Eicosanoid metabolism in squamous cell carcinoma cell lines derived from primary and metastatic head and neck cancer and its modulation by celecoxib

Eicosanoid metabolism through cyclooxygenases (COXs) and lipoxygenases (LOXs) generates various lipids that play a role in squamous cell carcinogenesis. We used pairs of head and neck squamous cell carcinoma (HNSCC) cell lines derived from primary and metastatic tumors of the same patient to analyze eicosanoid metabolites by ESI-LC/MS/MS and COX/LOX expression by western immunoblotting. The effects of celecoxib on eicosanoid synthesis and HNSCC cell growth were examined. Prostaglandin E2 (PGE2) was the major metabolite in three of six cell lines. COX-2 was detected in three cell lines, which produced PGE2 (two from metastases). We found low expression of COX-1 at similar intensities for each pair of cell lines. 5-LOX was detected in all cells. Some expressed 12-LOX, 15-LOX-1, and 15-LOX-2, but there was no correlation between enzyme expression and endogenous product content. Exogenous arachidonic acid did not change the profile of eicosanoid biosynthesis. Low doses of celecoxib inhibited formation of PGE2 in UMSCC-14A cells by 84% as early as 6 hours. In contrast, 5-HETE, 12-HETE, and 15-HETE levels were increased by approximately 40-, 5- and 3-fold, respectively, with a decline to baseline levels within 24 hours. High dose celecoxib increased the 12-HETE level 2.3-fold after 3 days of incubation. Celecoxib inhibited growth of all HNSCC cell lines in a concentration-dependent manner regardless of their COX expression (IC50 values after 3 days; 33 to 62 microM). Our findings provide new informations about individual eicosanoids produced by HNSCC cells and their differential regulation by the selective COX-2 inhibitor celecoxib.     

12/15 lipoxygenase regulation of colorectal tumorigenesis is determined by the relative tumor levels of its metabolite 12-HETE and 13-HODE in animal models

Colorectal cancer (CRC) continues to be a major cause of morbidity and mortality. The arachidonic acid (AA) pathway and linoleic acid (LA) pathway have been implicated as important contributors to CRC development and growth. Human 15-lipoxygenase 1 (15-LOX-1) converts LA to anti-tumor 13-S-hydroxyoctadecadienoic acid (13-HODE)and 15-LOX-2 converts AA to 15-hydroxyeicosatetraenoic acid (15-HETE). In addition, human 12-LOX metabolizes AA to pro-tumor 12-HETE. In rodents, the function of 12-LOX and 15-LOX-1 and 15-LOX-2 is carried out by a single enzyme, 12/15-LOX. As a result, conflicting conclusions concerning the role of 12-LOX and 15-LOX have been obtained in animal studies. In the present studies, we determined that PD146176, a selective 15-LOX-1 inhibitor, markedly suppressed 13-HODE generation in human colon cancer HCA-7 cells and HCA-7 tumors, in association with increased tumor growth. In contrast, PD146176 treatment led to decreases in 12-HETE generation in mouse colon cancer MC38 cells and MC38 tumors, in association with tumor inhibition. Surprisingly, deletion of host 12/15-LOX alone led to increased MC38 tumor growth, in association with decreased tumor 13-HODE levels, possibly due to inhibition of 12/15-LOX activity in stroma. Therefore, the effect of 12/15-LOX on colorectal tumorigenesis in mouse models could be affected by tumor cell type (human or mouse), relative 12/15 LOX activity in tumor cells and stroma as well as the relative tumor 13-HODE and 12-HETE levels.     

