COX-2 inhibition demonstrates potent anti-proliferative effects on bladder cancer in vitro

Natural-Derived COX-2 Inhibitors as Anticancer Drugs: A Review of their Structural Diversity and Mechanism of Action

Cyclooxygenase-2 (COX-2) is a key-type enzyme playing a crucial role in cancer development, making it a target of high interest for drug designers. In the last two decades, numerous selective COX-2 inhibitors have been approved for various clinical conditions. However, data from clinical trials propose that the prolonged use of COX-2 inhibitors is associated with life-threatening cardiovascular side effects. The data indicate that a slight structural modification can help develop COX-2 selective inhibitors with comparative efficacy and limited side effects. In this regard, secondary metabolites from natural sources offer great hope for developing novel COX-2 inhibitors with potential anticancer activity. In recent years, various nature-derived organic scaffolds are being explored as leads for developing new COX-2 inhibitors. The current review attempts to highlight the COX-2 inhibition activity of some naturally occurring secondary metabolites, concerning their capacity to inhibit COX-1 and COX-2 enzymes and inhibit cancer development, aiming to establish a structure-activity relationship.

Natural products as a means of overcoming cisplatin chemoresistance in bladder cancer

Cisplatin remains an integral part of the treatment for muscle invasive bladder cancer. A large number of patients do not respond to cisplatin-based chemotherapy and efficacious salvage regimens are limited. Immunotherapy has offered a second line of treatment; however, only approximately 20% of patients respond, and molecular subtyping of tumors indicates there may be significant overlap in those patients that respond to cisplatin and those patients that respond to immunotherapy. As such, restoring sensitivity to cisplatin remains a major hurdle to improving patient care. One potential source of compounds for enhancing cisplatin is naturally derived bioactive products such as phytochemicals, flavonoids and others. These compounds can activate a diverse array of different pathways, many of which can directly promote or inhibit cisplatin sensitivity. The purpose of this review is to understand current drug development in the area of natural products and to assess how these compounds may enhance cisplatin treatment in bladder cancer patients.

LncRNA MAFG-AS1 Promotes the Progression of Bladder Cancer by Targeting the miR-143-3p/COX-2 Axis

<b><i>Background:</i></b> Long noncoding RNAs (lncRNAs) are potential biomarkers that are very important for the development of cancer. Studies show that lncRNAs are significantly correlated with the carcinogenesis and progression of bladder cancer (BLCA). In this research, we aimed at probing into the role of lncRNA MAFG-AS1 in the tumorigenesis of BLCA. <b><i>Methods:</i></b> RT-qPCR was employed to detect MAFG-AS1 expression in BLCA tissues and cells. MAFG-AS1 siRNA and overexpression plasmid were transfected into 5637 and T24 BLCA cell lines to inhibit or upregulate MAFG-AS1 expression, respectively, and then the regulatory functions of MAFG-AS1 on BLCA cell proliferation, migration, and invasion were assessed using cell counting kit-8 (CCK-8) assay, EdU method, and Transwell experiments, respectively. Dual-luciferase reporter assay and RNA immunoprecipitation were conducted to validate the targeting relationships between MAFG-AS1 and miR-143-3p, and miR-143-3p and COX-2. In addition, miR-143-3p was repressed in MAFG-AS1-silenced 5637 and T24 cell lines, and the function of MAFG-AS1/miR-143-3p axis in BLCA cells was further evaluated. The regulatory effects of MAFG-AS1 and miR-143-3p on the expression of COX-2 protein were detected by Western blot. <b><i>Results:</i></b> MAFG-AS1 was remarkably upregulated in BLCA patient tissues and cell lines, and its high expression was closely related to histological grade, tumor size, and lymph node metastasis. Silencing of MAFG-AS1 inhibited BLCA cell proliferation, metastasis, and invasion, while overexpression of MAFG-AS1 in BLCA cells had opposite biological effects. MAFG-AS1 was proved to target miR-143-3p to repress its expression. Moreover, it was confirmed that MAFG-AS1 and miR-143-3p could modulate COX-2 expression. <b><i>Conclusion:</i></b> The MAFG-AS1/miR-143-3p/COX-2 axis contributes to BLCA progression.

