Cyclo-oxygenase-2 over-expression in sporadic colorectal carcinoma without lymph node involvement

PTGS2 (Cyclooxygenase-2) expression and survival among colorectal cancer patients: a systematic review

BACKGROUND

Studies have examined whether tumor expression of PTGS2 (also known as COX-2), an enzyme inhibited by nonsteroidal anti-inflammatory drugs such as aspirin, is associated with prognosis in patients with colorectal cancer. However, results to date have been mixed.

METHODS

Using terms for PTGS2 and colorectal cancer, the Medline, Embase, and Web of Science databases were systematically searched for studies published, in any language, until December 2011. Random effects meta-analyses were used to calculate pooled HRs [95% confidence intervals (CI)] for the association between PTGS2 expression and tumor recurrence, colorectal cancer-specific survival, and overall survival.

RESULTS

In total, 29 studies, which had prognostic data on 5,648 patients, met the inclusion criteria. PTGS2-positive patients were at an increased risk of tumor recurrence (n = 9 studies; HR, 2.79; 95% CI, 1.76-4.41; P < 0.001) and had poorer colorectal cancer-specific survival (n = 7; HR, 1.36; 95% CI, 1.02-1.82; P = 0.04). However, there was funnel plot asymmetry, possibly due to publication bias, for the association with cancer-specific survival but less so for recurrence. PTGS2 expression was not associated with overall survival [(n = 16; pooled unadjusted HR, 1.30; 95% CI, 0.94-1.79; P = 0.11) and (n = 9; pooled adjusted HR, 1.02; 95% CI, 0.72-1.45; P = 0.91)].

CONCLUSIONS

PTGS2 expression was associated with an increased risk of tumor recurrence and poorer colorectal cancer-specific survival but not overall survival among patients with colorectal cancer. However, confounding by tumor characteristics such as tumor stage seems likely.

IMPACT

There is insufficient evidence to recommend PTGS2 expression as a prognostic marker in patients with colorectal cancer. Furthermore, studies providing adjusted results are required.

Prognostic significance of COX-2 immunohistochemical expression in colorectal cancer: a meta-analysis of the literature

Background

Cyclooxygenase-2 (COX-2) is believed to be an important enzyme in the pathogenesis of colorectal cancer (CRC). Correlations between the expression of COX-2 with tumor growth and distant metastasis have become an issue; thus, attention has been paid to COX-2 as a prognostic factor. Various studies examined the relationship between COX-2 immunohistochemistry (IHC) overexpression with the clinical outcome in patients with colorectal cancer, but yielded conflicting results. The prognostic significance of COX-2 overexpression in colorectal cancer remains controversial.

Methods

Electronic databases updated to October 2012 were searched to find relevant studies. A meta-analysis was conducted with eligible studies which quantitatively evaluated the relationship between COX-2 overexpression and survival of patients with colorectal cancer. Survival data were aggregated and quantitatively analyzed.

Results

We performed a meta-analysis of 23 studies (n  =  4567 patients) that evaluated the correlation between COX-2 overexpression detected by IHC and survival in patients with colorectal cancer. Combined hazard ratios suggested that COX-2 overexpression had an unfavorable impact on overall survival (OS) (HR [hazard ratio]  =  1.193, 95% CI [confidence interval]: 1.02 ∼ 1.37), but not disease free survival (DFS) (HR  =  1.25, 95% CI: 0.99 ∼ 1.50) in patients with colorectal cancer.

Conclusions

Cox-2 overexpression in colorectal cancer detected by IHC appears to have slightly worse overall survival. However, the prognostic value of COX-2 on survival in colorectal cancer still needs further large-scale prospective trials to be clarified.

Expression of COX-2 and E-cadherin in Tunisian patients with colorectal adenocarcinoma

Cyclo-oxygenase 2 (COX-2) and E-cadherin are promising biomarkers for cancer diagnosis and therapy. The aim of this study was to examine the expression of these two proteins in primary colorectal adenocarcinomas and to investigate their association with clinicopathological characteristics including survival of patients. Immunostaining of E-cadherin and COX-2 was assessed in 70 primary colorectal adenocarcinomas from Tunisian patients. Membranous E-cadherin immunostaining and cytoplasmic COX-2 expression were observed in 74.3% and 68.6% of cases respectively. A significant association was found between COX-2 expression and age at diagnosis (P=0.02), and vessel invasion (P=0.037). The expression of E-cadherin correlated with age at diagnosis (P=0.01), and tumor size (P=0.02). In addition, by multivariate analysis, we revealed a significant association with 1-year disease free survival and a tendency with distant metastasis (P=0.017 and P=0.065 respectively). On the other hand, tumors exhibiting COX-2+/E-cadherin-profile were larger (P=0.006), and in an advanced stage (P=0.001). Survival analysis showed that COX-2 over-expression confers a reduced overall survival rate (Plog rank=0.036) and is an independent factor predictive for prognosis.

