Low 15-PGDH Research Articles

MiR-21-mediated regulation of 15-hydroxyprostaglandin dehydrogenase in colon cancer

Elevated prostaglandin E2 (PGE2) levels are observed in colorectal cancer (CRC) patients, and this increase is associated with poor prognosis. Increased synthesis of PGE2 in CRC has been shown to occur through COX-2-dependent mechanisms; however, loss of the PGE2-catabolizing enzyme, 15-hydroxyprostaglandin dehydrogenase (15-PGDH, HPGD), in colonic tumors contributes to increased prostaglandin levels and poor patient survival. While loss of 15-PGDH can occur through transcriptional mechanisms, we demonstrate that 15-PGDH can be additionally regulated by a miRNA-mediated mechanism. We show that 15-PGDH and miR-21 are inversely correlated in CRC patients, with increased miR-21 levels associating with low 15-PGDH expression. 15-PGDH can be directly regulated by miR-21 through distinct sites in its 3′ untranslated region (3′UTR), and miR-21 expression in CRC cells attenuates 15-PGDH and promotes increased PGE2 levels. Additionally, epithelial growth factor (EGF) signaling suppresses 15-PGDH expression while simultaneously enhancing miR-21 levels. miR-21 inhibition represses CRC cell proliferation, which is enhanced with EGF receptor (EGFR) inhibition. These findings present a novel regulatory mechanism of 15-PGDH by miR-21, and how dysregulated expression of miR-21 may contribute to loss of 15-PGDH expression and promote CRC progression via increased accumulation of PGE2.

Multiple drug resistance-associated protein (MRP4) exports prostaglandin E2 (PGE2) and contributes to metastasis in basal/triple negative breast cancer

Cyclooxygenase-2 (COX-2) and its primary enzymatic product, prostaglandin E2 (PGE2), are associated with a poor prognosis in breast cancer. In order to elucidate the factors contributing to intratumoral PGE2 levels, we evaluated the expression of COX-2/PGE2 pathway members MRP4, the prostaglandin transporter PGT, 15-PGDH (PGE2 metabolism), the prostaglandin E receptor EP4, COX-1, and COX-2 in normal, luminal, and basal breast cancer cell lines. The pattern of protein expression varied by cell line reflecting breast cancer heterogeneity. Overall, basal cell lines expressed higher COX-2, higher MRP4, lower PGT, and lower 15-PGDH than luminal cell lines resulting in higher PGE2 in the extracellular environment. Genetic or pharmacologic suppression of MRP4 expression or activity in basal cell lines led to less extracellular PGE2. The key finding is that xenografts derived from a basal breast cancer cell line with stably suppressed MRP4 expression showed a marked decrease in spontaneous metastasis compared to cells with unaltered MRP4 expression. Growth properties of primary tumors were not altered by MRP4 manipulation. In addition to the well-established role of high COX-2 in promoting metastasis, these data identify an additional mechanism to achieve high PGE2 in the tumor microenvironment; high MRP4, low PGT, and low 15-PGDH. MRP4 should be examined further as a potential therapeutic target in basal breast cancer.

Upregulation of Cyclooxygenase-2/Prostaglandin E2 (COX-2/PGE2) Pathway Member Multiple Drug Resistance-Associated Protein 4 (MRP4) and Downregulation of Prostaglandin Transporter (PGT) and 15-Prostaglandin Dehydrogenase (15-PGDH) in Triple-Negative Breast Cancer.

Elevated levels of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) are indicators of a poor prognosis in breast cancer. Using several independent publicly available breast cancer gene expression databases, we investigated other members of the PGE2 pathway. PGE2 is produced by COX-2 and actively exported by multiple drug resistance-associated protein 4 (MRP4) into the extracellular microenvironment, where PGE2 can bind four cognate EP receptors (EP1–EP4) and initiate diverse biological signaling pathways. Alternatively, PGE2 is imported via the prostaglandin transporter (PGT) and metabolized by 15-prostaglandin dehydrogenase (15-PGDH/HPGD). We made the novel observation that MRP4, PGT, and 15-PGDH are differentially expressed among distinct breast cancer molecular subtypes; this finding was confirmed in independent datasets. In triple-negative breast cancer, the observed gene expression pattern (high COX-2, high MRP4, low PGT, and low 15-PGDH) would favor high levels of tumor-promoting PGE2 in the tumor microenvironment that may contribute to the overall poor prognosis of triple-negative breast cancer.

