Lack of prognostic effect of Cox-2 expression in primary breast cancer on short-term follow-up

S-nitrosylated and non-nitrosylated COX2 have differential expression and distinct subcellular localization in normal and breast cancer tissue

Immunohistochemical (IHC) staining in breast cancer shows both gain and loss of COX2 expression with disease risk and progression. We investigated four common COX2 antibody clones and found high specificity for purified human COX2 for three clones; however, recognition of COX2 in cell lysates was clone dependent. Biochemical characterization revealed two distinct forms of COX2, with SP21 recognizing an S-nitrosylated form, and CX229 and CX294 recognizing non-nitrosylated COX2 antigen. We found S-nitrosylated and non-nitrosylated COX2 occupy different subcellular locations in normal and breast cancer tissue, implicating distinct synthetic/trafficking pathways and function. Dual stains of ~2000 breast cancer cases show early-onset breast cancer had increased expression of both forms of COX2 compared to postmenopausal cases. Our results highlight the strengths of using multiple, highly characterized antibody clones for COX2 IHC studies and raise the prospect that S-nitrosylation of COX2 may play a role in breast cancer biology.

EP3 (prostaglandin E2 receptor 3) expression is a prognostic factor for progression-free and overall survival in sporadic breast cancer

Background

In various cancers, overexpression of cyclooxygenase (COX)-2 and elevated prostaglandin (PG) E2 synthesis have been associated with tumor development and progression. The potential of COX-2 inhibitors in cancer prevention and treatment has been shown repeatedly; however, their clinical use is limited due to toxicity. PGE2 signals via EP receptors 1–4, whose functions are analyzed in current research in search for targeted anti-PG therapies. EP2 and EP4 rather promote tumorigenesis, while the role of EP3, especially in breast cancer, is not yet clear and both pro- and anti-tumorigenic effects have been described. Our study evaluates EP3 receptor expression in sporadic breast cancer and its association with clinicopathological parameters, progression-free and overall survival.

Methods

Two hundred eighty-nine sporadic breast cancer samples without primary distant metastasis were immunohistochemically analyzed for EP3 receptor expression. Tissue was stained with primary anti-EP3-antibodies. Immunoreactivity was quantified by the immunoreactivity-score (IRS); samples with an IRS ≥ 2 scored as EP3 positive. Chi-squared and Mann-Whitney-U test were used for comparison of data; Kaplan-Meier estimates and Cox-regression were used for survival analyses.

Results

EP3 receptor was expressed in 205 of 289 samples analyzed (70.9%). EP3 receptor expression was not associated with clinicopathological parameters (e. g. tumor size, hormone receptors, lymph node status). Kaplan-Meier estimates showed a significant association of EP3 positivity with improved progression-free survival (p = 0.002) and improved overall survival (p = 0.001) after up to 10 years. Cox regression analysis confirmed EP3 positivity as a significant prognostic factor even when other known prognosticators were accounted for.

Conclusions

In sporadic breast cancer, EP3 receptor expression is not significantly associated with clinicopathological parameters but is a significant prognostic factor for improved progression-free and overall survival. However, the functional aspects of EP3 receptor in breast cancer and the way how EP3 may oppose the pro-tumorigenic effects of PGE2 elevation and COX-2 overexpression are not fully understood so far. Further studies aiming at identification of the factors regulated by EP3 are necessary to evaluate the possibility of targeting EP3 in future anti-tumor therapy in breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4286-9) contains supplementary material, which is available to authorized users.

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.

Impact of cyclooxygenase-2 over-expression on the prognosis of breast cancer patients

OBJECTIVE

The aim of this present study was to assess the impact of COX-2 over-expression on breast cancer survival.

MATERIAL AND METHODS

Non-metastatic invasive breast cancer patients who received adequate loco-regional and systemic treatments were evaluated. Patients' demographic, clinical, pathologic, and treatment-related and survival data were retrieved from their hospital files. COX-2, estrogen/progesterone receptor (ER/PR), HER-2/neu expression and Ki67 index of the tumors were determined immunohistochemically. As the primary objective, COX-2 positive and negative patients were compared in terms of overall (OS), disease-free (DFS) and breast cancer-specific survival (BCSS). Secondary objectives were to assess the independent prognostic factors for survival. In addition, the correlation of COX-2 expression with conventional prognostic and predictive factors of breast cancer was assessed.

