Relationship between the expression of cyclooxygenase 2 and MDR1/P-glycoprotein in invasive breast cancers and their prognostic significance

Genistein, a Potential Phytochemical against Breast Cancer Treatment-Insight into the Molecular Mechanisms

Breast cancer (BC) is one of the most common malignancies in women. Although widespread successful synthetic drugs are available, natural compounds can also be considered as significant anticancer agents for treating BC. Some natural compounds have similar effects as synthetic drugs with fewer side effects on normal cells. Therefore, we aimed to unravel and analyze several molecular mechanisms of genistein (GNT) against BC. GNT is a type of dietary phytoestrogen included in the flavonoid group with a similar structure to estrogen that might provide a strong alternative and complementary medicine to existing chemotherapeutic drugs. Previous research reported that GNT could target the estrogen receptor (ER) human epidermal growth factor receptor-2 (HER2) and several signaling molecules against multiple BC cell lines and sensitize cancer cell lines to this compound when used at an optimal inhibitory concentration. More specifically, GNT mediates the anticancer mechanism through apoptosis induction, arresting the cell cycle, inhibiting angiogenesis and metastasis, mammosphere formation, and targeting and suppressing tumor growth factors. Furthermore, it acts via upregulating tumor suppressor genes and downregulating oncogenes in vitro and animal model studies. In addition, this phytochemical synergistically reverses the resistance mechanism of standard chemotherapeutic drugs, increasing their efficacy against BC. Overall, in this review, we discuss several molecular interactions of GNT with numerous cellular targets in the BC model and show its anticancer activities alone and synergistically. We conclude that GNT can have favorable therapeutic advantages when standard drugs are not available in the pharma markets.

Friend or foe: ABCG2, ABCC1 and ABCB1 expression in triple-negative breast cancer

BACKGROUND

ATP-binding cassette (ABC) transporters are responsible for the efflux of a wide variety of anti-cancer agents and have been implicated in the chemoresistance of various solid tumors. Chemoresistance is a major cause of therapeutic failure, especially in the highly aggressive triple-negative breast cancer (TNBC) in which, unlike estrogen receptor-expressing (ER+) BC, both endocrine and targeted treatments are ineffectual. We aimed to investigate the level and frequency of expression of the three most important ABC transporter, ABCG2, ABCC1, and ABCB1, according to breast cancer subtype.

METHODS

We evaluated ABCG2, ABCC1, and ABCB1 protein expressions in 124 primary breast tumors (78 samples were classified as TNBC, while 46 were classified as ER+) by immunohistochemistry and correlated it to clinicopathological characteristics and outcome.

RESULTS

All three transporters had significantly higher expression and were more frequently expressed in TNBC compared to ER+ tumors (p < 0.0001). ABCG2 and ABCC1 had a very high level of expression in TNBC that was significantly greater compared to ABCB1 (p < 0.0001). ABCB1 expression was associated with TNBC metastatic spread (p = 0.03). In contrast, TNBC patients with high ABCG2 expression level had significantly longer disease-free interval (p = 0.03) and overall survival (p = 0.007).

CONCLUSION

ABCG2, ABCC1, and ABCB1 expression in breast cancer is subtype-specific and associated with triple-negative tumors. The expression of ABCB1 may be useful as a marker of metastatic spread. Moreover, unexpectedly, our results showed a beneficial effect of ABCG2 expression on TNBC clinical behavior. These findings could have implications for the implementation of future TNBC treatment strategies.

MDR1 not CYP3A4 gene expression is the predominant mechanism of innate drug resistance in pediatric soft tissue sarcoma patients

BACKGROUND

Intratumoral up-regulation of genes coding for drug transporters and metabolizing enzymes, such as MDR1 and CYP3A4, after chemotherapy are linked to cancer drug resistance. However their expression in primary soft tissue sarcomas (STS) prior to drug treatment and their role in innate resistance remain unclear.

OBJECTIVE

The aim of this study was characterize MDR1 and CYP3A4 expression pattern before to chemotherapy and its clinical implication in pediatric STS.

METHODS

In this prospective study we analyzed MDR1 and CYP3A4 mRNA expression in both normal and tumor tissues from 28 newly diagnosed STS pediatric and then compared with patients' clinical-pathological data, including chemotherapy response.

RESULTS

Our data showed that the expression of the MDR1 gene was significantly higher in malignant tissue than in the normal tissues of patients with STS. In addition, high MDR1 expression was significantly associated with local advances, as well as poor response to treatment. In contrast, CYP3A4 expression level was negligible in both tumoral and non-tumoral tissues.

CONCLUSIONS

These results suggest that a significant mRNA level of MDR1 gene was intrinsically present in STS before exposure to chemotherapeutic drugs, suggesting that MDR1 may be important contributors of innate chemoresistance of this tumor type.

The effects of ultrasound exposure on P-glycoprotein-mediated multidrug resistance in vitro and in vivo

Background

Multidrug resistance (MDR) is often responsible for the failure of chemotherapy treatment, and current strategies for cancer MDR are not adequately satisfying as to their efficacy and safety. In this study, we sought to determine the anti-MDR effects of ultrasound (US) irradiation and its underlying mechanisms against drug-resistance.

Methods

MDR variant MCF-7/ADR cell lines and endothelial cell lines were used to determine the appropriate ultrasound intensity for in vitro experiments. MCF-7/ADR cell and HEPG2/ADM cells were used to assess the anti-MDR effect of US irradiation. Intracellular adriamycin (ADM) accumulation, Cell viability, cell proliferation and cell apoptosis were evaluated after ADM + US treatment or ADM treatment alone. MCF-7/ADR xenograft mice were used to investigate the appropriate ultrasound intensity for in vivo experiments and its effect on the long-term prognosis. Underlining mechanisms by which ultrasound exposure reversing MDR phenotype were investigated both in vitro and in vivo.

Results

Combination of ADM and 0.74 W/cm² US irradiation enhanced ADM intracellular concentration and nuclear accumulation in MCF-7/ADR and HEPG2/ADM cells, compared to those treated with ADM alone. Enhanced cellular ADM uptake and nuclei localization was associated with increased cytotoxicity of ADM to ADM-resistant cells, lower ADM-resistant cell viability and proliferative cell ratio, and higher apoptotic cell ratio. More importantly, US exposure increased the effectiveness of ADM to inhibit tumor growth in MCF-7/ADR xenograft mice. Mechanistically, US exposure promoted ADM accumulation in MDR cells mainly through down-regulation of P-glycoprotein (P-gp), which is dependent on US-induced intracellular reactive oxygen species (ROS) production. US-induced oxidative stress promoted miR-200c-3p and miR-34a-3p expression by forming miR-200c/34a/ZEB1 double-negative feedback loop. Finally, US-induced miR-200c/34a overexpression decreased P-gp expression and reversed MDR phenotype.

Conclusion

US irradiation could reverse MDR phenotype by activating ROS-ZEB1-miR200c/34a-P-gp signal pathway. Our findings offer a new and promising strategy for sensitizing cells to combat MDR and to improve the therapeutic index of chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0900-6) contains supplementary material, which is available to authorized users.

Pilot study: duodenal MDR1 and COX2 gene expression in cats with inflammatory bowel disease and low-grade alimentary lymphoma

Objectives Multidrug resistance 1 (MDR1) encodes a protein called P-glycoprotein (P-gp), which serves as an efflux pump membrane protein implicated in intestinal homeostasis and drug resistance. Cyclooxygenase-2 (COX2) is a key enzyme in the synthesis of proinflammatory prostaglandins, tumourigenesis and in mucosal defence. Despite the importance of MDR1 and COX2, changes in their mRNA levels have not been studied in cats with inflammatory bowel disease (IBD) and low-grade alimentary lymphoma (LGAL). The present study aimed to determine the mRNA levels of MDR1 and COX2 in cats with IBD and LGAL, and to evaluate their correlation with clinical signs, histological severity and between genes. Methods Cats diagnosed with IBD (n = 20) and LGAL (n = 9) between 2008 and 2015 were included in the current study. Three healthy animals composed the healthy control cats group in which endoscopy was performed immediately before the ovariohysterectomy. All duodenal biopsy samples were obtained by endoscopy. Feline chronic enteropathy activity index was calculated for all cases. IBD histopathology was classified according to severity. MDR1 and COX2 mRNA levels were determined by absolute reverse transcriptase-quantitative real-time PCR. Results Statistically significant differences were observed for MDR1 and COX2 mRNA levels between the IBD and LGAL groups. No correlations were observed between molecular gene expression, feline chronic enteropathy activity index and histological grading for IBD, and between MDR1 and COX2 genes. However, a positive statistically significant correlation was observed between MDR1 and COX2 expression in the duodenum of cats. Conclusions and relevance MDR1 and COX2 gene expression is increased in cats with LGAL compared with cats with IBD. The control group tended to have lower values than both diseased groups. These results suggest that these genes may be involved in the pathogenesis of IBD or LGAL in cats.