Carboranyl Derivatives of Rofecoxib with Cytostatic Activity against Human Melanoma and Colon Cancer Cells

Owing to the involvement of cyclooxygenase-2 (COX-2) in carcinogenesis, COX-2-selective inhibitors are increasingly studied for their potential cytotoxic properties. Moreover, the incorporation of carboranes in structures of established anti-inflammatory drugs can improve the potency and metabolic stability of the inhibitors. Herein, we report the synthesis of carborane-containing derivatives of rofecoxib that display remarkable cytotoxic or cytostatic activity in the micromolar range with excellent selectivity for melanoma and colon cancer cell lines over normal cells. Furthermore, it was shown that the carborane-modified derivatives of rofecoxib showed different modes of action that were dependent on the cell type.

Association of Cyclooxygenase-2 Immunoreactivity with Tumor Recurrence and Disease Progression in Superficial Urothelial Bladder Cancer

Aims and Background

The main characteristic of urothelial bladder cancer is a clear predisposition to recurrence and disease progression. The aim of this study was to assess the possible relationship between cyclooxygenase-2 (COX-2) immunoreactivity in superficial urothelial bladder carcinoma and tumor grade, stage, number of recurrences and clinical disease progression.

Methods

In this prospective study 70 consecutive patients who underwent transurethral resection for superficial urothelial bladder cancer were included. Tumor slides were immuno-histochemically stained for COX-2, and COX-2 immunoreactivity in tumor and inflammatory stromal cells was categorized as negative or mildly, moderately or strongly positive. Patients were followed up for 2 years, and during this period the possible association of COX-2 immunoreactivity with tumor stage and grade, number of recurrences and progression of disease was evaluated.

Results

COX-2 immunoreactivity in tumor cells was found in 57 (81.4%) patients and did not correlate with tumor grade, stage of disease, number of recurrences, and progression of disease. COX-2 immunoreactivity in inflammatory cells was found in 16 of the 57 patients with COX-2 positive tumors, and was significantly related to the number of recurrences, time to appearance of the first recurrence, and disease progression.

Conclusions

COX-2 immunoreactivity in inflammatory stromal cells adjacent to the COX-2-positive tumor might be useful in clinical practice for selection of patients with a high risk of tumor recurrence and disease progression.

Cox-2 inhibitors in mandibular third molar surgery

Pain control during and after any surgical procedure, is extremely essential for the comfort of patients. Pain killers used routinely act by inhibiting cyclooxygenase to control pain and inflammation. Cox-1 is constitutively expressed in most cell types, including platelets, whereas Cox-2 is absent from most healthy tissues but is induced by pro-inflammatory or proliferative stimuli. Cox-1 plays a role in the production of prostaglandins involved in protection of the gastric mucosal layer and thromboxanes (TX) in platelets. Cox-2 generally mediates elevations of prostaglandins associated with inflammation, pain, and pyresis. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen are generally nonselective inhibitors of Coxs. This lack of selectivity has been linked to their propensity to cause gastrointestinal side effects. The new Cox-2 selective inhibitors, or coxibs, show the same anti-inflammatory, analgesic, and antipyretic effects as nonselective NSAIDs but are supposed to have reduced side-effect profiles. This study evaluates whether rofecoxib (50 mg) given one hour pre-operatively or the same drug given one hour post-operatively is more effective in controlling the pain and swelling in mandibular third molar surgery.

Clinopodium vulgare L. (wild basil) extract and its active constituents modulate cyclooxygenase-2 expression in neutrophils

Clinopodium vulgare L. (wild basil) has a wide range of ethnopharmacological applications and accumulates a broad spectrum of phenolic compounds, recognized for their anti-inflammatory and anticancer properties. The triggered cyclooxygenase-2 (COX-2) expression is creating an immunosuppressive microenvironment in the inflamed tissue and considered to be the main cause of failure of even new anticancer-/immune-therapies. Nowadays, selective and novel plant-derived COX-2 inhibitors with safe profile are subject of profound research interest. This study aimed to analyze the metabolic profile of C. vulgare and search for phenolic molecules with potential biological properties. By application of ¹H and 2D-NMR (Nuclear Magnetic Resonance) profiling, caffeic, chlorogenic acids and catechin were identified along with a bunch of primary and secondary metabolites. Further, the biological effect of C. vulgare extract (CVE) and its constituents on zymosan-induced COX-2 expression and apoptosis of murine neutrophils have been studied. The CVE, caffeic and chlorogenic acids inhibited zymosan-induced COX-2 expression in bone marrow neutrophils, in vitro and in vivo activated. The obtained data indicate that CVE may have a good potential to manipulate neutrophil functions, however, its action may depend on the cellular state, the inflammatory milieu and the relative content of caffeic and chlorogenic acid in the extract.

