3248

HPGD

15-PGDH|PGDH|PGDH1|SDR36C1;hydroxyprostaglandin dehydrogenase 15-(NAD);HPGD;hydroxyprostaglandin dehydrogenase 15-(NAD)

15-hydroxyprostaglandin dehydrogenase [NAD+]|NAD+-dependent 15-hydroxyprostaglandin dehydrogenase|prostaglandin dehydrogenase 1|short chain dehydrogenase/reductase family 36C, member 1

4q34-q35

protein-coding

Count: 2; Generif,UniProt

We investigated the tumor suppressor activity and regulatory mechanism of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in gastric cancer; 15-PGDH expression was lost in 70.1% of malignant human gastric tissues, but was preserved in normal and metaplastic gastritis. KATO III and SNU-719 cells were transfected with pcDNA3.1-empty vector or an expression vector encoding wild-type 15-PGDH. In TUNEL assays apoptotic cell numbers were increased in KATO-PGDH-WT cells compared with control. We found that EGFR and ERK1/2 inhibitors clearly increased the expression of 15-PGDH in KATO III cells. Our findings demonstrate both downregulation and a tumor suppressor activity of 15-PGDH in gastric cancer.

Cyclooxygenase-2 (COX-2), the key enzyme in prostaglandin synthesis, is often over-expressed in human gastric cancer. Recently, 15-hydroxyprostaglandin dehydrogenase [NAD+] (15-PGDH), the key enzyme in prostaglandin degradation, was found to be down-regulated in human gastric cancer tissues, but little is known about its role in gastric tumorigenesis. In this study, expression plasmids containing 15-PGDH siRNA were constructed and transfected into the gastric cancer cell line MKN45, which expresses endogenous 15-PGDH at a high level. The 15-PGDH gene was also transfected into the gastric cancer cell line SGC7901, which expresses endogenous 15-PGDH at a low level. When compared with the empty vector transfectant, MKN45 cells stably transfected with the 15-PGDH siRNA plasmid had a significantly increased proliferation rate. In contrast, SGC7901 cells stably transfected with the 15-PGDH cDNA had a significantly decreased growth rate. Furthermore, increased expression of 15-PGDH suppressed clone formation of gastric cancer cells in plate and soft agar colony formation assays in vitro and suppressed tumor formation in athymic nude mice in vivo. Stable silencing of 15-PGDH in gastric cancer cells also enhanced cell cycle entry in vitro. These results demonstrate for the first time that 15-PGDH acts as a tumor suppressor in human gastric cancer and provide further validation for 15-PGDH as a potential therapeutic target for human gastric cancer.

The forkhead transcription factor hepatocyte nuclear factor 3beta (HNF3beta) is essential in foregut development and the regulation of lung-specific genes. HNF3beta expression leads to growth arrest and apoptosis in lung cancer cells and HNF3beta is a candidate tumor suppressor in lung cancer. In a transcriptional profiling study using a conditional cell line system, we now identify 15-PGDH as one of the major genes induced by HNF3beta expression. 15-PGDH is a critical metabolic enzyme of proliferative prostaglandins, an antagonist to cyclooxygenase-2 and a tumor suppressor in colon cancer. We confirmed the regulation of 15-PGDH expression by HNF3beta in a number of systems and showed direct binding of HNF3beta to 15-PGDH promoter elements. Western blotting of lung cancer cell lines and immunohistochemical examination of human lung cancer tissues found loss of 15-PGDH expression in approximately 65% of lung cancers. Further studies using in vitro cell-based assays and in vivo xenograft tumorigenesis assays showed a lack of in vitro but significant in vivo tumor suppressor activity of 15-PGDH via an antiangiogenic mechanism analogous to its role in colon cancer. In summary, we identify 15-PGDH as a direct downstream effector of HNF3beta and show that 15-PGDH acts as a tumor suppressor in lung cancer.