Clinicopathological and prognostic significance of COX-2 immunohistochemical expression in breast cancer: a meta-analysis

The prognostic significance of COX-2 in patients with breast cancer remains controversial. The aims of our meta-analysis are to evaluate its association with clinicopathological characteristics and prognostic value in patients with breast cancer. PubMed, EMBASE, Web of Science, the Ovid Database and Grey literature were systematically searched up to May 2016. Twenty-one studies including 6739 patients with breast cancer were analyzed. The meta-analysis indicated that the incidence difference of COX-2 expression was significant when comparing the lymph node positive group to negative group (OR = 1.76, 95% CI [1.30, 2.39]) and the tumor size ≥ 2cm group to the tumor size < 2cm group (OR = 1.71, 95% CI [1.22, 2.39]). None of other clinicopathological parameters such as the ER status, PR status, HER2 status and the vascular invasion status were associated with COX-2 overexpression. The detection of COX-2 was significantly correlated with the disease-free survival (DFS) of patients (HR = 1.58, 95% CI [1.23, 2.03]) and the overall survival (OS) of patients (HR = 1.51, 95% CI [1.31, 1.72]). Our meta-analysis demonstrates that the presence of high levels of COX-2 is associated with poor prognosis for breast cancer patients and predicts bigger tumor size and lymph node metastasis.

PD-1/PD-L1 interaction up-regulates MDR1/P-gp expression in breast cancer cells via PI3K/AKT and MAPK/ERK pathways

Programmed cell death ligand 1 (PD-L1) is an immunosuppressive molecule expressed on tumor cells. By interacting with programmed cell death-1 (PD-1) on T cells, it inhibits immune responses. Because PD-L1 expression on cancer cells increases their chemoresistance, we investigated the correlation between PD-L1 and multidrug resistance 1/ P-glycoprotein (MDR1/P-gp) expression in breast cancer cells. Analysis of breast cancer tissues using tissue microarrays revealed a significant correlation between PD-L1 and MDR1/P-gp protein levels. Increased expression of PD-L1 was associated with lymph node metastasis and histological tumor grade. In addition, interaction of PD-L1 with PD-1 induced phosphorylation of AKT and ERK, resulting in the activation of PI3K/AKT and MAPK/ERK pathways and increased MDR1/P-gp expression in breast cancer cells. The PD-1/PD-L1 interaction also increased survival of breast cancer cells incubated with doxorubicin. These findings suggest that the PD-1/PD-L1 inhibition may increase chemotherapy efficacy by inhibiting the MDR1/P-gp expression in breast cancer cells.

Loss of constitutive ABCB1 expression in breast cancer associated with worse prognosis

ABCB1 gene encodes an adenosine 5′-triphosphate–binding cassette transporter, which not only confers multidrug resistance phenotype in malignant cells, but is also present in several nonmalignant tissues. For the last thirty years, ABCB1 expression in breast cancer has been described by many authors, but the extent of expression differs among the studies, and there is no consensus regarding its potential role in carcinogenesis or in the tumor response to antineoplastic drugs. This study aimed to characterize the expression of ABCB1 in breast tumors as a function of genetic, clinical, and histopathological variables. The ABCB1 expression was also evaluated in nonmalignant mammary tissues adjacent to tumors and in benign lesions. The detection of ABCB1 protein was performed by immunohistochemistry in tissue specimens of excised breasts obtained from a prospective cohort of Brazilian women with breast cancer. The association of ABCB1 protein levels with ABCB1 mRNA, gene polymorphisms, and clinical and histopathological variables was also evaluated. The Kaplan–Meier curves and multivariate Cox regression analyses were conducted to identify independent predictors of disease-free survival of patients with breast cancer. ABCB1 was detected in 86.3% (656) of breast tumors, 98.8% (606) of nonmalignant mammary tissue adjacent to tumors, and 100% (28) of benign lesions. Reduced ABCB1 protein levels in breast tumors was associated with triple-negative subtype (adjusted odds ratio [OR_adj] =0.24; 95% confidence interval [CI] =0.13–0.45), lymph node status < pN2 (OR_adj =0.27; 95% CI =0.10–0.71), tumor size >2 cm (OR_adj =0.55; 95% CI =0.32–0.93), and hypertensive status (OR_adj =0.42; 95% CI =0.24–0.73), and it was significantly associated with shorter disease-free survival, either for all breast cancer patients (p log-rank =0.012; hazard ratio [HR] =3.46; 95% CI =1.21–9.91) or for those with triple-negative tumors (p log-rank =0.007; HR =11.41; 95% CI =1.29–100.67). The loss of constitutive ABCB1 expression in breast cancer, especially in triple-negative tumors, seems to indicate a subgroup of worse prognosis.

Inhibition of HIF-1α by PX-478 suppresses tumor growth of esophageal squamous cell cancer in vitro and in vivo

The aim of this study is to investigate the clinical significance of hypoxia inducible factor-1α (HIF-1α) expression in esophageal squamous cell cancer (ESCC) and clarify the effects of PX-478, a selective HIF-1α inhibitor, on ESCC both in vitro and in vivo. HIF-1α, cyclooxygenase-2 (COX-2) and programmed death ligand-1 (PD-L1) were markedly overexpressed in ESCC tissue and associated with poorer survival. In vitro, both COX-2 and PD-L1 expression of ESCC cells were significantly induced by CoCl₂ treatment, but inhibited by HIF-1α knock-down or PX-478 treatment. Furthermore, PX-478 significantly inhibited tumor cell proliferation by inhibiting the G2/M transition and promoting apoptosis of ESCC cells. In addition, inhibited epithelial-mesenchymal transition was observed after PX-478 treatment. In vivo, PX-478 significantly decreased tumor volume following subcutaneous implantation. Together, our results indicated that PX-478 had significant antitumor activity against HIF-1α over-expressing ESCC tumors in vitro and in vivo. These results opened up the possibility of inhibiting HIF-1α for targeted therapy of ESCC.

Celecoxib enhances anticancer effect of cisplatin and induces anoikis in osteosarcoma via PI3K/Akt pathway

Background

COX-2, an inducible enzyme, is associated with inflammatory diseases and carcinogenesis. Overexpression of COX-2 occurs in many human malignancies, including osteosarcoma. COX-2 positivity is form 67 to 92% in osteosarcoma, and COX-2 expresses 141-fold more in cancer stem cell spheres than daughter adherent cells. In our study, we have reported that celecoxib, a cyclooxygenase-2 inhibitor, induces apoptosis in human osteosarcoma cell line MG-63 via down-regulation of PI3K/Akt. It has been confirmed that celecoxib enhances apoptosis and cytotoxic effect of cisplatin, although the mechanism remains unclear.

Methods

We have attempted to identify the anti-proliferation of celecoxib, a selective COX-2 inhibitor, and the combination of celecoxib and cisplatin in MG-63 cells, and to explore the potential molecular mechanisms involved. MG-63 cells were treated with the combination of celecoxib and cisplatin or either agent alone for 48 h in serum-supplemented medium.

Results

MDR1, MRP1, BCRP and Trkb, E-cadherin, β-catenin were significantly downregulated in cells treated with the combination of celecoxib and cisplatin, and decreased β-catenin level was found in cells with wortmannin, a specific PI3K inhibitor.

Conclusion

Therefore, celecoxib enhances anticancer effect of cisplatin and induces anoikis in osteosarcoma, which may be PI3K/Akt-dependent, and MDR and β-catenin-related. PI3K may be at the center of the celecoxib effects, which play an essential role in the regulation of MDR and anoikis.