Abstract 2815: Sulindac reversal of 15-PGDH mediated resistance to colon tumor chemoprevention with NSAIDs

Abstract Background: Non-steroidal anti-inflammatory drugs (NSAIDs) protect against colorectal cancer development by inhibiting cyclooxygenase (COX) enzymes responsible for the production of tumor growth promoting prostaglandins. 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a colon tumor suppressor that degrades prostaglandins and antagonizes COX-mediated oncogenesis. Deletion of 15-PGDH in mice results in an increased susceptibility to azoxymethane (AOM)-induced colon tumor formation and resistance to the chemopreventive effects of the COX-2 selective inhibitor, celecoxib. Similar resistance to colon adenoma prevention with celecoxib has been shown in humans with low colonic 15-PGDH levels. In this study, we expanded the panel of NSAIDs tested in a mouse colon tumorigenesis model to include sulindac and aspirin to determine if these non-selective COX-1 and COX-2 inhibitors would be a better treatment for the prevention of colon adenomas in mice genetically lacking 15-PGDH. Materials and Methods: 15-PGDH wild-type and knockout mice on a FVB/NJ background were administered azoxymethane (AOM) by i.p. injection once per week for 6 weeks at 10mg/kg dose. Concurrent with the first AOM injection, all mice were fed for the length of the study with either a control (AIN-76A) diet or diet supplemented with celecoxib (1250 ppm), sulindac (167 ppm), or aspirin (300 ppm). Mice were euthanized 14 weeks after the last AOM injection, and the colons were removed and examined under a dissecting microscope to identify all tumors and inflammatory lesions. The effect of NSAID treatment on COX inhibition was determined by measuring colonic PGE2 levels. Results: We demonstrate a significant difference in tumor formation between aspirin and sulindac treated 15-PGDH knockout mice compared to celecoxib treatment. Sulindac significantly prevented colon tumor formation while aspirin had no protective effect, despite a comparable reduction in colonic mucosal PGE2 levels by both sulindac and aspirin. Additionally, we find that treatment of celecoxib or sulindac for an extended period of time results in a significant increase in colonic inflammation in both wild-type and knockout mice, with lymphoid aggregates and large proximal colon inflammatory lesions appearing, and that the incidence of inflammatory lesions correlate with NSAID efficacy. Conclusions: These findings suggest sulindac may be the most active NSAID for colon chemoprevention in populations with low 15-PGDH, but raise the caution that this agent may also give rise to inflammatory lesions in the colon. Citation Format: Stephen P. Fink, Dawn M. Dawson, Yongyou Zhang, Adam Kresak, Earl G. Lawrence, Peiying Yang, Yanwen Chen, Jill S. Barnholtz-Sloan, Joseph E. Willis, Levy Kopelovich, Sanford D. Markowitz. Sulindac reversal of 15-PGDH mediated resistance to colon tumor chemoprevention with NSAIDs. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2815. doi:10.1158/1538-7445.AM2015-2815

Sulindac reversal of 15-PGDH-mediated resistance to colon tumor chemoprevention with NSAIDs.

Non-steroidal anti-inflammatory drugs prevent colorectal cancer by inhibiting cyclooxygenase (COX) enzymes that synthesize tumor-promoting prostaglandins. 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a tumor suppressor that degrades tumor-promoting prostaglandins. Murine knockout of 15-PGDH increases susceptibility to azoxymethane-induced colon tumors. It also renders these mice resistant to celecoxib, a selective inhibitor of inducible COX-2 during colon neoplasia. Similarly, humans with low colonic 15-PGDH are also resistant to colon adenoma prevention with celecoxib. Here, we used aspirin and sulindac, which inhibit both COX-1 and COX-2, in order to determine if these broader COX inhibitors can prevent colon tumors in 15-PGDH knockout (KO) mice. Unlike celecoxib, sulindac proved highly effective in colon tumor prevention of 15-PGDH KO mice. Significantly, however, aspirin demonstrated no effect on colon tumor incidence in either 15-PGDH wild-type or KO mice, despite a comparable reduction in colonic mucosal Prostaglandin E₂ (PGE₂) levels by both sulindac and aspirin. Notably, colon tumor prevention activity by sulindac was accompanied by a marked induction of lymphoid aggregates and proximal colonic inflammatory mass lesions, a side effect seen to a lesser degree with celecoxib, but not with aspirin. These findings suggest that sulindac may be the most effective agent for colon cancer prevention in humans with low 15-PGDH, but its use may also be associated with inflammatory lesions in the colon.

