Antiproliferative effects of the histone deacetylase inhibitor FR901228 on small-cell lung cancer lines and drug-resistant sublines

FR901228 is a novel histone deacetylase (HDAC) inhibitor, and its antiproliferative effects on non-small cell lung cancer cells have been shown in vitro. However, there have been no reports concerning the effects on small-cell lung cancer (SCLC). We have recently demonstrated that the HDAC inhibitors trichostatin A and sodium butyrate inhibit expression of the catalytic subunit of telomerase (hTERT) mRNA and telomerase activity in prostate cancer cells. The present study was designed to evaluate the effects of FR901228 on proliferation and telomerase activity in SCLC cells in vitro. FR901228 at 5 to 10 nM increased the fraction of cells in the G(2)/M and sub-G(1) phases of the cell-cycle, and inhibited the growth of H69, H526 and H82 cell lines. The expression of hTERT mRNA was inhibited 6 hr after treatment, prior to obvious inhibition of cell growth or cell-cycle distribution shifts. The inhibition of hTERT mRNA expression and telomerase activity was not a consequence of cell-growth arrest or apoptosis. Cycloheximide blocked the suppression of hTERT mRNA induced by FR901228, and the inhibition of hTERT mRNA by FR901228 required newly synthesized proteins. FR901228 also effectively inhibited growth of etoposide-resistant UMCC-1/VP-16, irinotecan-resistant PC-6/SN2-5H and cisplatin-resistant H526/CDDP cells having decreased expression of hTERT mRNA and telomerase activity, as well as their parental cells. This implies that SCLC resistant to these key drugs are not cross-resistant to FR901228. The present study suggests that FR901228 may be a promising drug for chemotherapy of cancers including SCLC, even for refractory or relapsing tumors after conventional chemotherapy.     

Involvement of cell cycle regulatory proteins and MAP kinase signaling pathway in growth inhibition and cell cycle arrest by a selective cyclooxygenase 2 inhibitor, etodolac, in human hepatocellular carcinoma cell lines

Recent studies have shown that selective cyclooxygenase-2 (COX-2) inhibitors induce growth inhibition and cell cycle arrest in hepatocellular carcinoma (HCC) cell lines. However, the mechanism by which COX-2 inhibitors regulate the cell cycle and whether or not growth signal pathways are involved in the growth inhibition remain unclear. In this study, we investigated the mechanisms of growth inhibition and cell cycle arrest by etodolac, a selective COX-2 inhibitor, in HCC cell lines, HepG2 and PLC/PRF/5, by studying cell cycle regulatory proteins, and the MAP kinase and PDK1-PKB/AKT signaling pathways. Etodolac inhibited growth and PCNA expression and induced cell cycle arrest in both HCC cell lines. Etodolac induced p21WAF1/Cip1 and p27Kip1 expression and inhibited CDK2, CDK4, CDC2, cyclin A and cyclin B1 expression, but did not affect cyclin D1 or cyclin E. HGF and 10% FBS induced ERK phosphorylation, but phosphorylation of p38, JNK and AKT was down-regulated by etodolac. PD98059, a selective inhibitor of ERK phosphorylation, induced growth inhibition, the expression of p27Kip1 and cell cycle arrest. In conclusion, p21WAF1/Cip1, p27Kip1, CDK2, CDK4, CDC2, cyclin A, cyclin B1 and the MAP kinase signaling pathway are involved in growth inhibition and cell cycle arrest by a selective COX-2 inhibitor in HCC cell lines.     

黄芪对SGC7901胃癌细胞COX-1、COX-2、VEGF和PGE2表达的影响

目的：观察黄芪对人胃癌SGC7901细胞中COX-1、COX-2、VEGF和PGE2表达的影响。方法：采用MTT试验观察黄芪对胃癌细胞的抑制作用，用RT-PCR以及Western blot方法研究加药后人胃癌细胞COX-1、COX-2基因及其蛋白表达的变化。用ELISA方法检测培养基中VEGF、PGE2的表达情况。结果：黄芪能抑制人胃癌细胞生长，呈一定的量效特征；并能抑制人胃癌细胞COX-2、VEGF和PGE2的表达。结论：黄芪抗肿瘤的机制可能是通过抑制COX-2，进而抑制其下游产物PEG2的表达及使VEGF表达下调，从而抑制肿瘤的生长。     

