Discovery of Novel Allosteric Inhibitors of Deoxyhypusine Synthase.

Deoxyhypusine synthase (DHPS) utilizes spermidine and NAD as cofactors to incorporate a hypusine modification into the eukaryotic translation initiation factor 5A (eIF5A). Hypusine is essential for eIF5A activation, which, in turn, plays a key role in regulating protein translation of selected mRNA that are associated with the synthesis of oncoproteins, thereby enhancing tumor cell proliferation. Therefore, inhibition of DHPS is a promising therapeutic option for the treatment of cancer. To discover novel lead compounds that target DHPS, we conducted synthetic studies with a hit obtained via high-throughput screening. Optimization of the ring structures of the amide compound (2) led to bromobenzothiophene (11g) with potent inhibitory activity against DHPS. X-ray crystallographic analysis of 11g complexed with DHPS revealed a dramatic conformational change in DHPS, which suggests the presence of a novel allosteric site. These findings provide the basis for the development of novel therapy distinct from spermidine mimetic inhibitors.

New Series of Potent Allosteric Inhibitors of Deoxyhypusine Synthase.

Deoxyhypusine synthase (DHPS) is the primary enzyme responsible for the hypusine modification and, thereby, activation of the eukaryotic translation initiation factor 5A (eIF5A), which is key in regulating the protein translation processes associated with tumor proliferation. Although DHPS inhibitors could be a promising therapeutic option for treating cancer, only a few studies reported druglike compounds with this inhibition property. Thus, in this work, we designed and synthesized a new chemical series possessing fused ring scaffolds designed from high-throughput screening hit compounds, discovering a 5,6-dihydrothieno[2,3-c]pyridine derivative (26d) with potent inhibitory activity; furthermore, the X-ray crystallographic analysis of the DHPS complex with 26d demonstrated a distinct allosteric binding mode compared to a previously reported inhibitor. These findings could be significantly useful in the functional analysis of conformational changes in DHPS as well as the structure-based design of allosteric inhibitors.

Discovery and Characterization of a Eukaryotic Initiation Factor 4A-3-Selective Inhibitor That Suppresses Nonsense-Mediated mRNA Decay.

Eukaryotic initiation factor 4A-3 (eIF4A3) is an Asp-Glu-Ala-Asp (DEAD) box-family adenosine triphosphate (ATP)-dependent RNA helicase. Subtypes eIF4A1 and eIF4A2 are required for translation initiation, but eIF4A3 participates in the exon junction complex (EJC) and functions in RNA metabolism including nonsense-mediated RNA decay (NMD). No small molecules for NMD inhibition via selective inhibition of eIF4A3 have been discovered. Here, we identified allosteric eIF4A3 inhibitors from a high-throughput screening campaign. Chemical optimization of the lead compounds based on ATPase activity yielded compound 2, which exhibited noncompetitive inhibition with ATP or RNA and high selectivity for eIF4A3 over other helicases. The optimized compounds suppressed the helicase activity of eIF4A3 in an ATPase-dependent manner. Hydrogen/deuterium exchange mass spectrometry demonstrated that the deuterium-incorporation pattern of compound 2 overlapped with that of an allosteric pan-eIF4A inhibitor, hippuristanol, suggesting that compound 2 binds to an allosteric region on eIF4A3. We examined NMD activity using a luciferase-based cellular reporter system and a quantitative real-time polymerase chain-reaction-based cellular system to monitor levels of endogenous NMD substrates. NMD suppression by the compounds correlated positively with their ATPase-inhibitory activity. In conclusion, we developed a novel eIF4A3 inhibitor that targets the EJC. The optimized chemical probes represent useful tools for understanding the functions of eIF4A3 in RNA homeostasis.

A new role of GCN2 in the nucleolus.