Chemotherapeutic potential of quercetin on human bladder cancer cells

In an effort to improve local bladder cancer control, we investigated the cytotoxic and genotoxic effects of quercetin on human bladder cancer T24 cells. The cytotoxic effect of quercetin against T24 cells was examined by MTT test, clonogenic assay as well as DNA damaging effect by comet assay. In addition, the cytotoxic effect of quercetin on the primary culture of papillary urothelial carcinoma (PUC), histopathological stage T1 of low- or high-grade tumours, was investigated. Our analysis demonstrated a high correlation between reduced number of colony and cell viability and an increase in DNA damage of T24 cells incubated with quercetin at doses of 1 and 50 µM during short term incubation (2 h). At all exposure times (24, 48 and 72 h), the efficacy of quercetin, administered at a 10× higher dose compared to T24 cells, was statistically significant (P < 0.05) for the primary culture of PUC. In conclusion, our study suggests that quercetin could inhibit cell proliferation and colony formation of human bladder cancer cells by inducing DNA damage and that quercetin may be an effective chemopreventive and chemotherapeutic agent for papillary urothelial bladder cancer after transurethral resection.

Synergistic effects of exemestane and aspirin on MCF-7 human breast cancer cells

OBJECTIVE

The purpose of this study is to investigate the combined effects of exemestane and aspirin on MCF-7 human breast cancer cells.

METHODS

Antiproliferative effects of exemestane and aspirin, alone and in combination, on growth of MCF-7 human breast cancer cells were assessed using the MTT assay. Synergistic interaction between the two drugs was evaluated in vitro using the combination index (CI) method. The cell cycle distribution was analyzed by flow cytometry and Western blotting was used to investigate the expression of cyclooxygenase-1, cyclooxygenase-2 and Bcl-2.

RESULTS

MTT assays indicated that combination treatment obviously decreased the viability of MCF-7 human breast cancer cells compared to individual drug treatment (CI<1). In addition, the combination of exemestane and aspirin exhibited a synergistic inhibition of cell proliferation, significantly arrested the cell cycle in the G0/G1 phase and produced a stronger inhibitory effect on COX-1 and Bcl-2 expression than control or individual drug treatment.

CONCLUSION

These results indicate that the combination of exemestane and aspirin might become a useful method to the treatment of hormone- dependent breast cancer. The combination of the two inhibitors significantly increased the response as compared to single agent treatment, suggesting that combination treatment could become a highly effective approach for breast cancer.

Selective COX-2 inhibitor (celecoxib) decreases cellular growth in prostate cancer cell lines independent of p53

Celecoxib is a clinically available COX-2 inhibitor that has been reported to have antineoplastic activity. It has been proposed as a preventative agent for several types of early neoplastic lesions. Earlier studies have shown that sensitivity of prostatic carcinoma (PCa) to celecoxib is associated with apoptosis; however, these studies have not demonstrated adequately whether this effect is dependent on p53 status. We studied the relation between sensitivity to celecoxib and the phenotypic p53 status of PCa cells lines, LNCaP (wild type p53), PC3 (null p53) and DU145 (mutated p53). Cellular growth was assessed at 24, 48, 72 and 96 h after celecoxib treatment at concentrations of 0, 10, 30, 50, 70 and 100 μM using an MTT assay. Cellular proliferation (Ki-67 expression) was determined by immunocytochemistry. Phenotypic expression of p53 was analyzed by western blotting. The effects of celecoxib on cellular growth and its association with p53 were assessed after down-regulation of p53 using synthetic interfering RNAs (siRNA) in LNCaP cells. Expression of p53 and COX-2 at mRNA levels was assessed by quantitative real time polymerase reaction (qRT-PCR). We found that celecoxib inhibited cellular growth and proliferation in a dose-dependent manner in all three cell lines; LNCaP cells with a native p53 were the most sensitive to celecoxib. We observed a down- regulation effect on p53 in LNCaP cells exposed to ≥ 30 μM celecoxib for 72 h, but found no significant changes in the p53 levels of DU145 cells, which have a mutated p53. Reduced COX-2 expression was found with decreased p53 in LNCaP and PC-3 cells that were exposed to ≥ 20 μM of celecoxib for 72 h, but COX-2 expression was increased in DU145 cells. All three cell lines demonstrated pan-cytotoxicity when exposed to 100 μM celecoxib. When p53 expression was inhibited using siRNA in LNCaP cells, the inhibitory effects on cellular growth usually exerted by celecoxib were not changed significantly. Celecoxib reduces the growth of prostate cancer cell lines in part by decreasing proliferation, which suggests that the inhibition of growth of LNCaP cells by celecoxib is independent of normal levels of native p53.

