Epirubicin and meglumine gamma-linolenic acid: a logical choice of combination therapy for patients with superficial bladder carcinoma

The role of glucuronidation in drug resistance

The final therapeutic effect of a drug candidate, which is directed to a specific molecular target strongly depends on its absorption, distribution, metabolism and excretion (ADME). The disruption of at least one element of ADME may result in serious drug resistance. In this work we described the role of one element of this resistance: phase II metabolism with UDP-glucuronosyltransferases (UGTs). UGT function is the transformation of their substrates into more polar metabolites, which are better substrates for the ABC transporters, MDR1, MRP and BCRP, than the native drug. UGT-mediated drug resistance can be associated with (i) inherent overexpression of the enzyme, named intrinsic drug resistance or (ii) induced expression of the enzyme, named acquired drug resistance observed when enzyme expression is induced by the drug or other factors, as food-derived compounds. Very often this induction occurs via ligand binding receptors including AhR (aryl hydrocarbon receptor) PXR (pregnane X receptor), or other transcription factors. The effect of UGT dependent resistance is strengthened by coordinate action and also a coordinate regulation of the expression of UGTs and ABC transporters. This coupling of UGT and multidrug resistance proteins has been intensively studied, particularly in the case of antitumor treatment, when this resistance is "improved" by differences in UGT expression between tumor and healthy tissue. Multidrug resistance coordinated with glucuronidation has also been described here for drugs used in the management of epilepsy, psychiatric diseases, HIV infections, hypertension and hypercholesterolemia. Proposals to reverse UGT-mediated drug resistance should consider the endogenous functions of UGT.

Extractions of oil from Descurainia sophia seed using supercritical CO2, chemical compositions by GC-MS and evaluation of the anti-tussive, expectorant and anti-asthmatic activities

Descurainia sophia is widely distributed in China and is one of the most troublesome annual weeds. It has diverse medicinal usage. D. sophia has abundant oil, making it an important oil plant in China. The main goal of this study was to obtain the maximum yield of the oil by an optimal selection of supercritical fluid extraction parameters. According to the central composite design and response surface methodology for supercritical fluid extraction method, a quadratic polynomial model was used to predict the yield of D. sophia seed oil. A series of runs was performed to assess the optimal extraction conditions. The results indicated that the extraction pressure had the greatest impact on oil yield within the range of the operating conditions studied. A total of approximately 67 compounds were separated in D. sophia seed oil by GC-MS, of which 51 compounds represented 98.21% of the total oils, for the first time. This study was also aimed at evaluating the anti-asthmatic, anti-tussive and expectorant activities in vivo of D. sophia seed oil which supplied for further research on bioactive constituents and pharmacological mechanisms.

Blockade of a key region in the extracellular domain inhibits HER2 dimerization and signaling

BACKGROUND

Several treatment strategies target the human epidermal growth factor receptor 2 (HER2) in breast carcinomas, including monoclonal antibodies directed against HER2's extracellular domain (ECD) and small molecule inhibitors of its tyrosine kinase activity. Yet, novel therapies are needed that prevent HER2 dimerization with other HER family members, because current treatments are only partially effective.

METHODS

To test the hypothesis that HER2 activation requires a protein sequence in the HER2-ECD that mediates HER2 homo- and heterodimerization, we introduced a series of deletion mutations in the third subdomain of HER2-ECD. These deletion mutants were retrovirally expressed in breast cancer (BC) cells that naturally overexpress HER2 and in noncancerous, HER2-negative breast epithelial cells. One-factor analysis of variance or Student's t test were used to analyze differences. All statistical tests were two-sided.

RESULTS

The smallest deletion in the ECD domain of HER2, which removed only 16 amino acids (HER2-ECDΔ451-466), completely disrupted the oncogenic potential of HER2. In contrast to wild-type HER2, the mutant-inhibited anchorage-independent growth (mean number of colonies: mutant, 70, 95% confidence interval [CI] = 55 to 85; wild-type, 400, 95% CI = 320 to 480, P < .001) increased sensitivity to paclitaxel treatment in both transformed and nontransformed cells. Overexpression of HER2Δ451-466 efficiently inhibited activation of HER1, HER2, and HER3 in all cell lines tested.