The prognostic impact of COX-2 expression in breast cancer depends on oral contraceptive history, preoperative NSAID use, and tumor size

The association between tumor cyclooxygenase 2 (COX-2) expression and breast cancer prognosis has been inconsistent. The purpose of this study was to evaluate the prognostic significance of COX-2 tumor expression according to adjuvant treatment, and potential effect modifications of non-steroid anti-inflammatory drug (NSAID) use, and other tumor and lifestyle factors. A prospective cohort of 1,116 patients with primary breast cancer in Lund, Sweden, included 2002-2012 was followed until June 2014 (median 5 years). Tumor-specific COX-2 expression was evaluated on tissue microarrays using immunohistochemistry. Associations between COX-2 intensity (negative, weak-moderate, high) and patient and tumor characteristics as well as prognosis were analyzed. Tumor-specific COX-2 expression was available for 911 patients and was significantly associated with higher age at diagnosis and less aggressive tumor characteristics. Higher COX-2 expression was associated with lower risk for breast cancer events during the first five years of follow-up, _adj HR 0.60 (95%CI: 0.37-0.97), per category. The association between COX-2 expression and prognosis was significantly modified by oral contraceptive (OC) use (P_interaction  = 0.048), preoperative NSAID use (P_interaction  = 0.009), and tumor size (P_interaction  = 0.039). COX-2 negativity was associated with increased risk for events during the first five years in ever OC users, _adj HR 1.94 (1.01-3.72) and during the 11-year follow-up in preoperative NSAID users, _adj HR 4.51 (1.18-11.44) as well as in patients with large tumors, _adj HR 2.57 (1.28-5.15). In conclusion, this study, one of the largest evaluating COX-2 expression in breast cancer, indicates that the prognostic impact of COX-2 expression depends on host factors and tumor characteristics.

Repurposing Drugs in Oncology (ReDO)-diclofenac as an anti-cancer agent

Diclofenac (DCF) is a well-known and widely used non-steroidal anti-inflammatory drug (NSAID), with a range of actions which are of interest in an oncological context. While there has long been an interest in the use of NSAIDs in chemoprevention, there is now emerging evidence that such drugs may have activity in a treatment setting. DCF, which is a potent inhibitor of COX-2 and prostaglandin E2 synthesis, displays a range of effects on the immune system, the angiogenic cascade, chemo- and radio-sensitivity and tumour metabolism. Both pre-clinical and clinical evidence of these effects, in multiple cancer types, is assessed and summarised and relevant mechanisms of action outlined. Based on this evidence the case is made for further clinical investigation of the anticancer effects of DCF, particularly in combination with other agents - with a range of possible multi-drug and multi-modality combinations outlined in the supplementary materials accompanying the main paper.

Increase in cyclooxygenase-2 (COX-2) expression in keratinocytes and dermal fibroblasts in photoaged skin

BACKGROUND

Interleukins and NFκ-B are involved in the development of inflammatory reactions. It has been suggested that these proteins are important contributing factors in the process of photoaging of skin. Moreover, interleukins and NFκ-B are known to be capable of inducing expression of cyclooxygenase 2 (COX-2). Expression of COX-2 in various populations of skin cells has not been examined in the specific processes of aging.

OBJECTIVES

The study aimed at evaluating COX-2 expression in skin samples originating from patients with chronologically aged and photoaged skin at various stages of skin aging.

METHODS

Immunohistochemical analysis of COX-2 reactivity was conducted on samples originating from 52 women undergoing surgery for reasons other than skin pathology.

RESULTS

Our study demonstrated that COX-2 expression in keratinocytes and fibroblasts was significantly higher in skin samples affected by photoaging than in samples affected by endogenous aging or obtained from younger individuals.

CONCLUSIONS

The results indicate that COX-2 may be involved in the pathogenesis of the photoaging process. Inhibition of expression or activity of the enzyme may find application in photoaging treatment and/or prophylaxis.

Potency of non-steroidal anti-inflammatory drugs in chemotherapy

Cancer cell resistance, particularly multidrug resistance (MDR), is the leading cause of chemotherapy failure. A number of mechanisms involved in the development of MDR have been described, including the overexpression of ATP-dependent membrane-bound transport proteins. The enhanced expression of these proteins, referred to as ATP-binding cassette (ABC) transporters, results in an increased cellular efflux of the cytotoxic drug, thereby reducing its intracellular concentration to an ineffective level. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently consumed drugs worldwide. NSAIDs are mainly used to treat pain, fever and inflammation. Numerous studies suggest that NSAIDs also show promise as anticancer drugs. NSAIDs have been shown to reduce cancer cell proliferation, motility, angiogenesis and invasiveness. In addition to these effects, NSAIDs have been shown to induce apoptosis in a wide variety of cancer types. Moreover, several studies have indicated that NSAIDs may sensitise cancer cells to the antiproliferative effects of cytotoxic drugs by modulating ABC transporter activity. Therefore, combining specific NSAIDs with chemotherapeutic drugs may have clinical applications. Such treatments may allow for the use of a lower dose of cytotoxic drugs and may also enhance the effectiveness of therapy. The objective of this review was to discuss the possible role of NSAIDs in the modulation of antitumour drug cytotoxicity. We particularly emphasised on the use of COX-2 inhibitors in combination with chemotherapy and the molecular and cellular mechanisms underlying the alterations in outcome that occur in response to this combination therapy.

Effects and mechanism of downregulation of COX‑2 expression by RNA interference on proliferation and apoptosis of human breast cancer MCF‑7 cells

The aim of the present study was to investigate the effects of RNA interference with prostaglandin-endoperoxide synthase 2 (COX‑2) gene on the proliferation and apoptosis of breast cancer MCF‑7 cells, as well as the underlying mechanism. The present study constructed the eukaryotic expression vector of the targeted COX‑2 gene, transfected the MCF‑7 cells and screened the stably expressed clone. Changes in the COX‑2 gene expression in breast cancer MCF‑7 cells prior to and following transfection were examined; the proliferation and apoptosis of MCF‑7 cells were analyzed. Furthermore, changes in the protein levels of survivin, B-cell lymphoma 2 (Bcl‑2) and Bcl-2-associated X (Bax) genes were detected. RNA interference mediated by a lentiviral expression vector significantly decreased the protein expression levels of the COX‑2 gene, and therefore, the proliferation and growth of breast cancer MCF‑7 cells was significantly suppressed and the apoptotic rate increased. Of note, the mRNA and protein expression levels of survivin and Bcl‑2 decreased, while those of Bax increased following COX-2 silencing. RNA interference markedly deactivated the COX‑2 gene, suppressed the proliferation of breast cancer MCF‑7 cells, and, to a certain extent, enhanced the induced spontaneous apoptosis, which is regulated by the Bax gene. These results provided evidence for the potential applications of RNA interference of the targeted COX‑2 gene in gene therapy for the treatment of breast cancer.

Association of drug transporter expression with mortality and progression-free survival in stage IV head and neck squamous cell carcinoma

Drug transporters such as P-glycoprotein (ABCB1) have been associated with chemotherapy resistance and are considered unfavorable prognostic factors for survival of cancer patients. Analyzing mRNA expression levels of a subset of drug transporters by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or protein expression by tissue microarray (TMA) in tumor samples of therapy naïve stage IV head and neck squamous cell carcinoma (HNSCC) (qRT-PCR, n = 40; TMA, n = 61), this in situ study re-examined the significance of transporter expression for progression-free survival (PFS) and overall survival (OS). Data from The Cancer Genome Atlas database was used to externally validate the respective findings (n = 317). In general, HNSCC tended to lower expression of drug transporters compared to normal epithelium. High ABCB1 mRNA tumor expression was associated with both favorable progression-free survival (PFS, p = 0.0357) and overall survival (OS, p = 0.0535). Similar results were obtained for the mRNA of ABCC1 (MRP1, multidrug resistance-associated protein 1; PFS, p = 0.0183; OS, p = 0.038). In contrast, protein expression of ATP7b (copper transporter ATP7b), mRNA expression of ABCG2 (BCRP, breast cancer resistance protein), ABCC2 (MRP2), and SLC31A1 (hCTR1, human copper transporter 1) did not correlate with survival. Cluster analysis however revealed that simultaneous high expression of SLC31A1, ABCC2, and ABCG2 indicates poor survival of HNSCC patients. In conclusion, this study militates against the intuitive dogma where high expression of drug efflux transporters indicates poor survival, but demonstrates that expression of single drug transporters might indicate even improved survival. Prospectively, combined analysis of the ‘transportome’ should rather be performed as it likely unravels meaningful data on the impact of drug transporters on survival of patients with HNSCC.

