The MDR phenotype is associated with the expression of COX-2 and iNOS in a human hepatocellular carcinoma cell line

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.

20(S)-Protopanaxatriol, one of ginsenoside metabolites, inhibits inducible nitric oxide synthase and cyclooxygenase-2 expressions through inactivation of nuclear factor-kappaB in RAW 264.7 macrophages stimulated with lipopolysaccharide

Ginsenosides from Panax ginseng are metabolized by human intestinal bacteria after oral administration of ginseng extract. 20(S)-Protopanaxatriol (PPT) is one of the major metabolites of ginsenosides. Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are important enzymes that mediate inflammatory processes. Improper up-regulation of iNOS and/or COX-2 has been associated with the pathogenesis of inflammatory diseases and certain types of human cancers. Here, we investigated whether PPT could modulate iNOS and COX-2 expressions in RAW 264.7 macrophages stimulated with the endotoxin lipopolysaccharide (LPS). We found that PPT blocked the increase in LPS-induced iNOS and COX-2 expressions through inactivation of nuclear factor-kappaB by preventing I-kappaBalpha phosphorylation and degradation. Thus, it may be possible to develop PPT as a useful agent for chemoprevention of cancer or inflammatory diseases.

Apoptosis induced by mitomycin with sulindac on human gastric cancer cell SGC7901

AIM: To investigate the effects of mitomycin (MMC) with sulindac on the cell viability, apoptotic induction and expression of apoptosis-related gene Bcl-2 and cyclooxygenase-2 (COX-2) in gastric adenocarcinoma cell SGC7901.

METHODS: Human gastric cancer SGC7901 cells were divided into three groups, sulindac, MMC and sulindac with MMC. After treatment with drugs, cell viability was examined by MTT assay. Flow cytometry was used for the cell cycle distribution and apoptotic rates. The morphology of the cells was observed under light microscope and interactive laser cytometer. The expression of COX-2, Bcl-2 was determined by the immunocytochemical method.

RESULTS: After exposure for 12 h to three kinds of drugs, gastric cancer cells SGC7901 presented some morphologic features of apoptosis, including cell shrinkage, nuclear condensation, DNA fragmentation, formation of apoptotic bodies. The effects of growth inhibition were more obvious in cotreatment group with MMC and sulindac than MMC group. The apoptotic rates in cotreated cells and MMC-treated cells at 24 h after treatment were 12.0% and 7.2%, respectively. After exposure for 24 h to MMC, upregulation of COX-2 and Bcl-2 protein expression was noted, meanwhile, in cotreatment group, the levels of COX-2 were downregulated but the expression of Bcl-2 gene was not changed significantly.

CONCLUSION: MMC-induced apoptosis is reduced by upregulating the expression of COX-2 and Bcl-2 genes. MMC combined with sulindac can suppress growth of gastric cancer cells through induction of apoptosis which may be mediated by downregulation of apoptosis-related Bcl-2 gene and COX-2 gene.

Effects of cyclooxygenase-2 antisense vector on proliferation of human cholan-giocarcinoma cells

AIM

To transfect antisense vector of human COX-2 gene into COX-2 highly expressing cholangiocarcinoma cell line QBC939 and to explore its biological activities and role in carcinogenesis.

METHODS

QBC939 cells were transfected with antisense vector of human COX-2 gene using LipoVecTM transfecting technique. Transfected cells were selected with G418; COX-2 mRNA was examined by using reverse transcription polymerase chain reaction (RT-PCR) and COX-2 protein expression was detected by immunocytochemistry using isozyme selective antibodies. The proliferative status of transfected cells was measured by using methabenzthiazuron (MTT) assay; Cell cycle and apoptosis was analyzed by using flow cytometry (FCM).