General control nonderepressible 2 (GCN2) is activated by the accumulation of uncharged tRNA in response to amino acid shortage and regulates amino acid starvation response in the cytosol. Here we report the nucleolar localization of GCN2 and the association between GCN2 and small RNA transcripts. Immunofluorescence analysis revealed that GCN2 was constitutively localized to the nucleolus or recruited to the nucleolus by amino acid starvation stress. The nucleolus is the largest structure in the nucleus, where it primarily serves as the site of ribosome and RNA synthesis in addition to acting as a stress sensor through the regulation of p53 function. We found that siRNA-mediated depletion of GCN2 increases small RNA transcripts such as tRNA and 5S rRNA, and induces the p53 pathway activation. Derepression of these transcripts and p53 pathway activation by GCN2 depletion was restored by depletion of B-related factor 1 (BRF1), a primary subunit of RNA polymerase III (pol III) components. These data suggest that the excess amount of small RNA transcripts following GCN2 depletion was responsible for the p53 activation. Our findings reveal a role of GCN2 in the nucleolus that is involved in the expression of small RNA transcripts and serves as alternative stress-sensing machinery for nutrient deficiency. Thus, GCN2 may play pivotal roles in multiple protein translation checkpoints in both the nucleolus and cytosol.

Trends in cancer prognosis in a population-based cohort survey: can recent advances in cancer therapy affect the prognosis?

BACKGROUND: The aim of the study was to investigate trends in cancer prognosis by examining the relationship between period of diagnosis and probability of death from cancer in a population-based cohort. METHODS: Within a cohort of Japanese men and women aged 40-69 years and free of prior diagnosis of cancer and cardiovascular disease at baseline, data from 4403 patients diagnosed with cancer between 1990 and 2006 and followed up until 2012 were analyzed using survival regression models to assess the presence of an effect of the period of diagnosis (before 1998 versus after 1998) on the risk of dying from cancer. RESULTS: We noted a significant decrease in risk of dying from cancer among individuals diagnosed after 1998 with lung cancer (hazard ratio [HR]=0.676 [0.571-0.800]) or colorectal cancer (HR=0.801 [0.661-0.970]). A decrease in the estimated five-year probability of death from cancer was also noted between the first (before 1998) and the second (after 1998) period of diagnosis for lung and colorectal cancers (e.g., 85.4% vs. 73.3% for lung cancer and 44.6% vs. 37.7% for colorectal cancer, respectively, for stage III in men aged 60 at diagnosis). CONCLUSIONS: This study presented the first scientific evidence of improvement in prognosis for lung and colorectal cancer patients in a population-based cohort in Japan. Our results suggest that recent advances in cancer treatment could have influenced cancer survival differently among lung, colorectal and gastric cancers.

Multifocal and microscopic chromophobe renal cell carcinomatous lesions associated with 'capsulomas' without FCLN gene abnormality.

Chromophobe renal cell carcinoma (RCC) accounts for approximately 5% of renal epithelial neoplasms. Multiple and/or bilateral chromophobe RCCs in an individual are generally rare but frequently occur in patients with Birt-Hogg-Dubé syndrome (BHDS) and in patients with tuberous sclerosis complex (TSC). The responsible genes in both BHDS and TSC act as tumor suppressors. Therefore, it seems that some genetic backgrounds are required for the generation and progression of multiple chromophobe RCCs. Here, we report a case of multiple and bilateral chromophobe RCCs along with several small-sized capsular angiomyolipomas known as 'capsulomas' in a 39-year-old woman who had neither a particular medical history nor specific gene mutation. There has been no report of sporadic multiple chromophobe RCCs and 'capsulomas' developing in a patient without genetic features, having potential for novel genetic variation.

Risk factors for sudden cardiac death among Japanese: the Circulatory Risk in Communities Study.

OBJECTIVE: There is little evidence concerning risk factors for sudden cardiac death (SCD) among Asians. PATIENTS AND METHODS: A prospective, nested, case-control study of Japanese patients aged between 30 and 84 years was undertaken using data collected from 26 870 participants in cardiovascular risk surveys conducted in four communities between 1975 and 2005. The incidence of SCD was ascertained by systematic surveillance, with 239 cases of SCD identified over this period. For each case of SCD, three control patients were selected, matched by age, sex, examination year, follow-up time, and community. RESULTS: Hypertension, diabetes mellitus, smoking, major ST-T abnormalities, left high amplitude R waves, and increased heart rate (≥77 beat/min) were all independently associated with a 1.5-3.2-fold increase in SCD risk, whereas no associations were observed for body mass index and hypercholesterolemia. The population-attributable fraction [95% confidence interval (CI)] was 23.0% (2.9-39.0) for hypertension, 15.3% (3.8-25.5) for current smoking, 14.5% (8.0-20.5) for major ST-T abnormalities, and 8.1% (2.2-13.7) for diabetes mellitus. The number of SCD risk factors (hypertension, diabetes, smoking, and ECG abnormalities) was positively associated with increased SCD risk. The odds ratio for increased SCD risk with three or more risk factors versus zero risk factors was 5.76 (95% CI 3.20-10.39). CONCLUSIONS: Among the Japanese population, hypertension, smoking, major ST-T abnormalities, left high amplitude R waves, and diabetes mellitus were associated with an increased incidence of SCD, whereas there were no associations of body mass index or hypercholesterolemia with SCD incidence.

