Cyclooxygenase-2 In Breast Cancer Research Articles

To study the utility of COX-2 as immunohistochemical prognostic marker in comparison to various histopathological parameters and TNM staging in breast carcinoma: an observational, cross-sectional study protocol.

Breast cancer is the most prevalent cancer among women worldwide and is a well-known cause for cancer mortality in females. COX-2 (cyclooxygenase) plays a vital role in development of some human cancers such as lung, colon and breast. It is a potent enzyme that is important for the conversion of arachidonic acid into prostaglandins. These prostaglandins mediate cellular proliferation, apoptosis and angiogenesis which contributes to carcinogenesis. Overexpression of COX-2 has been detected in several malignancies including breast cancer. COX-2 overexpression is regarded as a poor prognostic marker of breast cancer.The present study will aim to study the immunohistochemical expression of COX-2 in breast cancer and compare it with known histopathological parameters thus assessing its prognostic value. This will be an observational study conducted in the Department of Pathology, JNMC, Wardha (Sawangi). Radical mastectomy specimens will be studied for COX-2 expression by immunohistochemistry in patients diagnosed with breast carcinoma. COX-2 expression will be quantified as immunohistochemical score and results will be correlated with various histopathological parameters. The expected result of our study will suggest an association of COX-2 expression to the factors associated with poor prognosis in breast carcinoma. A positive correlation is expected between larger tumor size, positive lymph node status, higher T stage and N stage and lymphovascular invasion. Conclusions will be drawn from the obtained results of the immunohistochemical study by using COX-2- for detection of overexpression of COX-2 when evaluated with TNM staging, histological grading and molecular types of breast cancer.

To study the utility of COX-2 as immunohistochemical prognostic marker in comparison to various histopathological parameters and TNM staging in breast carcinoma: an observational, cross-sectional study protocol

Background: Breast cancer is the most prevalent cancer among women worldwide and is a well-known cause for cancer mortality in females. COX-2 (cyclooxygenase) plays a vital role in development of some human cancers such as lung, colon and breast. It is a potent enzyme that is important for the conversion of arachidonic acid into prostaglandins. These prostaglandins mediate cellular proliferation, apoptosis and angiogenesis which contributes to carcinogenesis. Overexpression of COX-2 has been detected in several malignancies including breast cancer. COX-2 overexpression is regarded as a poor prognostic marker of breast cancer. The present study will aim to study the immunohistochemical expression of COX-2 in breast cancer and compare it with known histopathological parameters thus assessing its prognostic value. Methods: This will be an observational study conducted in the Department of Pathology, JNMC, Wardha (Sawangi). Radical mastectomy specimens will be studied for COX-2 expression by immunohistochemistry in patients diagnosed with breast carcinoma. COX-2 expression will be quantified as immunohistochemical score and results will be correlated with various histopathological parameters. Results: The expected result of our study will suggest an association of COX-2 expression to the factors associated with poor prognosis in breast carcinoma. A positive correlation is expected between larger tumor size, positive lymph node status, higher T stage and N stage and lymphovascular invasion. Conclusions: Conclusions will be drawn from the obtained results of the immunohistochemical study by using COX-2- for detection of overexpression of COX-2 when evaluated with TNM staging, histological grading and molecular types of breast cancer.

Beta-ionone-inhibited proliferation of breast cancer cells by inhibited COX-2 activity.

