Frequent co-localization of Cox-2 and laminin-5 gamma2 chain at the invasive front of early-stage lung adenocarcinomas

Cytokines differentially regulate the synthesis of prostanoid and nitric oxide mediators in tumorigenic versus non-tumorigenic mouse lung epithelial cell lines

Studies using transgenic and knockout mice have demonstrated that particular cytokines influence lung tumor growth and identified prostaglandin E2 (PGE2), prostacyclin (PGI2) and nitric oxide (NO) as critical mediators of this process. PGE2 and NO were pro-tumorigenic while PGI2 was antitumorigenic. We describe herein an in vitro experimental approach to examine interactions among cytokines, prostaglandins (PGs) and NO. PGE2, PGI2, and NO levels were assayed in culture media from non-tumorigenic mouse lung epithelial cell lines, their spontaneous transformants and mouse lung tumor-derived cell lines, before or after exposure to the cytokines TNFalpha, IFNgamma and IL1beta, alone and in combination. More PGE2 than PGI2 was produced by neoplastic cells, while the opposite was observed in non-tumorigenic lines. Cytokine exposure magnified the extent of these differential concentrations. The PGE2 to PGI2 ratio was also greater in chemically-induced mouse lung tumors than in adjacent tissue or control lungs, supporting the physiological relevance of this in vitro model. Expression of PG biosynthetic enzymes in these cell lines correlated with production of the corresponding PGs. Cytokine treatment enhanced NO production by inducing the inflammation-associated biosynthetic enzyme, inducible NO synthase (iNOS), but this did not correlate with the neoplastic status of cells. Inhibition of iNOS or cyclooxygenase 2 activity using aminoguanidine or NS-398 respectively, demonstrated that NO did not affect PG production nor did PGs influence NO production. Since lack of iNOS inhibits mouse lung tumor formation, we propose that this is independent of any modulation of PG synthesis in epithelial cells. The similar normal/neoplastic trends in PGE2 to PGI2 ratios both in vitro and in vivo, together with an amplification of this difference upon cytokine exposure, are consistent with the hypothesis that cytokines released during inflammation exacerbate differences in the behavior of neoplastic and normal lung cells.

Cyclooxygenase-2 expression in oral squamous cell carcinoma

Cyclooxygenase (COX), the key enzyme in prostaglandin cascade, is expressed in two isoforms: the constitutive COX-1 and the inducible COX-2. Hyper-expression of COX-2 has been implicated in the pathogenesis of colon-rectal cancer in humans but it appears to play a significant role as a tumour progression factor also in other forms of human cancer, including oral cancer. The aim of this study was to analyze the expression of COX-2, at the protein level, in 45 cases of oral squamous cell carcinoma. Standard immunohistochemical streptavidin-biotin peroxidase analysis was carried out with highly specific antibody against human COX-2 and cell specific markers, in 45 oral squamous cell carcinomas. Our study revealed a moderate to high COX-2 expression in 35 out of the 45 oral squamous cell carcinoma specimens (77.8%). COX-2 expression appeared particularly abundant in the superficial ulcerated layers of relatively well differentiated carcinomas. However, we were unable to assess any statistically significant association between COX-2 hyper-expression and tumor site, tumor grading, tumor size, presence of lymph node metastases, tumor stage and age at onset, respectively. Interestingly, COX-2 expression was detected not only in areas of epithelial dysplasia adjacent to the primary layers (86% of the cases) but also in normal-appearing epithelium at the boundaries of squamous cell carcinoma (77%), indicating a possible involvement in tumour progression by the apparently normal tissue surrounding the lesion. Moreover, intense COX-2 staining was observed in endothelial cells of intra-tumour vessels and extra-tumour vessels adjacent to the tumour nests, in a high proportion of cases (82%). COX-2 positivity was associated with CD34 and VEGF positivity, indicating that these vessels were probably neo-formed ones. From this study as well as from other works, it appears that indeed COX-2 is over-expressed in this important human malignancy. However, further studies are necessary to understand the exact magnitude of this over-expression and, mostly, the possible role of COX-2 in the pathogenesis and progression of oral cancer.