Selective cyclooxygenase-2 inhibitors inhibit growth and induce apoptosis of bladder cancer

Selective COX-2 inhibitors such as celecoxib and NS-398 are being evaluated as chemopreventive and therapeutic agents for bladder and other cancers. We investigated the effects of these nonsteroidal anti-inflammatory agents on a panel of bladder cancer cell lines, and assessed their effects on anchorage-dependent and -independent growth, cell cycle, apoptosis and morphology. The human bladder cancer cell lines UM-UC-1, -3, and -6 were assayed for COX-2 expression by Western analysis using a monoclonal antibody to COX-2. UM-UC-1, -3, and -6 cells were grown in the presence of increasing concentrations of NS-398 and celecoxib, and cell growth was quantitated over 7 days by crystal violet elution. The cell lines were treated with NS-398 and celecoxib for 48 h and analyzed by flow cytometry with propidium iodide staining and Br-dUTP staining for apoptosis. Anchorage-independent growth was assessed using an agarose growth assay. Western analysis demonstrated that COX-2 expression in UM-UC-1, -6, and -3 was high, low, and undetectable, respectively. NS-398 and celecoxib produced dose-dependent growth inhibition of UM-UC-1 and -6. Both NS-398 and celecoxib also inhibited anchorage-dependent and -independent growth of UM-UC-3 in a dose-dependent fashion, despite the low basal expression of COX-2 in this cell line. Cell cycle analyses of UM-UC-1 and -6 revealed a 50% reduction in S-phase in the presence of 100 microM NS-398 whereas a smaller reduction in S-phase was noted in UM-UC-3 cells. Furthermore, treatment with 100 microM celecoxib resulted in significant apoptosis in all three cell lines, which was associated with downregulation of Bcl-2. COX-2 selective inhibitors NS-398 and celecoxib produced dose-dependent growth inhibition of bladder cancer cells associated with a significant reduction in S-phase. Induction of apoptosis in all three cell lines by celecoxib was associated with downregulation of Bcl-2. These changes occur independently of COX-2 expression levels suggesting the presence of a COX-2 independent pathway.     

Increased cyclooxygenase-2 expression in human squamous cell carcinomas of the head and neck and inhibition of proliferation by nonsteroidal anti-inflammatory drugs

BACKGROUND: Cyclooxygenase-2 (COX-2) has been found to be up-regulated in several types of human cancers and its role in the carcinogenic process has been proposed The aim of this study was to examine the expression of COX-2 in human squamous cell carcinoma of the head and neck (SCCHN) and to find out the effects of COX-2 inhibitors on the growth of cultured cells. MATERIALS AND METHODS: We investigated the effect of indomethacin and NS-398 at various concentrations on the growth of SCCHN cell lines using cell proliferation assay, cell cycle analysis and quantification of apoptosis. RESULTS: Immunostaining revealed a significantly increased COX-2 expression in tumor tissues compared with normal controls (p<0.05). Western blotting analysis using a COX-2 antibody, indicated that seven SCCHN cell lines tested constitutively expressed COX-2 protein. Treatment of head and neck cancer cells with NS-398 (10-200 microM) or indomethacin (50-1000 microM) for 72 hours showed a significant dose-dependent inhibition of cell growth (p<0.01) and a significant increase in the number of cells in the G0/G1-phases of the cell cycle with a concomitant reduction at the S-phase in a dose-dependent manner (p<0.05). NS-398 was more effective in cell cycle arrest and growth inhibition than indomethacin (p<0.05) and induced significant apoptosis in two out of three SCCHN cell lines tested at the concentration of 100 microM. CONCLUSION: Our study showed that COX-2 could be a participant in carcinogenesis of SCCHN and that COX-2 inhibitors would be a potential tool for the treatment and prevention of SCCHN.     