Suppression of cyclooxygenase-2 overexpression by 15S-hydroxyeicosatrienoic acid in androgen-dependent prostatic adenocarcinoma cells

Emerging reports now implicate alterations of arachidonic acid (AA) metabolism with prostate carcinogenesis. To test this hypothesis, androgen-primed benign hyperplastic (BHC) and malignant tumorigenic (MTC) cells derived from the Lobund-Wistar rat model of autochthonous prostate adenocarcinoma were incubated with (14)C-AA. Our data using MTCs revealed enhanced dual metabolism of (14)C-AA via COX to generate increased PGE(2) and via 5-lipoxygenase (LOX) to generate increased 5S-HETE in tumorigenic cells. Western blot of MTCs revealed upregulation of COX-2 expression. This paralleled the increased biosynthesis of PGE(2). Since some polyunsaturated fatty acids have been reported to modulate AA metabolism and tumorigenesis, we primed the cells with either gamma-linolenic acid (GLA) or its in vivo metabolite, 15S-HETrE, prior to incubation with AA. Our data revealed suppression of COX-2 expression/PGE(2) biosynthesis. In parallel, priming cells with 15S-HETrE resulted in greater suppression of COX-2 expression/PGE(2) biosynthesis. These findings suggest that 15S-HETrE could function in vivo after dietary intake of GLA to suppress DHT-enhanced prostatic COX-2 expression/PGE(2) biosynthesis and, thus, alleviate tumor growth and progression.     

Reduced 15S-lipoxygenase-2 expression in esophageal cancer specimens and cells and upregulation in vitro by the cyclooxygenase-2 inhibitor,NS398

Alterations in arachidonic acid metabolism are involved in human carcinogenesis. Cyclooxygenase (COX) and lipoxygenase (LOX) are key enzymes in this metabolism. We analyzed the expression of 15S-lipoxygenase-2 (15-LOX-2) mRNA and protein in surgical specimens from normal (N=37) and malignant (63) esophageal tissues using in situ hybridization and immunohistochemistry (IHC), and in normal (1), premalignant (1), and malignant (5) esophageal cell lines using Northern and Western blotting. 15-LOX-2 was expressed in normal esophageal epithelial cells (EECs) at the highest levels, whereas an SV40-immortalized HET-1A line and three of five esophageal cancer cell lines failed to express it at detectable levels. 15-LOX-2 was detected in 76% (28/37) of the normal esophageal mucosae, but only in 46% (29/63) of the cancer specimens using IHC (P<.01). Transient transfection of 15-LOX-2 expression vectors into esophageal cancer cells significantly inhibited the proliferation of 15-LOX-2-negative cancer cells. The COX-2 inhibitor, NS398, induced 15-LOX-2 expression in esophageal cancer cells, which is associated with reduced cell viability. This study demonstrated that 15-LOX-2 expression is lost in esophageal cancers and that the induction of 15-LOX-2 can inhibit cancer cell proliferation. Further investigation of the effects of nonsteroidal anti-inflammatory drugs on 15-LOX-2 expression and apoptosis in esophageal cancer cells may be warranted.     

脂氧合酶在胃癌中的表达及其临床意义

目的:探讨脂氧合酶（lipoxygenases,LOXs）,包括5-LOX、15-LOX-1/2在胃癌组织中的表达及其与临床病理特征的关系。方法:收集42例胃癌患者的临床资料和胃癌组织及相应的癌旁组织的石蜡包块做病理切片。免疫组化法分析5-LOX、15-LOX-1/2在胃癌组织及癌旁组织中的表达,统计学分析两者表达的差异,及其与胃癌临床病理特征的关系。结果:5-LOX表达的阳性率在胃癌组织高于相应的癌旁组织（P＜0.05）;相反的,15-LOX-1和15-LOX-2的阳性率在胃癌组织表达低于相应的癌旁组织（P＜0.01;P＜0.01）;5-LOX与胃癌的TNM分期、淋巴结转移相关(P＜0.05);15-LOX-2与胃癌肿瘤大小、TNM分期、淋巴结转移相关(P＜0.05);15-LOX-1与胃癌临床特征未见明显相关。结论:5-LOX在胃癌组织中高表达;15-LOX-1和15-LOX-2在胃癌组织中低表达;提示LOXs在胃癌的发生发展中起作用。     