Membrane-type Matrix Metalloproteinase-1 (MT1-MMP) Is a Processing Enzyme for Human Laminin γ2 Chain

Processing of the laminin-5 (Ln-5) gamma 2 chain by membrane-type-1 matrix metalloproteinases (MT1-MMP) promotes migration and invasion of epithelial and tumor cells. We previously demonstrated that MT1-MMP cleaves the rat gamma 2 chain at two sites, producing two major C-terminal fragments of 100 (gamma 2') and 80 (gamma 2 x) kDa and releasing a 30-kDa fragment containing epidermal growth factor (EGF)-like motifs (domain III (DIII) fragment). The DIII fragment bound the EGF receptor (EGF-R) and stimulated cell scattering and migration. However, it is not yet clear whether human Ln-5 is processed in a similar fashion to rat Ln-5 because one of the two MT1-MMP cleavage sites present in rat gamma 2 is not found in human gamma 2. To identify the exact cleavage site for MT1-MMP in human Ln-5, we purified both the whole molecule as well as a monomeric form of human gamma 2 that is frequently expressed by malignant tumor cells. Like rat Ln-5, both the monomer of gamma 2, as well as the gamma 2 derived from intact Ln-5, were cleaved by MT1-MMP in vitro, generating C-terminal gamma 2' (100 kDa) and gamma 2 x (85 kDa) fragments and releasing DIII fragments (25 and 27k Da). In addition to the conserved first cleavage site used to generate gamma 2', two adjacent cleavage sites (Gly(559)-Asp(560) and Gly(579)-Ser(580)) were found that could generate the gamma 2 x and DIII fragments. Two of the three EGF-like motifs present in the rat DIII fragment are present in the 27-kDa human fragment, and like the rat DIII, this fragment can promote breast carcinoma cell migration by engaging the EGF-R. These results suggest that MT1-MMP processing of Ln-5 in human tumors may stimulate the EGF-R, resulting in increased tumor cell scattering and migration that could possibly increase their metastatic potential.

Multifaceted roles of cyclooxygenase-2 in lung cancer

Lung cancer is the leading cause of cancer death in the United States. Although the low 5-year survival rate (under 15%) has changed minimally in the last 25 years, new agents and combinations of agents that target tumor proliferation, invasion, and survival may lead to improvement in patient outcomes. There is evidence that cyclooxygenase-2 (COX-2) is overexpressed in lung cancer and promotes tumor proliferation, invasion, angiogenesis, and resistance to apoptosis. COX-2 inhibitors have been found to inhibit tumor growth in animal models and have demonstrated responses when combined with conventional therapy in phase II clinical trials. Further understanding of the mechanisms involved in COX-2-mediated tumorigenesis and its interaction with other molecules in lung cancer may lead to improved therapeutic strategies for this disease. In addition, delineation of how COX-2-dependent genes modulate the malignant phenotype will provide novel insights in lung cancer pathogenesis.

Hyaluronan mediates adhesion of metastatic colon carcinoma cells

BACKGROUND

Hyaluronan (HA) is a cell-surface glycosaminoglycan that has been implicated in cancer progression. Cells isolated from metastatic colon carcinoma (SW620) produce greater amounts of pericellular HA than cells isolated from a primary tumor (SW480). Inhibition of hyaluronan synthases (HAS) by transfection with antisense cDNA decreases HA production. Because adhesion to the extracellular matrix (ECM) is required for invasion and metastasis, we hypothesized that pericellular HA mediates adhesion to ECM proteins such as laminin, collagen, and fibronectin and that inhibition of HA production or removal of HA by digestion with hyaluronidase would impair adhesion.

MATERIALS AND METHODS

SW480, SW620, and antisense transfectants (SW620 cells transfected with vector alone, antisense HAS2, antisense HAS3, and both antisense HAS2 and HAS3) were assessed for adhesion to laminin, Type 1 collagen, or fibronectin-coated plates. To confirm that adhesion was mediated by HA, cells were treated with or without hyaluronidase prior to the assays.

RESULTS

Metastatic SW620 cells adhered well to laminin; SW480 cells demonstrated 46% less adhesion (P < 0.05; Student's t test). SW620 cell adhesion to Type 1 collagen and fibronectin was >50% less than adhesion to laminin. Inhibition of HAS2 and/or HAS3 or pretreatment with hyaluronidase significantly decreased adhesion of SW620 cells to laminin (P < 0.05), suggesting that adhesion was dependent upon pericellular HA.

CONCLUSIONS

Metastatic SW620 cells that produce large amounts of pericellular HA adhered well to laminin. Inhibition of HAS2 and/or HAS3 expression, or hyaluronidase digestion of pericellular HA significantly inhibited adhesion. These data suggest that HA promotes adhesion to laminin and may thereby facilitate invasion of the basement membrane and metastasis in colon carcinoma.

