but significantly fell in the NSAID groups. DMBA also caused a higher level of lipid peroxidation as well as the different antioxidant enzyme activity, which were corrected by the NSAIDs. A marked elevation was noticed in the total lipid composition and its individual constituents in the DMBA group, which was reverted back appreciably by the NSAIDs. The results suggest that the DMBA-induced lung tumor development in balb/c mice could be a reliable model to test the chemopreventive potential of the NSAIDs.

The cyclooxygenase-2 inhibitor etoricoxib is a potent chemopreventive agent of colon carcinogenesis in the rat model

Cyclooxygenase-2 (COX-2), an inducible prostaglandin G/H synthase, is overexpressed in several human cancers, including colon cancer, and therefore the potential ability of a selective COX-2 inhibitor, etoricoxib, is considered in the prevention of the 1,2-dimethyl hydrazine (DMH)-induced colon carcinogenesis in the rat model. DMH was injected s.c. for 6 weeks, whereas etoricoxib was fed orally to the rats on a daily basis. The results showed that DMH produced a very high number of multiple plaque lesions (MPLs), putative neoplastic biomarkers, localized throughout the colon, whereas considerable regression was observed with etoricoxib treatment. In addition, the etoricoxib group was the only group that exhibited very few of these lesions. Histopathological analysis revealed extreme dysplasia, a few adenomas, and other carcinogenic changes in the DMH group, which are distinctly absent in the etoricoxib-treated group. COX-2 was also seen to be highly expressed following DMH treatment. The DMH treatment caused very few apoptotic cells, as determined by the TUNEL assay of the colonic mucosa in paraffin sections whose number greatly increased following etoricoxib treatment. Because all these changes were clearly reversed by etoricoxib in DMH-treated animals, and the use of etoricoxib alone did not produce a neoplastic effect per se, it appears that etoricoxib, a selective COX-2 inhibitor, might be a safe and potentially chemopreventive agent in colon cancer.

Effect of non-steroidal anti-inflammatory drug etoricoxib on the hematological parameters and enzymes of colon and kidney

The present study was designed to investigate the effects of a selective COX-2 inhibitor, etoricoxib in rats on the hematological and toxicity parameters in colon and kidney at two different doses of the drug, one within the therapeutic anti-inflammatory range as based on the reported ED50 value (Eto-1) while the other at ten times higher (Eto-2), relative to the toxicity studies which have not been reported so far. The results showed that the control and the drug treated animals achieved similar linear growth rate and also showed no major alterations in the histological parameters in the liver and kidney tissue. The animals treated with lower dose of etoricoxib showed an overall decrease in total leukocytes counts as well as in the number of neutrophils, lymphocytes, monocytes and eosinophills while the higher dose of the drug produced a highly significant increase in all the cell counts. However, the drug treatment at both the dose level produced significant fall in the activities of alkaline phosphatase, sucrase, lactase and maltase in the kidney but increased the activity of alkaline phosphatase in colon. The treatment of etoricoxib did not produce any change in the nitric oxide and citrulline levels in kidney while an increase was noted in the colonic tissue. It was concluded that etoricoxib is a relatively safe drug at its anti-inflammatory ED50 dose in rats when the hematological parameters and the structural and functional characteristics of kidney and colonic tissues were studied.

Pulmonary carcinogenesis in mice with a single intratracheal instillation of 9, 10-dimethyl benz[a]anthracene

A single intratracheal instillation of 9,10-dimethyl benz(a)anthracene (DMBA) at 3 different doses of 5, 10, and 20 mg/kg body weight to Balb/c mice for 12 weeks had caused a significant incidence of pulmonary tumors along with inflammatory changes. The number of macrophages in the broncho-alveolar lavage (BAL) fluid increased significantly, while the neutrophil and lymphocyte count as well as the protein content in the BAL fluid remained unchanged. A marked elevation in the lipid peroxidation product as well as the antioxidative enzymes were noted in the DMBA-treated group. The BAL fluid, which contains the surfactant membrane, was tested for rotational diffusion of the small hydrocarbon fluorophore, diphenyl hexatriene, and resulted in an enhanced fluorescence polarization and anisotropy value as well as the order parameter. DMBA treatment also altered the toxicity parameters, such as the lipid peroxidation, catalase, total protein, reduced glutathione, and alanine and amino transferase activities in the liver and kidney tissues. The results suggest that DMBA-induced lung tumor development in Balb/c mice could be an important model for the study of pathophysiology of BAL-fluid-associated surfactant and offers to test a variety of promising chemopreventive/chemotherapeutic agents.