Elevated 12- and 20-hydroxyeicosatetraenoic acid in urine of patients with prostatic diseases

The role of eicosanoids (metabolites of arachidonic acid) in prostate diseases is receiving increased attention. We investigated the relationship between the concentrations of urinary free acids of 12- and 20-hydroxyeicosatetraenoic acids (12- and 20-HETE) and the benign prostatic hypertrophy (BPH) and prostate cancer (Pca). Urinary concentrations of 12-HETE and 20-HETE of BPH and Pca patients were significantly higher than normal subjects. After removal of the prostate gland, the urinary concentrations of these eicosanoids decreased to concentrations similar to the normal subjects. These results suggest that urinary free acids of 12-HETE and 20-HETE indicate an abnormality of the prostate gland.     

Cyclooxygenase-2 pathway correlates with VEGF expression in head and neck cancer. Implications for tumor angiogenesis and metastasis

We evaluated the role of COX-2 pathway in 35 head and neck cancers (HNCs) by analyzing COX-2 expression and prostaglandin E2 (PGE2) production in relation to tumor angiogenesis and lymph node metastasis. COX-2 activity was also correlated to vascular endothelial growth factor (VEGF) mRNA and protein expression. COX-2 mRNA and protein expression was higher in tumor samples than in normal mucosa. PGE2 levels were higher in the tumor front zone in comparison with tumor core and normal mucosa (P<.0001). Specimens from patients with lymph node metastasis exhibited higher COX-2 protein expression (P=.0074), PGE2 levels (P=.0011) and microvessel density (P<.0001) than specimens from patients without metastasis. A significant correlation between COX-2 and tumor vascularization (r(s)=0.450, P=.007) as well as between COX-2 and microvessel density with VEGF expression in tumor tissues was found (r(s)=0.450, P=.007; r(s)=0.620, P=.0001, respectively). The induction of COX-2 mRNA and PGE2 synthesis by EGF and Escherichia coli lipopolysaccharide (LPS) in A-431 and SCC-9 cell lines, resulted in an increase in VEGF mRNA and protein production. Indomethacin and celecoxib reversed the EGF- and LPS-dependent COX-2, VEGF, and PGE2 increases. This study suggests a central role of COX-2 pathway in HNC angiogenesis by modulating VEGF production and indicates that COX-2 inhibitors may be useful in HNC treatment.     

脂氧合酶在胃癌中的表达及其意义

 目的 检测5-脂氧合酶（5-lipoxygenase,5-LOX）和15-脂氧合酶-1（15-lipoxygenase-1,15-LOX-1）mRNA及蛋白在胃癌及癌旁正常组织中的表达,并研究两者间的关系。方法 采用RT-PCR和western blot检测胃癌组织及相匹配的癌旁正常组织中5-LOX、15-LOX-1mRNA和蛋白的表达。结果 5-LOX mRNA及蛋白在胃癌组织中的表达均显著高于癌旁正常组织（P〈0.05）,而15-LOX-1mRNA及蛋白在胃癌组织中的表达均显著低于癌旁正常组织（P〈0.05）。5-LOX与15-LOX-1在胃癌组织中的表达无明显相关（P〉0.05）。结论 胃癌组织中存在5-LOX和15-LOX-1的表达失衡,且可能与胃癌的发生发展有关,但二者之间无相关性。     

Association Between Single Nucleotide Polymorphisms in the XRCC1 Gene and Susceptibility to Prostate Cancer in Chinese Men