Akt regulates COX-2 mRNA and protein expression in mutated-PTEN human endometrial cancer cells

In human endometrial cancer, the fourth most common cancer in women, tumor suppressor phosphatase tensin homologue (PTEN) is frequently mutated. In the presence of a mutated PTEN protein, Akt phosphorylation levels are increased leading to the activation of this survival pathway. Numerous studies indicated that COX-2 is inappropriately induced and up-regulated in a number of malignant cancer cells. COX-2 plays an important role in tumor cell biology, taking part actively in angiogenesis particularly via the production of prostaglandin E2 (PGE2). The present study was undertaken to determine the involvement of PI 3-K/Akt pathway in the regulation of COXs expression and PGE2 synthesis. Three different human endometrial cancer cell lines known to have wild-type PTEN (HEC 1-A) or a mutated inactive PTEN protein (RL 95-2 and Ishikawa) were used for these studies. Results showed that Akt phosphorylation was high in mutated PTEN cells. RT-PCR studies revealed that Akt1 and Akt2 were the regulated forms whereas Akt3 mRNA was nearly undetectable. COX-2 mRNA expression and protein levels were high in these cells compared to wild-type PTEN cells as demonstrated by RT-PCR and Western analysis respectively. PGE2 production was higher in mutated-PTEN expressing phospho-Akt and COX-2 compared to wild-type PTEN cells. Inhibition of PI 3-K with Wortmannin and LY294002 blocked Akt phosphorylation and inhibited expression of COX-2 in mutated-PTEN cells. Inhibition of Akt phosphorylation with specific PI 3-K inhibitors and down-regulation of COX-2 increased apoptosis in human endometrial cancer cells. Likewise, transfection of mutated-PTEN cells with a dominant negative Akt vector, resulted in COX-2 down-regulation and activation of apoptosis, as demonstrated by Hoechst nuclear staining. On the opposite, activation of Akt using a constitutively active expression vector, resulted in the up-regulation of COX-2 protein expression. Specific inhibition of COX-2 with NS-398 induced apoptosis in COX-2 expressing human endometrial cancer cells. It is concluded that the PI 3-K/Akt survival pathway is involved in the regulation of COX-2 and PGE2 synthesis in human endometrial cancer cells.     

Combined treatment with selective cyclooxygenase-2 inhibitor and fluorinated pyrimidines for liver metastasis of colon cancer

Liver metastasis is a major contributor to mortality in patients with colorectal cancer. Hence, it is essential to establish preventive therapy to control liver metastasis. Recently, it has become widely accepted that cyclooxygenase (COX)-2 inhibitors possess anti-cancer activity for various types of tumor, especially colorectal. The clinical application of COX-2 inhibitors may therefore be beneficial. In this study, we have developed a combined treatment with a selective COX-2 inhibitor and fluorinated pyrimidines for liver metastasis of colorectal cancer, and examined the effect of these agents on proliferation and invasion of a highly metastatic human colon cancer cell line, LM-H3. The COX-2 inhibitor etodolac was found to inhibit cell invasion of LM-H3. 5-Fluorouracil (5-FU) inhibited proliferation of this line in vitro. Etodolac did not increase the inhibitory effect of 5-FU on cell proliferation. We also examined the inhibitory effect of etodolac and UFT, belonging to the fluorinated pyrimidines, on liver metastasis by using a liver metastatic model in the nude mouse. Combined treatment with etodolac and UFT markedly reduced liver metastasis. Serious side effects were not observed. In conclusion, combined treatment with etodolac and UFT might be a promising preventive therapy for liver metastasis of colon cancer.     

尼美舒利抑制胃癌细胞蛋白激酶B活性的研究

目的 观察选择性环氧化酶-2(COX-2)抑制剂尼美舒利对胃癌细胞株SGL-7901增殖、端粒酶活性和蛋白激酶(PKB)的影响,以探讨其抗肿瘤作用机制。方法 尼美舒利作用胃癌细胞株SGC7901不同时间后,采用噻唑蓝(MTT)比色法和PCR-ELISA半定量法检测细胞的生存率和端粒酶活性,PKB活性的检测采用非放射性蛋白激酶活性分析法。结果 尼美舒利抑制SGC7901细胞的生长呈时间,剂量依赖性,同时它也显著抑制SGC7901细胞的端粒酶和PKB活性,且端粒酶活性的降低与PKB活性的抑制有关。结论 选择性COX-2抑制剂能抑制胃癌细胞株的端粒酶活性,其作用机制可能与阻碍PKB的活性有关,这可能是选择性COX-2抑制剂抗肿瘤的又一新的机制。     

Colon cancer cells with high invasive potential are susceptible to induction of apoptosis by a selective COX-2 inhibitor