Structure-activity relationships and cancer-cell selective toxicity of novel inhibitors of glioma-associated oncogene homologue 1 (Gli1) mediated transcription.

We report novel inhibitors of Gli1-mediated transcription as potential anticancer agents. Focused chemical libraries were designed and assessed for inhibition of functional cell-based Gli1-mediated transcription and selective toxicity toward cancer cells. The SAR was revealed, and the selectivity of the lead compounds' inhibition of Gli1-mediated transcription over that of Gli2 was determined. Compound 63 (NMDA298-1), which inhibited Gli1-mediated transcription in C3H10T1/2 cells with an IC(50) of 6.9 muM, showed 3-fold selectivity for inhibiting transcription mediated by Gli1 over that by Gli2. Cell-viability assays were performed to evaluate the chemical library in a normal cell line and a panel of cancer cell lines with or without up-regulated expression of the Gli1 gene. These compounds decreased the viability of several cancer cell lines but were less active in the noncancerous BJ-hTERT cells.

Transient inhibition of the Hedgehog pathway in young mice causes permanent defects in bone structure.

The Hedgehog (Hh) pathway plays critical roles in normal development and in tumorigenesis. We generated Gli-luciferase transgenic mice to evaluate the Smo inhibitor, HhAntag, by whole animal functional imaging. HhAntag rapidly reduced systemic luciferase activity in 10- to 14-day-old mice following oral dosing. Although pathway activity was restored 2 days after drug removal, brief inhibition caused permanent defects in bone growth. HhAntag inhibited proliferation and promoted differentiation of chondrocytes, leading to dramatic expansion of the hypertrophic zone. After drug removal, osteoblasts invaded the cartilage plate, mineralization occurred, and there was premature fusion of the growth plate resulting in permanent disruption of bone epiphyses.

[The fourth report from Sapporo Tsukisamu Hospital - chemotherapy and its regimen as second choice for patients with early gastric cancer].

Surgical treatments for early gastric cancer, such as endoscopic procedures, are currently performed as standard therapy. However, when surgery is not possible due to physical or mental conditions, effective chemotherapy with minimum side effects is a second choice, although a suitable regimen has yet to be recommended. We thus retrospectively evaluated the Int FP regimen for 10 early gastric cancer patients. The results show an efficacy ratio of 100% (CR 8 cases, PR 2 cases). The two PR cases subsequently underwent surgical treatment. The 1-, 3-, and 5-year survival rates of all cases were 100%, 90% and 60%, respectively. The 1-, 3-, and 5-year survival rates of patients with chemotherapy alone were 100%, 87.5% and 50%, respectively, although none of the patients died of cancer (5-year survival rate of 100%). One out of the 8 CR cases relapsed 7 months after achieving CR. This patient then received chemotherapy with the same regimen, achieving a second CR and survived for 66 months without disease. All cases developed hematological toxicities, although they were all under grade 2 except for 2 cases which were grade 3 (decrease of WBC or Hb). Non-hematological toxicities were seen in 7 cases, all under grade 2. These results, although from a limited number of subjects, indicated that the IntFP regimen is safe and may contribute to achieving pathological CR and long-term survival of patients with early gastric cancer.

[The third report from Sapporo Tsukisamu Hospital--chemotherapy for patients with advanced gastric cancer (peritoneal dissemination, peritonitis carcinomatosa)].