Background: Prostate cancer (Pca) is one of the most common complex and polygenic diseases in men. TheX-ray repair complementing group 1 gene (XRCC1) is an important candidate in the pathogenesis of Pca. Thepurpose of this study was to evaluate the association between single nucleotide polymorphisms in the XRCC1gene and susceptibility to Pca. Materials and Methods: XRCC1 gene polymorphisms and associations withsusceptibility to Pca were investigated in 193 prostate patients and 188 cancer-free Chinese men. Results: Thec.910A>G variant in the exon9 of XRCC1 gene could be detected by polymerase chain reaction-restriction fragmentlength polymorphism (PCR-RFLP) and DNA sequencing methods. Significantly increased susceptibility toprostate cancer was noted in the homozygote comparison (GG versus AA: OR=2.95, 95% CI 1.46-5.42, χ2=12.36,P=0.001), heterozygote comparison (AG versus AA: OR=1.76, 95% CI 1.12-2.51, χ2=4.04, P=0.045), dominantmodel (GG/AG versus AA: OR=1.93, 95% CI 1.19-2.97, χ2=9.12, P=0.003), recessive model (GG versus AG+AA:OR=2.17, 95% CI 1.33-4.06, χ2=8.86, P=0.003) and with allele contrast (G versus A: OR=1.89, 95% CI 1.56-2.42,χ2=14.67, P<0.000). Conclusions: These findings suggest that the c.910A>G polymorphism of the XRCC1 geneis associated with susceptibility to Pca in Chinese men, the G-allele conferring higher risk.     

良性前列腺增生及前列腺癌的ADC值与PAP、P504S、PSA表达的相关性研究

目的：探讨良性前列腺增生和前列腺癌的ADC值与前列腺相关标志物PAP、P504S、PSA表达的关系。方法收集经病理证实的65例前列腺疾病患者,其中良性前列腺增生30例,前列腺癌35例。病理检查前3个月内均行前列腺MRI、DWI检查,采用单次激发EPI序列,b值为0 s/mm2和800 s/mm2,并采用免疫组化检测组织标本中PAP、P504S、PSA的表达,分析ADC值与PAP、P504S、PSA表达的关系。结果良性前列腺增生和前列腺癌的ADC值分别为（1.73±0.21）×10-3 mm2/s和（1.34±0.15）×10-3 mm2/s,差异具有统计学意义（t=8.545,P=0.000）。PAP和PSA在良性前列腺增生和前列腺癌中均表达,差异无统计学意义（P均＞0.05）,P504S在前列腺癌中的表达显著高于良性增生（Z=-7.055,P=0.000）,双变量相关分析显示ADC值与P504S的表达呈显著负相（Spearman's相关系数r=-0.654,P=0.000）;结论 PAP和PSA不能区别前列腺良恶性病变;P504S可以作为前列腺癌标志物;ADC值可以定量评价良性前列腺增生和前列腺癌,且与P504S存在负相关,可以作为前列腺良恶性病变MRI诊断的参考指标。     

Expression of cyclooxygenase-2 and inducible nitric oxide synthase in human ovarian tumors and tumor-associated macrophages