Cyclooxygenase-2 (COX-2) expression has been shown to correlate with the invasiveness of colon cancer cells. To further investigate this positive correlation and its possible therapeutic implications, a selective COX-2 inhibitor, etodolac, was tested on three variants of HT-29 colon cancer cell lines, HT-29/lnv1, HT-29/ Inv2 and HT-29/lnv3, with graded increases of in vitro Matrigel invasive potential and COX-2 expression levels. HT-29 variants with higher invasive potential were found to be more sensitive to etodolac by in vitro growth inhibition assays, the estimated LD₅₀ being 0.5 m M for highly invasive HT-29/lnv2 and HT-29/lnv3 cells, 0.6 m M for slightly less invasive HT-29/lnv1, and 1.8 m M for the parental HT-29. Treatment of the highly invasive HT-29/lnv2 and Inv3 variants with as little as 0.1 m M etodolac in the growth medium produced signs of apoptosis, as detected by DNA fragmentation and TUNEL (terminal deoxynucleotidyl transferase dUTP-biotin nick end labeling) assay. In vivo experiments in SCID mice showed that etolodac inhibited the growth of subcutaneous tumors induced by HT-29/lnv3 cells significantly more than those by the parental HT-29 cells. These results suggest that COX-2 inhibitors have a potential role in prevention of tumor invasion in colon cancer patients. (Cancer Sci 2003; 94: 253–258)     

Sinomenine inhibits proliferation of SGC-7901 gastric adenocarcinoma cells via suppression of cyclooxygenase-2 expression

Sinomenine (SIN) is a bioactive alkaloid extracted from the Chinese medicinal plant Sinomenium acutum. Results of studies have shown that the anti-inflammatory, immunosuppressive and anti-arthritic effects of SIN are partially attributed to the inhibition of cyclooxygenase-2 (COX-2) expression. COX-2 overexpression is associated with enhanced proliferation and angiogenesis of gastric cancer (GC). SGC-7901 cells were treated with different concentrations of SIN in order to observe its effect on the proliferation of human gastric adenocarcinoma cells and to explore the potential underlying molecular mechanism via the detection of COX-2 expression. Celecoxib was used as the positive control. Morphological alterations of the cells were observed microscopically. Cell proliferation was evaluated using MTT assay. COX-2 expression was detected using semi-quantitative RT-PCR and Western blotting. The results showed that SIN inhibited the proliferation of SGC-7901 cells in a time- and dose-dependent manner. In the presence of SIN or celecoxib, SGC-7901 cells became round and detached morphologically, indicating cell apoptosis. The expression of COX-2 was inhibited by SIN in a dose-dependent manner at both the mRNA and protein levels. Our findings indicate that the protective effects of SIN are mediated through the inhibition of COX-2 expression. These findings suggest a novel therapy to treat inflammation-mediated gastric adenocarcinomata.     

Cyclooxygenase-2 level and culture conditions influence NS398-induced apoptosis and caspase activation in lung cancer cells

Cyclooxygenases (COXs) catalyze the synthesis of prostaglandins (PGs) from arachidonic acid. Overexpression of COX-2 is frequently found in human cancers and is suggested to play an important role in tumorigenesis. Recent studies indicated that COX-2 inhibitors exert potent anti-cancer effects on a number of cancers. Interestingly, some COX-2 inhibitors potently induce apoptosis, while other COX-2 inhibitors primarily induce growth inhibition. Therefore, there is a variability in the effects that different COX-2 inhibitors have on cancer cells. In this study, we demonstrated that induction of apoptosis of high COX-2-expressing A549 lung cancer cells by a specific COX-2 inhibitor NS398 was observed in cells cultured under serum-free condition. However, this drug induced G1 growth arrest rather than apoptosis in A549 cells maintained in 10% serum medium. Conversely, low COX-2-expressing H226 lung cancer cells were resistant to NS398-induced apoptosis under both serum-free and serum-containing conditions. Moreover, our results showed that NS398-induced apoptosis is associated with activation of caspase-3, a cysteine protease that plays a crucial role in the execution phase of apoptosis. These results suggest that the cytotoxic effect of COX-2 inhibitors on cancer cells may be influenced by extracellular environments and the anti-cancer action of these inhibitors in vivo needs careful evaluation. Additionally, a correlation between the level of COX-2 expression and the extent of apoptosis induced by COX-2 inhibitors was found.     

Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits cyclooxygenase-2 expression in colon carcinogenesis

Tea, one of the most widely consumed beverages worldwide, has been shown to have anti-cancer activity in various cancers including colon cancer. It has been demonstrated that overexpression of the inducible isoform of cyclooxygenase (COX-2) occurs during colon tumorigenesis and inhibition of COX-2 by non-steroidal anti-inflammatory drugs (NSAIDs) is chemopreventive. To determine whether the anti-cancer effect associated with green tea impacted COX-2 expression levels, human colorectal cancer cell lines HT-29 and HCA-7, were treated with (-)-epigallocatechin-3-gallate (EGCG), the most abundant and effective polyphenol of green tea. EGCG significantly inhibited constitutive COX-2 mRNA and protein overexpression. The inhibitory effects of EGCG on signaling pathways controlling COX-2 expression were examined. We observed that EGCG down regulated the ERK1/2 and Akt pathways in colon cancer cells. The effect of EGCG on COX-2 expression resulted in decreased COX-2 promoter activity via inhibition of nuclear factor kappaB (NF-kappaB) activation. EGCG also promoted rapid mRNA decay mediated through the COX-2 3'untranslated region (3'UTR). In conclusion, these data suggest that inhibition of COX-2 is a mechanism for the anti-proliferative effect of green tea and emphasizes the role that dietary factors have as anti-cancer agents.     

COX-2-mediated stimulation of the lymphangiogenic factor VEGF-C in human breast cancer

Increased expression of COX-2 or VEGF-C has been correlated with progressive disease in certain cancers. Present study utilized several human breast cancer cell lines (MCF-7, T-47D, Hs578T and MDA-MB-231, varying in COX-2 expression) as well as 10 human breast cancer specimens to examine the roles of COX-2 and prostaglandin E (EP) receptors in VEGF-C expression or secretion, and the relationship of COX-2 or VEGF-C expression to lymphangiogenesis. We found a strong correlation between COX-2 mRNA expression and VEGF-C expression or secretion levels in breast cancer cell lines and VEGF-C expression in breast cancer tissues. Expression of LYVE-1, a selective marker for lymphatic endothelium, was also positively correlated with COX-2 or VEGF-C expression in breast cancer tissues. Inhibition of VEGF-C expression and secretion in the presence of COX-1/2 or COX-2 inhibitors or following downregulation of COX-2 with COX-2 siRNA established a stimulatory role COX-2 in VEGF-C synthesis by breast cancer cells. EP1 as well as EP4 receptor antagonists inhibited VEGF-C production indicating the roles of EP1 and EP4 in VEGF-C upregulation by endogenous PGE2. Finally, VEGF-C secretion by MDA-MB-231 cells was inhibited in the presence of kinase inhibitors for Her-2/neu, Src and p38 MAPK, indicating a requirement of these kinases for VEGF-C synthesis. These results, for the first time, demonstrate a regulatory role of COX-2 in VEGF-C synthesis (and thereby lymphangiogenesis) in human breast cancer, which is mediated at least in part by EP1/EP4 receptors.     

塞来昔布对子宫内膜癌细胞增生和COX-2 mRNA表达的影响

 【目的 探讨塞来昔布对子宫内膜癌细胞HEC-1-B的作用及对COX-2 mRNA表达的影响。方法 采用细胞培养、MTT试验研究不同浓度的塞来昔布对人类子宫内膜癌细胞HEC-1-B生长的抑制作用，通过RT-PCR法检测塞来昔布作用后COX-2 mRNA表达的变化。结果 塞来昔布能够有效地抑制HEC-1-B细胞的生长，并呈一定的剂量和时间依赖关系，同时能够抑制其COX-2 mRNA表达，20 μmol／L和50 μmol／L塞来昔布对COX-2 mRNA表达的抑制率分别为25.92 ％和50.81％。结论 塞来昔布可能是通过降低COX-2 mRNA的表达而抑制子宫内膜癌细胞的生长。     

Anti-tumor effects of herbal medicines on endometrial carcinomas via estrogen receptor-alpha-related mechanism

This study was performed to examine the relationship between the anti-tumor effects of herbal medicine and endometrial carcinoma with ER-related mechanisms. An endometrial cancer cell line (Ishikawa) was used for this study. The cell viability and expression of estrogen receptors (ER) were determined by MTT and RT-PCR. A dose-dependent decrease of viability and apoptosis of the cancer cells was generated by exposure to the herbal medicines, Juzen-taiho-to or Shimotsu-to. The expression of ER-alpha mRNA, but not ER-beta mRNA was suppressed by Juzen-taiho-to or Shimotsu-to in an endometrial cancer cell line. The anti-tumor effect of these herbal medicines against endometrial carcinoma might be correlated to the ER-alpha related mechanism.     