Stromal, rather than epithelial cyclooxygenase-2 (COX-2) expression is associated with overall survival of breast cancer patients

Background

Prognostic value of enhanced COX-2 expression in breast cancer has been controversial for a long time. The opinions vary widely between studies. Moreover, significant majority of studies considered only COX-2 expression in cancer epithelial cells.

Methods

We examined the prognostic value of COX-2 expression in both epithelial and stromal cells using three different antibodies and three algorithms of immunohistochemical scoring and categorizing the tumours into COX-2 overexpressing groups.

Results

Our results demonstrate that COX-2 expression in stromal cells is independent prognostic factor indicating worse overall survival of patients. Such a result was obtained using each of the three antibodies and two of the algorithms used for evaluations of COX-2 expression levels. We also show that immunohistochemical assessment of the prognostic value of COX-2 expression in cancer epithelial cells depends to a large extent on a combination of primary antibodies and algorithms used for determination of the COX-2 over-expressing tumours.

Conclusions

Our results indicate that stromal expression of COX-2 is independent prognostic parameter relatively insensitive to variations in sensitivity of antibodies used for its determination. Wide scatter of the published results concerning prognostic value of COX-2 expression in breast cancer tissues seems to be due to a large extent to multitude of antibodies and scoring algorithms used by different groups.

Nuclear-cytoplasmic PARP-1 expression as an unfavorable prognostic marker in lymph node‑negative early breast cancer: 15-year follow-up

PARP-1 plays an important role in DNA damage repair and maintaining genome integrity by repairing DNA single-strand breaks (SSBs) by base excision repair (BER). The aim of the present study was to examine the expression of PARP-1 in breast cancer (BC) patients and to assess the relationship between the subcellular localization of this protein and clinicopathological characteristics. The reactivity of PARP-1 was analyzed by immunohistochemistry in a homogeneous group of 83 stage II ductal BC patients with a 15-year follow-up. Immunostaining of PARP-1 was also evaluated in 4 human BC cell lines and resistance prediction profile for 11 anticancer agents was performed using 3 models of drug-resistant cell lines. Nuclear-cytoplasmic expression (NCE) was associated with shorter overall survival, which was not statistically significant during the 10-year follow-up but became statistically significant after 10 years of observation, during the 15-year follow-up (P=0.015). Analysis performed in subgroups of patients with (N+) and without (N-) nodal metastases showed that NCE was associated with poor clinical outcome in N- patients (P=0.017). Multivariate analysis confirmed a significant impact of NCE on unfavorable prognosis in N- early BC. The presence of PARP-1 NCE may be a new potential unfavorable prognostic factor in lymph node- negative early BC.

Metabolism and transport of tamoxifen in relation to its effectiveness: new perspectives on an ongoing controversy

Tamoxifen reduces the rate of breast cancer recurrence by approximately a half. Tamoxifen is metabolized to more active metabolites by enzymes encoded by polymorphic genes, including cytochrome P450 2D6 (CYP2D6). Tamoxifen is a substrate for ATP-binding cassette transporter proteins. We review tamoxifen's clinical pharmacology and use meta-analyses to evaluate the clinical epidemiology studies conducted to date on the association between CYP2D6 inhibition and tamoxifen effectiveness. Our findings indicate that the effect of both drug-induced and/or gene-induced inhibition of CYP2D6 activity is likely to be null or small, or at most moderate in subjects carrying two reduced function alleles. Future research should examine the effect of polymorphisms in genes encoding enzymes in tamoxifen's complete metabolic pathway, should comprehensively evaluate other biomarkers that affect tamoxifen effectiveness, such as the transport enzymes, and focus on subgroups of patients, such as premenopausal breast cancer patients, for whom tamoxifen is the only guideline endocrine therapy.

Celecoxib Up Regulates the Expression of Drug Efflux Transporter ABCG2 in Breast Cancer Cell Lines

Elevated expression of the drug efflux transporter ABCG2 seems to correlate with multidrug resistance of cancer cells. Specific COX-2 inhibitor celecoxib has been shown to enhance the sensitivity of cancer cells to anticancer drugs. To clarify whether ABCG2 inhibition is involved in the sensitizing effect of celecoxib, we investigated whether the expression of ABCG2 in breast cancer cell lines, could be modulated by celecoxib. The expression of the multidrug resistant gene (ABCG2) at mRNA and protein level was detected by real-time quantitative reverse transcription-polymerase chain reaction and flow cytometry analysis, respectively. Among three human breast cancer cell lines ABCG2 and COX-2 were highly expressed in MCF7-MX and MDA-MB-231 cells, respectively. The COX-2 inhibitor celecoxib up-regulated the expression of ABCG2 mRNA in MCF-7 and MCF7-MX cells, which was accompanied by increased ABCG2 protein expression. While celecoxib was able to block the 12-O-tetradecanoylphorbol-13-acetate (TPA)-mediated increase in COX-2 expression in MDA-MB-231 cells, it increased the expression of ABCG2 up to 4.27 times to the control level at mRNA level and with less intensity at protein level. Our findings provide evidence that celecoxib up-regulates ABCG2 expression in human breast cancer cells and proposed that ABCG2 is not involved in chemosensitizing effects of celecoxib.

P-glycoprotein associates with Anxa2 and promotes invasion in multidrug resistant breast cancer cells

Several recent studies have suggested that the acquisition of the multidrug resistance (MDR) phenotype is associated with elevated invasion and metastasis of tumor cells. P-glycoprotein (P-gp), the major determinant in the generation of the MDR phenotype, was reported to be correlated with a more aggressive phenotype and poor prognosis in many forms of malignancies. However, a clear understanding of the association is still lacking. We previously showed that Anxa2, a calcium-dependent phospholipid-binding protein, interacts with P-gp and contributes to the invasiveness of MDR breast cancer cells. In the present study, a strong positive correlation between MDR1 and Anxa2 mRNA expression in invasive breast cancer tissues during cancer progression was observed. In addition, exposure to adriamycin significantly enhanced motility in breast cancer cells and increased levels of P-gp and Anxa2. Moreover, inhibition of P-gp activity, using selective P-gp modulators, was found to significantly inhibit the invasive capacity of MCF-7/ADR cells without affecting the interaction and co-localization between P-gp and Anxa2. However, suppression of P-gp pump activity and knockdown of MDR1 expression both disrupted adriamycin-induced Anxa2 phosphorylation. Interestingly, P-gp was further demonstrated to interact with Src, a tyrosine kinase upstream of Anxa2. Taken together, our results indicate that P-gp may promote the invasion of MDR breast cancer cells by modulating the tyrosine phosphorylation of Anxa2. The interaction between Anxa2 and P-gp is possibly, at least in part, responsible for the association between MDR and invasive potential in breast cancer cells.

Hexokinase II in breast carcinoma: a potent prognostic factor associated with hypoxia-inducible factor-1α and Ki-67

Hypoxia-inducible factor-1α (HIF-1α) mediates adaptive responses to changes under tissue hypoxia in carcinoma cells by controlling the expression of various target genes. Previous studies have demonstrated that HIF-1α is associated with adverse clinical outcome in breast carcinoma patients, but details of HIF-1α's role have remained largely unknown. Therefore, in this study, we examined the expression profiles of HIF-1α-induced genes in 10 breast carcinoma cases using microarray data. As a result, we demonstrated that the status of hexokinase II (HKII) was associated with carcinoma recurrence in patients with these genes. The enzyme HKII is involved in the first, and rate-limiting, step of glycolysis, but its clinical significance has not yet been examined in breast carcinoma. Therefore, we immunolocalized HKII in 118 breast carcinomas, and HKII immunoreactivity was detected in 44% of the cases. It is significantly associated with histological grade, Ki-67 labeling index and HIF-1α immunoreactivity. Also, HKII status is significantly associated with increased risk of recurrence and adverse clinical outcome in breast cancer patients. Subsequent multivariate analysis demonstrated that HKII status was an independent prognostic factor for disease-free survival of patients. These results all suggest that HKII is induced by HIF-1α and plays important roles in the proliferation and/or progression of breast carcinoma possibly through increased glycolytic activity. The status of HKII is therefore considered a potent prognostic factor in human breast cancer patients.