This study investigates whether and to what extent cyclooxygenase type-2 (COX-2) and inducible nitric oxide-synthase (iNOS), both known to have an immunosuppressive effect, are expressed in human ovarian tumors. Because COX-2 and iNOS can be expressed by activated macrophages, the presence of tumor-associated macrophages and the expression of COX-2 and iNOS by these tumor-associated macrophages were determined. The results obtained may provide insight into the function of COX-2 and iNOS expression by tumors. The expression of COX-2 and iNOS in tumor cells and macrophages was assessed in 18 malignant, 15 borderline, and 14 benign human ovarian tumors by immunohistochemical staining of frozen tissue sections. The intra- and peritumoral macrophages were stained using an anti-CD68 monoclonal antibody. Most of the malignant tumors (15 of 18), 10 of 15 borderline, and 9 of 14 benign tumors showed COX-2 expression in the epithelial cells, a result which indicates that COX-2 expression is not exclusive to malignancy. In addition, COX-2 staining was more intense in the epithelial cells of benign and borderline tumors than in malignant tumors. Weak iNOS staining was observed in 5 of 18 malignant, 4 of 15 borderline, and 5 of 14 benign tumors. The number of tumor-associated macrophages varied widely between the different tumors. The highest number of tumor-associated macrophages (> or =20/0.125 mm(2)) was observed in malignant tumors, whereas low to moderate intra- and peritumoral macrophage infiltration (5-20/0.125 mm(2)) was observed in the borderline and benign tumors. COX-2-positive tumor-associated macrophages were found in 3 of 18 malignant tumors, 7 of 15 borderline tumors, and 1 of 14 benign tumors. The number of COX-2-positive tumor-associated macrophages ranged from 3 to 30% of the total macrophage population. Some malignant (4 of 18), borderline (5 of 15), and benign (2 of 14) tumors contained iNOS-positive macrophages. Notable was that COX-2- and iNOS-positive macrophages were predominantly located in the tumor stroma, the regions between tumor and stroma, and in the lumina of the tumor when located in the tumor tissue. These data indicate that not only malignant but also borderline and benign ovarian tumors can exhibit increased levels of COX-2 and iNOS expression. In addition, a small proportion of the tumor-associated macrophages found in malignant, borderline, and benign tumors seems to be in an activated state, judged by their iNOS and COX-2 expression. This subpopulation of tumor-associated macrophages was invariably located in the tumor stroma or in the lumina of the tumor, specifically suggesting that macrophages outside the tumor can be tumor cytotoxic.     

15-Lipoxygenase-1 mediates cyclooxygenase-2 inhibitor-induced apoptosis in gastric cancer

It has been found that expression of 15-lipoxygenase-1 (15-LOX-1) and its main product, 13-S-hydroxyoctadecadienoic acid (13-S-HODE), are decreased in human colorectal and esophageal cancers and that non-steroidal anti-inflammatory drugs (NSAIDs) can therapeutically induce 15-LOX-1 expression to trigger apoptosis in those cancer cells. We found that a specific cyclooxygenase-2 (COX-2) inhibitor SC-236 similarly induced apoptosis in gastric cancer cells. In the present study, we tested whether SC-236 induced apoptosis through up-regulation of 15-LOX-1 in gastric cancer. We found that: (i) SC-236 inhibited growth of gastric cancer cells mainly by inducing apoptosis; (ii) SC-236 induced 15-LOX-1 expression and increased endogenous 13-S-HODE product, instead of 15-S-HETE during apoptosis; (iii) SC-236 did not affect expression of COX-1, COX-2, 5-LOX and 12-LOX; and (iv) 15-LOX-1 inhibition suppressed SC-236 induced apoptosis. These findings demonstrated that SC-236 induced apoptosis in gastric cancer cells via up-regulation of 15-LOX-1, and 13-S-HODE. These are potential and new targets for prevention and treatment of gastric cancer.     

Differential expression of neuropilin-1 in malignant and benign prostatic stromal tissue

Neuropilin-1 (NRP-1), a co-receptor for VEGF165, is overexpressed in various prostate cancer cell lines and in advanced prostate tumors. However, distribution of the NRP-1 in prostate tumors has not yet been evaluated. Using immunohistochemical analysis, we evaluated 21 archival prostate tumors and 5 benign glands for the expression of NRP-1. In addition, we utilized a quantitative RT-PCR method to examine mRNA expression in 9 additional prostate tumors obtained from radical prostatectomy specimens and compared this expression to the adjacent normal tissue. The RT-PCR analyses demonstrated overexpression of NRP-1 mRNA in malignant tissue samples by 10.0-fold as compared to adjacent normal tissue. By immunohistochemistry, NRP-1 protein was undetected or minimally detected in the epithelial tumor cells. However, NRP-1 immuno-reaction was detected in the surrounding tumor stroma. Variable immuno-reaction for NRP-1 was also seen in the adjacent normal tumor stroma and the stroma of the benign prostate samples. These observations suggest that neuropilin-1 is expressed in the prostatic stromal cells, not epithelial tumor cells, and this expression is significantly increased in the malignant phenotype.