Bioactivity and structure of biophenols as mediators of chronic diseases

Biophenols and their associated activity have generated intense interest. Current topics of debate are their bioavailability and bioactivity. It is generally assumed that their plasma concentrations are insufficient to produce the health benefits previously attributed to their consumption. However, data on localized in vivo concentrations are not available and many questions remain unanswered. Potential mechanisms by which they may exert significant bioactivity are discussed together with structure activity relationships. Biophenols are highly reactive species and they can react with a range of other compounds. Products of their reaction when functioning as antioxidants are examined.

Effects of Celecoxib and Nimesulide on the Proliferation of Ectopic Endometrial Stromal Cells in vitro

The effects of cyclooxygenase 2 (COX-2) selective inhibitors on the proliferation of ectopic endometrial stromal cells in vitro were investigated. Ectopic endometrial stromal cells were treated with either celecoxib or nimesulide for 24 and 48 h. The results showed that (i) both celecoxib and nimesulide inhibited the proliferation of ectopic endometrial stromal cells in vitro in a time- and dose-dependent manner; (ii) the expression of prostaglandin E2 was significantly inhibited by both celecoxib and nimesulide in a dose-dependent manner; (iii) the percentage of apoptotic cells was significantly higher for cells treated with celecoxib or nimesulide than for untreated cells; and (iv) the percentage of the cells in the G0/G1 phase increased after the cells were treated with either agent in a dose-dependent manner. These data suggest that celecoxib and nimesulide inhibited proliferation of ectopic endometrial stromal cells by inducing apoptosis and blocking the cell cycle at the G0/G1 phase.

Expression of Cyclooxygenase-2 in Normal Urothelium, and Superficial and Advanced Transitional Cell Carcinoma of Bladder

PURPOSE

We compared the differential expression of cyclooxygenase-2 in normal bladder tissue, primary bladder transitional cell carcinoma and transitional cell carcinoma metastases to lymph nodes, and determined whether cyclooxygenase-2 expression is associated with molecular alterations commonly found in bladder transitional cell carcinoma and clinical outcomes after radical cystectomy.

MATERIALS AND METHODS

Immunohistochemical staining for cyclooxygenase-2, survivin (Novus Biologicals, Littleton, Colorado), p21, p27, pRB, p53, MIB-1, Bax, Bcl-2, cyclin D(1) (Dakotrade mark), cyclin E (Oncogene, Cambridge, Massachusetts) and caspase-3 (Cell Signaling, Beverley, Massachusetts) was performed on archival bladder specimens from 9 subjects who underwent cystectomy for benign causes, 21 patients who underwent transurethral resection and 157 consecutive patients after radical cystectomy, and on 41 positive lymph nodes.

RESULTS

Cyclooxygenase-2 was expressed in none of the 9 normal bladder specimens (0%), 52% of transurethral resection specimens, 62% of cystectomy specimens and 80% of lymph nodes involved with transitional cell carcinoma. Cyclooxygenase-2 expression was associated with higher pathological stage, lymphovascular invasion and metastases to lymph nodes (p=0.001, 0.045 and 0.002, respectively). Cyclooxygenase-2 expression was associated with altered expression of p53 (p=0.039), pRB (p=0.025), cyclin D1 (p=0.034) and caspase-3 (p=0.014). On univariate analysis cyclooxygenase-2 expression was associated with an increased risk of disease recurrence and bladder cancer specific mortality (p=0.0189 and 0.0472, respectively). However, on multivariate analysis only pathological stage and metastases to lymph nodes were associated with disease recurrence (p<0.001 and <0.001) and survival (p<0.001 and 0.015, respectively).