As one of the isoprenoids and widely derived from many fruits and vegetables, β-ionone (BI) has a potent inhibitory proliferation of cancer cells in vitro and in vivo. However, its exact mechanism is still uncompleted understood and needs to be further verified. Cyclooxygenase-2 (COX-2), as a potential target of cancer chemoprevention, has been played pivotal roles in proliferation of tumor cells and carcinogenesis. Thus, the objective of present study was to determine that BI inhibited the activity of COX-2 in breast cancer and related to cancer cell models. Cell proliferation, DNA synthesis, the distribution of cell cycle, apoptosis induction and the expression of P38-MAPK protein were determined in MCF-7 cells by methylene blue, 3H-thymidine (TdR) incorporation, flow cytometry, TUNEL and Western blotting assays. Quinone reductase (QR) activity was determined in murine hepatoma Hepa1c1c7 cells by enzyme-linked immunosorbent assay (ELISA). The expression of COX-2 in a phorbol-12-myristate-13-acetate (PMA)-induced cell model and mammary tumor tissues was examined by Western blotting and immunohistochemistry. The results showed that BI significantly inhibited cell proliferation and DNA synthesis, arrested the distribution of cell cycle at the S phase or decreased proteins related to cell cycle such as cyclin D1 and CDK4, induced apoptosis and increased the expression of p-P38 in MCF-7 cells. BI at low doses (< 50μmol/L) significantly increased QR activity, decreased the expression of COX-2 protein and prostaglandin E2 (PEG2) release in cell models. In addition, BI also significantly decreased the expression of COX-2 protein in rat mammary tumor tissues. Therefore, our findings indicate that BI possesses inhibitory proliferation of breast cancer cells through down-regulation of COX-2 activity.

Expression of PCNA, Ki-67 and COX-2 in breast cancer based on DCE-MRI image information

In order to explore the application value of DCE-MRI in clinical diagnosis and treatment, guide early clinical diagnosis, evaluate prognosis, guide clinical selection of treatment options and improve medical level, the expression of adenocarcinoma, its relationship with clinicopathology, and the significance of co-expression of the proliferating cell nuclear antigen (PCNA), Ki67 protein and cyclooxygenase 2 (COX-2) in breast cancer are analyzed. The results show that the positive expression rates of ki67, PCNA, and COX-2 in breast cancer patients are significantly higher than those in breast cancer patients (P<0.05). Positive expressions of ki67, PCNA, and COX-2 in breast cancer patients are not correlated with age, tumor size and clinical stage (P>0.05). There is no significant difference (P>0.05) between the pathological types of breast cancer and positive expressions of ki67, PCNA and COX-2 in all the samples studied. Therefore, there is a correlation between DCE-MRI imaging features and prognostic indicators in breast cancer.

Expression and significance of carcinoembryonic antigen, cancer antigen 153, and cyclooxygenase-2 in breast cancer ⁎

Abstract Objective This study aimed to evaluate serum and nipple discharge levels of carcinoembryonic antigen (CEA) and cancer antigen 153 (CA153) and tissue cyclooxygenase-2 (COX-2) expression in breast cancer cases and associations of these proteins with breast cancer metastasis. Methods The immunohistochemical Ultra Sensitive TM S-P method was used to detect COX-2 expression in 77 cases of invasive breast carcinoma. Of these cases, 52 exhibited CEA and CA153 in both serum and nipple discharge (electrochemiluminescence method), and associations of these biomarkers with breast cancer prognosis were studied. Sixty cases of benign breast lesion were selected as a control group. Overall survival of breast carcinoma patients was evaluated. COX-2 expression was evaluated relative to clinicopathological features and CEA and CA153 levels, and its role in invasiveness was investigated. Results Among cases of invasive breast cancer, 72.7% (56/77) were COX-2 immunopositive, compared to 16.7% of benign lesions (χ2 = 66.745, P = 0.000) percentage of positive cells. COX-2 overexpression in breast cancer correlated positively with histological grade (II vs III; χ2 = 4.064, P = 0.043), lymph node metastasis (χ2 = 9.135, P = 0.003), and distant metastasis (χ2 = 8.021, P = 0.003). However, COX-2 expression did not correlate with age (≤ 50 vs 50 years) or tumor size (≤ 5 vs &gt; 5 cm) (χ2 = 0.081, P = 0.776 and χ2 = 3.702, P = 0.054, respectively). Among breast cancer patients, COX-2 overexpression in tumors also correlated with shorter overall survival (P &lt; 0.05). In brief, increased COX-2 expression correlates with worse prognosis and shorter overall survival. Malignant lesions were associated with significantly higher serum and nipple discharge levels of biomarkers, relative to benign lesions (P &lt; 0.05). These biomarkers were present at significantly higher levels in nipple discharge than in serum (P &lt; 0.05). Furthermore, significantly higher nipple discharge levels of CEA and CA153 were observed in COX-2-positive breast carcinoma patients, compared to COX-2-negative patients (P &lt;0.05). Shorter overall survival in cancer patients group related to COX-2 overexpression in tumors (P &lt; 0.05). Conclusion The study suggests that COX-2 overexpression correlates with poor clinicopathological parameters in breast cancers and might be an important biological marker of invasion and metastasis. The findings of the present study suggest that combined detection of COX-2 tissue expression and CEA and CA153 in serum and nipple discharge could facilitate clinical monitoring and diagnosis of metastasis in patients with breast cancer.