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.

Phorbol ester TPA modulates chemoresistance in the drug sensitive breast cancer cell line MCF-7 by inducing expression of drug efflux transporter ABCG2

Recent studies have indicated a link between levels of cyclooxygenase-2 (COX-2) and development of the multidrug resistance (MDR) phenotype. The ATP-binding cassette sub-family G member 2 (ABCG2) is a major MDR-related transporter protein that is frequently overexpressed in cancer patients. In this study, we aimed to evaluate any positive correlation between COX-2 and ABCG2 gene expression using the COX-2 inducer 12-O-tetradecanoylphorbol-13-acetate (TPA) in human breast cancer cell lines. ABCG2 mRNA and protein expression was studied using real-time RT-PCR and flow cytometry, respectively. A significant increase of COX-2 mRNA expression (up to 11-fold by 4 h) was induced by TPA in MDA-MB-231 cells, this induction effect being lower in MCF-7 cells. TPA caused a considerable increase up to 9-fold in ABCG2 mRNA expression in parental MCF-7 cells, while it caused a small enhancement in ABCG2 expression up to 67 % by 4 h followed by a time-dependent decrease in ABCG2 mRNA expression in MDA-MB-231 cells. TPA treatment resulted in a slight increase of ABCG2 protein expression in MCF-7 cells, while a time-dependent decrease in ABCG2 protein expression was occurred in MDA-MB-231 cells. In conclusion, based on the observed effects of TPA in MDA-Mb-231 cells, it is proposed that TPA up-regulates ABCG2 expression in the drug sensitive MCF-7 breast cancer cell line through COX-2 unrelated pathways.

Cyclooxygenase-2 inhibitor combined with capecitabine and oxaliplatin (XELOX) as a first-line therapy for advanced gastric cancer: An analysis of 24 cases

AIM: To evaluate the efficacy and toxicity of oxaliplatin combined with capecitabine (XELOX regimen) plus cyclooxygenase-2 (COX-2) inhibitor celecoxib in the treatment of advanced gastric cancer (AGC).

METHODS: Forty-seven eligible patients were randomly assigned to a trial group and a control group. In the trial group, 24 patients were treated with celecoxib plus the XELOX regimen, while 23 patients in the control group omitted the oral intake of celecoxib. Treatment was repeated every 3 wk.

RESULTS: There was no significant difference in the overall response rate (RR) between the trial group and control group (50.0% vs 39.1%, P > 0.05). The disease control rate (DCR) was significantly higher in the trial group than in the control group (91.7% vs 65.2%, P < 0.05). The percentage of patients with improved quality of life (QOL) was significantly higher in the trial group than in the control group (83.3% vs 56. 5%, P < 0.05). The median time to progression (mTTP) was significantly longer in the trial group than in the control group (7.2 mo vs 5.7 mo, P < 0.05). The median survival time (MST) and one-year overall survival (OS) rate in the trial group were higher than these in the control group, but there was no statistically significant difference between the two groups (MST: 12.5 mo vs 11.3 mo; OS rate: 47.6% vs 41.2%; both P > 0.05). The incidence of hand-foot syndrome (HFS) was significantly lower in the trial group than in the control group (12.5% vs 39.1%, P < 0.05). Other toxicities were similar between the two groups. No chemotherapy-related death occurred.

CONCLUSION: COX-2 inhibitor combined with the XELOX regimen can improve the disease control rate and quality of life, reduce the incidence of hand-foot syndrome, and benefit median time to progression, but not overall survival time, in the treatment of advanced gastric cancer.

Expressions of putative cancer stem cell markers ABCB1, ABCG2, and CD133 are correlated with the degree of differentiation of gastric cancer

BACKGROUND

The present study was carried out to determine whether a quantitative relationship exists between the expressions of 3 cancer stem cell (CSC) markers and the degree of differentiation of gastric cancer.

METHODS

The expressions of 3 putative CSC markers, ABCB1, ABCG2, and CD133, were detected in 90 human gastric adenocarcinoma cases by immunofluorescence assay. The differentiation statuses of 3 gastric cancer cell lines (the undifferentiated gastric cancer cell line HGC-27, the poorly differentiated gastric cancer cell line BGC-823, and the moderately-poorly differentiated gastric adenocarcinoma cell line SGC-7901) were observed and compared by performing the 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. Gastric xenotransplant cancers in nude mice were constructed to compare the malignancy of the 3 variously differentiated gastric cancer cell lines. The expressions of the 3 putative CSC markers were also detected in the 3 gastric cancer cell lines in vitro by flow cytometric analysis and in the 3 gastric xenotransplant cancers in vivo by immunofluorescence staining.

RESULTS

The expressions of ABCB1, ABCG2, and CD133 were generally correlated with the degree of differentiation of the gastric cancers. In the human gastric adenocarcinomas and in the cancer cell lines, the expressions of ABCB1, ABCG2, and CD133 increased with the increases in the malignancy grades of the gastric cancers. In the human gastric adenocarcinomas, poorly differentiated adenocarcinoma expressed more ABCB1, ABCG2, and CD133 than well-differentiated adenocarcinoma. In addition, the expressions of ABCB1 and CD133 were higher in the diffuse type than in the intestinal type of human gastric cancers. The undifferentiated cell line HGC-27 expressed more putative CSC markers than the moderately-poorly differentiated cell line SGC-7901. Similar results were observed in the xenotransplant tumors that arose from the 3 gastric cancer cell lines.

CONCLUSIONS

The expressions of the CSC markers ABCB1, ABCG2, and CD133 differed in the gastric cancers with various degrees of differentiation, with poorly differentiated gastric cancer expressing relatively more CSC markers.

Immunohistochemical expression of epithelial and stromal immunomodulatory signalling molecules is a prognostic indicator in breast cancer

Background

The immune system has paradoxical roles during cancer development and the prognostic significance of immune modulating factors is controversial. The aim of this study was to determine the expression of cyclooxygenase 2 (COX-2), transforming growth factor-beta (TGF- beta), interleukin-10 (IL-10) and their prognostic significance in breast cancers. Ki67 was included as a measure of growth fraction of tumor cells.

Methods

On immunohistochemical stained slides from 38 breast cancer patients, we performed digital video analysis of tumor cell areas and adjacent tumor stromal areas from the primary tumors and their corresponding lymph node metastases. COX-2 was recorded as graded staining intensity.

Results

The expression of TGF-beta, IL-10 and Ki67 were recorded in tumor cell areas and adjacent tumor stromal areas. In both primary tumors and metastases, the expression of COX-2 was higher in the tumor stromal areas than in the tumor cell areas (both P < 0.001). High stromal staining intensity in the primary tumors was associated with a 3.9 (95% CI 1.1-14.2) times higher risk of death compared to the low staining group (P = 0.036). The expression of TGF-beta was highest in the tumor cell areas of both primary tumors and metastases (both P < 0.001). High stromal expression of TGF-beta was associated with increased mortality. For IL-10, the stromal expression was highest in the primary tumors (P < 0.001), whereas in the metastases the expression was highest in tumor cell areas (P < 0.001). High IL-10 expression in tumor- and stromal cell areas of primary tumors predicted mortality. Ki67 was higher expressed in tumor stromal areas of the metastases, and in tumor cell areas of the primary tumors (P < 0.001). Ki67 expression in tumor cell areas and stromal areas of the metastases was independently associated with breast cancer mortality.

Conclusions

Stromal expression of COX-2, TGF-beta and Ki67 may facilitate tumor progression in breast cancer.