CONCLUSIONS

Cyclooxygenase-2 is not expressed in normal bladder urothelium. Cyclooxygenase-2 over expression is associated with pathological and molecular features of biologically aggressive disease, suggesting a role for cyclooxygenase-2 in bladder cancer development and invasion.

Celecoxib Inhibits Cellular Growth, Decreases Ki-67 Expression and Modifies Apoptosis in Ovarian Cancer Cell Lines

BACKGROUND

There is controversy on the safety of inhibitors of cyclooxygenase administered at high doses; however, these drugs have been reported to be effective in the prevention of a variety of human cancers. To determine if celecoxib influences cellular growth, we evaluated several effects in ovarian carcinoma cell lines.

METHODS

CAOV3, OVCAR3 and SKOV3 cell lines were exposed to different concentrations of celecoxib (0-100 microM) for 24-96 h. Cellular growth was assessed using a cell viability assay. Immunohistochemistry was performed to evaluate Ki-67 and cleaved caspase-3. Apoptosis was determined by a TUNEL assay, and Western blot was used to determine COX-2 protein expression.

RESULTS

We observed a significant decrease in the cellular growth of all cell lines studied exposed to > or = 70 microM of celecoxib for 72 and 96 h (p < 0.02). All cells demonstrated pancytotoxicity at 100 microM of celecoxib. A significant decrease in Ki-67 expression in all cell lines exposed to > or = 30 microM of celecoxib (p < or = 0.05) for 72 h was observed. We observed significant changes in apoptosis and cleaved caspase-3 expression in SKOV3 cells exposed to 50 microM of celecoxib. Downregulation of COX-2 protein expression caused by celecoxib was observed in SKOV3 cells.

CONCLUSIONS

We found that celecoxib inhibits cellular growth and proliferation in a dose-dependent manner in all cell lines studied. SKOV3 cells showed an increase in cleaved caspase-3 expression. Additional studies are in progress to evaluate the effects of celecoxib on other aspects of the control of the cell cycle in cancer cells.

Inhibition of cyclooxygenase-2 decreases breast cancer cell motility, invasion and matrix metalloproteinase expression

BACKGROUND

Cyclooxygenase (COX) is the rate-limiting enzyme that catalyzes the formation of prostaglandins. The inducible isoform of COX (COX-2) is highly expressed in aggressive metastatic breast cancers and may play a critical role in cancer progression (i.e. growth and metastasis). However, the exact mechanism(s) for COX-2-enhanced metastasis has yet to be clearly defined. It is well established that one of the direct results of COX-2 action is increased prostaglandin production, especially prostaglandin E2 (PGE2). Here, we correlate the inhibition of COX-2 activity with decreased breast cancer cell proliferation, migration, invasion and matrix metalloproteinase (MMP) expression.

METHODS

Breast cancer cells (Hs578T, MDA-MB-231 and MCF-7) were treated with selective COX-2 inhibitors (NS-398 and Niflumic acid, NA). Cell proliferation was measured by staining with erythrosin B and counting the viable cells using a hemacytometer. Cell migration and invasion were measured using migration and invasion chamber systems. MMP expression was determined by enzyme immunoassay (secreted protein) and real-time quantitative polymerase chain reaction (mRNA).

RESULTS

Our results show that there is a decline in proliferation, migration and invasion by the Hs578T and MDA-MB-231 breast cancer cell lines in the presence of either low concentrations (1 microM or lower) NA or NS-398. We also report that MMP mRNA and protein expression by Hs578T cells is inhibited by NS-398; there was a 50% decrease by 100 muM NS-398. PGE2 completely reversed the inhibitory effect of NS-398 on MMP mRNA expression.

CONCLUSION

Our data suggests that COX-2-dependent activity is a necessary component for cellular and molecular mechanisms of breast cancer cell motility and invasion. COX-2 activity also modulates the expression of MMPs, which may be a part of the molecular mechanism by which COX-2 promotes cell invasion and migration. The studies suggest that COX-2 assists in determining and defining the metastatic signaling pathways that promote the breast cancer progression to metastasis.