Abstract P4-09-03: Prognostic and predictive value of COX2 in breast cancer, correlation with PIK3CA mutations

Abstract Background: Cyclooxygenase-2 (COX2) is responsible for the synthesis of prostaglandins from arachidonic acid. This enzyme is weakly expressed in normal tissues and implicated in oncogenic and inflammatory processes. Treatment with a COX2 inhibitor (aspirin) increases overall survival of patients with colorectal cancer only for PIK3CA mutated tumors confirming an interaction between COX2 and the PI3K/AKT pathway. PIK3CA gene mutations are detected in 10-40% of BC depending on the molecular subtype. We hypothesized that COX inhibition could have an impact in Breast Cancer (BC) treatment. Methods: COX2 mRNA expression levels were analyzed in 446 BC samples and 61 patient-derived xenografts (PDX) using qRT-PCR. Protein expression of COX2 was studied by immunohistochemistry (IHC) in 26 BC and 14 PDX. The prognostic impact of COX2 expression level according to PIK3CA mutation status was also analyzed in BC patients. The activity of celecoxib, a selective COX2 inhibitor, was tested in two PDX of triple-negative BC: the HBCx50 PDX (PIK3CA wild-type, expressing COX2) and the HBCx4B PDX (PIK3CA mutated, expressing COX2). Results: COX2 transcript was under-expressed in 74% and overexpressed in 2% of the BC samples. COX2 overexpression is significantly associated with triple-negative subtype (11%, 7/68 cases, p&amp;lt;0.0001). Moreover, immunostaining of COX2 was well correlated with COX2 mRNA expression level. PIK3CA mutations were detected in 33% of patients. We showed that metastasis-free survival (MFS) was significantly better in patients who do not under-express COX2 (p=0.007) or in patients with PIK3CA mutation (p=0.02) regardless the BC subtype and adjuvant treatment. In the PIK3CA wild-type (wt) subgroup, MFS of patients was significantly better in patients not under-expressing COX2 than in patients under-expressing COX2 (p=0.01). In PDX, the strongest expression levels of COX2 were found in triple-negative (median 36 [0-1673]) compared to luminal (median 0 [0-202]) and HER2 positive subtypes (median 6 [0-601]). In vivo studies showed that celecoxib has no effect on the HBCx50 (PIK3CA wt) PDX growth while a significant antitumoral effect of celecoxib is observed in HBCx4B (PIK3CA mutated) PDX (tumor growth inhibition=41%, p=0.03). Conclusion: In BC, COX2 underexpression is frequent and impact prognosis. BC overexpressing COX2 are rare and mainly belong to the triple-negative subtype. In vivo PDX studies show that the antitumoral effect of celecoxib may be restricted to BC expressing COX2 with PIK3CA mutation. Analyses of signaling pathways, expression levels of COX2 and its target proteins, tumor proliferation and apoptosis induction are ongoing on tumors and serum of mice to elucidate the antitumoral effect of celecoxib. This work could help to identify a subgroup of BC patients who may benefit from celecoxib especially as COX2 immunostaining and PIK3CA mutation status could routinely be used as COX2 inhibitor sensitivity biomarkers. These results need to be validated in a phase II clinical trial. Citation Format: Tury S, Becette V, Assayag F, Vacher S, Marangoni E, Bièche I, Lerebours F, Callens C. Prognostic and predictive value of COX2 in breast cancer, correlation with PIK3CA mutations. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-03.