Targeting MDR in breast and lung cancer: discriminating its potential importance from the failure of drug resistance reversal studies

This special issue of Drug Resistance Updates is dedicated to multidrug resistance protein 1 (MDR-1), 35 years after its discovery. While enormous progress has been made and our understanding of drug resistance has become more sophisticated and nuanced, after 35 years the role of MDR-1 in clinical oncology remains a work in progress. Despite clear in vitro evidence that P-glycoprotein (Pgp), encoded by MDR-1, is able to dramatically reduce drug concentrations in cultured cells, and that drug accumulation can be increased by small molecule inhibitors, clinical trials testing this paradigm have mostly failed. Some have argued that it is no longer worthy of study. However, repeated analyses have demonstrated MDR-1 expression in a tumor is a poor prognostic indicator leading some to conclude MDR-1 is a marker of a more aggressive phenotype, rather than a mechanism of drug resistance. In this review we will re-evaluate the MDR-1 story in light of our new understanding of molecular targeted therapy, using breast and lung cancer as examples. In the end we will reconcile the data available and the knowledge gained in support of a thesis that we understand far more than we realize, and that we can use this knowledge to improve future therapies.

COX-2 expression and tumor angiogenesis in thyroid carcinoma patients among northeast Chinese population-result of a single-center study

OBJECTIVE

Cyclooxygenase-2 (COX-2), one of the rate-limiting enzymes in the metabolism of arachidonic acid which is reported to be involved in the pathogenesis of many human tumors. As well, Vascular endothelial growth factor (VEGF) is well known to be involved in the infiltration and metastasis of many kinds of cancers. The aim of this study was to further elucidate the clinicopathologic significance of the immunohistochemical expressions of COX-2 and VEGF in thyroid carcinoma.

METHODS

Eighty-five patients with thyroid neoplasms were enrolled in our study from December 2003 to January 2010 from the authors' institution retrospectively. Their tumors were examined in the Department of Pathology, the First Bethune Hospital of Jilin University. Immunohistochemistry was performed on paraffin-embedded tissues sections using monoclonal anti-human COX-2 and VEGF antibodies. The tissues were classified into four types: papillary, follicular, medullary and undifferentiated. The patients ranged in age from 23 to 71 years. Breast cancer slides acted as control slides. The immunohistochemical stains were quantified by staining intensity and by the proportion of positively stained cells which were stained brown or yellow.

RESULTS

The results were analysed by χ(2) test. COX-2 and VEGF expressions were stronger in thyroid carcinoma than in thyroid adenomas and normal tissues (P<0.01). COX-2 and VEGF expressions in thyroid carcinoma correlated with the tumor type and TNM stage.

CONCLUSION

Our results suggest that expression of COX-2 and VEGF may promote angiogenesis of thyroid carcinoma, its infiltration, and metastasis.

ABCB1/MDR1 contributes to the anticancer drug-resistant phenotype of IPH-926 human lobular breast cancer cells

Contribution of the ABCB1/MDR1/P-glycoprotein drug transporter to breast cancer resistance has been controversial. One issue is that ABCB1-dependent drug-resistance has primarily been investigated in mammary epithelial cell models technically manipulated to overexpress ABCB1, either by gene transfer using appropriate expression vectors or by chronic anticancer drug-selection. However, an unmodified human breast cancer cell line with an endogenous overexpression of ABCB1 has not been described thus far. Using Affymetrix microarray analyses, we identified an endogenous overexpression of several tumor-biologically relevant transcripts including ABCB1, BCAR4, CCL28, SCGB2A2 and PIP in IPH-926, an anticancer drug-resistant human lobular breast cancer cell line derived from a chemo-refractory mammary carcinoma patient. In a panel of twenty breast cancer cell lines examined, overexpression of ABCB1 mRNA and protein was exclusively detected in IPH-926. This was further validated using chronically in vitro drug-selected KB-V-1 cells as a widely used reference model to accurately define an ABCB1 overexpression. IPH-926 and KB-V-1 displayed a similar overexpression of ABCB1. Flow cytometric analyses showed that IPH-926 but not ABCB1-negative breast cancer cells extruded the anticancer agent doxorubicin, a classical substrate of the ABCB1 drug transporter. PSC-833 (valspodar), a selective ABCB1 inhibitor, blocked this efflux, restored apoptotic PARP cleavage and increased doxorubicin sensitivity in IPH-926 and KB-V-1. To our knowledge, IPH-926 represents the first human breast cancer cell line with a genuine, endogenous overexpression of ABCB1. IPH-926 provides evidence that ABCB1 can occasionally cause anticancer drug-resistance in breast cancer patients and offers a new tool for the evaluation of compounds to overcome drug-resistance.

ABCC2 (MRP2, cMOAT) localized in the nuclear envelope of breast carcinoma cells correlates with poor clinical outcome

Nuclear expression of ABCC2 can be specific for lower differentiated cells and stem cells. The study aimed at examination of ABCC2 expression in breast cancers. The immunohistochemical analyses were performed on 70 samples of breast cancer. We have also studied prognostic value of the ABCC2 mRNA expression using the KM plotter which assessed the effect of 22,277 genes on survival in 1809 breast cancer patients. Immunohistochemical studies demonstrated that ABCC2 expression may be manifested in nuclear envelope of neoplastic cells (ABCC2n) as well as in their cell membrane and cytoplasm (ABCC2c). The univariate and multivariate analyses showed that higher expression of ABCC2n and ABCC2c was typical for cases of a shorter overall survival time. Higher ABBC2n expression was also typical for cases of a shorter disease-free survival and a shorter progression-free time. The KM plotter analysis of the prognostic value of ABCC2 mRNA expression showed that elevated ABCC2 expression was specific for cases of a shorter relapse-free survival only in the estrogen receptor-negative subgroup. The study demonstrated hat breast cancers manifest ABCC2 expression and that it is linked to a less favourable prognosis. Our results suggested that immunohistochemical tests represent a reliable way to detect prognostic value of ABCC2 expression, allowing to demonstrate differences related to subcellular localization of the protein. Cases with nuclear expression of ABCC2 manifested a more aggressive clinical course, which might reflect a less advanced differentiation of neplastic cells, resistance to the applied cytostatic drugs and tamoxifen.

COX-2 expression predicts worse breast cancer prognosis and does not modify the association with aspirin

Some previous studies have found worse prognosis among cyclooxygenase-2 (COX-2)-expressing breast cancers. Aspirin and NSAIDs inhibit COX-2. Three studies, including ours, have reported a survival advantage among women with breast cancer who take either aspirin or NSAIDs. Through this study we hypothesized that in the Nurses' Health Study (NHS), COX-2 expression would be associated with worse prognosis, and aspirin use would be associated with better survival particularly among women with COX-2 positive tumors. In this study we investigated 2,001 women presenting with invasive breast cancers stained for COX-2 by immunohistochemistry. Tumor prognostic factors were from medical records. Aspirin use was assessed at least 12 months after diagnosis and updated. Cause of death was identified from death certificates. Statistical analyses included logistic regression of prognostic factors with COX-2 status as the outcome, and proportional hazards regression with breast cancer death as the outcome. Tumor COX-2 expression was associated with higher diagnostic stage. Compared with stage I, the RR(95% CI) for stages II-IV were 1.16 (0.93-1.45), 1.68 (1.27-2.22), and 1.76 (0.93-3.32). COX-2 expression was associated with lobular compared with ductal histology (1.40 [1.02-1.92]), and estrogen receptor positive compared with negative (2.22 [1.66-2.95]). The RR(95% CI) of breast cancer death for current aspirin use was similar for women with COX-2-positive and COX-2-negative tumors; 0.64 (0.43-0.96) and 0.57 (0.44-0.74), respectively. In the NHS, COX-2 breast cancer expression was associated with higher stage at diagnosis. The survival benefit associated with aspirin use did not differ by COX-2 status. COX-2 breast cancer expression is associated with worse prognosis. If aspirin truly impacts breast cancer survival, then it is not solely via COX-2.

A systematic review to establish the frequency of cyclooxygenase-2 expression in normal breast epithelium, ductal carcinoma in situ, microinvasive carcinoma of the breast and invasive breast cancer

Background:

Epidemiological studies have suggested a protective effect of cyclooxygenase (COX)-inhibiting non-steroidal anti-inflammatory drugs in breast cancer risk and disease progression. We performed a systematic review to evaluate the frequency of COX-2 expression in normal breast epithelium, ductal carcinoma in situ of breast (DCIS), DCIS-adjoining invasive breast cancer, microinvasive carcinoma of the breast (MICB) and invasive breast cancer.