Recently, it became possible to reduce the size of tumors in patients with advanced or relapsed gastric cancer by chemotherapy with the combination of several kinds of anti-cancer drugs which are all effective and allowed for use with gastric cancer patients. However, chemotherapy alone can not cure patients with advanced gastric cancer that was shown to improve median survival time (MST), compared with patients provided with the best supportive care (BSC). According to reports from Europe, US and Japan,the MST of patients with advanced gastric cancer and those with peritoneal expansion treated by chemotherapy is almost 7-12 months and 5-6 months,respectively, both of which are short and unsatisfactory. From March 2002, we started to treat patients with advanced gastric cancer (stage IV) with a new regimen; intermittent dosage of 5-FU (-->S-1), CDDP and paclitaxel utilizing the difference of cell cycle between normal and cancer cells (intermittent FP . weekly PTX). In the present study, therefore, we analyzed advanced gastric cancer patients with peritoneal expansion (9 cases, 4 with cancerous peritonitis) treated with this regimen. The results were as follows. The one-and 2-year survival rate was 55.6% and 27.8%, respectively, and the MST was 14 months. Four patients (44.4%) had hematological toxicities over grade 3. All of them had anemia (3 cases) and neutropenia (3 cases). Toxicities of thrombocytopenia were all under grade 1 and nonhematological toxicities were all under grade 2, which were clinically manageable. These results, although the sample was small, suggested that this may contribute to the extension of survival time of patients with stage IV advanced gastric cancer with peritoneal expansion.

[The second report from Sapporo Tsukisamu hospital--chemotherapy for patients with advanced colorectal cancer].

The remedy,especially recent chemotherapy,against colorectal cancer is improving median survival time (MST) of patients with Stage IV advanced colorectal cancer. According to other reports,however,it seems to be difficult to improve it longer than 20 months. In May 2002, we devised a new regimen by intermittent dosage of 5-FU (-->S-1), CDDP and paclitaxel utilizing the difference of cell cycle between normal and cancer cells, and thirteen patients with advanced colorectal cancer (Stage IV) were treated with this regimen. As a result, a satisfactory efficacy rate of 53.8%, 1-year survival rate of 69 .2%, 2-year survival rate of 53.9%, 3-year survival rate of 44.9%, 5-year survival rate of 17.9%, and MST 36 months were achieved. Five patients had hematological toxicities over grade 3 (38.5%) and most of them were anemia (3 cases) and neutropenia (5 cases). Thrombocytopenia and gastroenterological toxicity were all under grade 2. Adverse effects related to this regimen were clinically manageable. These results, although for a limited number of patients, indicated that this may contribute to the extension of survival time of patients with Stage IV advanced colorectal cancer.

[The first report from Sapporo Tsukisamu Hospital--chemotherapy and chemoradiotherapy for patients with advanced pancreatic cancer].

The remedy, especially chemotherapy, for advanced pancreatic cancer is hardly ever successful in terms of efficacy rate and survival period, because it is virtually unable to contribute to the improvement of median survival time (MST). Thus,we devised a new intermittent dosage regimen utilizing the cell cycle difference of normal GI tract, bone marrow cell and pancreatic cancer cell, making use of 5-FU (-->S-1), CDDP and paclitaxel in March 2002. Ten patients with advanced pancreatic cancer (4 in Stage IVa and 6 in Stage IVb) were treated with this new regimen. As a result, an efficacy ratio of 50.0% and a 1-year survival ratio of 60.0% were achieved. However, 2-year survival ratio of 12.0% was low, and there was no 3-year survivor. The MST was 19 months as of December 31, 2006. All of the non-hematological toxicities were under grade 2. Eight patients had hematological toxicities over grade 3 and most of them were anemia and neutropenia. Only 2 cases had thrombocytopenia. Although adverse effects related to this regimen were clinically manageable, it was difficult to improve MST of patients with advanced pancreatic cancer with chemotherapy alone including this regimen. Hence, we devised another regimen with the joint use of radiotherapy along with the same chemotherapy regimen in January 2003. Twenty patients with advanced pancreatic cancer (Stage IV) were treated with this regimen. It is presently under way, and an efficacy ratio of 35.0%, 1-year survival ratio of 86.3% and 2-year survival ratio of 64.0% were obtained by May 2005, showing that this may contribute to the extension of survival time of Stage IV pancreatic cancer patients.

Medulloblastomas derived from Cxcr6 mutant mice respond to treatment with a smoothened inhibitor.