Targeting of COX-2 expression by recombinant adenovirus shRNA attenuates the malignant biological behavior of breast cancer cells.

Cyclooxygenase-2 (COX-2), considered to have tumor-promoting potential, is highly expressed in a variety of tumors, including breast cancer. Since the functions and action mechanisms of COX-2 in breast cancer have not been fully elucidated, in the present study, the effects of target inhibiting COX-2 with recombinant adenovirus Ad-COX-2-shRNA on malignant biological behavior were investigated in representative cell lines. Breast cancer MDA-MB-231 and MCF-7 cells were transfected with Ad-COX-2-shRNA and COX-2 expression was tested by RT-PCR and Western blotting. Changes in proliferation, apoptosis and invasion of breast cancer cells were detected with various assays including MTT, colony forming, flowcytometry and Transwell invasion tests. The expression of related proteins involved in the cell cycle, apoptosis, invasion and signaling pathways was assessed by Western blotting. COX-2 expression was significantly reduced in both breast cancer cell lines infected with Ad-COX-2-shRNA, with obvious inhibition of proliferation, colony forming rate, G2/M phase passage and invasion, as well as induction of apoptosis, in MDA-MB-231 and MCF-7 cells, respectively. At the same time, proteins related to the cell cycle, anti-apoptosis and invasion were significantly downregulated. In addition, c-myc expression and phosphorylation activation of Wnt/β-catenin and p38MAPK pathways were reduced by the Ad-COX-2-shRNA. COX-2 expression is associated with proliferation, apoptosis and invasion of breast cancer cells, and its mechanisms of action involve regulating expression of c-myc through the p38MAPK and Wnt/β-catenin pathways.

TGF β1 Mediates Epithelial Mesenchymal Transition via β6 Integrin Signaling Pathway in Breast Cancer

Background: To understand the function of β6 integrin and elucidate its signaling pathways in TGF-β-induced EMT in breast cancer. Methods: The interactions between TGF-β1 and β6 integrin were measured by coimmunoprecipitation. The EMT responses, phospherlation of PI3K/Akt and COX-2 expression were determined by real-time PCR, transwell assay, and western blot after the blockage of β6 integrin. Results: TGF-β1 and β6 integrin could bind with each other. Blockage of β6 integrin rescued TGF-β1-induced EMT phenotype and reduced expression of COX-2 via dephosphorylation of PI3K/Akt. Conclusions: β6 integrin plays a critical role in TGF-β1-induced EMT and overexpression of COX-2 in breast cancer.

Deletion of cyclooxygenase 2 in mouse mammary epithelial cells delays breast cancer onset through augmentation of type 1 immune responses in tumors

Inhibition of cyclooxygenase (COX) 2, which is associated with >40% of breast cancers, decreases the risk of tumorigenesis and breast cancer recurrence. To study the role of COX-2 in breast cancer, we engineered mice that lack selectively mammary epithelial cell (MEC) COX-2 (COX-2 KO(MEC)). Compared with wild type (WT), MEC from COX-2 KO(MEC) mice expressed >90% less COX-2 messenger RNA (mRNA) and protein and produced 90% less of the dominant pro-oncogenic COX-2 product, prostaglandin (PG) E(2). We confirmed COX-2 as the principle source of PGE(2) in MEC treated with selective COX-2 and COX-1 inhibitors. Tumors were induced in mice using medroxyprogesterone acetate and 7,12-dimethylbenz[a]anthracene. Breast cancer onset was significantly delayed in COX-2 KO(MEC) compared with WT (P = 0.03), equivalent to the delay following systemic COX-2 inhibition with rofecoxib. Compared with WT, COX-2 KO(MEC) tumors showed increased mRNA for Caspase-3, Ki-67 and common markers for leukocytes (CD45) and macrophages (F4/80). Analysis of multiple markers/cytokines, namely CD86, inducible nitric oxide synthase (iNOS), interleukin-6, tumor necrosis factor α (TNFα) and Tim-3 indicated a shift toward antitumorigenic type 1 immune responses in COX-2 KO(MEC) tumors. Immunohistochemical analysis confirmed elevated expression of CD45, F4/80 and CD86 in COX-2 KO(MEC) tumors. Concordant with a role for COX-2 in restraining M1 macrophage polarization, CD86 and TNFα expression were offset by exogenous PGE(2) in bone marrow-derived macrophages polarized in vitro to the M1 phenotype. Our data reveal the importance of epithelial COX-2 in tumor promotion and indicate that deletion of epithelial COX-2 may skew tumor immunity toward type 1 responses, coincident with delayed tumor development.