RESULTS

Two hundred and seventeen patients who underwent adequate breast cancer treatment between November 2004 and December 2013 were included in the study. The median follow-up was 37 months (range: 5-107). Eighty-one (37%) patients were COX-2 positive. OS, DFS, and BCSS were similar in COX-2 positive and negative patients. Ki67 index and age were significantly correlated with COX-2 expression (r=-0.116; p=0.02; r=0.159; p=0.02). PR expression was found to be the only independent factor for predicting OS, tumor size and molecular subtype classification were found to be the only independent factors for predicting DFS, and PR expression was found to be the only independent factor for predicting BCSS.

CONCLUSION

Among the independent predictive and prognostic factors of breast cancer, COX-2 over-expression was only correlated with Ki67 index and age.

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.

COX2 expression in high-grade breast cancer: evidence for prognostic significance in the subset of triple-negative breast cancer patients

COX2 expression correlates with high-grade breast cancer, but the clinical significance and possible prognostic influence in these patients have not been studied in depth. Our goal was to evaluate the significance of COX2 expression in a group of patients with high-grade breast cancer. Three hundred and three patients (median age 55; age range 25-95 years) with high-grade breast cancer entered this retrospective study. Mean follow-up was 65.2 months (4-179 months). COX2 expression was studied by immunohistochemistry. The distribution of patients with high-grade tumors according to staining for COX2 was as follows: score 0-28/303 (9.3 %); score 1-101/303 (33.3 %); score 2-114/303 (37.6 %); score 3-60/303 (19.8 %). Patients with score 2 and 3 were classified as COX2 positive (174 of 303 patients (57.4 %). There was no correlation between any clinicopathological pattern, ER, PR, Her2 status and COX2 expression. In the group of patients with triple-negative breast cancer, the 5-year disease-free survival rate was 58.3 % for patients with COX2 expression compared with 83.9 % for patients without COX2 expression (P = 0.042). COX2 expression did not provide any prognostic significance for the other biological subtypes of breast cancer with high-grade histological features.

Fatty acid metabolites in rapidly proliferating breast cancer

PURPOSE

Breast cancers that over-express a lipoxygenase or cyclooxygenase are associated with poor survival possibly because they overproduce metabolites that alter the cancer's malignant behaviors. However, these metabolites and behaviors have not been identified. We here identify which metabolites among those that stimulate breast cancer cell proliferation in vitro are associated with rapidly proliferating breast cancer.

EXPERIMENTAL DESIGN

We used selective ion monitoring-mass spectrometry to quantify in the cancer and normal breast tissue of 27 patients metabolites that stimulate (15-, 12-, 5-hydroxy-, and 5-oxo-eicosatetraenoate, 13-hydroxy-octadecaenoate [HODE]) or inhibit (prostaglandin [PG]E2 and D2) breast cancer cell proliferation. We then related their levels to each cancer's proliferation rate as defined by its Mib1 score.

RESULTS

13-HODE was the only metabolite strongly, significantly, and positively associated with Mib1 scores. It was similarly associated with aggressive grade and a key component of grade, mitosis, and also trended to be associated with lymph node metastasis. PGE2 and PGD2 trended to be negatively associated with these markers. No other metabolite in cancer and no metabolite in normal tissue had this profile of associations.

CONCLUSIONS

Our data fit a model wherein the overproduction of 13-HODE by 15-lipoxygenase-1 shortens breast cancer survival by stimulating its cells to proliferate and possibly metastasize; no other oxygenase-metabolite pathway, including cyclooxygenase-PGE2/D2 pathways, uses this specific mechanism to shorten survival.