Expression of COX-2 is increased with age in papillary thyroid cancer

AIMS

To study cyclooxygenase-2 (COX-2) and matrix metalloproteinase-2 (MMP-2) expression in papillary thyroid cancer (PTC). Expression of COX-2 is elevated in various human tumours and it has an important role in carcinogenesis. MMP-2 is also an important component of the metastatic potential of tumours. In PTC the most important factor affecting survival is age, but it is poorly understood why older PTC patients have a worse prognosis.

METHODS AND RESULTS

This retrospective study comprised 108 patients with PTC, and we compared patients who were either younger than 35 (n = 59) or older than 55 (n = 49). Paraffin-embedded tumour samples were analysed for COX-2 and MMP-2 protein expression using immunohistochemistry. High (scores 2-3) COX-2 immunostaining was observed in 38/108 (35%) of the tumours, and COX-2 expression was significantly (P = 0.002) higher in the older age group (25/49; 51%) than in the young one (13/59; 22%).

CONCLUSIONS

Our study shows that COX-2 expression increases with age. It is possible that the age-related increase in COX-2 expression could explain the more aggressive behaviour of PTC in the older age group compared with the young one.

Aberrant expression of laminin gamma 2 chain and its prognostic significance in intrahepatic cholangiocarcinoma according to growth morphology

Laminin gamma 2 chain is an extracellular matrix protein that plays an important role in cell migration and tumor invasion. We report altered expression and characteristic localization of this chain in a series of 105 cases of intrahepatic cholangiocarcinomas examined immunohistochemically. All tumors were grossly classified into the following three types: intraductal growth type (n=9), periductal infiltrating type (n=8) and mass-forming type (n=88). The tumors exhibited three distinct staining types: basement membrane staining, cytoplasmic staining and stromal staining. The basement membranous staining of laminin gamma 2 chain was more frequent in biliary dysplasia, intraductal growth and periductal infiltrating type than in mass-forming type. The cytoplasmic staining of carcinoma cells was observed especially at the cancer-stromal interface or at the invasive front of tumors. Stromal staining of laminin gamma 2 chain was essentially localized in the stroma around cancer cells at the invasive area, and the expression was significantly correlated with tumor aggressive factors and a poor prognosis in patients with intrahepatic cholangiocarcinoma. We conclude that laminin gamma 2 chain exhibits aberrant expression in a stepwise manner through different aggressive stages of tumor progression.

Co-expression of Cox-2 and EGFR in stage I human bronchial adenocarcinomas

Cyclooxygenase (Cox)-2 plays an important role in cell proliferation, carcinogenesis and tumor growth, in part through the synthesis of prostaglandin E2 (PGE2) as well as through other yet unknown routes. Epidermal growth factor receptor (EGFR) signaling regulates Cox-2 expression, which has not been thoroughly examined in bronchial carcinomas. The current study examined the expression of Cox-2, EGFR, P53 and proliferative marker Ki-67 immunoreactivities by immunohistochemistry in 71 surgically removed stage I bronchial adenocarcinomas. Furthermore, we evaluated the prognostic value of these molecules to elucidate the biological significance of Cox-2 expression. Higher Cox-2 expression (more than 10% immunoreactivities in tumor cells) was strongly associated with higher EGFR and P53 expression as well as a Ki-67 LI above 20% (P < 0.01). Cox-2 and EGFR immunoreactive tumor cells showed a similar distribution pattern. Five-year survival rate was 73% in 57 cases showing higher Cox-2 expression and 100% in 14 cases showing lower expression, indicating a significant difference in survival (P = 0.040). Higher Cox-2 expression might be associated with tumor progression and worse prognosis through EGFR signaling interaction in Stage I bronchial adenocarcinomas.

Expression of COX-2, iNOS, p53 and Ki-67 in gastric mucosa-associated lymphoid tissue lymphoma

AIM: To assess the expression of cyclooxygenase-2 (COX-2), nitric oxide synthase (iNOS), p53 and Ki-67 in gastric mucosa-associated lymphoid tissue (MALT) lymphoma and clarify the relationship between COX-2 expression and iNOS or p53 expression in these patients.

METHODS: The expressions of COX-2, iNOS, p53 and Ki-67 were detected in 32 gastric MALT lymphoma specimens and 10 adjacent mucosal specimens by immunohistochemical Envision method.