Abstract P4-08-11: Surface Plasmon Resonance (SPR) Analysis of COX-2 Expression for Early Detection and Progression of Breast Cancer and Evaluation of a Novel Class of Peptides as Its Inhibitor

Abstract Background: Cyclooxygenase-2 (COX-2) over expression has been observed in different cancers. Till date, COX-2 expression in breast cancer has been studied using RT-PCR and immunohistochemistry. The aim of this study was to use surface plasmon resonance (SPR) technology for determining the expression levels of COX-2 in breast cancer and design peptide inhibitors to evaluate their enzyme inhibition in vitro. Patients and methods: This case-controlled study was performed on 84 biopsy proven breast cancer patients having invasive ductal carcinoma and 40 age, sex and ethnicity matched healthy subjects. Blood and tissue samples were collected and serum and tissue lysate was prepared. Serum and tissue levels of COX-2 were evaluated using SPR where samples were allowed to flow over anti-COX-2 antibody immobilized sensor chip to obtain the respective RUs. Similarly, standard curve of COX-2 was prepared from cloned, expressed and purified protein to deduce the concentrations in different samples. To evaluate enzyme inhibition, fifteen peptides were synthesized using the solid and solution-phase peptide synthesis based on the active site structure of COX-2 and enzyme activity was evaluated spectrophotometrically. Results: A significant increase in COX-2 levels in breast cancer patients 11.23-30.77μg/ml (Mean±SD=14.55±5.74) as compared to normal controls 2.13-5.16µg/ml (Mean±SD=3.71±0.86) (P&amp;gt;0.0001) was observed. Serum COX-2 levels were significantly higher (P&amp;lt;0.0061) in patients with lymph node involvement. More than 65% patients showed significantly (P&amp;lt;0.0025) reduced COX-2 levels after chemotherapy. This was confirmed by western blot to check tissue level expression and spectrophotometrically to determine the activity of COX-2 at different stages. In addition, the peptides showed significant in vitro enzyme inhibition, and had a KD ranging from 1 X 10-8 to 1X10-10. Conclusion: SPR is a useful proteomic technique for early detection and monitoring progession of breast cancer and peptides are a novel class of COX-2 inhibitors that can be further developed for anti-tumor therapy. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-08-11.

Down-regulation of CacyBP is associated with poor prognosis and the effects on COX-2 expression in breast cancer