778 Durability of Radiofrequency Ablation (RFA) in Barrett's Esophagus With Dysplasia: the AIM Dysplasia Trial At Five Years

colorectal cancer cases that developed during 3,166,880 person-years of follow-up and from which we could assess 15-PGDH expression in normal colonic mucosa from the cancer resection. The association of regular aspirin use with risk of colorectal cancer appeared to differ significantly according to 15-PGDH expression level in normal colonic mucosa (P= 0.018). Compared with non-users, regular aspirin users had a multivariable HR for colorectal cancer with high 15-PGDH expression in normal colonic mucosa of 0.49 (95% CI, 0.340.71). In contrast, regular aspirin use was not associated with a lower risk of colorectal cancer with low 15-PGDH expression in normal colonic mucosa (multivariable HR=0.90; 95% CI, 0.63-1.27). Conclusion: Regular aspirin use is associated with lower risk of colorectal cancer that develops within a background of colonic mucosa with high but not low levels of 15-PGDH expression. This suggests that the anticancer effect of aspirin is mediated at least in part in cooperation with the 15-PGDH tumor suppressor pathway. Further studies are needed to determine the potential utility of using 15-PGDH expression level in colonic mucosa as a biomarker to risk-stratify individuals for aspirin-based chemoprevention.

15-Hydroxyprostaglandin Dehydrogenase in Colorectal Mucosa as a Potential Biomarker for Predicting Colorectal Neoplasms

15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is downregulated during the early stages of colorectal carcinogenesis. The aim of the present study was to investigate the potential role of 15-PGDH in normal-appearing colorectal mucosa as a biomarker for predicting colorectal neoplasms. We obtained paired tumor and normal tissues from the surgical specimens of 32 sporadic colorectal cancer patients. mRNA expression of 15-PGDH was measured using a quantitative real-time PCR assay. We evaluated the association between 15-PGDH mRNA expression in normal-appearing mucosa, the presence of synchronous adenoma, and the cumulative incidence of metachronous adenoma. The relative 15-PGDH expression of normal-appearing mucosa in patients with synchronous adenoma was significantly lower than in patients without synchronous adenoma (0.71 vs 1.00, P = 0.044). The patients in the lowest tertile of 15-PGDH expression in normal-appearing mucosa were most likely to have synchronous adenoma (OR: 10.5, P = 0.024). Patients with low 15-PGDH expression in normal-appearing mucosa also demonstrated more advanced stage colorectal cancer (P = 0.045). However, there was no significant difference in the cumulative incidence of metachronous adenoma according to 15-PGDH mRNA expression in normal-appearing mucosa (P = 0.333). Hence, 15-PGDH in normal-appearing colorectal mucosa can be a useful biomarker of field effect for the prediction of sporadic synchronous neoplasms.

Lubiprostone Suppresses Growth of Colon Cancer Cells in vitro and in vivo

Purpose: Colon and other tumors show low levels of expression of 15-hydroxy-prostaglandin dehydrogenase [NAD+] (HPGD), also known as 15-PGDH, a prostone synthetase, which converts prostaglandins to their metabolites, prostones. 15-PGDH, a tumor suppressor, is low in HT-29 colon cancer cells. Deficiency in 15-PGDH results in high prostaglandin levels (and perhaps low prostone levels), which in turn may lead to stimulation of tumor growth. Lubiprostone is a prostone derivative that activates ClC-2 Cl- channels and is used for the treatment of chronic idiopathic constipation in adults and irritable bowel syndrome with constipation in adult women. Cellular effects of lubiprostone include activation of ion channels, subsequent membrane hyperpolarization, reduced intracellular free calcium ([Ca2+]i), and no effect on [cAMP]i. In contrast, PGE1 and PGE2 cause membrane depolarization and increased [Ca2+]i and [cAMP]i by binding to EP receptors (Prostaglandin and Other Lipid Mediators 86: 56-60, 2008). The effect of lubiprostone on tumor growth rate was investigated using wild-type, mock-transfected and 15-PGDH-transfected HT-29 colon cancer cells and HT-29-derived tumors orthotopically implanted on the cecum mucosa of nude mice. Methods: For in vitro studies, HT-29 cells were plated in 60-mm Petri dishes in triplicate and counted in a 1 mm2 area using a microscope grid in a randomly chosen field. Lubiprostone or vehicle (0.1% DMSO) was added after 48 h of plating and cells were then counted 24, 48, 72 and 96 h later. For the animal study, HT-29 tumors were surgically implanted on the cecum mucosa in nude mice and tumor sizes were measured once/week. Lubiprostone and vehicle were given daily orally at day 15 after tumor implantation and monitored at day 22 and day 29 after implantation. Results: Growth of HT-29 cells was significantly inhibited even at 24 h by 100 nM lubiprostone in vitro and inhibited up to about 73% by 72 h. Lubiprostone inhibition of HT-29 cell growth was dose dependent with IC50=1.8±0.3 nM. In PGDH-transfected-HT-29 cells, the inhibitory effect of lubiprostone was lost compared to mock-transfected or non-transfected cells. Lubiprostone (1, 3, 5 mg/kg) also significantly suppressed growth of HT-29 orthotopically implanted tumors by 40-50%. Conclusion: Lubiprostone suppresses growth of HT-29 colon cancer cells in vitro and HT-29 tumor growth in vivo. The mechanism might involve interference with the growth effects caused by high prostaglandin levels in tumor cells with low 15-PGDH (low prostone synthetase activity). These results suggest that lubiprostone might be useful for treatment and/or prevention of colon and potentially other cancers. Supported by Sucampo Pharmaceuticals, Inc. Disclosure: John Cuppoletti is a consultant to, holds stock options in, and has a research grant from Sucampo Pharmaceuticals Inc. Danuta H. Malinowska and Jayati Chakrabarti are supported by the grant from Sucampo Pharmaceuticals Inc. Takashi Sekida is an employee of Sucampo Pharmaceuticals, Inc. Ryuji Ueno is CEO and Chief Scientific Officer, Chairman of the Board and Founder of Sucampo Pharmaceuticals, Inc. This research was supported by an industry grant from Sucampo Pharmaceuticals Inc.