RESULTS: COX-2 and iNOS expressions were significantly higher in gastric MALT lymphoma tissues than those in adjacent normal tissues. The expression of COX-2 was observed in 22 of 32 cases of MALT lymphoma tissues (68.8%). A positive cytoplasmic immunoreactivity for iNOS was detected in 17 of 31 cases (53.1%). COX-2 expression in gastric MALT lymphoma tissues was positively correlated with iNOS expression (r = 0.448, P = 0.010) and cell proliferative activity analyzed by Ki-67 labeling index (r = 0.410, P = 0.020). The expression of COX-2 protein did not correlate with age, sex, stage of disease, lymph node metastasis or differentiation. The accumulation of p53 nuclear phosphoprotein was detected in 19 (59.4%) of tumors. p53 protein was expressed in 11 of 23 assessed LG tumors and in 8 of 9 assessed HG tumors. The difference of p53 positivity was found statistically significant between LG and HG cases (P = 0.0302). The p53 accumulation correlated with advanced clinical stage (stage III + IV vs stage I + II, P = 0.017). There was a significant positive correlation between COX-2 expression and p53 accumulation status (r = 0.403, P = 0.022). The mean PI of Ki-67 in each grade group were 36.0% ± 7.73% in HG and 27.4% ± 9.21% in LG. High-proliferation rate correlated with HG tumors (r = 0.419, P = 0.017). The correlation coefficient showed a significant positive correlation between PI and COX-2 expression in MALT lymphoma patients (r = 0.410, P = 0.020).

CONCLUSION: COX-2 expresses in the majority of gastric MALT lymphoma tissues and correlates with cellular proliferation and iNOS expression. COX-2 overexpression is closely associated with p53 accumulation status. iNOS and COX-2 may play a synergistic role in the pathogenesis of gastric MALT lymphoma.

Fibronectin-induced COX-2 mediates MMP-2 expression and invasiveness of rhabdomyosarcoma

Although accumulating evidence suggests the importance of cyclooxygenase-2 (COX-2) and prostaglandin E(2) (PGE(2)) in the pathogenesis of many cancers, the mechanism by which this enzyme and its metabolite promote cancer progression is unknown. In this study, we investigated the role of COX-2 in fibronectin-induced up-regulation of rhabdomyosarcoma matrix metalloproteinase (MMP)-2 activity and cellular invasiveness. We tested three human rhabdomyosarcoma cell lines: RMS559, RD, and SJRH30. Cell attachment to fibronectin up-regulated both COX-2 expression and PGE(2) production and concomitantly enhanced MMP-2 activity. Exogenous PGE(2) stimulated MMP-2 promoter activity, increased MMP-2 expression, and increased cellular invasiveness. Aspirin and rofecoxib (non-selective and selective COX-2 inhibitor, respectively) each abolished fibronectin-associated induction of MMP-2 and induced dose-dependent reductions in cellular invasiveness. These data implicated a role for inducible COX-2 and PGE(2) in the regulation of rhabdomyosarcoma cellular invasiveness and MMP-2 activity.

Effect of carbonic anhydrase-related protein VIII expression on lung adenocarcinoma cell growth

Carbonic anhydrase-related protein VIII (CA-RP VIII) is expressed in most non-small cell lung cancer, and especially strongly at the front of tumor progression. Screening analysis of CA-RP VIII expression in a panel of cultured lung cancer cell lines showed that a well differentiated adenocarcinoma cell line, PC-9, appeared to lack CA-RP VIII. Subsequently, CA8 cDNA was transfected with an expression vector into PC-9. Ectopic overexpression of CA-RP VIII reduced the growth of PC-9 cells on uncoated culture dishes, especially when the cultures were started at low cell density, but increased cell growth on laminin-coated dishes. Interestingly, ectopic CA-RP VIII expression markedly reduced caspase-3 activity induced by serum starvation and anti-cancer agents in PC-9 cells. The present findings suggest that CA-RP VIII expression promotes progression of lung cancer by multifarious mechanisms.

Effects of COX-2 inhibitor with cisplatin on proliferation and apoptosis of pancreatic cancer cells

AIM: To investigate the effects of proliferation and apoptosis induced by cyclooxygenase-2 (COX-2) inhibitor celecoxib in combination with cisplatin.

METHODS: The human pancreatic cancer cell line BxPC-3 cells were treated with COX-2 inhibitors celecoxib and cisplatin. The cell relative viability was examined using 3 (4, 5-dimethylethiazoly 1-2-) 2, 5-diphonyl tetrazolium bromide (MTT) assays. the expression of COX-2 mRNA was detected by RT-PCR, flow cytometry and Hoechst-33258 were used to demonstrate apoptotic changes in celecoxib and cisplatin treated cells.