Calcyclin-binding protein (CacyBP) is a tumor suppressor in gastric and renal cell carcinoma, but an oncogene in pancreatic cancer. However, the function of CacyBP in breast cancer has not been well elucidated. In this study, we explored the clinical relevance of CacyBP and investigated the relationship between CacyBP and COX-2 in breast cancer. Immunohistochemical analysis in 172 cases of breast tissues showed that the positive rate of CacyBP protein expression in normal breast tissues (NBT) (89.3%) was higher than that in invasive ductal carcinoma (IDC) (56.1%) (P<0.05). RT-PCR and Western blot analysis showed that CacyBP mRNA and protein expression were significantly lower in tumor tissues as compared to those in the corresponding non-tumorous tissues (P<0.05). The expression trend of COX-2 was opposite with CacyBP in breast carcinogenesis. Moreover, the CacyBP expression was significantly negatively associated with the COX expression in the 132 breast cancer samples (correlation coefficient = 0.505, P<0.001). The clinicopathological data analysis in 132 breast cancer samples showed that CacyBP expression was positively correlated with well differentiated samples (P=0.021), low pathologic TNM stage (P=0.009), and no lymphatic metastasis (P=0.027) of patients with breast cancer. Furthermore, reduced CacyBP expression was associated with poor prognosis. Knockdown of CacyBP gene using siRNA enhanced the proliferation and invasion ability of breast cancer cells, which was dependent on COX-2 expression. In conclusion, CacyBP regulation of COX-2 expression may play an important role in human breast carcinogenesis. Restoration of CacyBP gene is a potential therapeutic target of breast cancer.

Lymphatic metastasis is related to the epithelial-mesenchymal transition and expressions of VEGF, MMP-9, and COX-2 in breast cancer

The invasion and metastasis of breast cancer are supposed to involve several stages in which epithelial-mesenchymal transition (EMT) is regarded as the mechanistic basis for the behavior of cancer cells. A series of factors related to EMT are apparently involved in such process. The current study aimed to investigate the contributions of EMT and related factors in lymph node metastasis of breast cancer. The expressions of E-cadherin (E-Cad), N-cadherin (N-Cad), vascular endothelial cell growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), cyclooxygenase-2 (COX-2), and CD34 were examined in 74 cases of breast cancer, including 39 cases with lymph node metastasis and 35 cases without lymph node metastasis by immunohistochemistry. Multivariable Cox proportional hazards model was used to analyze the patients’ prognosis. The expressions of N-Cad, VEGF, MMP-9, and COX-2 in cases with lymph node metastasis were significantly higher than those without lymph node metastasis (P<0.05), while the E-Cad level was inversely related to status of lymph node metastasis (P<0.05). The metastasis rate of lymph node in the cases with EMT (lower E-Cad expression and higher N-Cad expression) was 78.3%, while that without EMT (higher E-Cad expression and lower N-Cad expression) was 11.1%. There was a statistical difference in the expression of COX-2 protein between histological grade I and grade II or III, respectively (P<0.05). In the cases with higher grade, the expression of E-Cad was decreased, while that of N-Cad was increased. Higher microvascular density (MVD) was also found to be significantly associated with lymphatic metastasis (P<0.05), and the cases with higher MVD had shorter survival time. This study indicates that EMT and expressions of VEGF, MMP-9 and COX-2, and MVD value are strongly correlated with lymph node metastasis in breast cancer.

Research status of COX-2 and its inhibitor in breast cancer

COX-2 is the rate-limiting enzyme in prostaglandin biosynthesis,which may promote the human tumorigenesis and tumor development through a variety of pathogenic mechanisms.The over expression of COX-2 in breast cancer is significantly correlated with the clinicopathological pammeters and prognosis.COX-2 inhibitors play anti-tumor effects through different mechanisms.Recent studies indicate that COX-2 inhibitors are effective both in breast cancer chemoprevention and treatment of breast cancer combined with cytotoxic drugs and aromatase inaetivators,and therefore may provide a potential new therapy of breast cancer prevention and treatment. Key words: Epoxide hydrolases; Enzyme inhibitors; Breast neoplasms

