Alteration in genes which takes place during malignant conversion and progression could be potential targets for gene therapy. We previously identified REIC/Dkk-3 as a gene whose expression is reduced in many human cancers. Here, we showed that expression of REIC/Dkk-3 was consistently reduced in human prostate cancer tissues in a stagedependent manner. Forced expression of REIC/Dkk-3 induced apoptosis in human prostate cancer cell lines lacking endogenous REIC/Dkk-3 expression but not in REIC/Dkk-3-proficient normal prostate epithelial and stromal cells. The apoptosis involved c-Jun-NH 2 -kinase activation, mitochondrial translocation of Bax, and reduction of Bcl-2. A single injection of an adenovirus vector carrying REIC/Dkk-3 showed a dramatic antitumor effect on a xenotransplanted human prostate cancer. Thus, REIC/Dkk-3 could be a novel target for gene-based therapy of prostate cancer. (Cancer Res 2005; 65(21): 9617-22)

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Insulin causes endothelium-derived nitric oxide (NO)-dependent vascular relaxation, and increases L-arginine transport via cationic amino acid transporter 1 (hCAT-1) and endothelial NO synthase (eNOS) expression and activity in human umbilical vein endothelium (HUVEC). We studied insulin effect on SLC7A1 gene (hCAT-1) expression and hCAT-transport activity role in insulin-modulated human fetal vascular reactivity. HUVEC were used for L-arginine transport and L-[(3) H]citrulline formation (NOS activity) assays in absence or presence of N-ethylmaleimide (NEM) or L-lysine (L-arginine transport inhibitors). hCAT-1 protein abundance was estimated by Western blot, mRNA quantification by real time PCR, and SLC7A1 promoter activity by Luciferase activity (-1,606 and -650 bp promoter fragments from ATG). Specific protein 1 (Sp1), and total or phosphorylated eNOS protein was determined by Western blot. Sp1 activity (at four sites between -177 and -105 bp from ATG) was assayed by chromatin immunoprecipitation (ChIP) and vascular reactivity in umbilical vein rings. Insulin increased hCATs-L-arginine transport, maximal transport capacity (V(max) /K(m) ), and hCAT-1 expression. NEM and L-lysine blocked L-arginine transport. In addition, it was trans-stimulated (∼7.8-fold) by L-lysine in absence of insulin, but unaltered (~1.4-fold) in presence of insulin. Sp1 nuclear protein abundance and binding to DNA, and SLC7A1 promoter activity was increased by insulin. Insulin increased NO synthesis and caused endothelium-dependent vessel relaxation and reduced U46619-induced contraction, effects blocked by NEM and L-lysine, and dependent on extracellular L-arginine. We suggest that insulin induces human umbilical vein relaxation by increasing HUVEC L-arginine transport via hCATs (likely hCAT-1) most likely requiring Sp1-activated SLC7A1 expression.

REIC/Dickkopf-3 (Dkk-3), a tumor suppressor gene, has been investigated in gene therapy studies. Our previous study suggested that REIC/Dkk-3-induced apoptosis mainly resulted from phosphorylation of c-Jun-NH 2 kinase (JNK) in prostate cancer cells. However, the precise mechanisms, especially the molecular mechanisms regulating JNK phosphorylation, remain unclear. In this study, we investigated the mechanisms participating in JNK phosphorylation in the context of a refractory cancer disease, malignant mesothelioma (MM). Adenovirus-mediated overexpression of REIC/Dkk-3 induced apoptosis mainly through JNK activation in immortalized MM cells (211H cells). Interestingly, transcriptional downregulation of inhibition of differentiation-1 (Id-1) was detected in REIC/Dkk-3-overexpressed 211H cells. Moreover, restoration of Id-1 expression antagonized REIC/Dkk-3-induced JNK phosphorylation and apoptosis. Mutagenesis experiments with the 2.1-kb human Id-1 promoter revealed that activating transcription factor 3 (ATF3) and Smad interaction, with their respective binding motifs, was essential for REIC/Dkk-3-mediated suppression of Id-1 promoter activity. ATF3 activation was probably induced by endoplasmic reticulum stress. Finally, we showed strong antitumor effects from REIC/Dkk-3 gene transfer into the pleural cavity in an orthotopic MM mouse model. Relative to control tumor tissue, REIC/Dkk-3-treated tumor tissue showed downregulated expression of Id-1 mRNA, enhanced expression of phosphorylated JNK, and an increased number of apoptotic cells. In summary, we first showed that both ATF3 and Smad were crucially and synergistically involved in down-regulation of Id-1, which regulated JNK phosphorylation in REIC/Dkk-3-induced apoptosis. Thus, gene therapy with REIC/Dkk-3 may be a promising therapeutic tool for MM. [Cancer Res 2008;68(20):8333-41]