The sonic hedgehog (Shh) pathway is activated in approximately 30% of human medulloblastoma resulting in increased expression of downstream target genes. In about half of these cases, this has been shown to be a consequence of mutations in regulatory genes within the pathway, including Ptc1, Smo, and Sufu. However, for some tumors, no mutations have been detected in known pathway genes. This suggests that either mutations in other genes promote tumorigenesis or that epigenetic alterations increase pathway activity in these tumors. Here, we report that 3% to 4% of mice lacking either one or both functional copies of Cxcr6 develop medulloblastoma. Although CXCR6 is not known to be involved in Shh signaling, tumors derived from Cxcr6 mutant mice expressed Shh pathway target genes including Gli1, Gli2, Ptc2, and Sfrp1, indicating elevated pathway activity. Interestingly, the level of Ptc1 expression was decreased in tumor cells although two normal copies of Ptc1 were retained. This implies that reduced CXCR6 function leads to suppression of Ptc1 thereby increasing Smoothened function and promoting tumorigenesis. We used a direct transplant model to test the sensitivity of medulloblastoma arising in Cxcr6 mutant mice to a small-molecule inhibitor of Smoothened (HhAntag). We found that transplanted tumors were dramatically inhibited in mice treated for only 4 days with HhAntag. These findings suggest that HhAntag may be effective against tumors lacking mutations in known Shh pathway genes.

[Long-term repeatable chemotherapy for patients with advanced pancreatic cancer].

At present, the advanced pancreatic cancer is known to be one of the most resistant malignancies on chemotherapy. To improve the efficacy of chemotherapy, we shifted the aim of chemotherapy from a tumor regression to long-term survival, and sought for a repeatable regimen with little toxicity. Some of the novel (repeatable) regimens used a combination of 5-FU/S-1, CDDP and paclitaxel performed for 10 patients with advanced pancreatic cancer (4 cases of Stage IVa and 6 cases of Stage IVb). As a result, the survival ratios of one and two years were 85.7% and 22.9%, respectively. The efficacy rate was 50% (5 cases of PR and 5 cases of NC). Hematological adverse reactions over grade 3 were observed in 8 out of 10 cases, although the decrease of platelet count was observed only in 2 cases (grade 3 and 4). The majority of hematological adverse reactions over grade 3 were leukocytepenia and anemia which were easy to control safely. All of non-hematological adverse reactions were observed under grade 2 and did not disrupt the maintenance of chemotherapy.

Gli1 is important for medulloblastoma formation in Ptc1+/- mice.

Germline mutations in the human homolog of the patched1 (PTCH1) are associated with basal cell nevus carcinoma syndrome (BCNS or Gorlin syndrome), which is characterized by developmental anomalies, radiation hypersensitivity and a predisposition to medulloblastomas and skin tumors. Patched1 (Ptc1) functions as a receptor for Sonic hedgehog (Shh) in a wide range of biological processes. Binding of Shh to Ptc1 results in activation of Smoothened (Smo), which in turn stimulates expression of downstream target genes including Ptc1 and Gli1. Gli1 is a member of a family of DNA-binding zinc-finger proteins, including Gli2 and Gli3, that function in transcription control. Here, we report that inactivation of both Gli1 alleles in Ptc1+/- mice significantly reduces spontaneous medulloblastoma formation. Therefore, Gli1 is not only a marker of pathway activation but also plays a functional role in medulloblastoma formation. Interestingly, Gli2 levels were elevated in medulloblastoma cells but not in normal granule neuron precursors during cerebellar development in mice lacking Gli1. In cultured fibroblasts, Gli1 was more potent than Gli2 at inducing cell transformation. These results demonstrate that Gli1 plays a central role in medulloblastoma formation in Ptc1+/- mice and that Gli2 may also contribute to oncogenesis.

Suppression of the Shh pathway using a small molecule inhibitor eliminates medulloblastoma in Ptc1(+/-)p53(-/-) mice.

Medulloblastoma is the most common malignant pediatric brain tumor. Current treatment is associated with major long-term side effects; therefore, new nontoxic therapies, targeting specific molecular defects in this cancer, need to be developed. We use a mouse model of medulloblastoma to show that inhibition of the Sonic Hedgehog (Shh) pathway provides a novel therapy for medulloblastoma. A small molecule inhibitor of the Shh pathway, HhAntag, blocked the function of Smoothened in mice with medulloblastoma. This resulted in suppression of several genes highly expressed in medulloblastoma, inhibition of cell proliferation, increase in cell death and, at the highest dose, complete eradication of tumors. Long-term treatment with HhAntag prolonged medulloblastoma-free survival. These findings support the development of Shh antagonists for the treatment of medulloblastoma.

Phase I clinical study of anti-apoptosis protein, survivin-derived peptide vaccine therapy for patients with advanced or recurrent colorectal cancer.