RESULTS: After treatment of BxPC-3 cells with celecoxib, as measured by MTT, cell viability was inhibited in a dose-dependent and time-dependent manner with an IC50 of 100 nM at the time of 24h. The expression of COX-2 mRNA could be significantly decreased by celecoxib. Furthermore, we demonstrated that the combination of celecoxib with cisplatin inhibited cell growth and induced cell apoptosis to a greater degree than either compound alone. The apoptotic morphologies were demonstrated by Hoechst-33 258.

CONCLUSION: Combination of celecoxib with cisplatin inhibits cell proliferation and induces cell apoptosis, and the potent effectiveness of celecoxib in combination with gemcitabine may hold a promise in the clinical treatment of pancreatic cancer.

Synthesis and biological evaluation of 2,3-diarylpyrazines and quinoxalines as selective COX-2 inhibitors

Several 2,3-diaryl pyrazines and quinoxalines with 4-sulfamoyl (SO(2)NH(2))/methylsulfonyl (SO(2)Me)-phenyl pharmacophores have been synthesized and evaluated for the cyclooxygenase (COX-1/COX-2) inhibitory activity. Smaller groups such as methoxy, methyl and fluoro when substituted at/around position-4 of the adjacent phenyl ring, have great impact on the selective COX-2 inhibitory activity of the series. Many potential compounds were obtained from a brief structure-activity relationship (SAR) study. Two of these, compounds 11 and 25 exhibited excellent in vivo activity in the established animal model of inflammation. Since compound 25 possessed an amenable sulfonamide group, two of its prodrugs 48 and 49 were also synthesized. Both of them have excellent in vivo potential, and represent a new class of COX-2 inhibitor.

Polar substitutions in the benzenesulfonamide ring of celecoxib afford a potent 1,5-diarylpyrazole class of COX-2 inhibitors

Several chemical modifications in the N(1)-benzenesulfonamide ring of celecoxib are presented. The series with a hydroxymethyl group adjacent to the sulfonamide was found to be the most potent modification that yielded many compounds selectively active against COX-2 enzyme in vitro.

Role of Cyclooxygenase-2 Inhibitors in Combination with Radiation Therapy in Lung Cancer

Cyclooxygenase-2 (COX-2) is an enzyme involved in prostaglandin production in pathologic states such as inflammatory disorders and cancer. The enzyme is often overexpressed in premalignant lesions and cancer of the lung. Overexpression of COX-2 in lung cancer is associated with more aggressive biological tumor behavior and adverse patient outcome. In preclinical studies, inhibition of this enzyme with selective COX-2 inhibitors enhances tumor response to radiation and chemotherapeutic agents. These findings have been rapidly advanced to clinical oncology. Clinical trials of the combination of selective COX-2 inhibitors with radiation therapy, chemotherapy, or both in patients with lung cancer have been initiated and some preliminary results are available. In this review, we describe the relationship between overexpression of COX-2 and lung cancer, the antitumor effect of selective COX-2 inhibitors, discuss the rationale for using selective COX-2 inhibitors combined with radiation therapy and chemotherapy, and summarize current clinical protocols and initial findings.

Binding to EGF receptor of a laminin-5 EGF-like fragment liberated during MMP-dependent mammary gland involution

Extracellular matrix (ECM) fragments or cryptic sites unmasked by proteinases have been postulated to affect tissue remodeling and cancer progression. Therefore, the elucidation of their identities and functions is of great interest. Here, we show that matrix metalloproteinases (MMPs) generate a domain (DIII) from the ECM macromolecule laminin-5. Binding of a recombinant DIII fragment to epidermal growth factor receptor stimulates downstream signaling (mitogen-activated protein kinase), MMP-2 gene expression, and cell migration. Appearance of this cryptic ECM ligand in remodeling mammary gland coincides with MMP-mediated involution in wild-type mice, but not in tissue inhibitor of metalloproteinase 3 (TIMP-3)-deficient mice, supporting physiological regulation of DIII liberation. These findings indicate that ECM cues may operate via direct stimulation of receptor tyrosine kinases in tissue remodeling, and possibly cancer invasion.