Resveratrol interferes with AKT activity and triggers apoptosis in human uterine cancer cells

Background  

Endometrial cancer is the fourth most prominent cancer among all feminine cancers in the Western world. Resveratrol, a natural anti-oxidant found in red wine emerging as a novel anticancer agent, exerts antiproliferative and pro-apoptotic activity in various cancer cell types, but its effect on uterine cancer cells is poorly understood. At the molecular level, resveratrol has been reported to inhibit cyclooxygenase (COX) expression and/or activity; in endometrial cancer cells, COX-2 is overexpressed and confers cellular resistance to apoptosis. The aim of the present study was to determine if resveratrol could exert anti-proliferative and pro-apoptotic activity over uterine cancer cells upon inhibition of COX-2 expression and/or activity. Six different human uterine cancer cell lines were used as a model (HeLa, Hec-1A, KLE, RL95-2, Ishikawa and EN-1078D).     

Inhibition of cyclooxygenase-2 suppresses lymph node metastasis via reduction of lymphangiogenesis

Cyclooxygenase-2 (COX-2) inhibitor has been reported to suppress tumor progression. However, it is unclear whether this inhibitor can also prevent lymphatic metastasis. To determine the effects of COX-2 inhibitor on lymphatic metastasis, etodolac, a COX-2 inhibitor, was given p.o. to mice bearing orthotopic xenografts or with carcinomatous peritonitis induced with a highly metastatic human diffuse-type gastric carcinoma cell line, OCUM-2MLN. Tumor lymphangiogenesis was significantly decreased in etodolac-treated mice compared with control mice. Consistent with this decrease in lymphangiogenesis, the total weight of metastatic lymph nodes was less in etodolac-treated mice than in control mice. Immunohistochemical analysis revealed that the major source of vascular endothelial growth factor-C (VEGF-C) and VEGF-D was F4/80-positive macrophages in our models. The mRNA levels of VEGF-C in mouse macrophage-like RAW264.7 cells, as well as those in tumor tissues, were suppressed by etodolac. The growth of human dermal lymphatic microvascular endothelial cells was also suppressed by etodolac. Supporting these findings, etodolac also inhibited lymphangiogenesis in a model of chronic aseptic peritonitis, suggesting that COX-2 can enhance lymphangiogenesis in the absence of cancer cells. Our findings suggest that COX-2 inhibitor may be useful for prophylaxis of lymph node metastasis by reducing macrophage-mediated tumor lymphangiogenesis.     

Non-steroidal anti-inflammatory drugs inhibit cellular proliferation and upregulate cyclooxygenase-2 protein expression in endometrial cancer cells

We determined the effects of several non-steroidal anti-inflammatory drugs (NSAIDs), aspirin (acetylsalicylic acid, ASA), indomethacin and a cyclooxygenase-2 (COX-2)-selective inhibitor (NS398), on cellular proliferation and regulation of COX-2 protein expression in endometrial cancer cells in vitro, and investigated their modes of action. All three NSAIDs markedly inhibited the proliferation of Ishikawa, HEC-1A and AN3CA endometrial cancer cell lines in a time- and concentration-dependent manner. ASA and indomethacin triggered apoptosis in cells of all three lines through release of cytosolic cytochrome c, activation of caspase-9 and-3, and cleavage of poly(ADP-ribose) polymerase (PARP), but NS398 induced minimal apoptosis only in Ishikawa cells. ASA altered the cell cycle distribution, with G2/M phase accumulation of cells, and induced overexpression of Ki-67 protein. Both ASA and indomethacin reduced the protein levels of Bcl-2 and Bcl-xl, but upregulated those of Bax and Bcl-xs. COX-2 protein expression and PGE(2) production were upregulated by ASA and indomethacin in all three cell lines. However, NS398 did not alter COX-2 protein expression or PGE(2) production in these cells. These results indicate that NSAIDs inhibit proliferation of endometrial cancer cells independently of the reduction of COX-2 protein expression. A cytochrome c-dependent apoptotic pathway and/or cell cycle arrest may contribute to the inhibitory effects of these NSAIDs.