TPL-2/COT AND COX-2 IN BREAST CANCER

Breast cancer is the most common cancer in women worldwide and although mortality (129,000/year) stagnates, incidence (370,000/year) is increasing. In addition to histological type, grade, stage, hormonal and c-erbB2 status there is therefore a strong need for new and reliable prognostic and predictive factors. This minireview focuses on two potential prognostic and predictive candidates Tpl2/Cot and COX-2 and summarise information about them. Tumor progression locus 2 (Tpl2/Cot) is a serine/threonine protein kinase belonging to the family of MAP3 kinases. Activated Tpl2/Cot leads to induction of ERK1/2, JNK, NF-kappaB and p38MAPK pathways. The first study on Tpl2/Cot mRNA in breast cancer showed its increase in 40 % of cases of breast cancer but no available data exist on protein expression. Cyclo-oxygenase 2 (COX-2) is inducible by growth and inflammatory factors and contributes to the development of various tumours. Expression of COX-2 in breast cancer varied from 5-100 % in reviewed papers with significantly higher values in poorly differentiated tumours. Tpl2/Cot and COX-2 have their importance in different intracellular pathways and some of these are involved in cancer development. Briefly, the results from recent studies suggest that Tpl2/Cot and COX-2 could be prognostic factors in breast cancer.

The role of cyclooxygenase-2 in breast cancer: review

There is a growing body of evidence that COX-2 expression s a fundamental step in breast cancer pathogenesis acting through prostaglandin-dependent and independent mechanisms. Epidemiological studies suggest that NSAIDs confer a moderate degree of benefit against breast cancer. However further work is required to establish how this enzyme system can be best manipulated for therapeutic benefit.

Expression of cyclooxygenase-2 and 12-lipoxygenase in human breast cancer and their relationship with HER-2/neu and hormonal receptors: Impact on prognosis and therapy

A number of studies have shown over-expression of cox-2 in breast cancer. Also it has been recorded that human breast cancer expresses high level of cox-2 and 12-lipoxygenase which may be beneficial in future therapy plan for those patients. The present study aims to examine the level of transcripts of cox-2 and 12-lipoxygenase in Egyptian breast cancer patients and to compare between the expressions of both enzymes and TNM staging, hormone receptors status (including estrogen and progesterone) and HER2/neu expression. Total cellular RNA was extracted from 64 frozen tissue samples of breast carcinoma and their corresponding normal adjacent tissues. Cox-2 and 12-lipooxygenase expressions were detected using RT-PCR. Hormonal receptors as well as HER2/neu were detected immuno-histochemically for each patient. About 47 and 62.5% of carcinoma samples showed over-expression of cox-2 and 12-lipooxygenase respectively as compared to their corresponding normal tissues. The results revealed that cox-2 significantly associated with TNM staging (P = 0.0047) and hormonal receptors status (P = 0.0201). The relationship between cox-2 and HER2/neu expression was close to a significant value (P = 0.0747). 12-lipooxygenase showed only significant association with TNM staging (P = 0.0076). Neither hormonal receptors nor HER2/neu showed significant association with this enzyme. Elevated levels of cox-2 and 12-lipoxygenase expression were detected in human breast cancer. Also, the results revealed that cox-2 and 12-lipooxygenase mRNA expressions are associated with TNM staging in human breast cancer. Furthermore, there is an inverse association between cox-2 expression and hormonal receptor status. This observation may drive us to the possible role of those two enzymes in determining the plan of therapy of breast cancer patients.

Elevated expression of cyclooxygenase‐2 in breast cancer and ductal carcinoma in situ has no correlation with established prognostic markers

Elevated expression of cyclooxygenase-2 (COX-2) has been established to be a feature of breast cancer. There has been inconsistency in the literature regarding the precise significance of this-some studies have found no clinicopathological relevance at all, whilst others have concluded COX-2 expression is an important biomarker in invasive disease and pre-cancerous lesions, correlating with poor prognostic features. We studied COX-2 expression in invasive ductal cancer (IDC) specimens and ductal carcinoma in situ (DCIS) in order to clarify these issues. Archival specimens of IDC and DCIS (n = 39) were stained with a polyclonal antibody to COX-2. Results were correlated with recognised clinicopathological parameters. COX-2 expression occurred in 36.7% of IDCs and 54.5% of DCIS lesions. There was no correlation between increased expression and any clinicopathological features. COX-2 expression did not occur in adjacent non-cancerous tissue (ANCT). We have confirmed that COX-2 expression does occur in invasive cancers, in DCIS, and is not associated with established prognostic markers. The presence of COX-2 expression in DCIS and invasive cancers has positive implications for the future prevention and treatment of breast cancer with COX-2 inhibitors. A large proportion of tumours are, however, COX-2 negative and may be poor candidates for COX-2 suppression.