Clinical relevance of cyclooxygenase-2 and matrix metalloproteinases (MMP-2 and MT1-MMP) in human breast cancer tissue

Breast cancer (BC) is the most common neoplasm among women in most developed countries, including Egypt. Elevated levels of certain proteins in human BC are associated with unfavorable prognosis and progressive stages of the disease. The aim of our study was to evaluate the protein expression profile and prognostic significance of cyclooxygenase-2 (COX-2), matrix metalloproteinase-2 (MMP-2), MMP-9 and membrane type 1-MMP (MT1-MMP) and their interaction in operable BC patients. The protein expression of COX-2, MMP-2 and MT1-MMP were evaluated by western blot technique, whereas enzymatic activity of MMP-2 and MMP-9 was determined by zymography in 47 breast cancer patients as well as normal adjacent tissues. Also, the correlation between these proteins and age, tumor size, LN stage, TNM stage, estrogen receptor, progesterone receptor, disease-free survival, and overall survival (OS) has been investigated. As compared to adjacent normal tissues, COX-2, MMP-2 and MT1-MMP were over-expressed in 43, 64, and 60 % of tumor tissues, respectively. In the same pattern, the activity of MMP-2 (62 %) and MMP-9 (45 %) was elevated in BC tissues. Multivariate analysis showed a positive correlation between the protein expression of COX-2, MMP-2, and MT1-MMP and the activity of MMP-2 and MMP-9 in BC patients. However, the enzymatic activity showed no correlation with clinicopathological features. This study confirms the preclinical evidence that COX-2 increased the expression of MT1-MMP, which in turn activates MMP-2. The lack of correlation with clinicopathological features, OS or disease-free survival ascertains the complexity of tumor progression and metastasis with many pro- and counter regulatory factors.

COX2 overexpression is a prognostic marker for Stage III breast cancer

To determine the significance of (Cyclooxygenase 2) COX2 for clinical outcome in breast cancer, we analyzed the correlation between COX2 overexpression and survival in 687 patients with invasive breast cancer. Cytoplasmic immunoreactivity of COX2 was determined as positive in 325 of 687 (47.3%) invasive breast cancers. COX2 positivity was significantly correlated with high histologic grade, negative estrogen receptor (ER), high Ki67, luminal B and triple-negative tumors, Bcl2 negativity, and p53 overexpression. In univariate analysis, COX2 overexpression resulted in significantly shorter relapse-free survival (RFS) [hazard ratio (HR) 1.487, 95% CI 1.035-2.110, P = 0.032]. Multivariate analysis revealed no significant association between COX2 overexpression and either overall survival (OS) or RFS. Kaplan-Meier analysis of the whole patient group showed significantly reduced RFS in patients with high COX2 expression, compared to those that did not overexpress COX2 (91 vs. 162 months, P = 0.031). Stratified subgroup analysis by TNM stage disclosed marked differences in OS and RFS rates in Stage III patients. We observed a significant association of COX2 overexpression with shorter RFS in the ER-negative subgroup of Stage III patients. The results show that COX2 overexpression is a significant unfavorable prognostic factor in Stage III breast cancer, and provide selective criteria for COX2 inhibitor combinations for invasive breast cancer therapy.

COX2 expression in prognosis and in prediction to endocrine therapy in early breast cancer patients

In breast cancer, the prognostic impact of COX2 expression varies widely between studies. We examined the prognostic value of COX2 expression in a large cohort of breast cancer patients treated with primary surgery between 1985 and 1994 and explained the variable results of COX2 expression found in the literature. A tissue microarray was constructed of available tumour material, and ER, PgR, HER2, Ki67 and COX2 were examined by immunohistochemistry. Median follow-up was 19 years. Fifty-five percent (n = 369/677) of patients received no systemic treatment. COX2 was scored using a weighted histoscore. Analysis of COX2 expression in two groups based on the median (148; below vs. above) showed an increased hazard ratio (HR) of 1.35 (95% CI 1.05-1.75, P = 0.021) for disease-free survival (DFS) and of 1.39 (95% CI 1.03-1.82, P = 0.016) for overall survival (OS). However, COX2 did not remain independent in multivariate analysis. In patients with hormone receptor positive tumours, COX2 expression had a negative influence on outcome (low vs. high: DFS: HR 1.37, 95% CI 1.07-1.76, P = 0.013). This effect disappeared when endocrine therapy was administered (low vs. high: DFS: HR 0.93, 95% CI 0.51-1.70, P = 0.811) while it remained statistically significant when endocrine therapy was omitted (low vs. high: DFS: HR 1.48, 95% CI 1.12-1.94, P = 0.005). Our results show that COX2 plays a role in hormonal pathways. Our results can explain the results found in previously published studies.