Pharmacogenetics of anticancer drug sensitivity in non-small cell lung cancer

In mammalian cells, the process of malignant transformation is characterized by the loss or down-regulation of tumor-suppressor genes and/or the mutation or overexpression of proto-oncogenes, whose products promote dysregulated proliferation of cells and extend their life span. Deregulation in intracellular transduction pathways generates mitogenic signals that promote abnormal cell growth and the acquisition of an undifferentiated phenotype. Genetic abnormalities in cancer have been widely studied to identify those factors predictive of tumor progression, survival, and response to chemotherapeutic agents. Pharmacogenetics has been founded as a science to examine the genetic basis of interindividual variation in drug metabolism, drug targets, and transporters, which result in differences in the efficacy and safety of many therapeutic agents. The traditional pharmacogenetic approach relies on studying sequence variations in candidate genes suspected of affecting drug response. However, these studies have yielded contradictory results because of the small number of molecular determinants of drug response examined, and in several cases this approach was revealed to be reductionistic. This limitation is now being overcome by the use of novel techniques, i.e., high-density DNA and protein arrays, which allow genome- and proteome-wide tumor profiling. Pharmacogenomics represents the natural evolution of pharmacogenetics since it addresses, on a genome-wide basis, the effect of the sum of genetic variants on drug responses of individuals. Development of pharmacogenomics as a new field has accelerated the progress in drug discovery by the identification of novel therapeutic targets by expression profiling at the genomic or proteomic levels. In addition to this, pharmacogenetics and pharmacogenomics provide an important opportunity to select patients who may benefit from the administration of specific agents that best match the genetic profile of the disease, thus allowing maximum activity.

Expression of cyclooxygenase-2 in pancreatic cancer and its correlation with p53

AIM: To investigate the expressions of COX-2 and p53 in human pancreatic cancer and their correlation with biological behaviors of pancreatic cancer.

METHODS: The expressions of COX-2 and p53 in 51 specimens of human pancreatic ductal adenocarcinoma and 11 specimens of normal tissues adjacent human pancreatic ductal adenocarcinoma were detected with immunohistochemistry by Envision.

RESULTS: The detectable rate of COX-2 and p53 in pancreatic ductal adenocarcinoma were 74.5% and 60.8%, respectively; but none in adjacent normal tissues. The expression of COX-2 was significantly associated with the clinical stages and metastasis status of lymph nodes (P = 0.022, 0.036), but not with histological grade (P = 0.152). The expression of p53 was significantly correlated with the lymph node metastasis status (P = 0.035), but not with their histological grades and clinical stages (P = 0.131, 0.078). There was a significant correlation between the expression of COX-2 and p53 (r = 0.452, P = 0.001). Conditions such as age, sex, tumor size and location had no relation with expression of COX-2 or p53.

CONCLUSION: The cooperation of COX-2 and p53 may play a pivotal role in the carcinogenesis and the progression in pancreatic cancer. They may provide new targets for the therapy of pancreatic cancer.

Autocrine/paracrine prostaglandin E2 production by non-small cell lung cancer cells regulates matrix metalloproteinase-2 and CD44 in cyclooxygenase-2-dependent invasion

Tumor cyclooxygenase-2 (COX-2) expression is known to be associated with enhanced tumor invasiveness. In the present study, we evaluated the importance of the COX-2 product prostaglandin E2 (PGE2) and its signaling through the EP4 receptor in mediating non-small cell lung cancer (NSCLC) invasiveness. Genetic inhibition of tumor COX-2 led to diminished matrix metalloproteinase (MMP)-2, CD44, and EP4 receptor expression and invasion. Treatment of NSCLC cells with exogenous 16,16-dimethylprostaglandin E2 significantly increased EP4 receptor, CD44, and MMP-2 expression and matrigel invasion. In contrast, anti-PGE2 decreased EP4 receptor, CD44, and MMP-2 expression in NSCLC cells. EP4 receptor signaling was found to be central to this process, because antisense oligonucleotide-mediated inhibition of tumor cell EP4 receptors significantly decreased CD44 expression. In addition, agents that increased intracellular cAMP, as is typical of EP4 receptor signaling, markedly increased CD44 expression. Moreover, MMP-2-AS treatment decreased PGE2-mediated CD44 expression, and CD44-AS treatment decreased MMP-2 expression. Thus, PGE2-mediated effects through EP4 required the parallel induction of both CD44 and MMP-2 expression because genetic inhibition of either MMP-2 or CD44 expression effectively blocked PGE2-mediated invasion in NSCLC. These findings indicate that PGE2 regulates COX-2-dependent, CD44- and MMP-2-mediated invasion in NSCLC in an autocrine/paracrine manner via EP receptor signaling. Thus, blocking PGE2 production or activity by genetic or pharmacological interventions may prove to be beneficial in chemoprevention or treatment of NSCLC.