Survivin is a member of the inhibitor of apoptosis protein (IAP) family containing a single baculovirus IAP repeat domain. It is expressed during fetal development but becomes undetectable in terminally differentiated normal adult tissues. We previously reported that survivin and its splicing variant survivin-2B was expressed abundantly in various types of tumor tissues as well as tumor cell lines and was suitable as a target antigen for active-specific anti-cancer immunization. Subsequently, we identified an HLA-A24-restricted antigenic peptide, survivin-2B80-88 (AYACNTSTL) recognized by CD8+ cytotoxic T lymphocytes (CTLs). We, therefore, started a phase I clinical study assessing the efficacy of survivin-2B peptide vaccination in patients with advanced or recurrent colorectal cancer expressing survivin. Vaccinations with survivin-2B peptide were given subcutaneously six times at 14-day intervals. Of 15 patients who finished receiving the vaccination schedule, three suffered slight toxicities, including anemia (grade 2), general malaise (grade 1), and fever (grade 1). No severe adverse events were observed in any patient. In 6 patients, tumor marker levels (CEA and CA19-9) decreased transiently during the period of vaccination. Slight reduction of the tumor volume was observed in one patient, which was considered a minor responder. No changes were noted in three patients while the remaining eleven patients experienced tumor progression. Analysis of peripheral blood lymphocytes of one patient using HLA-A24/peptide tetramers revealed an increase in peptide-specific CTL frequency from 0.09% to 0.35% of CD8+ T cells after 4 vaccinations. This phase I clinical study indicates that survivin-2B peptide-based vaccination is safe and should be further considered for potential immune and clinical efficacy in HLA-A24-expression patients with colorectal cancer.

Transcription of mouse DNA methyltransferase 1 (Dnmt1) is regulated by both E2F-Rb-HDAC-dependent and -independent pathways.

Abnormal expression of Dnmt1 in vivo induces cellular alterations such as transformation, and an increase in Dnmt1 mRNA plays a causal role in c-fos-, ras- and SV40 large T antigen-induced transformation of fibroblasts in vitro. Here, we have investigated the regulation of Dnmt1 transcription. We identified the promoter region and major transcription start sites of mouse Dnmt1 and found two important cis-elements within the core promoter region. One is an E2F binding site, and the other is a binding site for an as yet unidentified factor. Point mutations in the two cis-elements decreased promoter activity in both non-transformed and transformed cells. Thus, both sites play a critical role in regulation of Dnmt1 transcription in proliferating cells. Treatment with trichostatin A, a specific inhibitor of histone deacetylase, increased Dnmt1 promoter activity in G0/G1-arrested NIH 3T3 cells. Furthermore, the decrease in promoter activity induced by expression of E2F-1 and Rb was reversed by trichostatin A treatment of Saos-2 cells. Taken together, these data indicate that transcription of Dnmt1 is regulated in a complex fashion by E2F and other transcription factors through E2F-Rb-HDAC-dependent and -independent pathways. These findings suggest that Dnmt1 is a target gene of these pathways in cell proliferation, cell transformation and tumorigenesis.

Hepatocyte nuclear factor (HNF)-4alpha induces expression of endothelial Fas ligand (FasL) to prevent cancer cell transmigration: a novel defense mechanism of endothelium against cancer metastasis.

Endothelial Fas ligand (FasL) contributes to the "immune privilege" of tissues such as testis and eye, in which apoptosis is induced in infiltrating Fas-positive activated T cells and results in the inhibition of leukocyte extravasation. In this study, we examined the role of endothelial FasL in controlling cancer cell transmigration using rat lung endothelial (RLE) cell line bearing a doxycycline-inducible hepatocyte nuclear factor (HNF)-4alpha expression system. We showed that a detectable level of FasL was expressed in RLE cells and that this expression was markedly up-regulated and well correlated to the degree of HNF-4alpha expression in a time-dependent manner. When various cancer cells were overlaid on an RLE monolayer sheet, we examined the ability of endothelial FasL to induce massive apoptosis in Fas-expressing cancer cells and found a causal link to inhibition of the transmigration. Finally, we showed that FasL was expressed in capillaries of the rat brain by immunohistochemical staining, suggesting that FasL serves its functions not only in vitro, but also in vivo. These results raise the possibility that HNF-4alpha is involved in regulating cancer cell transmigration by modulating the Fas-FasL system.