Elevated prostaglandin E2 level via cPLA2--COX-2--mPGES-1 pathway involved in bladder carcinogenesis induced by terephthalic acid-calculi in Wistar rats

To investigate the prostaglandin E2 (PGE2) biosynthetic mechanism in bladder carcinogenesis, we established Wistar rat model of bladder papilloma and transitional cell carcinoma (TCC) induced by 5% terephthalic acid (TPA) treatment. Then, the mRNA level of cytosolic phospholipase A2 (cPLA2), cyclooxygenases (COX)-1 and -2, membrane-bound PGE2 synthases (mPGES)-1 and -2 was detected using reverse transcription polymerase chain reaction (RT-PCR). Immunoblotting was applied to detect the expression of COX-2 protein. Proliferating cell nuclear antigen (PCNA) was determined by immunohistochemistry. In addition, the level of PGE2 was measured by radioimmunoassay (RIA). Bladder papilloma (100%, 8/8) was examined in rats after 24-week treatment, and bladder TCC (80%, 16/20) was found after 48-week treatment. Histopathological changes were not found in control group rats. The incidence of bladder papilloma and TCC in test group was significantly higher than that in control group (P<0.01). The mRNA levels of cPLA2, COX-2 and mPGES-1 in the bladder papilloma and TCC were significantly higher than those in normal bladder (P<0.01), while the mRNA levels of COX-1 and mPGES-2 in TCC were unchanged compared with normal bladder. Bladder TCC exhibited a substantial expression of COX-2 protein. On the contrary, normal bladder tissue barely expresses COX-2 protein. PCNA labeling index (LI) and the level of PGE2 in bladder papilloma are much higher than those in normal bladder (P<0.01), but lower than those in bladder TCC (P<0.05). In conclusion, increasing PGE2 level via cPLA2--COX-2--mPGES-1 pathway may play an important role in rat bladder carcinogenesis. PGE2 may be a biomarker for the development of bladder TCC. cPLA2 and mPGES-1 may be targets for development of novel chemoprevention strategies for bladder TCC.

Expression of cyclooxygenase-2 in colorectal adenocarcinoma is associated with p53 accumulation and hdm2 overexpression

Elevated cyclooxygenase-2 (COX-2) expression has been observed in various types of cancer. Induction of COX-2 expression has been reported to increase invasiveness and angiogenesis of tumours. While COX-2 overexpression has been repeatedly proven to promote tumor growth, little is known about what initiates its induction. There has been evidence to suggest that COX-2 expression is normally suppressed by wild-type p53 but not mutant p53, suggesting that loss of p53 function may result in the induction of COX-2 expression. Loss of p53 function is not only caused by gene mutation, but also through the overexpression of its negative regulator, so called human double minute 2 (hdm2). The aim of this study was to examine the correlation between COX-2 overexpression, p53 accumulation and HDM2 overexpression, as indications of p53 anomalies, and their relationship to clinicopathologic features of colorectal adenocarcinoma. Tumor tissues and the adjacent normal mucosa were obtained from 73 colorectal cancer patients who underwent curative resection at Maharaj Nakorn Chiang Mai Hospital. Protein levels of COX-2, p53 and HDM2 were determined by Western blot analysis. No normal colorectal tissues possessed detectable levels of COX-2, p53 or HDM2. In contrast, 38.3% (28 cases), 54.8% (40 cases) and 8.2% (6 cases) of tumour tissues were found to express COX-2, p53 and HDM2, respectively. Interestingly, there was a significantly positive relationship between COX-2 overexpression and p53 accumulation and/or HDM2 overexpression (P=0.007). Higher COX-2 overexpression was observed in p53-accumulated or HDM2 overexpressed-tumours (22/43 cases, 51.1%) in comparison to tumours with no evidence of p53 and HDM2 alterations (6/30 cases, 20%). The results obtained from this study indicate that overexpression of COX-2 is frequently associated with p53 protein accumulation and HDM2 overexpression, therefore the COX-2 overexpression observed in colorectal cancer cells may be partly due to the dysfunction of p53. Although mutation of p53 has been previously reported to be associated with COX-2 induction, to our knowledge, this is the first study to show the relationship between HDM2 overexpression and COX-2 overexpression.

Chemopreventive effects of cyclooxygenase-2 inhibitor and epidermal growth factor-receptor kinase inhibitor on rat urinary bladder carcinogenesis

OBJECTIVE

To examine the chemopreventive effects of a selective cyclooxygenase (COX)-2 inhibitor, meloxicam, and a selective epidermal growth factor (EGF)-receptor tyrosine kinase inhibitor, gefitinib (as a single agent) on a carcinogen-induced rodent bladder carcinogenesis model.