Inflammation and breast cancer. Cyclooxygenase/prostaglandin signaling and breast cancer

Many human cancers exhibit elevated prostaglandin (PG) levels due to upregulation of cyclooxygenase-2 (COX-2), a key enzyme in eicosanoid biosynthesis. COX-2 over-expression has been observed in about 40% of cases of invasive breast carcinoma and at a higher frequency in preinvasive ductal carcinoma in situ tumors, Extensive pharmacologic and genetic evidence implicates COX enzymes in neoplasia. Epidemiologic analyses demonstrate a protective effect of COX-inhibiting nonsteroidal anti-inflammatory drugs with respect to human cancer. Complementary experimental studies have established that both conventional nonsteroidal anti-inflammatory drugs and selective COX-2 inhibitors suppress mammary tumor formation in rodent breast cancer models. Furthermore, knocking out Cox-2 reduces mammary tumorigenesis and angiogenesis, and, conversely, transgenic COX-2 over-expression induces tumor formation. The utility of COX/PG signaling as a target for chemoprevention has been established by randomized controlled clinical trials. However, these studies also identified increased cardiovascular risk associated with use of selective COX-2 inhibitors. Thus, current efforts are directed toward identifying safer approaches to antagonizing COX/PG signaling for cancer prevention and treatment, with a particular focus on PGE₂ regulation and signaling, because PGE₂ is a key protumorigenic prostanoid.

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.

Cyclooxygenase-2 expression in advanced nasopharyngeal carcinoma—a prognostic evaluation and correlation with hypoxia inducible factor 1α and vascular endothelial growth factor

Cycloxygenase-2 (COX-2), hypoxia inducible factor 1-alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) can be induced by the Epstein-Barr virus oncoprotein latent membrane protein-1 (LMP-1) in nasopharyngeal cancer (NPC) cell lines. This study examined the prognostic relevance of COX-2 and its relationship with HIF-1alpha and VEGF expression in NPC biopsies. Primary tumor biopsies were obtained from 78 participants of a randomized trial who received radiotherapy (RT) with or without concurrent chemotherapy for locoregionally advanced NPC. These were analyzed for COX-2 expression and then correlated with age, sex, disease stage, treatment arm, survival and disease recurrence, VEGF and HIF-1alpha expression in a regression model. 83% of tumors expressed COX-2, 47% co-expressed COX-2 and VEGF, 38% co-expressed COX-2 and HIF-1alpha. On univariate analysis, COX-2 expression did not correlate with survival and recurrence, but moderate to high COX-2 expression was associated with advanced nodal stage (p=0.03). Although univariate analysis showed that COX-2-HIF-1alpha co-expression was associated with worse progression-free survival (p=0.046), time to local (p=0.004) and regional recurrence (p=0.007), multivariate analysis failed to confirm any correlation between COX-2-HIF-1alpha or COX-2-VEGF co-expression and survival or disease recurrence. Contrary to previous report, this study failed to demonstrate any prognostic significance of COX-2 expression alone or co-expression with HIF-1alpha or VEGF in advanced NPC.

The status of cyclooxygenase-2 expression in ductal carcinoma in situ lesions and invasive breast cancer correlates to cyclooxygenase-2 expression in normal breast tissue

OBJECTIVES

There is a paucity of data on cyclooxygenase (COX)-2 expression in normal breast tissue and on the changes in COX-2 expression from normal tissue via ductal carcinoma in situ (DCIS) lesions to invasive cancer. The aim of this study, therefore, was to investigate COX-2 protein expression in normal breast tissue, DCIS, and invasive breast cancer in samples from the same patients.

