Potential use of COX-2-aromatase inhibitor combinations in breast cancer

Antiproliferative and antimigratory effects of 3-(4-substituted benzyl)-5- isopropyl-5-phenylhydantoin derivatives in human breast cancer cells

In this study, a series of synthesized 3-(4-substituted benzyl)-5-isopropyl-5-phenylhydantoin derivatives as a potential antiproliferative and antimigratory agents were investigated. The possible antitumor mechanisms of investigated hydantoin derivatives were examined on human breast cancer cell line MDA-MB-231. The cells were treated with different concentrations of compounds (from 0.01 µM to 100 µM) during 24 h and 72 h. The proliferation index, nitric oxide production, apoptosis rate, and migration capacity were measured. The cell invasion potential was examined by measuring the level of MMP-9 and COX-2 gene expression. All tested compounds expressed antiproliferative activity and induced dose- and time-dependent increase in the level of nitrites. The investigated molecules significantly decreased cell survival rate, migration capacity and the expression levels of genes included in the process of tumor invasion. Obtained data suggest that the tested hydantoin derivatives express considerable antitumor activity by reducing cell division rate, elevating apoptosis level, and inhibiting the motility and invasiveness of breast cancer cells. The results obtained in this study indicate that investigated compounds express potential as a novel chemotherapeutic agents against breast cancer growth and progression.

MicroRNA-708 activation by glucocorticoid receptor agonists regulate breast cancer tumorigenesis and metastasis via downregulation of NF-κB signaling

Therapeutic administration of glucocorticoids (GCs) is frequently used as add-on chemotherapy for palliative purposes during breast cancer treatment. Recent studies have shown that GC treatment induces microRNA-708 in ovarian cancer cells, resulting in impaired tumor cell proliferation and metastasis. However, the regulatory functions of GCs on miR-708 and its downstream target genes in human breast cancer cells (BCCs) are poorly understood. In this study, we found that treatment with either the synthetic GC dexamethasone (DEX) or the natural GC mimic, antcin A (ATA) significantly increased miR-708 expression by transactivation of glucocorticoid receptor alpha (GRα) in MCF-7 and MDA-MB-231 human BCCs. Induction of miR-708 by GR agonists resulted in inhibition of cell proliferation, cell-cycle progression, cancer stem cell (CSC)-like phenotype and metastasis of BCCs. In addition, GR agonist treatment or miR-708 mimic transfection remarkably inhibited IKKβ expression and suppressed nuclear factor-kappaB (NF-κB) activity and its downstream target genes, including COX-2, cMYC, cyclin D1, Matrix metalloproteinase (MMP)-2, MMP-9, CD24, CD44 and increased p21CIP1 and p27KIP1 that are known to be involved in proliferation, cell-cycle progression, metastasis and CSC marker protein. BCCs xenograft models indicate that treatment with GR agonists significantly reduced tumor growth, weight and volume. Overall, our data strongly suggest that GR agonists induced miR-708 and downstream suppression of NF-κB signaling, which may be applicable as a novel therapeutic intervention in breast cancer treatment.

Development and evaluation of exemestane-loaded lyotropic liquid crystalline gel formulations

Introduction: The use of liquid crystalline (LC) gel formulations for drug delivery has considerably improved the current delivery methods in terms of bioavailability and efficacy. The purpose of this study was to develop and evaluate LC gel formulations to deliver the anti-cancer drug exemestane through transdermal route. Methods: Two LC gel formulations were prepared by phase separation coacervation method using glyceryl monooleate (GMO), Tween 80 and Pluronic® F127 (F127). The formulations were characterized with regard to encapsulation efficiency (EE), vesicle size, Fourier transform infrared (FTIR) spectroscopy, surface morphology (using light and fluorescence microscopy), in vitro release, ex vivo permeation, in vitro effectiveness test on MDA-MB231 cancer cell lines and histopathological analysis. Results: Results exhibited that the EE was 85%-92%, vesicle size was 119.9-466.2 nm while morphology showed spherical vesicles after hydration. An FTIR result also revealed that there was no significant shift in peaks corresponding to Exemestane and excipients. LC formulations release the drug from cellulose acetate and Strat-MTM membrane from 15%-88.95%, whereas ex vivo permeation ranges from 37.09-63%. The in vitro effectiveness study indicated that even at low exemestane concentrations (12.5 and 25 μg/mL) the formulations were able to induce cancer cell death, regardless of the surfactant used. Histopathological analysis thinning of the epidermis as the formulations penetrate into the intercellular regions of squamous cells. Conclusion: The results conjectured that exemestane could be incorporated into LC gels for the transdermal delivery system and further preclinical studies such as pharmacokinetic and pharmacodynamic studies will be carried out with suitable animal models.

