Cyclooxygenase-2 expression in borderline ovarian tumors

EP2/EP4 targeting prevents tumor-derived PGE2-mediated immunosuppression in cDC2s

Tumor-derived prostaglandin E2 (PGE2) impairs antitumor immunity by priming suppressive functions on various immune cell types, including dendritic cells (DCs). In this way, tumors mediate DC dysfunction and hamper their antitumoral activity. PGE2 is known to modulate DC function via signaling through the E-type prostanoid receptor 2 (EP2) and EP4. Preclinical studies have demonstrated the therapeutic value of targeting EP2/4 receptor signaling in DCs. Ongoing phase 1 clinical trials with EP antagonists have shown immunomodulation in cancer patients. However, the systemic drug administration leads to off-target events and subsequent side effects. To limit the off-target effects of EP targeting, EP2 and EP4 antagonists were encapsulated in polymeric nanoparticles (NPs). In this study, we evaluated the efficacy of EP2/4-specific antagonists encapsulated in NPs to protect conventional type 2 DCs (cDC2s) from suppressive effects of tumor-derived PGE2 in different tumor models. We show that tumor-derived PGE2 signals via EP2/4 to mediate the acquisition of a suppressive phenotype of cDC2s. EP2/4 antagonists encapsulated in NPs impaired the conversion of cDC2s toward a suppressive state and inhibited the occurrence of suppressive features such as interleukin-10 production or the ability to expand regulatory T cells. Importantly, the NPs abolished the transition toward this suppressive state in different tumor models: melanoma-conditioned media, ascites fluid derived from ovarian cancer patients (2-dimensional), and upon coculture with colorectal cancer patient-derived organoids (3-dimensional). We propose that targeting the PGE2-EP2/4 axis using NPs can achieve immunomodulation in the immune system of cancer patients, alleviate tumor-derived suppression, and thus facilitate the development of potent antitumor immunity in cancer patients.

Cyclooxygenase-2 promotes ovarian cancer cell migration and cisplatin resistance via regulating epithelial mesenchymal transition

OBJECTIVE

Drug-resistance and metastasis are major reasons for the high mortality of ovarian cancer (OC) patients. Cyclooxygenase-2 (COX-2) plays a critical role in OC development. This study was designed to evaluate the effects of COX-2 on migration and cisplatin (cis-dichloro diammine platinum, CDDP) resistance of OC cells and explore its related mechanisms.

METHODS

Cell counting kit-8 (CCK-8) assay was used to detect the cytotoxicity effects of celecoxib (CXB) and CDDP on SKOV3 and ES2 cells. The effect of COX-2 on migration was evaluated via the healing test. Western blot and real-time quantitative polymerase chain reaction (qPCR) were used to analyze E-cadherin, vimentin, Snail, and Slug levels.

RESULTS

COX-2 promoted drug-resistance and cell migration. CXB inhibited these effects. The combination of CDDP and CXB increased tumor cell sensitivity, reduced the amount of CDDP required, and shortened treatment administration time. COX-2 upregulation increased the expression of Snail and Slug, resulting in E-cadherin expression downregulation and vimentin upregulation.

CONCLUSIONS

COX-2 promotes cancer cell migration and CDDP resistance and may serve as a potential target for curing OC.

Cox-2 expression in ovarian malignancies: a review of the clinical aspects

COX-2 is an inducible enzyme expressed only in response to stimuli such as mitogens, cytokines, growth factors or hormones, and is pro-inflammatory. It plays an important role in tumorigenesis. The purpose of the present report is to review the clinical aspects of COX-2 expression in ovarian malignancies. A PubMed (http://www.pubmed.gov/) search of investigations published from July 2001 until August 2008 and containing the term COX-2 in combination with ovarian malignancies was conducted. The clinical aspects of the relevant investigations were reviewed. COX-2 is expressed in ovarian tumors of low malignant potential (LMP), in epithelial ovarian carcinoma (EOC) and primary peritoneal carcinoma (PPC) and apparently plays a role in their carcinogenesis. Its expression seems to be correlated with VEGF that serves as a predictor of poor prognosis in some non-gynecologic malignancies. COX-2 expression is higher in EOC than in LMPs. The results with regard to the association between COX-2 expression and prognostic factors, response to treatment and outcome in ovarian malignancies are inconsistent. Clinical studies dealing with the effect of COX-2 inhibitors on outcome are scarce. The use of COX-2 expression in gynecological malignancies in clinical practice remains to be elucidated.