CONCLUSIONS

These findings reveal that an essential "activating" sequence exists in the extracellular domain of HER2. Disruption of this sequence disables the HER2 dimerization loop, blocks subsequent activation of HER2-driven oncogenic signaling, and generates a dominant-negative form of HER2. Reagents specifically against this molecular activation switch may represent a novel targeted approach for the management of HER2-overexpressing carcinomas.

Phospholipase A(2)-susceptible liposomes of anticancer double lipid-prodrugs

A novel approach to anticancer drug delivery is presented based on lipid-like liposome-forming anticancer prodrugs that are susceptible to secretory phospholipase A(2) (sPLA(2)) that is overexpressed in several cancer types. The approach provides a selective unloading of anticancer drugs at the target tissues, as well as circumvents the necessity for "conventional" drug loading. In our attempts to improve the performance of the liposomes in vivo, several PEGylated and non-PEGylated liposomal formulations composed of a retinoid prodrug premixed with the sPLA(2)-hydrolyzable DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) were prepared. Besides favorably modifying the physicochemical properties of the liposomes, the incorporation of DPPC and PEG-lipids in the liposomes should substantially enhance the enzymatic activity, as concluded from literature. In addition, one can reap benefits from the presumed permeability enhancing effect of the liberated fatty acids and lysolipids. The size distribution of the prepared liposomes as well as their phase behavior, enzymatic hydrolysis, and cytotoxicity, in the presence and absence of sPLA(2), were determined. The liposomes were around 100nm in diameter and in the gel/fluid coexistence region at 37°C. The enzymatic hydrolysis of the prodrug was pronouncedly accelerated upon the premixing with DPPC, and the hydrolysis was further enhanced by PEGylation. Interestingly, the faster hydrolysis of the prodrug and the released fatty acids and lysolipids from DPPC did not improve the cytotoxicity of the mixture; the effect of combining the prodrug with DPPC was additive and not synergistic. The data presented here question the significance of the permeability enhancing effects claimed for fatty acids and lysolipids at the target cell membrane, and whether these effects can be achieved using physiologically achievable concentrations of fatty acids and lysolipids.

Effect of free fatty acids and lysolipids on cellular uptake of doxorubicin in human breast cancer cell lines

Several fatty acids and lysolipids have been shown earlier to increase the permeability of membranes of artificial liposomes, thereby increasing the release of drugs such as doxorubicin (Dox) contained within them. Free fatty acids can also inhibit cancer cell growth in vitro, and it has been suggested that this inhibition results from increased membrane permeability. Clearly, therefore, increased membrane permeability could be used in the design of liposomes for targeted drug delivery. For example, as free fatty acids and lysolipids are released upon phospholipase degradation of the liposome, the liposome could deliver membrane permeability enhancers in addition to the drug to increase the targeted anticancer effect. In this study, we examined the effect on Dox uptake in the breast cancer cell lines MDA-MB-231, MCF7, and MCF7-MDR when incubated with a large panel of different free fatty acids and lysolipids. Dox uptake was quantified by flow cytometry and fluorescence microscopy. We observed no increased Dox uptake in any of the breast cancer cell lines, suggesting that growth inhibitory effects observed earlier subsequent to the addition of free fatty acids to cancer cells are not caused by increased cell membrane permeability.

New therapies for non-muscle-invasive bladder cancer

The treatment of non-muscle-invasive bladder cancer (NMIBC) remains a challenge owing to its increased tendency to recur and the possibility of progression to potentially dangerous muscle-invasive disease. Treatment outcomes by current therapeutic modalities are still not optimal. In recent years, there have been a number of substantive advances in the therapeutic options for the management of NMIBC. New chemotherapeutic drugs have been introduced, along with efforts made to improve the efficacy of existing agents and enhance delivery of agents to the bladder. There is also a growing trend toward combination of agents and multimodal therapy. Also of considerable interest are the investigation of newer approaches such as gene therapy, chemoenhancement and newer forms of immunotherapy. Here, we review the recent pre-clinical and clinical developments in the treatment of NMIBC, described in the broad categories of immunotherapy, chemotherapeutic agents, improved or device-assisted agent delivery and gene therapy.