The prostanoid EP4 receptor and its signaling pathway

The EP4 prostanoid receptor is one of four receptor subtypes for prostaglandin E2. It belongs to the family of G protein-coupled receptors. It was originally identified, similar to the EP2 receptor as a G(s)α-coupled, adenylyl cyclase-stimulating receptor. EP4 signaling plays a variety of roles through cAMP effectors, i.e., protein kinase A and exchange protein activated by cAMP. However, emerging evidence from studies using pharmacological approaches and genetically modified mice suggests that EP4, unlike EP2, can also be coupled to G(i)α, phosphatidylinositol 3-kinase, β-arrestin, or β-catenin. These signaling pathways constitute unique roles for the EP4 receptor. EP4 is widely distributed in the body and thus plays various physiologic and pathophysiologic roles. In particular, EP4 signaling is closely related to carcinogenesis, cardiac hypertrophy, vasodilation, vascular remodeling, bone remodeling, gastrointestinal homeostasis, renal function, and female reproductive function. In addition to the classic anti-inflammatory action of EP4 on mononuclear cells and T cells, recent evidence has shown that EP4 signaling contributes to proinflammatory action as well. The aim of this review is to present current findings on the biologic functions of the EP4 receptor. In particular, we will discuss its diversity from the standpoint of EP4-mediated signaling.

Anastrozole and celecoxib for endometriosis treatment, good to keep them apart?

Endometriosis is a benign gynecological disease. Cyclooxygenase-2 (COX-2) and aromatase proteins have been shown to be overexpressed in eutopic endometrium from women suffering from this disease compared to disease-free women. Furthermore, inhibition of these molecules individually was demonstrated to have antiproliferative and proapoptotic effects both in vitro and in vivo in several models. In this study, the effect of combining celecoxib, a selective COX-2 inhibitor, and anastrozole, an aromatase inhibitor, on the implantation and growth of endometriotic like lesions in a murine model of endometriosis was evaluated. Endometriosis was surgically induced in female BALB/c mice. After 28 days of treatment with celecoxib, anastrozole, or their combination, animals were killed and lesions were counted, measured, excised, and fixed. Immunohistochemistry for proliferating cell nuclear antigen and CD34 was performed for assessment of cell proliferation and vascularization. TUNEL technique was performed for apoptosis evaluation. Celecoxib was the only treatment to significantly reduce the number of lesions established per mouse, their size and vascularized area. In addition, cell proliferation was significantly diminished and apoptosis was significantly enhanced by both individual treatments. When the therapies were combined, they reversed their effects. These results confirm that celecoxib and anastrozole separately decrease endometriotic growth, but when combined they might have antagonizing effects.

Radiation induced COX-2 expression and mutagenesis at non-targeted lung tissues of gpt delta transgenic mice

BACKGROUND

Although radiation-induced bystander effects have been confirmed using a variety of endpoints, the mechanism(s) underlying these effects are not well understood, especially for in vivo study.

METHODS

A 1-cm(2) area (1 cm × 1 cm) in the lower abdominal region of gpt delta transgenic mice was irradiated with 5 Gy of 300 keV X-rays, and changes in out-of-field lung and liver were observed.

RESULTS

Compared with sham-treated controls, the Spi(-) mutation frequency increased 2.4-fold in non-targeted lung tissues at 24 h after partial body irradiation (PBIR). Consistent with dramatic Cyclooxygenase 2 (COX-2) induction in the non-targeted bronchial epithelial cells, increasing levels of prostaglandin, together with 8-hydroxydeoxyguanosine, in the out-of-field lung tissues were observed after PBIR. In addition, DNA double-strand breaks and apoptosis were induced in bystander lung tissues after PBIR.