Methods:

Literature searches were carried out on MEDLINE, EMBASE and Web of Science from their commencement until September 2010. Primary studies examining COX-2 expression by immunohistochemistry methodology were included. Meta-analyses were carried out using random effects models for individual study estimates of COX-2 expression and pooled to give an overall estimate.

Results:

The pooled prevalences (95% confidence intervals) of COX-2 expressions were 53% (44–61) in DCIS studies and 42% (36–49) in the invasive breast cancer studies. There were too few studies involving normal breast epithelium, DCIS-adjoining invasive breast cancer and MICB to conduct meta-analyses.

Conclusion:

The findings from our meta-analyses have shown similar COX-2 expression in DCIS and invasive breast cancer. This may suggest the involvement of COX-2 in early carcinogenesis. Further studies of COX-2 expression in DCIS are required to investigate the use of COX-2 as a potential drug target for prevention of disease progression in DCIS.

Increased expression of P-glycoprotein is associated with doxorubicin chemoresistance in the metastatic 4T1 breast cancer model

Development of drug resistance is one of the major causes of breast cancer treatment failure. The goal of this study was to understand the chemoresistance mechanism using the highly metastatic 4T1 breast cancer model, which emulates stage IV breast cancer in humans. The metastatic 4T1 breast cancer cell line treated with either doxorubicin or 5-FU showed a concentration-dependent reduced cell proliferation, with induced G2-phase growth arrest (doxorubicin) or G1-phase growth arrest (5-FU). Doxorubicin treatment partially suppressed the multiorgan metastasis of 4T1 breast cancer cells in the lung, heart, liver, and bone, compared with either 5-FU or cyclophosphamide. We isolated and characterized 4T1 breast cancer cells from doxorubicin-resistant metastatic tumors (cell line 4T1-R). Multiorgan metastasis of drug-resistant 4T1 breast tumors was totally resistant to doxorubicin treatment. Our results indicate that doxorubicin is localized exclusively in the cytoplasm of resistant 4T1 breast cancer cells and that it cannot reach the nucleus because of increased nuclear expression of P-glycoprotein. Pretreatment of doxorubicin-resistant 4T1-R breast cancer cells with verapamil, a general inhibitor of P-glycoprotein, increased nuclear translocation of doxorubicin and cellular cytotoxicity. Thus, impaired nuclear translocation of doxorubicin due to increased expression of P-glycoprotein is associated with doxorubicin resistance of highly metastatic 4T1 breast cancer.

Cox-2 and its association with prognostic factors and response to primary chemotherapy in patients with breast cancer

OBJECTIVE

To evaluate the immunohistochemical expression of cox-2 before primary chemotherapy with 5-fluorouracil, epirubicin and cyclophosphamide (FEC) and its association with initial tumor size, lymph node status, hormone receptors, expression of HER2 and the clinical and pathological response in patients with breast cancer.

METHODS

We conducted a retrospective study with 41 women with histopathological diagnosis of ductal breast carcinoma. They underwent primary chemotherapy with FEC regimen (5-fluorouracil, epirubicin and cyclophosphamide) at 500mg/m2, 75mg/m2 and 500 mg/m2, respectively. Inclusion criteria were age range between 30 and 70 years, stage II to IIIA, absence of metastasis, primary tumor of the breast, single, unilateral, with ductal invasion at histology and absence of heart disease and pregnancy. To evaluate the expression of HER2/neu protein we used rabbit monoclonal antibodies. To visualize the expression of cox-2 protein we used polyclonal antibodies obtained from goats' serum. The evaluation of clinical response to treatment was performed during physical examination by measuring the major tumor axis with a pachymeter. Measurements were taken at admission and after primary chemotherapy cycles. After three chemotherapy sessions at intervals of 21 days the surgical procedure was carried out. We adopted the criteria of RECIST. After the operation we evaluated the local pathological response, which was considered complete when there was absence of invasive neoplasia and of the in situ component. In immunohistochemical assessing of estrogen receptors we used estrogen receptor NCL-ER6F11 and, for progesterone, progesterone receptor NCL-PGR-312, considering positive the staining of 10% or more tumor cells.

RESULTS

The distribution according to UICC clinical stage classified six patients in stage IIA (14.6%), 22 in stage IIB (53.6%) and 13 stage IIIA (31.8%). The initial clinical evaluation of the major tumor axis ranged from 2.5 to 15 cm and a median of 5 cm. We identified 14 patients (34.1%) with negative lymph node status, and 27 positive (65.9%). It was observed that 19 (46.3%) were in premenopause and 22 (53.6%) in menopause.

CONCLUSION

There was an association of the expression of Cox-2 to the factors associated with poor prognosis in breast cancer, such as positive lymph node status, negative hormone receptors and HER2 expression.

Multidrug resistance in breast cancer: from in vitro models to clinical studies

The development of multidrug resistance (MDR) and subsequent relapse on therapy is a widespread problem in breast cancer, but our understanding of the underlying molecular mechanisms is incomplete. Numerous studies have aimed to establish the role of drug transporter pumps in MDR and to link their expression to response to chemotherapy. The ATP-binding cassette (ABC) transporters are central to breast cancer MDR, and increases in ABC expression levels have been shown to correlate with decreases in response to various chemotherapy drugs and a reduction in overall survival. But as there is a large degree of redundancy between different ABC transporters, this correlation has not been seen in all studies. This paper provides an introduction to the key molecules associated with breast cancer MDR and summarises evidence of their potential roles reported from model systems and clinical studies. We provide possible explanations for why despite several decades of research, the precise role of ABC transporters in breast cancer MDR remains elusive.

COX-2 activation is associated with Akt phosphorylation and poor survival in ER-negative, HER2-positive breast cancer

Background

Inducible cyclooxgenase-2 (COX-2) is commonly overexpressed in breast tumors and is a target for cancer therapy. Here, we studied the association of COX-2 with breast cancer survival and how this association is influenced by tumor estrogen and HER2 receptor status and Akt pathway activation.

Methods

Tumor COX-2, HER2 and estrogen receptor α (ER) expression and phosphorylation of Akt, BAD, and caspase-9 were analyzed immunohistochemically in 248 cases of breast cancer. Spearman's correlation and multivariable logistic regression analyses were used to examine the relationship between COX-2 and tumor characteristics. Kaplan-Meier survival and multivariable Cox proportional hazards regression analyses were used to examine the relationship between COX-2 and disease-specific survival.

Results

COX-2 was significantly associated with breast cancer outcome in ER-negative [Hazard ratio (HR) = 2.72; 95% confidence interval (CI), 1.36-5.41; comparing high versus low COX-2] and HER2 overexpressing breast cancer (HR = 2.84; 95% CI, 1.07-7.52). However, the hazard of poor survival associated with increased COX-2 was highest among patients who were both ER-negative and HER2-positive (HR = 5.95; 95% CI, 1.01-34.9). Notably, COX-2 expression in the ER-negative and HER2-positive tumors correlated significantly with increased phosphorylation of Akt and of the two Akt targets, BAD at Ser136 and caspase-9 at Ser196.

Conclusions

Up-regulation of COX-2 in ER-negative and HER2-positive breast tumors is associated with Akt pathway activation and is a marker of poor outcome. The findings suggest that COX-2-specific inhibitors and inhibitors of the Akt pathway may act synergistically as anticancer drugs in the ER-negative and HER2-positive breast cancer subtype.

Cyclooxygenase-2 expression in animal cancers

Cyclooxygenase (COX; also known as prostaglandin endoperoxide synthase) is a key enzyme in the biochemical pathway leading to the synthesis of prostaglandins. A large amount of epidemiological and experimental evidence supports a role for COX-2, the inducible form of the enzyme, in human tumorigenesis, notably in colorectal cancer. COX-2 mediates this role through the production of PGE(2) that acts to inhibit apoptosis, promote cell proliferation, stimulate angiogenesis, and decrease immunity. Similarly, COX-2 is believed to be involved in the oncogenesis of some cancers in domestic animals. Here, the author reviews the current knowledge on COX-2 expression and role in cancers of dogs, cats, and horses. Data indicate that COX-2 upregulation is present in many animal cancers, but there is presently not enough information to clearly define the prognostic significance of COX-2 expression. To date, only few reports document an association between COX-2 expression and survival, notably in canine mammary cancers and osteosarcomas. Some evidence suggests that COX inhibitors could be useful in the prevention and/or treatment of certain cancers in domestic animals, the best example being urinary transitional cell carcinomas in dogs. However, determination of the levels of COX-2 in a tumor does not appear to be a good prognostic factor or a good indicator for the response to nonsteroidal anti-inflammatory drug therapy. Clearly, additional research, including the development of in vitro cell systems, is needed to determine if COX-2 expression can be used as a reliable prognostic factor and as a definite therapeutic target in animal cancers.