Cyclooxygenase-2 inhibition by etoricoxib modulates plasma membrane fluidity in rat colon

The present study was designed to investigate the effects of a selective cycloogenase-2 (COX-2) inhibitor, etoricoxib, on the membrane-specific enzymes, lipid composition, and changes in fluidity parameters of rat colonic plasma membrane. Two doses of the drug were used, one within its therapeutic anti-inflammatory range as based on the ED50 value in rats (Eto-1), while the other at 10 times higher dose relating to the toxicity studies (Eto-2), which have not been reported so far. The activity of the membrane alkaline phosphatase was found to be increased after treatment with both the doses of etoricoxib as compared to the control. The total lipid and the cholesterol content showed a decrease while an increase in ganglioside sialic acid content was noted. Phospholipid content and the cholesterol-phospholipid molar ratio showed no change in either of the treatment groups. Fluorescence polarization studies with diphenylhexatriene showed that membrane fluidity was least altered in the isolated brush border membrane from colon or in the liposomes prepared from the membrane lipid extracts. Also, the translational diffusion studied with pyrene showed that the fluidity parameter was decreased as measured by the excimer formation. It is concluded that etoricoxib, a new generation COX-2 inhibitor (called the coxibs), appeared to be a safe nonsteroidal anti-inflammatory drug (NSAID) in the colonic membranes.

Chemoprevention of 1,2-dimethylhydrazine-induced colon carcinogenesis by a non-steroidal anti-inflammatory drug, etoricoxib, in rats: inhibition of nuclear factor kappaB

Etoricoxib, a highly selective cyclooxygenase- 2 (COX-2) inhibitor (a non steroidal anti-inflammatory drug) used for the treatment of rheumatoid arthritis and osteoarthritis, has been newly marketed and studied for the chemopreventive response in the 1,2-dimethylhydrazine dihydrochloride (DMH) induced rat colon cancer model. Male Sprague-Dawley rats were divided into four groups. Group I served as the Control and received the vehicle treatment, while Groups 2 and 3 were administered freshly prepared DMH (30 mg/kg body weight, subcutaneously) in 1mM EDTA-saline (pH 7.0). Groups 3 and 4 received Etoricoxib (0.64 mg/kg body weight, orally) daily prepared in 0.5% carboxymethyl cellulose. After a 6 week treatment period, animals were sacrificed and the colons were subjected to macroscopic and histopathological studies. Well characterized pre-neoplastic features such as multiple plaque lesions (MPLs), aberrant crypts (ACs) and aberrant crypt foci (ACF) were found in the DMH group. The number was reduced in DMH + Etoricoxib group, while very few MPLs and ACFs were recorded in the Etoricoxib only group. Also, histologically well characterized dysplasia and hyperplasia were observed in DMH treated group. The simultaneous administration of DMH and Etoricoxib reduced these features. To study apoptosis, colonocytes were isolated by metal chelation from colonic sacs and studied by fluorescent staining. The DMH treated animals produced much less apoptotic nuclei as compared to the Control. The number of apoptotic nuclei was also found higher in the DMH + Etoricoxib group as well as in Etoricoxib only group. Studies of a nuclear transcription factor (NF-kB) and COX-2 by Western blot analysis and immunohistochemistry demonstrated expression of both to be elevated in the DMH treated group but reduced in the DMH + Etoricoxib group. Expression was also low in the Etoricoxib only group. It may be concluded that the drug, Etoricoxib, has the potential to reduce DMH induced colon cancer development.