CONCLUSION

The PBIR induces DNA damage and mutagenesis in non-targeted lung tissues, especially in bronchial epithelial cells, and COX-2 has an essential role in bystander mutagenesis.

The inhibitory effect of celecoxib and rosiglitazone on experimental endometriosis

OBJECTIVE

To evaluate the effects of celecoxib and rosiglitazone on the implantation and growth of endometriotic-like lesions in a murine model of endometriosis.

DESIGN

Prospective experimental study.

SETTING

Animal research and laboratory facility.

ANIMAL(S)

Two-month-old female BALB/c mice.

INTERVENTION(S)

Surgically induced endometriosis in female BALB/C mice; 28 days of treatment with celecoxib, rosiglitazone, or their combination; counting, measuring, excising, and fixing lesions.

MAIN OUTCOME MEASURE(S)

Immunohistochemical examination for proliferating cell nuclear antigen (PCNA), CD31, and CD34 to assess cell proliferation and vascularization, with the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) technique for apoptosis evaluation.

RESULT(S)

Celecoxib and the combined treatment (celecoxib and rosiglitazone) statistically significantly reduced the mean number of lesions established per mouse, and all treatments diminished the implant volume. In addition, cell proliferation within the implants was statistically significantly reduced, and apoptosis was statistically significantly enhanced by all treatments. Also, we found that all treatments diminished the vascularized area in the lesion.

CONCLUSION(S)

These results are promising and reveal that celecoxib and rosiglitazone, combined or separately, have a beneficial effect on overall endometriotic growth.

Targeting apoptosis pathways by Celecoxib in cancer

Celecoxib is a paradigmatic selective inhibitor of cyclooxygenase-2 (COX-2). This anti-inflammatory drug has potent anti-tumor activity in a wide variety of human epithelial tumor types, such as colorectal, breast, non-small cell lung, and prostate cancers. Up to now, the drug found application in cancer prevention in patients with familial adenomatous polyposis. Moreover, the use of Celecoxib is currently tested in the prevention and treatment of pancreatic, breast, ovarian, non-small cell lung cancer and other advanced human epithelial cancers. Induction of apoptosis contributes to the anti-neoplastic activity of Celecoxib. In most cellular systems Celecoxib induces apoptosis independently from its COX-2 inhibitory action via a mitochondrial apoptosis pathway which is however, not inhibited by overexpression of Bcl-2. In addition, Celecoxib exerts antagonistic effects on the anti-apoptotic proteins Mcl-1 and survivin. Consequently, the use of Celecoxib may be of specific value for the treatment of apoptosis-resistant tumors with overexpression of Bcl-2, Mcl-1, or survivin as single drug or in combination with radiotherapy, chemotherapy, or targeted pro-apoptotic drugs that are inhibited by survivin, Bcl-2 or Mcl-1. As COX-2 inhibition has been associated with cardiovascular toxicity, the value of drug derivatives without COX-2 inhibitory action should be validated for prevention and treatment of human epithelial tumors to reduce the risk for heart attack or stroke. However, its additional COX-2 inhibitory action may qualify Celecoxib for a cautious use in COX-2-dependent epithelial tumors, where the drug could additionally suppress COX-2-mediated growth and survival promoting signals from the tumor and the stromal cells.

Polymorphisms in regulatory regions of cyclooxygenase-2 gene and breast cancer risk in Brazilians: a case-control study

Background

Cyclooxygenase-2 (COX-2) is up-regulated in several types of cancer, and it is hypothesized that COX-2 expression may be genetically influenced. Here, we evaluate the association between single-nucleotide polymorphisms (SNPs) in the COX-2 gene (PTGS2) and the occurrence of breast cancer among Brazilian women.

Methods

The study was conducted prospectively in two steps: First, we screened the promoter region and three fragments of the 3'-untranslated region of PTGS2 from 67 healthy Brazilians to identify SNPs and to select those with a minor allele frequency (MAF) of at least 0.10. The MAF of these selected SNPs was further characterized in 402 healthy volunteers to evaluate potential differences related to heterogeneous racial admixture and to estimate the existence of linkage disequilibrium among the SNPs. The second step was a case-control study with 318 patients and 273 controls designed to evaluate PTGS2 genotype- or haplotype-associated risk of breast cancer.