15-Hydroxyprostaglandin Dehydrogenase Is Down-regulated in Gastric Cancer

We have investigated the expression and regulation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in gastric cancer. Clinical gastric adenocarcinoma samples were analyzed by immunohistochemistry and quantitative real-time PCR for protein and mRNA expression of 15-PGDH and for methylation status of 15-PGDH promoter. The effects of interleukin-1beta (IL-1beta) and epigenetic mechanisms on 15-PGDH regulation were assessed in gastric cancer cell lines. In a gastric cancer cell line with a very low 15-PGDH expression (TMK-1), the 15-PGDH promoter was methylated and treatment with a demethylating agent 5-aza-2'-deoxycytidine restored 15-PGDH expression. In a cell line with a relatively high basal level of 15-PGDH (MKN-28), IL-1beta repressed expression of 15-PGDH mRNA and protein. This effect of IL-1beta was at least in part attributed to inhibition of 15-PGDH promoter activity. SiRNA-mediated knockdown of 15-PGDH resulted in strong increase of prostaglandin E(2) production in MKN-28 cells and increased cell growth of these cells by 31% in anchorage-independent conditions. In clinical gastric adenocarcinoma specimens, 15-PGDH mRNA levels were 5-fold lower in gastric cancer samples when compared with paired nonneoplastic tissues (n = 26) and 15-PGDH protein was lost in 65% of gastric adenocarcinomas (n = 210). 15-PGDH is down-regulated in gastric cancer, which could potentially lead to accelerated tumor progression. Importantly, our data indicate that a proinflammatory cytokine linked to gastric carcinogenesis, IL-1beta, suppresses 15-PGDH expression at least partially by inhibiting promoter activity of the 15-PGDH gene.

Δ13-Reductase dependent metabolism of prostaglandins in the mammalian brain and eye

This paper describes the distribution of NAD +-dependent 15-hydroxy prostaglandin dehydrogenase ( Δ 13-reductase) in the mammalian brain and eye tissues. In addition, an NADH-dependent 15-ketoprostaglandin Δ 13-reductase (15-PGDH) activity was determined in the brain and eye tissue of some species. The rabbit brain and eye tissues were obtained after arterial perfusion with PBS buffer while the monkey, bovine and porcine tissues were obtained without any treatment. [ 3H]-PGF 2α or [ 3H]-15-keto-17-phenyl-18,19,20-trinor-PGF 2α-1-isopropyl ester was incubated with different eye tissue preparations under various conditions. No 15-PGDH activity was observed in the monkey brain while 14% of exogenous PGF 2α was metabolized to its 15-keto-13,14-dihydro-metabolite by the porcine brain. The 15-PGDH activity in the monkey eye tissue was undetectable. Both brain and different eye tissues hydrolysed 15-keto-17-phenyl-18,19,20-trinor-PGF 2α-1-isopropyl ester to its free acid and the free acid was further metabolized to 15-keto-13,14-dihydro-17-phenyl-18,19,20-trinor-PGF 2α by the reduction of 13,14-double bond indicating the presence of a Δ 13-reductase in these tissues. These data suggest that besides the presence of esterases the mammalian brain and eye tissues possess variable amounts of Δ 13-reductase in spite of their low 15-PGDH activity which may be of importance in physiology and drug metabolism of these tissues.