MATERIALS AND METHODS

The study comprised 103 male Fisher-344 rats (8 weeks old); after initial carcinogen treatment for 8 weeks with 0.05%N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in drinking water, the rats were divided into five groups, i.e. group 1, control (vehicle only); group 2, gefitinib high-dose (15 mg/kg by gavage once daily); group 3, gefitinib low-dose (5 mg/kg); group 4, meloxicam high-dose (1.8 mg/kg by gavage once daily); and group 5, meloxicam low-dose (0.6 mg/kg). Twelve weeks later the rats were killed; after fixing the bladder in 10% formalin, the number and size of hyperplasia and carcinoma foci were recorded microscopically in sections stained with haematoxylin and eosin, submitted entirely as multiple strips.

RESULTS

The incidence of carcinoma, confirmed microscopically, was: control 14/20 (70%); high-dose gefitinib, 7/20 (35%); low-dose gefitinib, 7/20 (35%); high-dose meloxicam 7/21 (33%); and low-dose meloxicam, 12/20 (60%). The mean numbers of carcinomas per bladder in groups 1-5 were 1.2, 0.5, 0.4, 0.5 and 1.1, respectively. The incidence and the mean number of carcinomas per bladder were significantly lower in the treatment groups (P < 0.05) than in the control group, except in the low-dose meloxicam group. There were no significant adverse effects.

CONCLUSION

Both meloxicam and gefitinib have inhibitory effects on rat bladder carcinogenesis with no significant adverse effects. A combination of these drugs would be worth studying for their synergistic effects.

Transitional Cell Hyperplasia and Carcinomas in Urinary Bladders of Transgenic Mice with Keratin 5 Promoter-Driven Cyclooxygenase-2 Overexpression

The inducible form of cyclooxygenase (COX), COX-2, is up-regulated in many epithelial cancers and its prostaglandin products increase proliferation, enhance angiogenesis, and inhibit apoptosis in several tissues. Pharmacologic inhibition and genetic deletion studies showed a marked reduction of tumor development in colon and skin. COX-2 has also been strongly implicated in urinary bladder cancer primarily by studies with nonselective COX- and COX-2-selective inhibitors. We now show that forced expression of COX-2, under the control of a keratin 5 promoter, is sufficient to cause transitional cell hyperplasia (TCH) in 17% and 75% of the heterozygous and homozygous transgenic lines, respectively, in an age-dependent manner. TCH was strongly associated with inflammation, primarily nodules of B lymphocytes; some T cells and macrophage infiltration were also observed. Additionally, transitional cell carcinoma was observed in approximately 10% of the K5.COX-2 transgenic mice; no TCH or transitional cell carcinoma was observed in wild-type bladders. Immunohistochemistry for vascular proliferation and vascular endothelial growth factor showed significant increases above that in wild-type urinary bladders. Our results suggest that overexpression of COX-2 is sufficient to cause hyperplasia and carcinomas in the urinary bladder. Therefore, inhibition of COX-2 should continue to be pursued as a potential chemopreventive and therapeutic strategy.

Synergistic effects of Cox-1 and -2 inhibition on bladder and prostate cancer in vitro

BACKGROUND

We hypothesized that combined treatment with cyclooxygenase (Cox)-1 (catechin) and Cox-2 (NS398)-specific inhibitors would reduce cellular proliferation synergistically in genitourinary cancer.

METHODS

Bladder (T24 and TCCSUP) and prostate (DU145, LnCaP, and PC3) cancer cell lines were treated with catechin and NS398 at a dose of 100 mumol/L as single and combined treatments. Viability was measured by MTT assay at 24 and 72 hours.

RESULTS

Significant synergism of Cox-1 and Cox-2 inhibitors was observed in both bladder cancer lines at both 24 and 72 hours. Synergism of Cox-1 and -2 inhibitors also was noted in the DU145 cells at 72 hours, LnCap cells at 24 hours, and PC3 at both 24 and 72 hours.

CONCLUSIONS

Significant synergistic effects exhibited by the combination of Cox-1 and Cox-2 inhibitors suggest that these could become a highly effective treatment modality for carcinoma of both the bladder and prostate.