METHODS

In 39 patients, we investigated and compared COX-2 expression in paired samples of invasive cancer and normal adjacent breast epithelium by immunohistochemistry with a monoclonal COX-2 antibody. Furthermore, in 29 of these cases, we also analyzed a concomitant DCIS lesion.

RESULTS

Patients without COX-2 expression in normal breast tissue also do not express COX-2 in invasive breast cancer and in DCIS lesions, respectively. Conversely, COX-2 expression in normal breast tissue was an indicator for COX-2 expression in the paired breast tumors. There was no significant correlation between COX-2 expression and pathologic tumor stage, nodal status, hormone receptor status, tumor size, grading, and lymphovascular space involvement.

CONCLUSIONS

This is the largest study to date investigating COX-2 in paired samples of breast tumors and normal adjacent breast tissue. Our data are consistent with the hypothesis that COX-2 overexpression is an early event in breast carcinogenesis.

Cox-2 expression on tissue microarray of breast cancer

AIM

To measure cyclooxygenase-2 (Cox-2) expression in a series of breast cancers and evaluate its potential as a predictive marker for doxorubicin chemotherapy.

PATIENTS AND METHODS

Cox-2 expression was analyzed in 178 node-positive patients treated with doxorubicin-based adjuvant chemotherapy by immunohistochemistry on tissue microarray (TMA).

RESULTS

Cox-2 was over-expressed in 70 out of the 178 invasive breast cancers. Cox-2 expression was significantly increased in undifferentiated tumors. There was no significant association between Cox-2 over-expression and tumor size, histologic grade, and estrogen receptor expression. Disease-free survival and overall survival of the patients having Cox-2 expressing tumor were significantly decreased when compared with the patients having Cox-2 negative tumor (p=0.009 for DFS, p=0.011 for OS).

CONCLUSION

Cox-2 expression may represent an aggressive phenotype of breast cancer which is resistant to doxorubicin.

Expression of cyclooxygenase-2 in breast carcinogenesis and its relation to HER-2/neu and p53 protein expression in invasive ductal carcinoma

The purpose of this study was to evaluate cyclooxygenase-2 (COX-2) expression in the successive steps of breast carcinogenesis and to determine its correlation with HER-2/neu and p53 expression in invasive ductal carcinomas of the breast. Immunohistochemical staining with anti-COX-2 antibody was performed in normal breast tissue, usual hyperplasia, ductal carcinoma in situ, and invasive ductal carcinoma. Expression of COX-2 in invasive ductal carcinoma was correlated with immunohistochemical expression of HER-2/neu and p53 protein. COX-2 expression was found to be progressively elevated along the continuum from normal breast tissue to invasive ductal carcinoma (P<0.001). COX-2 expression significantly correlated with p53 and HER-2/neu protein expression (P<0.05 and P<0.001). On multivariate analysis, only TNM stage and elevated COX-2 expression correlated with survival. Our results suggest that COX-2 may be involved in the carcinogenesis of the breast and may be an independent prognostic indicator in patients with invasive ductal carcinoma. HER-2/neu and p53 are likely to be involved in the regulation of COX-2 expression in invasive ductal carcinomas of the breast.

Overexpression of cyclooxygenase-2 is associated with a favorable prognostic phenotype in breast carcinoma

OBJECTIVES

Cyclooxygenase (COX) is the rate-limiting enzyme that catalyzes the conversion of arachidonic acid to prostaglandins. The purpose of the present study was to investigate the involvement of COX-2 protein in breast cancer biological behavior through its correlation with the well-known clinicopathological parameters and the expression of p53, c-erbB-2, topoisomerase IIalpha (topoIIalpha) and peroxisome proliferator-activated receptor (PPARgamma) proteins, as well as its effect on patients' survival.

METHODS

We performed immunohistochemistry to detect COX-2, estrogen receptor (ER), progesterone receptor (PR), p53, c-erbB-2, topoIIalpha and PPARgamma proteins in 175 cases of invasive breast carcinomas. The results were elaborated by statistic analysis.