Gamma-linolenic acid modulates the response of multidrug-resistant K562 leukemic cells to anticancer drugs

Gamma-linolenic acid (GLA) is known to have selective tumoricidal action. It is also reported that GLA may increase the cytotoxic activity of cancer chemotherapeutic agents in some cancer cells. The present study examined whether GLA pretreatment could modulate the response of multidrug-resistant K562/ADM leukemic cells to anticancer drugs. The cell viability assay results showed that GLA at 10 microg/ml enhanced cell growth inhibition induced by the MDR-type drugs doxorubicin, etoposide and vincristine, but could not enhance or even attenuated cell growth inhibition induced by the non-MDR-type drug cisplatin, mitomycin and fluorouracil in K562/ADM cells. Further flow cytometry results showed that GLA decreased the expression of P-glycoprotein, enhanced the accumulation of doxorubicin and rhodamine 123 in K562/ADM cells and inhibited the efflux of rhodamine 123 from K562/ADM cells, lowered the efflux rate. These results suggest that GLA could modulate the response to anti-cancer agents in P-gp overexpressing multidrug-resistant cells, and the mechanism may be by decreasing the P-gp expression and inhibiting P-gp function.

Mechanisms of action of eicosapentaenoic acid in bladder cancer cells in vitro: alterations in mitochondrial metabolism, reactive oxygen species generation and apoptosis induction

PURPOSE

Eicosapentaenoic acid has been tested in bladder cancer as a synergistic cytotoxic agent in the form of meglumine-eicosapentaenoic acid, although its mechanism of action is poorly understood in this cancer. The current study analyzed the mechanisms by which eicosapentaenoic acid alters T24/83 human bladder cancer metabolism in vitro.

MATERIALS AND METHODS

T24/83 human bladder cancer cells were exposed to eicosapentaenoic acid for 6 to 24 hours in vitro and incorporation profiles were determined. Effects on membrane phospholipid incorporation, energy metabolism, mitochondrial activity, cell proliferation and apoptosis were analyzed. Reactive oxygen species and lipid peroxide production were also determined.

RESULTS

Eicosapentaenoic acid was readily incorporated into membrane phospholipids with a considerable amount present in mitochondrial cardiolipin. Energy metabolism was significantly altered by eicosapentaenoic acid, accompanied by decreased mitochondrial membrane potential, and increased lipid peroxide and reactive oxygen species generation. Subsequently caspase-3 activation and apoptosis were detected in eicosapentaenoic acid exposed cells, leading to decreased cell numbers.

CONCLUSIONS

These findings confirm that eicosapentaenoic acid is a potent cytotoxic agent in bladder cancer cells and provide important insight into the mechanisms by which eicosapentaenoic acid causes these changes. The changes in membrane composition that can occur with eicosapentaenoic acid likely contribute to the enhanced drug cytotoxicity reported previously in meglumine-eicosapentaenoic acid/epirubicin/mitomycin studies. Dietary manipulation of the cardiolipin fatty acid composition may provide an additional method for stimulating cell death in bladder cancer. In vivo studies using intravesical and dietary manipulation of fatty acid metabolism in bladder cancer merit further attention.

Meglumine Eicosapentaenoic acid (MeEPA) a new soluble omega-3 fatty acid formulation: in vitro bladder cancer cytotoxicity tests in combination with epirubicin and mitomycin

OBJECTIVE

To determine if Meglumine-Eicosapentaenoic Acid (MeEPA) acts synergistically with epirubicin and mitomycin to enhance cytotoxicity towards bladder cancer cell lines in vitro.

MATERIALS AND METHODS

Bladder cancer cells were exposed to MeEPA in combination with epirubicin or mitomycin. Residual viable cell biomass was estimated with the methyl-thiazoldiphenyl tetrazolium (MTT) assay following drug exposure. Drug interaction was analysed using median effect analysis to determine levels of synergism.