We previously showed that the tumor suppressor gene REIC/ Dkk-3, when overexpressed by an adenovirus (Ad-REIC), exhibited a dramatic therapeutic effect on human cancers through a mechanism triggered by endoplasmic reticulum stress. Adenovirus vectors show no target cell specificity and thus may elicit unfavorable side effects through infection of normal cells even upon intra-tumoral injection. In this study, we examined possible effects of Ad-REIC on normal cells. We found that infection of normal human fibroblasts (NHF) did not cause apoptosis but induced production of interleukin (IL)-7. The induction was triggered by endoplasmic reticulum stress and mediated through IRE1␣, ASK1, p38, and IRF-1. When Ad-REIC-infected NHF were transplanted in a mixture with untreated human prostate cancer cells, the growth of the cancer cells was significantly suppressed. Injection of an IL-7 antibody partially abrogated the suppressive effect of Ad-REIC-infected NHF. These results indicate that Ad-REIC has another arm against human cancer, an indirect host-mediated effect because of overproduction of IL-7 by mis-targeted NHF, in addition to its direct effect on cancer cells.Cancer cells, like normal cells, cannot be free from regulation by other cells in the body (1). The microenvironment can exert both promotive and suppressive effects on malignant cells (2). The embryonic environment has been shown to suppress malignant phenotypes (3, 4), and this was recently indicated to be due to suppression of Nodal function by Lefty (5). Cells comprising cancer stroma in adult tissues are also involved in tumor suppression (6, 7). Mobilization of such potential tumor-suppressive effects of the microenvironment would provide an additional arm for cancer therapy (8).Adenovirus vectors combined with appropriate cargo genes have great potential in cancer gene therapy because of their high infection efficiency and marginal genotoxicity (9). However, they show no target cell specificity and thus may also infect normal cells present in the surroundings of cancer cells. Provided that the interaction between cancer cells and normal cells is relevant to progression/suppression of cancer, it is critically important to understand not only cell autonomous phenomena in individual cell types infected by a therapeutic virus vector but also potential effects of the therapeutic virus vector on the composite system of interacting cell populations.We have been studying the possible utility of an adenovirus vector carrying the tumor suppressor gene REIC/Dkk-3 (Ad-REIC) for gene therapy against human cancer. REIC/Dkk-3 was first identified as a gene that was down-regulated in association with immortalization of normal human fibroblasts (NHF) 2 (10). Expression of REIC/Dkk-3 gene was shown to be reduced in many human cancer cells and tissues, including prostate cancer, renal clear cell carcinoma, testicular cancer, and non-small cell lung cancer (11-14), probably due to hypermethylation of the promoter (15). A single injection of Ad-REIC into tumors formed by...

Human testicular cancer is very sensitive to chemotherapy and radiation therapy and is regarded as a curable cancer. The cancer prevails in the young reproductive generation and testicular dysfunction is often observed as a side effect, remaining a serious challenge. In the present study, we examined the potential utility of REIC/Dkk-3-based gene therapy against human testicular cancer. Expression of REIC/Dkk-3 was reduced in all of the human seminoma and non-seminomatous germ cell tumor tissues. Overexpression of REIC/Dkk-3 using an adenovirus vector (Ad-REIC) induced apoptosis in a testicular germ cell cancer cell line NCCIT but not in normal human fibroblasts. c-Jun terminal kinase (JNK) was activated by Ad-REIC and the induction of apoptosis was abrogated by a JNK inhibitor. A single intratumoral injection of Ad-REIC markedly inhibited the tumorigenic growth of NCCIT cells in nude mice. These results indicate that Ad-REIC may lead to developing less insulting and non-genotoxic therapeutic measures against human testicular cancer.