Prognostic Impact of Cyclooxygenase-2 in Breast Cancer

Cyclooxygenase (COX)—2, an inducible isoform of cyclooxygenases, regulates the rapid production of high levels of prostaglandins during inflammation. Cyclooxygenase-2 is overexpressed in a variety of malignant tumors. This review discusses epidemiologic and preclinical data on the role of COX-2 in the development and progression of breast cancer, and it will focus on recent studies that investigate the prognostic role of COX-2 in breast cancer. In rodent tumor models it has been shown that treatment with COX-1 or COX-2 inhibitors reduces incidence and growth of breast carcinomas. Possible mechanisms include regulation of invasion, increased proliferation, and suppression of apoptosis by COX-2. Moreover, there may be an indirect effect of prostaglandins, for example in tumor—host interactions such as induction of stromal aromatase activity or enhancement of angiogenesis in tumor tissue. At least 8 different immunohistochemical studies have investigated expression of COX-2 in a total of 2392 primary breast carcinomas, of which 40% were found to be COX- 2—positive. Overexpression of COX-2 is associated with indicators of poor prognosis, such as lymph node metastasis, poor differentiation, and large tumor size. Four studies have found that overexpression of COX-2 is linked to poor prognosis in breast cancer. These investigations provide the basis for further evaluation of a possible therapeutic effect of COX inhibitors in therapy of breast cancer.

Breast cancer chemoprevention: additional observations

We would like to comment on Salih and Fentiman's considered and timely review of breast cancer chemoprevention.1 Firstly, the preliminary results of the International Breast Intervention Study-l (IBIS-l) have now been presented.2 With a median follow-up of 50 months, a 33% reduction in breast cancer incidence was observed in the tamoxifen-treated group. The greatest risk reduction was observed in patients with ductal carcinoma in situ and was confined to patients with oestrogen-receptor positive tumours. Tamoxifen use was associated with a significant increase in the incidence of venous thromboembolism and endometrial carcinoma, and a 2.5 fold increase in mortality from all causes. These results are of some concern, as apart from confirming the significant morbidity of tamoxifen therapy, they suggest that chemoprevention will need to be individualised to specific subgroups of patients. Lack of individualisation of therapy could explain the apparent non-significant effect observed during the fenretinide trial3 quoted by the authors. It is likely retinoids exert their anti-cancer activity by modifying the IGF-l/IGFBP-3 system.4 This effect may be genetically determined. AA-type individuals, for example, produce high levels of IGFBP-3 in response to retinoids,5 so it is possible that these women, who may have derived significant benefit from retinoids, were not represented with significant power in the Veronesi study. Regarding the newer candidates for chemoprevention, there is now considerable evidence to demonstrate overexpression of COX-2 in breast cancer, and a role for cyclo-oxygenase inhibitors in treatment.6, 7 A recent meta-analysis8 described a risk reduction in breast cancer incidence of 20% with the use of NSAIDs. While it might be attractive to minimise the adverse sequelae of COX-1 suppression by using selective COX-2 inhibition, concern has recently been raised regarding the toxicity profile of COX-2 inhibitors. Reappraisal of the original celecoxib long term arthritis safety study (CLASS) data uncovered flaws in the original study design.9 Revised data now indicate that COX-2 inhibitors may have a similar incidence of ulcer complications to traditional NSAIDs. COX-1 overactivity is also present in some breast cancers,10, 11 and experimental studies with COX-1 or COX-2 null cells have shown prostaglandin levels remain high in the cells, because of increased transcription of the remaining functional gene.12 Although there are many remaining questions regarding the application of COX-suppression in breast cancer, it is possible that some will be answered with carefully planned randomised controlled clinical trials. The significant challenge for the future will, however, reside in identifying chemoprevention strategies that will provide the most benefit for individual patients, particularly those with oestrogen-receptor negative disease.