RESULTS

Most combinations of MeEPA with both epirubicin and mitomycin showed a high-level of synergism. At high doses, drug precipitation adversely affected MTT assay analysis suggesting antagonism of action. However, the predominant pattern was of synergism for most dose combinations tested.

CONCLUSION

Bladder cancer treated by endoscopic resection alone is subject to high recurrence rates. Post-operative intravesical instillation of epirubicin and mitomycin can halve recurrence rates, but there is no evidence that disease progression to invasive bladder cancer is altered. Thus, optimisation of current treatment strategies is required. The anti-tumour activity of fatty acids is well established and MeEPA is a new, soluble formulation with the potential to enhance intravesical drug efficacy.

Epirubicin Glucuronidation and UGT2B7 Developmental Expression

The usefulness of epirubicin in the treatment of adult and childhood malignant diseases is related in part to the potential reduction in cardiac toxicity compared with that of other anthracyclines given at equivalent doses. An important pathway for epirubicin detoxification is UGT2B7-dependent glucuronidation. This study was implemented to provide a preclinical evaluation of the metabolism of epirubicin with respect to age-related changes in epirubicin glucuronidation in pediatric liver microsomes. Rates of epirubicin glucuronidation and levels of UGT2B7 were determined for liver microsomes from four pediatric age categories (n = 32) and one adult age category (n = 8). Both sets of data showed an increase in UGT2B7 activity and content with increasing age. Epirubicin glucuronidation activity in the adult group was statistically higher compared with all pediatric age groups (p < or = 0.01). UGT2B7 expression also was statistically higher in adults compared with children below 11 years of age, with evidence of significant differences in protein levels among the pediatric age categories. A positive correlation (r = 0.68) between UGT2B7 levels and postnatal age was observed, suggesting a progressive increase in UGT2B7 protein expression with increasing age. However, allometric scaling using the (3/4) power rule suggested no difference in activity between any of the pediatric age categories and the adult, although only a single neonatal sample was included in the analysis. In summary, these in vitro data show differences in epirubicin glucuronidation and UGT2B7 content within pediatric age groups and support the use of epirubicin in pediatric patients at least 6 months of age.

Effect of gamma-linolenic acid on the transcriptional activity of the Her-2/neu (erbB-2) oncogene

The omega-6 polyunsaturated fatty acid gamma-linolenic acid (GLA; 18:3n-6), which is found in several plant oils and is used as an herbal medicine, has antitumor activity in vitro. We examined the effect of GLA on the expression of the Her-2/neu (erbB-2) oncogene, which is involved in development of numerous types of human cancer. Flow cytometric and immunoblotting analyses demonstrated that GLA treatment substantially reduced Her-2/neu protein levels in the Her-2/neu-overexpressing cell lines BT-474, SK-Br3, and MDA-MB-453 (breast cancer), SK-OV3 (ovarian cancer), and NCI-N87 (gastrointestinal tumor derived). GLA exposure led to a dramatic decrease in Her-2/neu promoter activity and a concomitant increase in the levels of polyomavirus enhancer activator 3 (PEA3), a transcriptional repressor of Her-2/neu, in these cell lines. In transient transfection experiments, a Her-2/neu promoter bearing a PEA3 site-mutated sequence was not subject to negative regulation by GLA in Her-2/neu-overexpressing cell lines. Concurrent treatments of Her-2/neu-overexpressing cancer cells with GLA and the anti-Her-2/neu antibody trastuzumab led to synergistic increases in apoptosis and reduced growth and colony formation.