Objective-Human pregnancy that courses with maternal supraphysiological hypercholesterolemia (MSPH) correlates with atherosclerotic lesions in fetal arteries. It is known that hypercholesterolemia associates with endothelial dysfunction in adults, a phenomenon where nitric oxide (NO) and arginase are involved. However, nothing is reported on potential alterations in the fetoplacental endothelial function in MSPH. The aim of this study was to determine whether MSPH alters fetal vascular reactivity via endothelial arginase/urea and l-arginine transport/NO signaling pathways. Approach and Results-Total cholesterol <280 mg/dL was considered as maternal physiological hypercholesterolemia (n=46 women) and ≥280 mg/dL as MSPH (n=28 women). Maternal but not fetal total cholesterol and low-density lipoprotein-cholesterol levels were elevated in MSPH. Umbilical veins were used for vascular reactivity assays (wire myography), and primary cultures of umbilical vein endothelial cells to determine arginase, endothelial NO synthase (eNOS), and human cationic amino acid transporter 1 and human cationic amino acid transporter 2A/B expression and activity. MSPH reduced calcitonine gene-related peptide-umbilical vein relaxation and increased intima/media ratio (histochemistry), as well as reduced eNOS activity (l-citrulline synthesis from l-arginine, eNOS phosphorylation/dephosphorylation), but increased arginase activity and arginase II protein abundance. Arginase inhibition increased eNOS activity and l-arginine transport capacity without altering human cationic amino acid transporter 1 or human cationic amino acid transporter 2A/B protein abundance in maternal physiological hypercholesterolemia and MSPH. Conclusions-MSPH is a pathophysiological condition altering umbilical vein reactivity because of fetal endothelial dysfunction associated with arginase and eNOS signaling imbalance. We speculate that elevated maternal circulating cholesterol is a factor leading to fetal endothelial dysfunction, which could have serious consequences to the growing fetus. Maternal Hypercholesterolemia in Pregnancy AssociatesWith Umbilical Vein Endothelial Dysfunction Leiva et al MSPH and Umbilical Vein Endothelial Dysfunction 2445NO synthases. Because NO synthesis depends on l-arginine uptake in human placenta endothelium, 10-17 MSPH could result in altered l-arginine transport and NO synthesis, that is, the l-arginine/NO pathway, in fetal endothelium.l-Arginine uptake occurs predominantly via the human cationic amino acid transporters (hCATs) family.13 hCATs family includes ≥5 members, that is, hCAT-1, hCAT-2A, hCAT-2B, hCAT-3, and hCAT-4, 12,13 of which the high-affinity, lowcapacity hCAT-1 is the main isoform expressed in human umbilical vein endothelial cells (HUVEC), 15,16 a cell type exposed to oxygen-and nutrient-enriched blood (ie, arteriallike blood, reaching fetal circulation).18 Interestingly, altered hCAT-1 activity could result in abnormal NO synthesis in HUVEC. 10,11,15,17 Hypercholesterolemia also associates with reduced endotheli...

We had previously reported that REIC/Dkk-3, a member of the Dickkopf (Dkk) gene family, works as a tumor suppressor. In this study, we evaluated the therapeutic effects of an intratumoral injection with adenoviral vector encoding REIC/Dkk-3 gene (Ad-REIC) using an orthotopic mouse prostate cancer model of RM-9 cells. We also investigated the in vivo anti-metastatic effect and in vitro anti-invasion effect of Ad-REIC gene delivery. We demonstrated that the Ad-REIC treatment inhibited prostate cancer growth and lymph node metastasis, and prolonged mice survival in the model. These therapeutic responses were consistent with the intratumoral apoptosis induction and in vitro suppression of cell invasion/migration with reduced matrix metalloprotease-2 activity. We thus concluded that in situ Ad-REIC/Dkk-3 gene transfer may be a promising therapeutic intervention modality for the treatment of prostate cancer.