Results

The screening analysis indicated nine SNPs with the following MAFs: rs689465 (0.22), rs689466 (0.15), rs20415 (0.007), rs20417 (0.32), rs20419 (0.015), rs5270 (0.02), rs20424 (0.007), rs5275 (0.22) and rs4648298 (0.01). The SNPs rs689465, rs689466, rs20417 and rs5275 were further studied: Their genotypic distributions followed Hardy-Weinberg equilibrium and the MAFs were not affected by gender or skin color. Strong linkage disequilibrium was detected for rs689465, rs20417 and rs5275 in the three possible pairwise combinations. In the case-control study, there was a significant increase of rs5275TC heterozygotes in cases compared to controls (OR = 1.44, 95% CI = 1.01-2.06; P = 0.043), and the haplotype formed by rs689465G, rs689466A, rs20417G and rs5275C was only detected in cases. The apparent association with breast cancer was not confirmed for rs5275CC homozygotes or for the most frequent rs5275C-containing haplotypes.

Conclusions

Our results indicate no strong association between the four most frequent PTGS2 SNPs and the risk of breast cancer.

The value of COX-2 expression in the prognostic parameters of invasive ductal carcinoma of the breast

Cyclooxygenase is an enzyme that changes the immune response to malign cells and catalyzes prostaglandins that may have an impact on cell proliferation. The purpose of this study was to examine the relation between established clinicopathological parameters in breast carcinomas and COX-2 protein expression. COX-2, estrogen receptor (ER), progesterone receptor (PR) and c-erB-2 primary antibodies were assessed in the slides prepared from the paraffin blocks of 62 invasive ductal carcinoma cases. The relation between ER, PR, and c-erbB-2 positivity, histological grade, nuclear grade, lymphovascular invasion, tumor diameter, lymph node positivity, metastasis, and age were evaluated. The results were analyzed statistically. Cytoplasmic COX-2 expression was seen in 75.8% of all breast carcinomas. In both univariate and multivariate logistic regression analysis, there was a positive correlation between COX-2 expression and negative ER status, respectively (P=0.0173) (P=0.016). There was any statistically significant relation between PR positivity, c-erbB-2 positivity, histological grade, nuclear grade, lymphovascular invasion, tumor diameter, lymph node positivity, metastasis, and age (P≥0.05). Given that there was found a statistically significant relation between COX-2 expression and negative ER status, which is considered a poor prognostic parameter, suggests that COX-2 expression can have a place among the other prognostic parameters of breast carcinoma.

Cyclooxygenase-2 inhibition for the prophylaxis and treatment of preinvasive breast cancer in a her-2/neu mouse model

Ductal carcinoma in situ (DCIS) is the most common form of preinvasive breast cancer. Several molecular alterations have been identified in DCIS. Among them, cyclooxygenase 2 (COX-2) overexpression has been shown in 60% to 80% of DCIS cases. Celecoxib is a nonsteroidal anti-inflammatory drug that selectively inhibits COX-2. In this study, we evaluated whether COX-2 inhibition by celecoxib can reduce the incidence of preinvasive breast cancer and its progression to invasive breast cancer in a mouse model exhibiting a similar phenotype to human solid-pattern DCIS. We have used the mouse model mouse mammary tumor virus (MMTV)-Neu to investigate this possibility. These mice carry a rat Her-2/Neu transgene and are known to develop DCIS-like lesions. Our results showed that celecoxib (500 ppm) given as prophylaxis was neither able to prevent tumor development nor delay tumor appearance compared with untreated mice. Furthermore, when the drug was given early in tumorigenesis, it did not reduce the progression of preinvasive to invasive tumors nor prevent lung metastasis. Reduction of prostaglandin levels was, however, achieved in mammary tumors of treated mice. In addition, celecoxib treatment caused an increase in apoptosis and decreased vascular endothelial growth factor expression in treated animals. Our results contrast with some previously published studies and highlight the complexity of the relationship between COX-2 and breast cancer.