Cyclooxygenase-2 (cox-2) and the inflammogenesis of cancer

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that aberrant induction of COX-2 and up-regulation of the prostaglandin cascade play a significant role in carcinogenesis, and reciprocally, blockade of the process has strong potential for cancer prevention and therapy. Supporting evidence includes the following: [1] expression of constitutive COX-2-catalyzed prostaglandin biosynthesis is induced by most cancer-causing agents including tobacco smoke and its components (polycylic aromatic amines, heterocyclic amines, nitrosamines), essential polyunsaturated fatty acids (unconjugated linoleic acid), mitogens, growth factors, proinflammatory cytokines, microbial agents, tumor promoters, and other epigenetic factors, [2] COX-2 expression is a characteristic feature of all premalignant neoplasms, [3] COX-2 expression is a characteristic feature of all malignant neoplasms, and expression intensifies with stage at detection and cancer progression and metastasis, [4] all essential features of carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis, and immunosuppression) are linked to COX-2-driven prostaglandin (PGE-2) biosynthesis, [5] animal studies show that COX-2 up-regulation (in the absence of genetic mutations) is sufficient to stimulate the transformation of normal cells to invasive cancer and metastatic disease, [6] non-selective COX-2 inhibitors, such as aspirin and ibuprofen, reduce the risk of human cancer and precancerous lesions, and [7] selective COX-2 inhibitors, such as celecoxib, reduce the risk of human cancer and precancerous lesions at all anatomic sites thus far investigated. Results confirming that COX-2 blockade is effective for both cancer prevention and therapy have been tempered by observations that some COX2 inhibitors pose a risk to the cardiovascular system, and more studies are needed in order to determine if certain of these drugs can be taken at dosages that prevent cancer without increasing cardiovascular risk. It is emphasized that the "inflammogenesis model of cancer" is not mutually exclusive and may in fact be synergistic with the accumulation of somatic mutations in tumor suppressor genes and oncogenes or epigenetic factors in the development of cancer.

Cell proliferation activity unrelated to COX-2 expression in ovarian tumors

The objective of this study was to assess the expression of Cyclooxygenase-2 (COX-2) and cell proliferation activity (Ki67 expression) in benign, borderline, and malignant serous and mucinous ovarian tumors. Expression of COX-2 and Ki67 proteins were evaluated by immunohistochemistry, in paraffin-embedded sections of ovarian epithelial tumors. The study included 113 serous (67 benign, 15 borderline, and 31 malignant) and 85 mucinous (48 benign, 28 borderline, and 9 malignant) tumors, removed from women who underwent laparotomy between January 1997 and December 2003. From benign to malignant tumors, there was a progressive positive trend in COX-2 expression in both serous and mucinous tumors, more evident in mucinous ones (P < 0.001). Comparing histologic types, COX-2 expression was more prominent in serous than in mucinous benign tumors (P < 0.01), but this difference was not significant in the borderline (P= 0.11) or malignant categories (P= 0.71). There was a progressive Ki67 positivity in line with the tumor histologic gradient for both serous (P < 0.01) and mucinous lesions (P < 0.01), but this increasing expression did not correlate with COX-2 expression in the present series (P= 0.78). There was a higher COX-2 expression in serous ovarian adenomas than in mucinous ones. COX-2 positivity increases in line with the morphologic gradient, from benign to malignant in both histologic types, but it was more prominent in mucinous lesions, pointing to different oncogenic pathways related to different histologic types. A correlation between the expression of COX-2 and Ki67 was not found, suggesting that COX-2 may be required for carcinogenesis, but this pathway is not responsible for cell proliferation in ovarian tumors.

Cyclooxygenase-2 (COX-2) Immunostaining Does Not Correlate With the Degree of Vulvar Neoplasia

OBJECTIVE

The cyclooxygenase-2 (COX-2) enzyme is up-regulated in inflammatory and neoplastic conditions. In the last decade, its biological role has been investigated in various pre-invasive and invasive cancers with the hope that it can serve as a target for cancer prevention and treatment.

METHODS

We evaluated the expression of COX-2 in vulvar biopsies to determine its relationship to the degree of dysplasia. COX-2 expression was studied by immunohistochemistry in 62 consecutive vulvar biopsies divided into four diagnostic groups. Group 1 included inflamed vulva (n = 14); group 2, vulvar intraepithelial neoplasia (VIN) I and VIN II (n = 20); group 3, VIN III and carcinoma in situ (n = 18); and group 4, invasive squamous cell carcinoma (n = 10). Representative sections were immunostained using polyclonal anti-COX-2 antibodies at concentration 1:25 without pretreatment. Immunostaining was scored according to the proportion of positive epithelial cells in the vulvar mucosa as 0 (no positive cells), 1(< 5% positive), 2 (6-50% positive), or 3 (> 50% positive).

RESULTS

Mean immunostaining scores were 1.6, 1.4, 0.7, and 1.2 for groups 1, 2, 3, and 4, respectively. Scores were different between the groups (chi(2) = 9.908, P = 0.019) as shown by Cochran-Mantel-Haenszel statistical analysis (modified ridit scores), but did not correlate with age or the degree of dysplasia. The strongest staining for COX-2 was in the inflammatory group.

CONCLUSION

COX-2 staining in inflamed, dysplastic, and malignant vulvar epithelium is variable but, as shown in this study, does not correlate with the degree of vulvar dysplasia or malignancy.