Cyclooxygenase-2 expression correlates with membrane-type-1 matrix metalloproteinase expression in colorectal cancer tissue

PURPOSE

Elevated expression of cyclooxygenase-2 has been found in colorectal cancer. One of the mechanisms through which cyclooxygenase-2 affects tumorigenesis is through its overexpression, which leads to increased invasiveness of cancer cells. A crucial step in this pathway is thought to be the induction of membrane-type-1 matrix metalloproteinase, which activates matrix metalloproteinase-2. However, to date there have been few clinicopathologic studies concerning cyclooxygenase-2-mediated invasiveness in human colorectal cancer tissues.

METHODS

We performed immunohistochemical analysis of the respective antigens on colorectal cancer specimens obtained by surgical resections from 96 patients with colorectal cancer.

RESULTS

Cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression was positive exclusively in cancer cells in 88 cases (92 percent) and 23 cases (24 percent), respectively. All 23 cases expressing membrane-type-1 matrix metalloproteinase also expressed cyclooxygenase-2. Matrix metalloproteinase-2 expression was positive in cancer cells in 20 cases (21 percent) and stromal cells in 52 cases (54 percent). Expression of matrix metalloproteinase-2 in cancer cells correlated with lymphatic invasion and local recurrence. Statistically, a significant correlation was found between cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression, and membrane-type-1 matrix metalloproteinase and matrix metalloproteinase-2 expression in cancer cells. There was no association between cyclooxygenase-2 expression and matrix metalloproteinase-2 expression. However, immunostaining of serial sections revealed that in the majority of cases examined, nearly 100 percent of cancer cells expressing matrix metalloproteinase-2 also coexpressed cyclooxygenase-2.

CONCLUSIONS

This study indicates strong association between both cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression, and membrane-type-1 matrix metalloproteinase and matrix metalloproteinase-2 in colorectal cancer. These results support our thesis of a direct correlation between cyclooxygenase-2 and membrane-type-1 matrix metalloproteinase expression--with consequent association between cyclooxygenase-2 and matrix metalloproteinase-2 activation, and tumor invasiveness andrecurrence in certain cases of colorectal cancer.

The PPAR(gamma) K422Q mutation does not contribute to troglitazone inefficiency in colon cancer treatment

Peroxisome proliferator-activated receptor gamma (PPAR(gamma)) ligands inhibit cell growth of colorectal cancer cells in most experimental models, but no significant effect could be observed in patients with colorectal cancer. We therefore, screened human colorectal tumors to determine the prevalence of the PPAR(gamma) K422Q loss-of-function mutation, recently identified in 50% of colonic cancer cell lines. A sensitive allele-specific real-time amplification assay was developed and 170 colorectal primary tumors and 12 liver metastasis were analyzed. We did not find the K422Q mutation in any of these samples. We can therefore exclude this alteration as a mechanism of resistance to PPAR(gamma) ligands in patients with colon cancer.

Cyclooxygenase-2 Expression

PURPOSE

Recent studies have shown that cyclooxygenase (Cox)-2 may be involved in colorectal carcinogenesis. We aimed to determine whether Cox-2 expression in itself can predict outcome of colorectal cancer patient after surgery. In addition, the expression of Cox-1 was also evaluated.

EXPERIMENTAL DESIGN

Tissue samples of primary and secondary tumors from 288 patients undergoing surgical resections for colorectal adenocarcinoma were immunohistochemically examined for Cox-2 and Cox-1 expressions. The specimens were graded based on the intensity and extent of staining; then, the correlations between Cox-2 and Cox-1 expressions with clinicopathologic parameters and survival time were analyzed.

RESULTS

Expression of Cox-2 was positive in 70.8% of primary tumor, 92.0% of lymph node metastases, 100.0% of hepatic metastases, and was significantly associated with tumor size, depth of invasion, lymph node metastasis, vessels invasion, stage and recurrence. In contrast, Cox-1 was positive in 42.7% of primary tumor, 84.0% of lymph node metastases, 37.5% hepatic metastases, and was associated with only tumor size. Patients with Cox-2-positive tumors had a significant shorter survival time than those with negative tumors did (P = 0.0006 by log-rank test); and, in a multivariate analysis, Cox-2 was an independent prognostic factor (P = 0.0103; relative risk 4.114; 95% confidence interval, 1.397-12.120). Cox-1 status had no statistically effect on patient survival time.

CONCLUSIONS

Elevated Cox-2 expression, but not that of Cox-1, was significantly associated with reduced survival and recognized as an independent prognostic factor in our cohort of colorectal cancer patients.