A novel single nucleotide polymorphism of the cyclooxygenase-2 gene associated with breast cancer

AIMS

Cyclooxygenase-2 (COX-2) is involved in carcinogenesis, immune response suppression, apoptosis inhibition, angiogenesis, and tumour cell invasion and metastasis. The gene for COX-2, designated as PTGS2, carries several polymorphisms, such as -765G >C, 1195G/A in the promoter region, and 8473T >C in the 3' UTR, which have been associated with susceptibility to malignant disease. The aim of this study was to search for new mutations and polymorphisms in the COX-2 gene and to assess the relationship with breast cancer.

MATERIALS AND METHODS

In the present study, we identified a novel single nucleotide polymorphism, 169C >G, in exon 2 using polymerase chain reaction-single-strand conformation polymorphism analysis. This nucleotide change causes the amino acid change from proline to alanine at codon 57. To investigate the role of this polymorphism for breast cancer, we determined the prevalence of PTGS2 genotypes in 310 women with breast cancer and 310 gender- and age-matched healthy control subjects.

RESULTS

Homozygous carriers of the 169-GG genotype were more frequent among patients (15.16%) than among controls (9.35%; P = 0.03). The odds ratio for carriers of this genotype for breast cancer was 1.76 (95% confidence interval, 1.20-3.05). Among patients, oestrogen receptor positivity was less frequent among carriers of a GG genotype (61.7%) than among carriers of a CC or GC genotype (72.3%; P = 0.02). Tumour size, histological grade, presence of primary lymph node metastases, progesterone receptor positivity, or age at diagnosis were not associated with PTGS2 genotypes.

CONCLUSION

We conclude that the homozygous PTGS2 169-GG genotype may be associated with breast cancer risk.

The combined effects of celecoxib and minocycline hydrochloride on inhibiting the osseous metastasis of breast cancer in nude mice

Breast carcinomas show a trend toward bone metastasis that is prevalent worldwide. Celecoxib (CX) and minocycline hydrochloride (MH) have both been widely used in treating breast cancer; however, their combined effects on the osseous metastasis of breast cancer have not yet been studied. In the present study, breast cancer cells were injected into the back of the femoral bone of nude mice, and CX and MH were intraperitoneally administered every other day at doses of 30 and 40 mg/kg/day, respectively, for 30 days. Tumor weights and volumes were significantly lower and the tumor inhibition rate was significantly higher in the CX + MH group than those of the control and CX or MH alone groups (p < 0.05). The cell density in the tumor tissue was significantly decreased and apoptotic and necrotic cell death was significantly increased in the CX + MH group, as compared with those of the control and CX or MH alone groups. Microvessel density and expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 in the tumor tissues of the CX + MH group were significantly lower than those of the CX, MH, and control groups. The serum alkaline phosphatase level of the CX + MH group was significantly lower than those of the other groups (p < 0.01). These results suggest that a combined use of CX and MH has better inhibitory effects on the osseous metastasis of breast cancer, as compared to CX or MH alone. They exerted their combined effects by increasing tumor-cell death and decreasing the tumor expression of MMP-9 and VEGF systems.

Effect of phenytoin on celecoxib pharmacokinetics in patients with glioblastoma

Cyclooxygenase-2 (COX-2) expression has been linked to the prognosis, angiogenesis, and radiation sensitivity of many malignancies. Celecoxib, a selective COX-2 inhibitor, is predominantly eliminated by hepatic metabolism. This study was conducted to determine the effects of hepatic enzyme-inducing antiseizure drugs (EIASDs) on the pharmacokinetics of celecoxib. The safety of celecoxib administered with radiation for glioblastoma and the effect of the combined treatment on survival were also evaluated. Patients were stratified based on concomitant use of EIASDs. Celecoxib (400) mg was administered orally twice a day until tumor progression or dose-limiting toxicity. Standard radiation was administered without adjuvant chemotherapy. Sampling was performed to define the plasma concentration/time profile for the initial dose of celecoxib and steady-state trough concentrations. Thirty-five patients (22 +EIASD, 13 -EIASD) were enrolled. There were no significant differences in age, performance status, extent of surgery, or Mini Mental State Exam scores between the two cohorts. The treatment was well tolerated. All patients in the +EIASD arm were taking phenytoin. There were no significant differences in any celecoxib pharmacokinetic parameters between 15 +EIASD and 12 -EIASD patients. With 31 of 35 patients deceased, estimated median survival time for all patients was 12 months (+EIASD, 11.5 months; - EIASD, 16 months; p = 0.11). The pharmacokinetics of celecoxib is not significantly affected by the concomitant administration of phenytoin. Celecoxib administered during and after radiation is well tolerated. The potential difference in survival between the +EIASD and -EIASD groups deserves further evaluation.