RESULTS

Cytoplasmic expression of COX-2 was detected in 66.9% of breast carcinoma samples and was inversely correlated with both nuclear and histological grade (p < 0.0001 and p = 0.039, respectively), whereas its association with PR was found to be positive (p = 0.016). COX-2 expression was inversely correlated with topoIIalpha and p53 (p = 0.033 and p = 0.002, respectively), whereas its association with PPARgamma was parallel (p < 0.0001). In addition, c-erbB-2 of tumor cells was inversely correlated with COX-2 in stromal cells of the tumor (p = 0.011). Neither univariate nor multivariate analysis demonstrated any association between COX-2 expression and patient overall or disease-free survival.

CONCLUSIONS

The current data suggest that increased expression of COX-2 may be related to breast carcinomas with less aggressive phenotype. This suggestion is further supported by the positive correlation between COX-2 and PPARgamma, since the latter is considered to be indicative of a less malignant phenotype of tumor cells.

Optimisation of an extraction method for the determination of prostaglandin E2 in plasma using experimental design and liquid chromatography tandem mass spectrometry

A new extraction method has been developed for the extraction of prostaglandin E(2) (PGE(2)) from human plasma of patients suffering chronic inflammatory disorders. The extraction solvents were optimised systematically and simultaneously by using a central composite design. The optimised method involves precipitation of the protein fraction, centrifugation, evaporation and dissolution of the supernatant in the mobile phase, screening to confirm the presence of the analyte, and quantification of the positive samples by liquid chromatography tandem ion-trap mass spectrometry. Tandem mass spectrometry in negative mode was performed by isolating and fragmenting the ion [PGE(2)-H](-) signal m/z 351. Identification and quantification was carried out by extracting the ion fragment chromatograms at 333, 315 and 271 m/z. The quantitative determination was linear for the low nanogram (1-50 ng/ml) and upper picogram (400-1000 pg/ml) range studied, using 15 and 0.5 ng/ml of internal standard, respectively. The lower limit of detection was 2.5 pg for an injection volume of 25 microl. The optimised extraction method showed high reproducibility (coefficients of variation<4%) and recovery values, estimated from standard addition experiments, ranging from 96 to 98%.

Relationship between expression and distribution of cyclooxygenase-2 and bcl-2 in human gastric adenocarcinoma

AIM: To explore expression and distribution features of COX-2 and bcl-2 in human gastric adenocarcinoma tissues and to study its biological significance.

METHODS: Totally 36 human gastric carcinoma samples were enrolled in this study (cardiac adenocarcinoma 16 cases, distal gastric adenocarcinoma 20 cases). The expressions of COX-2 and bcl-2 in cancerous tissues and corresponding para-cancerous tissues were investigated by immunohistochemistry using COX-2 polyclonal antibody and bcl-2 monoclonal antibody. The normal gastric mucosa tissues were used as control.

RESULTS: The expressions of COX-2 and bcl-2 in gastric carcinoma were significantly higher than that in the para-cancerous tissues (77.8% vs 47.2%, P<0.01, 80.56% vs 58.33%, P<0.05). The expression of COX-2 in cardiac adenocarcinoma was remarkably higher than that in the distal gastric carcinoma (93.8% vs 65.0%, P<0.01). The expression of COX-2 was mainly localized in the cytoplasm of tumor cells and partly in the nucleus. There is a transition of the COX-2 cytoplasmic positivity to nucleic in tumor cells with the increase of gastric carcinoma pathological grade. Interstitial macrophages, fibroblasts and vascular endothelial cells also expressed COX-2. The tissues with higher expression of COX-2 also expressed high level of bcl-2 protein.

CONCLUSION: Abnormal expression pattern of COX-2 within the tissues of human gastric cancer is correlated with tumor location and lymph node metastasis. COX-2 may regulate expression of apoptosis suppressor gene (bcl-2) through interaction of tumor cells and stromal cells and play an important role in the generation and development of tumors, which will be of great help in developing new methods for antitumor therapy.

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

BACKGROUND AND OBJECTIVES

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.

METHOD

Archival specimens of IDC and DCIS (n = 39) were stained with a polyclonal antibody to COX-2. Results were correlated with recognised clinicopathological parameters.

RESULTS

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).

CONCLUSION

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.