Microtubule-associated protein tau: a marker of paclitaxel sensitivity in breast cancer

Breast cancers show variable sensitivity to paclitaxel. There is no diagnostic test to identify tumors that are sensitive to this drug. We used U133A chips to identify genes that are associated with pathologic complete response (pCR) to preoperative paclitaxel-containing chemotherapy in stage I-III breast cancer (n = 82). Tau was the most differentially expressed gene. Tumors with pCR had significantly lower (P < 0.3 x 10(-5)) mRNA expression. Tissue arrays from 122 independent but similarly treated patients were used for validation by immunohistochemistry. Seventy-four percent of pCR cases were tau protein negative; the odds ratio for pCR was 3.7 (95% confidence interval, 1.6-8.6; P = 0.0013). In multivariate analysis, nuclear grade (P < 0.01), age <50 (P = 0.03), and tau-negative status (P = 0.04) were independent predictors of pCR. Small interfering RNA experiments were performed to examine whether down-regulation of tau increases sensitivity to chemotherapy in vitro. Down-regulation of tau increased sensitivity of breast cancer cells to paclitaxel but not to epirubicin. Tubulin polymerization assay was used to assess whether tau modulates binding of paclitaxel to tubulin. Preincubation of tubulin with tau resulted in decreased paclitaxel binding and reduced paclitaxel-induced microtubule polymerization. These data suggest that low tau expression renders microtubules more vulnerable to paclitaxel and makes breast cancer cells hypersensitive to this drug. Low tau expression may be used as a marker to select patients for paclitaxel therapy. Inhibition of tau function might be exploited as a therapeutic strategy to increase sensitivity to paclitaxel.

α-Tocopherol Suppresses Mammary Tumor Sensitivity to Anthracyclines in Fish Oil-Fed Rats

Polyunsaturated fatty acids (PUFAs) have been reported to enhance the efficacy of chemotherapeutic agents that produce reactive oxygen species such as anthracyclines. We previously reported in a human breast cancer cell line that the increased cytotoxic activity of anthracyclines by several PUFAs was abolished by antioxidants and enhanced by pro-oxidants, suggesting that lipid peroxidation was involved in this effect. To determine the relevance of this observation in vivo, we examined the effect of the oxidative status of the diet on the activity of epirubicin against N-methylnitrosourea-induced mammary tumors in Sprague-Dawley rats. Three groups of rats were fed a basal diet enriched with dietary n-3 PUFA (sardine oil, 15%) alone (control group), with addition of an antioxidant (alpha-tocopherol, 100 UI/kg diet), or with addition of an oxidant system (dehydroascorbate/naphthoquinone). When the first mammary tumor reached 1 cm2, epirubicin was administrated weekly for 3 wk, and subsequent change in tumor size was documented over time. Two weeks after the end of epirubicin injections, tumor size was increased by 34% in the control group. In the pro-oxidant group, tumor size was decreased by 50%. In contrast, tumor size was increased by 188% in the antioxidant group. Thus, addition of pro-oxidants in a fish oil-enriched diet increased the sensitization of mammary tumors to chemotherapy, whereas addition of alpha-tocopherol suppressed tumor response in vivo, indicating that interaction between components of the diet has to be carefully controlled during chemotherapy.

The current status of intravesical therapy for superficial bladder cancer

PURPOSE OF REVIEW

To analyse recent advances in intravesical instillation therapy for superficial bladder cancer.

RECENT FINDINGS

Although intravesical bacillus Calmette-Guérin has been used for many years in the treatment of superficial bladder cancer, its mechanism of action remains unclear, its poor tolerance remains a problem, the prediction of its efficacy has still to be validated, and its long-term effects on progression and survival are controversial. The exact timing and place of intravesical chemotherapy needs to be better defined, as well as the place of some new molecules. Finally, new approaches need to be explored for overcoming the limitations of the usual intravesical agents.

SUMMARY

No dramatic advances have been made in understanding the mechanisms of action of bacillus Calmette-Guérin during the past year. However, a careful dissection of this complex immunological pathway continues and immunological criteria are promising for predicting the response to bacillus Calmette-Guérin. Evidence has been accumulating to suggest that a dose reduction during the initial treatment remains effective and reduces side-effects. In addition, bacillus Calmette-Guérin maintenance therapy is useful for high-risk patients. However, long-term tolerance remains an important issue, and the optimal protocol has not yet been defined. On the other hand, it has been proved that intravesical chemotherapy, when administered early after transurethral resection, is effective in preventing frequent recurrences, whereas maintenance chemotherapy is ineffective. Finally, new approaches, including instillations of activated immune cells or targeted gene therapy, are being explored.