RESULTS

RT-PCR showed a lower COX-2 mRNA level in transfected cells and immunocytochemistry showed weaker COX-2 protein expression in transfected cells. The proliferative index of the transfected cells decreased significantly(P<0.01), the percentage of S phase decreased remarkably in transfected cells(9.27±1.91%) compared with that in QBC939 cells without transfection (16.35±2.87%)(P<0.05), and the percentage of G0/G1 phase increased remarkably in transfected cells (75.16±4.13%) compared with that in QBC939 cells without transfection (57.31±10.16%)(P<0.05). Transfection with antisense vector of human COX-2 gene had no significant influence on the apoptosis in QBC939 cells (P>0.05).

CONCLUSION

Transfection with antisense vector of human COX-2 gene is able to inhibit the proliferation of human cholangiocarcinoma QBC939 cells.

Inducible nitric oxide synthase expression in human colorectal cancer: correlation with tumor angiogenesis

To investigate the potential involvement of the nitric oxide (NO) pathway in colorectal carcinogenesis, we correlated the expression and the activity of inducible nitric oxide synthase (iNOS) with the degree of tumor angiogenesis in human colorectal cancer. Tumor samples and adjacent normal mucosa were obtained from 46 surgical specimens. Immunohistochemical expression of iNOS, vascular endothelial growth factor (VEGF), and CD31 was analyzed on paraffin-embedded tissue sections. iNOS activity and cyclic GMP levels were assessed by specific biochemical assays. iNOS protein expression was determined by Western blot analysis. iNOS and VEGF mRNA levels were evaluated using Northern blot analysis. Both iNOS and VEGF expressions correlated significantly with intratumor microvessel density (r(s) = 0.31, P = 0.02 and r(s) = 0.67, P < 0.0001, respectively). A significant correlation was also found between iNOS and VEGF expression (P = 0.001). iNOS activity and cyclic GMP production were significantly higher in the cancer specimens than in the normal mucosa (P < 0.0001 and P < 0.0001, respectively), as well as in metastatic tumors than in nonmetastatic ones (P = 0.002 and P = 0.04, respectively). Western and Northern blot analyses confirmed the up-regulation of the iNOS protein and gene in the tumor specimens as compared with normal mucosa. NO seems to play a role in colorectal cancer growth by promoting tumor angiogenesis.

Phyllanthus amarus has anti-inflammatory potential by inhibition of iNOS, COX-2, and cytokines via the NF-kappaB pathway

BACKGROUND/AIMS

Phyllanthus amarus is a herbal medicine traditionally applied in the treatment of viral hepatitis. Aim of this study was to investigate potential anti-inflammatory properties of standardized P. amarus extracts concerning a potential influence of P. amarus on endotoxin-induced nitric oxide synthase (iNOS), cyclooxygenase (COX-2), and cytokine production in vivo and in vitro.

METHODS

Investigations were performed in rat Kupffer cells (KC), in RAW264.7 macrophages, in human whole blood, and in mice. Cells were stimulated with lipopolysaccharides (LPS) in the presence or absence of P. amarus extracts (hexane, EtOH/H(2)O), mice were treated with galactosamine/LPS as a model for acute toxic hepatitis. Nitrite was measured by Griess assay, prostaglandin E(2) (PGE(2)) by radioimmunoassay, and cytokines by enzyme-linked immunosorbent assay. iNOS and COX-2 were determined by Western blot, activation of NF-kappaB and AP-1 by EMSA.

RESULTS

P. amarus EtOH/H(2)O and hexane extracts showed an inhibition of LPS-induced production of NO and PGE(2) in KC and in RAW264.7. The extracts also attenuated the LPS-induced secretion of tumor necrosis factor (TNF-alpha) in RAW264.7 as well as in human whole blood. Both extracts reduced expression of iNOS and COX-2 and inhibited activation of NF-kappaB, but not of AP-1. P. amarus inhibited induction of interleukin (IL)-1beta, IL-10, and interferon-gamma in human whole blood and reduced TNF-alpha production in vivo.

CONCLUSIONS

This work shows that standardized extracts of P. amarus inhibit the induction of iNOS, COX-2, and TNF-alpha. Therefore, we report for the first time an anti-inflammatory potential of this traditionally employed herbal medicine both in vitro and in vivo.