Estrogen-dependent prognostic significance of cyclooxygenase-2 expression in early-stage invasive breast cancers treated with breast-conserving surgery and radiation

PURPOSE

To evaluate the prognostic significance of cyclooxygenase-2 (COX-2) in breast cancer patients treated with conservative surgery and radiation therapy (CS+RT).

METHODS AND MATERIALS

Between 1975 and 2003, we retrieved specimens from 504 breast cancer patients treated with CS+RT. The specimens were constructed into tissue microarrays processed and stained for estrogen receptor (ER), progesterone receptor, Her2/neu, and COX-2. Each core was scored as positive or negative. All data including demographics, clinical, pathologic, staging, and outcome variables were entered into a computerized database.

RESULTS

Expression of COX-2 was positive in 58% of cases and correlated with younger age (p = 0.01) and larger tumor size (p = 0.001). Expression of COX-2 was predictive of local relapse (relative risk[RR], 3.248; 95% confidence interval [CI], 1.340-7.871; p = 0.0091), distant metastasis (RR, 2.21; 95% CI, 1.259-3.896; p = 0.0058), and decreased survival (RR, 2.321; 95% CI, 1.324-4.071; p = 0.0033). Among ER-positive patients, COX-2 expression was predictive of worse local control (85% vs. 93%, p = 0.04), distant metastasis (75% vs. 95%, p = 0.002) and worse survival (65% vs. 94%, p = 0.002). Among ER-negative tumors COX-2 expression was not significantly correlated with local control (87 vs. 95%, p = 0.12), distant metastasis (73% vs. 78%, p = 0.39), or survival (77% vs. 87%, p = 0.15).

CONCLUSIONS

In breast cancer patients treated with CS+RT, COX-2 expression is associated with younger age, larger tumor size, worse local control, distant metastasis, and worse overall survival. The significance is limited to hormone receptor-positive tumors, consistent with the known effect of COX-2/PGE2 on aromatase activity. Use of COX-2 inhibitors in estrogen-dependent breast cancers warrants further investigation.

Cyclo-oxygenase-2 and its inhibition in cancer: is there a role?

Despite recent improvements in chemotherapy and radiation therapy in cancer management with the addition of biological agents, novel treatment approaches are needed to further benefit patients. Cyclo-oxygenase (COX)-2 inhibition represents one such possibility. COX-2 is an enzyme induced in pathological states such as inflammatory disorders and cancer, where it mediates production of prostanoids. The enzyme is commonly expressed in both premalignant lesions and malignant tumours of different types. A growing body of evidence suggests an association of COX-2 with tumour development, aggressive biological tumour behaviour, resistance to standard cancer treatment, and adverse patient outcome. COX-2 may be related to cancer development and propagation through multiple mechanisms, including stimulation of growth, migration, invasiveness, resistance to apoptosis, suppression of the immunosurveillance system, and enhancement of angiogenesis. Epidemiological data suggest that NSAIDs and selective COX-2 inhibitors might prevent the development of cancers, including colorectal, oesophageal and lung cancer. Preclinical investigations have demonstrated that inhibition of this enzyme with selective COX-2 inhibitors enhances tumour response to radiation and chemotherapeutic agents. These preclinical findings have been rapidly advanced to clinical oncology. Clinical trials of the combination of selective COX-2 inhibitors with radiotherapy, chemotherapy or both in patients with a number of cancers have been initiated, and preliminary results are encouraging. This review discusses the role of COX-2, its products (prostaglandins) and its inhibitors in tumour growth and treatment.

