Cyclooxygenase-2 Expression in Uterine Leiomyosarcomas

The cyclooxygenase-2 inhibitor NS-398 inhibits proliferation and induces apoptosis in human osteosarcoma cells via downregulation of the survivin pathway

Cyclooxygenase-2 (COX-2) is frequently overexpressed in human malignancies and plays a crucial role in tumorigenesis and cancer progression. The present study aimed to investigate the expression and clinical significance of COX-2 and survivin (SUV) in human osteosarcomas (OS), and explore the effects and molecular mechanisms of a selective COX-2 inhibitor NS-398 and SUV on tumor proliferation and apoptosis. Fifty cases of human OS and osteochondromas (OC) were collected. The expression of COX-2 and SUV was assessed using immunohistochemical assays in biopsy samples. MG-63 human OS cells were treated with different concentrations of NS-398, used to investigate their effects on cell proliferation and apoptosis. The recombinant small hairpin RNA adenovirus vector rAd5-SUV was constructed, and the effects and molecular mechanisms of knockdown of SUV on proliferation and apoptosis were evaluated in MG-63 cells. A subcutaneous xenograft tumor model was established, validating the effects of rAd5-SUV on tumor growth in vivo. Based on the results, the expression of COX-2 and SUV in OS showed a higher strong reactivity rate compared with OC (73.3 vs. 25.0%, P=0.001; 63.3 vs. 30.0%, P=0.02), but it did not correlate with the clinicopathological characteristics of OS. NS-398 inhibited proliferation, induced apoptosis and decreased the mRNA expression of COX-2 and SUV in MG-63 cells. Furthermore, adenovirus-mediated knockdown of SUV inhibited proliferation, induced apoptosis, reduced the expression of proliferating cell nuclear antigen (PCNA), increased the expression of caspase-3 (CAS-3) and slowed the growth of xenograft tumors in MG-63 cells. Taken together, the expression of COX-2 and SUV is closely correlated with human OS, and inhibition of COX-2 or knockdown of SUV suppresses tumor proliferation and induces apoptosis, suggesting that COX-2 may be involved in OS cell proliferation and apoptosis through SUV-mediated regulation of PCNA and CAS-3 expression, and provides a potential therapeutic strategy for the treatment of cancer.

Cyclooxygenase-2 Is an Independent Predictor of Poor Prognosis in Uterine Leiomyosarcomas

Introduction:

Cyclooxygenase-2 (COX-2) is a well-known enzyme that promotes tumor growth and metastasis. Cyclooxygenase-2 is upregulated in a number of human epithelial tumors, but data about the significance of COX-2 in mesenchymal tumors are lacking. The purpose of this study was to determine COX-2 expression in uterine sarcomas and whether a relationship exists between COX-2 expression and clinicopathologic outcomes.

Methods:

Immunohistochemical staining for COX-2 was performed on paraffin-embedded tissue blocks of 49 uterine sarcomas (30 leiomyosarcomas, 14 endometrial stromal sarcomas, and 5 carcinosarcomas). Positive staining was defined as moderate or strong staining in 5% or more of tumor cells.

Results:

Four of 30 leiomyosarcomas, 1 of 14 endometrial stromal sarcomas, and 2 of 5 carcinosarcomas were positive for COX-2 expression. In leiomyosarcomas, COX-2 expression correlated with tumor stage with marginal significance (P = 0.058). Patients with leiomyosarcoma positive for COX-2 expression had a lower overall survival rate than those without COX-2 expression (P = 0.025). In the multivariate Cox proportional hazards regression model, COX-2 expression, tumor stage, and mitotic count were independently associated with overall survival in leiomyosarcomas.

Conclusions:

Our data suggest that immunohistochemically determined COX-2 expression is an independent prognostic factor in uterine leiomyosarcomas. Assessment of COX-2 status might be useful for determining the prognosis in patients with uterine leiomyosarcomas.

Expression of cyclooxygenase-2, c-kit, progesterone and estrogen receptors in uterine smooth muscle tumors: differential diagnosis

We examined the expression pattern of cyclooxygenase-2 (COX-2) and c-kit in uterine smooth muscle neoplasms and tried to determine the role of these markers in differential diagnosis. Archival tissue from 64 patients with uterine smooth muscle neoplasms (20 leiomyomas (LMs), 22 atypical leiomyomas (ALMs), and 22 leiomyosarcomas (LMSs)) was immunostained with antibodies against estrogen (ER) and progesterone receptors (PR), COX-2 and c-kit. 7 of 20 LM cases and 5 of 22 ALM cases were immunopositive for COX-2, whereas none of the LMS cases stained immunopositive (p< or =0.05). 4 of 20 LM cases and 5 of 22 ALM cases were immunopositive for c-kit, whereas 15 of 22 LMS cases showed c-kit immunopositivity (p< or =0.05). In conclusion, very few LMs and ALMs show COX-2 immunopositivity. LMSs usually do not express COX-2. COX-2 expression in smooth muscle tumors is not a prominent feature. Therefore, COX-2 inhibitors may not be useful in LMS therapy. C-kit was significantly expressed in uterine LMSs.

Cyclooxygenase-2: a novel target in human solid tumors

The enzyme cyclooxygenase-2, which is involved in the conversion of arachidonic acid-to-prostanoid synthesis, plays a key role in many inflammatory and proliferative reactions. Experimental data have shown that prostaglandins have a central action in therapeutic targeting not only in the treatment of many inflammatory diseases but also in several types of human cancers. Inhibitors of cyclooxygenase activity seem to protect against carcinoma development and show promise as chemopreventive agents and possible target therapies. Data support new treatments for patients with solid cancers tailored to the molecular characteristics of the individual tumor.