Cyclo-oxygenase 2 up-regulates the effect of multidrug resistance

COX-2 (cyclo-oxygenase 2), an inducible form of the enzyme that catalyses the first step in the synthesis of prostanoids, is associated with inflammatory diseases and carcinogenesis, which is suspected to promote angiogenesis and tissue invasion of tumours and resistance to apoptosis. COX-2 is also involved in drug resistance and poor prognosis of many neoplastic diseases or cancers. The activation of the COX-2/PGE2 (prostaglandin E2)/prostaglandin E receptor signal pathway can up-regulate the expression of all three ABC (ATP-binding-cassette) transporters, MDR1/P-gp (multidrug resistance/P-glycoprotein), MRP1 (multidrug-resistance protein 1) and BCRP (breast-cancer-resistance protein), which encode efflux pumps, playing important roles in the development of multidrug resistance. In addition, COX inhibitors inhibit the expression of MDR1/P-gp, MRP1 and BCRP and enhance the cytotoxicity of anticancer drugs. Therefore we can use the COX inhibitors to potentialize the effects of chemotherapeutic agents and reverse multidrug resistance to facilitate the patient who may benefit from addition of COX inhibitors to standard cytotoxic therapy.

CpG hypomethylation of MDR1 gene in tumor and serum of invasive ductal breast carcinoma patients

OBJECTIVES

Multidrug resistance 1 (MDR1) gene encodes P-glycoprotein (P-gp), a transmembrane calcium-dependent efflux pump, implicated in drug resistance. In this prospective study, methylation status of MDR1 promoter and its correlation with clinicopathological parameters were evaluated in tumor and serum of breast cancer patients.

DESIGN AND METHODS

Methylation-specific PCR was carried out to investigate the promoter methylation status of MDR1 in tumor and serum of 100 patients with invasive ductal carcinomas of breast (IDCs). The effect of promoter methylation on protein expression was evaluated by immunohistochemistry.

RESULTS

MDR1 was hypomethylated in 47% tumors and 44% paired sera of IDC patients and correlated significantly with increased tumor size and advanced tumor stage. Promoter hypomethylation of MDR1 in serum DNA showed 98% specificity and 50% sensitivity.

CONCLUSIONS

Hypomethylation of MDR1 promoter in IDCs accounted for P-gp overexpression and aggressive biologic behavior in a subset of patients. Detection of these epigenetic changes in circulating DNA may not only enhance insight into the biological behavior of the primary tumor of an individual but may also provide valuable information regarding prognosis that can be readily monitored throughout the disease course.

Corticotropin Releasing Factor promotes breast cancer cell motility and invasiveness

INTRODUCTION

Cancer cells secrete bioactive peptides that act in an autocrine or paracrine fashion affecting tumor growth and metastasis. Corticotropin-releasing factor (CRF), a hypothalamic neuropeptide that controls the response to stress, has been detected in breast cancer tissues and cell lines. CRF can affect breast cancer cells in an autocrine or paracrine manner via its production from innervating sympathetic neurons or immune cells.

METHODS

In the present study we report our findings regarding the impact of CRF on breast cancer cell motility and invasiveness. For this purpose we used the MCF7 breast cancer cell line and evaluated the effect of CRF on motility and invasiveness using the wound-healing and boyden-chamber assays. In addition, we measured the effect of CRF on molecules that mediate motility by western blot, immunofluorescence, ELISA and RT-PCR.

RESULTS

Our findings show that: 1. CRF transiently inhibited the apoptosis of MCF7 cells. 2. CRF enhanced MCF7 cell motility in a wound healing assay and their invasiveness through extracellular matrix. 3. CRF increased actin polymerization, phosphorylation of Focal Adhesion Kinase (FAK), providing a potential mechanism for the observed induction of MCF7 motility. 4. CRF induced the expression of Cox-1 but not Cox-2 in MCF7 cells as well as the production of prostaglandins, factors known to promote invasiveness and metastasis.

CONCLUSION

Overall, our data suggest that CRF stimulates cell motility and invasiveness of MCF7 cells most probably via induction of FAK phosphorylation and actin filament reorganization and production of prostaglandins via Cox1. Based on these findings we postulate that the stress neuropeptide CRF present in the vicinity of tumors (either produced locally by the tumor cells themselves or by nearby normal cells or secreted from the innervations of surrounding tissues) may play an important role on breast tumor growth and metastatic capacity, providing a potential link between stress and tumor progression.

Methylated NEUROD1 promoter is a marker for chemosensitivity in breast cancer

PURPOSE

Chemotherapy can be an integral component of the adjuvant management strategy for women with early stage breast cancer. To date, no tool is available to predict or monitor the efficacy of these therapies. The aim of this proof-of-principle study was to assess whether NEUROD1 DNA methylation is able to predict the response to neoadjuvant and adjuvant chemotherapy.

EXPERIMENTAL DESIGN

Recently, we showed that NEUROD1 DNA is differentially methylated in neoplastic versus nonneoplastic breast tissue samples. In this study, we used MethyLight and analyzed NEUROD1 methylation in (a) 74 breast cancer tissue samples, (b) two independent sets of pretreatment core biopsies of 23 (training set) and 21 (test set) neoadjuvantly treated breast cancer patients, and (c) pretherapeutic and posttherapeutic serum samples from 107 breast cancer patients treated with adjuvant chemotherapy.

RESULTS

High-grade tumors showed higher NEUROD1 methylation levels. Estrogen receptor-negative breast cancers with high NEUROD1 methylation were 10.8-fold more likely to respond with a complete pathologic response following neoadjuvant chemotherapy. Patients with positive serum pretreatment NEUROD1 methylation, which persisted after chemotherapy, indicated poor relapse-free and overall survival in univariate and multivariate analyses (relative risk for relapse, 6.2; 95% confidence interval, 1.6-24; P = 0.008, and relative risk for death, 14; 95% confidence interval, 1.6-120; P = 0.02).

CONCLUSIONS

These data support the view that NEUROD1 methylation is a chemosensitivity marker in estrogen receptor-negative breast cancer.

Single nucleotide polymorphisms in the multidrug resistance gene 1 (ABCB1): effects on its expression and clinicopathological characteristics in breast cancer patients

OBJECTIVES

Resistance of tumor cells to multiple cytostatic agents is one of the major impediments of successful cancer chemotherapy. A large part of resistance of tumors to chemotherapy is caused by the ABC transporter P-glycoprotein encoded by the ABCB1 gene. The main aim of this study was to assess the prognostic value of ABCB1 genotype and phenotype in breast cancer.

METHODS

Six ABCB1 single nucleotide polymorphisms (SNPs) were determined in 90 Czech breast cancer patients by a novel method that allows simultaneous assessment of multiple polymorphisms on a single electronic microarray. Expression levels of ABCB1 were quantified in tumor and nontumor samples of breast cancer patients by real-time PCR. T-test, analysis of variance and Fisher's exact test were used to analyze the effect of ABCB1 polymorphisms on ABCB1 expression levels and for the analysis of associations between ABCB1 expression, genotype and clinical and pathological characteristics.

RESULTS

ABCB1 was expressed in 98.9% of the tumor and in 97.5% of the nontumor samples. ABCB1 was downregulated in 79.5% of tumors compared with the nontumor samples. No significant correlation was observed between ABCB1 mRNA expression levels and clinical and pathological characteristics. High frequencies of the variant alleles in ABCB1 exon 12 (1236C>T, 38.3%) and exon 26 (3435C>T, 54.0%) were observed. Individuals with variant alleles in exons 12 and 26 had significantly lower ABCB1 expression levels in their tumors. SNPs in exons 12 and 26 also correlated with estrogen receptor status of patients.

CONCLUSION

ABCB1 SNPs may affect function of P-glycoprotein by influencing the expression level and modify breast cancer prognosis.