Aromatase inhibitor-associated arthralgia syndrome

Aromatase inhibitors (AIs) are widely used as an adjuvant endocrine treatment in postmenopausal women with early-stage breast cancer. Clinical trials have assessed 5 years of AI therapy, either as an alternative to tamoxifen for primary adjuvant therapy of breast cancer, or after 5 years of adjuvant tamoxifen. Treatment of 2-3 years' duration after 2-3 years of tamoxifen has also been studied. AI therapy brings side effects related to estrogen deprivation, and this side effect profile differs in clinically relevant ways from that seen with tamoxifen. In particular, the selective estrogen receptor modulatory effects of tamoxifen contribute to menopausal symptoms, vaginal discharge, and the rare but worrisome risks of thromboembolism and uterine carcinoma. By contrast, the low levels of estrogen achieved with aromatase inhibition contribute to menopausal symptoms, vaginal dryness and sexual dysfunction, and accelerated bone demineralization with risk of osteoporosis and osteoporotic fracture. Clinical experience also suggests that AI therapy is associated with a novel musculoskeletal side effect consisting of an arthralgia syndrome. The actual incidence of AI-associated arthralgias or musculoskeletal symptoms is not known, though such symptoms are quite prevalent and appear more commonly with AI use than with tamoxifen. Arthralgias can be a reason for discontinuation of AI treatment. The possible mechanisms of AI-associated arthralgia are unclear. Estrogen deficiency causes bone loss, which in turn contributes to arthralgia. Less well-studied functions of estrogen include regulating immune cells and cytokines involved in bone remodeling, and modulating pain sensitivity at the level of the central nervous system. Arthralgia and arthritis have seldom been rigorously differentiated in clinical trials of AIs. Assessment of inflammatory and rheumatologic markers, as well as detailed evaluation of patient symptoms using appropriate quality-of-life instruments, may be warranted in order to understand both the symptoms and the etiology of the arthralgia syndrome. Treatment options for arthralgia (primarily non-steroidal anti-inflammatory drugs) are currently inadequate, but areas of active research include high-dose vitamin D and new-targeted therapies to inhibit bone loss.

Comparison of effects of 4-hydroxy tamoxifen and trilostane on oestrogen-regulated gene expression in MCF-7 cells: up-regulation of oestrogen receptor beta

4-Hydroxy tamoxifen (OHT) and trilostane interact differently with the oestrogen receptor (ER). OHT is a competitive inhibitor whereas trilostane has direct, but non-competitive effects on ER. This study compared the effects of OHT and trilostane, in the presence of 17beta-oestradiol (E2) on gene expression in MCF-7 breast cancer cells using microarrays each representing nearly 20,000 human genes. Striking differences between the sets of genes affected by these two drugs were observed. Both OHT and trilostane affected transcription of genes involved in cell cycle regulation, cell adhesion and matrix formation, however, only 12.5% of trilostane down-regulated genes and 9.2% of up-regulated genes were similarly regulated by OHT. A selective up-regulation of ERbeta by trilostane, but not OHT, was observed and confirmed by qRT-PCR. Similar up-regulation of this gene by trilostane was observed in the uterus of trilostane-treated (4 mg/kg for 7 days) rats, in which ERbeta mRNA (3-fold) and ERbeta protein expression (10-fold) were both increased. These data show that OHT and trilostane regulate the expression of different sets of genes, reflecting their different modes of interaction with ER. Trilostane-specific up-regulation of ERbeta could explain its positive benefit rates in acquired tamoxifen resistance.

Non-steroidal anti-inflammatory drug (NSAID) use and levels of a lipid oxidation marker in plasma and nipple aspirate fluids

Non-steroidal anti-inflammatory drugs (NSAIDs) are thought to reduce cancer risk by inhibiting cyclo-oxygenases, resulting in deceased formation of inflammatory mediators and oxidative stress. We examined whether the level of one oxidative stress marker, 15-F(2t)-isoprostane, was affected by NSAID use in plasma and breast nipple aspirate fluids (NAF) of pre-menopausal women who were participating in a dietary intervention trial (n=121). Baseline levels of 15-F(2t)-isoprostane were lower in NSAID users than non-users in both NAF and plasma, although the differences did not persist after intervention. Over the duration of the study, information on NSAID use was collected five times, and average 15-F(2t)-isoprostane levels in both NAF and plasma exhibited a statistically significant trend for decreases with increased frequency of NSAID use. These results indicate that NSAID use can result in lower levels of 15-F(2t)-isoprostane, which may have implications for the effects of NSAID use on breast cancer risk.