Causality assessment between reported fatal cerebral haemorrhage and suspected drugs: developing a new algorithm based on the analysis of the Japanese Adverse Event Report (JADER) database and literature review.

PURPOSE: Cerebral haemorrhage is a life-threatening event with various causes including adverse drug reactions (ADRs). Several methods have been proposed for the causality assessment of ADRs, but none specific for cerebral haemorrhage. The purpose of this study was to develop an algorithm for causality assessment between drugs and fatal cerebral haemorrhage, based on the analysis of data from the Japanese Adverse Drug Event Report (JADER) database and literature review. METHODS: All fatal ADRs reported in the JADER database between April 2004 and March 2020 were searched, and literature on drug-related cerebral haemorrhage or general causality assessment was reviewed to summarise the information on causality between cerebral haemorrhage and ADRs. RESULTS: Of the 50,095 cases identified in the JADER database, cerebral haemorrhage was the fifth most reported cause of fatal ADRs, but the causality of >80% of the events was published as 'Unassessable'. The literature review identified articles on drug-related cerebral haemorrhage and causality assessment methods in general. Based on these articles, information on five categories (temporal relationship, previous knowledge about the relationship between drug action and ADRs, alternative aetiological candidate, appropriateness of drug use, and the relationship between death and ADRs) was determined for causality assessment between a suspected drug and fatal cerebral haemorrhage; a new algorithm was created using this information. CONCLUSION: In this study, the information considered necessary for causality assessment between drugs and fatal cerebral haemorrhage was reviewed and an assessment algorithm was developed. Future studies are needed to validate the usefulness of this method.

Does arteriosclerosis contribute to hemifacial spasm?

BACKGROUND: Hemifacial spasm (HFS) is caused by pulsative vascular compression of the root exit zone (REZ) of the facial nerve. However, the mechanism that causes the offending vessels to compress the REZ has not been clarified. Elongation of intracranial arteries due to arteriosclerosis is one possibility, but such arteriosclerotic changes are not observed very frequently among patients with HFS. The aim of the present study was to investigate whether arteriosclerotic changes would contribute to the pathogenesis of HFS. METHODS: This study included 111 HFS patients, all of whom were Japanese. The prevalence rates of hypertension, hyperlipidemia, and diabetes mellitus were examined as risk factors of atherosclerosis, and the cardio-ankle vascular index (CAVI) was measured as an indicator of arteriosclerotic change. The severity of white matter lesions (WMLs) in HFS patients was measured by magnetic resonance imaging. These data were compared with data from healthy Japanese controls. RESULTS: The prevalence rates of the risk factors for atherosclerosis in the HFS patients were not higher than those in the general Japanese population. The CAVI scores for the HFS patients were similar to, or lower than those in the healthy controls for all age groups except 60 to 69-year-old men. The severity of WMLs in the HFS patients was not significantly worse than that in the controls. CONCLUSIONS: It is suggested that arteriosclerotic changes are not involved in the pathogenesis of HFS, and that vascular compression syndromes are attributable to anatomical features of the intracranial arteries and facial nerves formed during the prenatal stage.

Preoperative assessment of hemifacial spasm by the coronal heavily T2-weighted MR cisternography.

BACKGROUND: Microvascular decompression (MVD) has become a well-established surgical procedure for hemifacial spasm (HFS). Before surgery, it is essential to evaluate any possible deformity of the brainstem and establish the precise location of the offending vessels. In the present study of HFS patients we examined coronal sections taken by heavily T2-weighted MR cisternography in addition to routine axial sections, and assessed the usefulness of these images through comparison with intraoperative findings. METHODS: Eighty patients with HFS underwent preoperative coronal heavily T2-weighted MR cisternography before microvascular decompression surgery. Three neurosurgeons examined the preoperative axial and coronal MR images and evaluated vessel invagination into the brainstem. The usefulness of coronal sections was assessed statistically by the Mann-Whitney U test. RESULTS: Invagination of the offending vessel into the brainstem was observed in 24 cases (30.0%). In 19 patients, it was predicted preoperatively that compression of the flocculus and brainstem would be required in order to approach the offending vessels. Coronal MR cisternography was significantly more useful in cases with vessel invagination into the brainstem than in cases without invagination. CONCLUSIONS: Coronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.

Causality Assessment Between Drugs and Fatal Cerebral Haemorrhage Using Electronic Medical Records: Comparative Evaluation of Disease-Specific and Conventional Methods.

INTRODUCTION: A new algorithm for causality assessment of drugs and fatal cerebral haemorrhage (ACAD-FCH) was published in 2021. However, its use in clinical practice has not been verified. OBJECTIVES: This study aimed to explore the practical value of the ACAD-FCH when applying information available in clinical practice. METHODS: The medical records of patients who died at the University of Tokyo Hospital in 2020 were reviewed, and cases with intracranial haemorrhage were selected. Two evaluators independently assessed these cases using three methods (the ACAD-FCH, Naranjo algorithm, and WHO-UMC scale). The number of 'Yes', 'No', and 'No information/Do not know' responses to each question by both evaluators were summed and compared. Inter-rater reliability was evaluated for each method using agreement rates and kappa coefficients with 95% confidence intervals (CI). RESULTS: Among 316 deaths, 24 cases with intracranial haemorrhage were evaluated. The proportion of ?No information/Do not know' responses for each question was 35.6% (95% CI 31.4-40.6%) for the ACAD-FCH and 66.9% (95% CI 62.5-71.1%) for the Naranjo algorithm. The respective agreement rates and kappa coefficients were 0.917 (0.798-1.00) and 0.867 (0.675-1.00) for the ACAD-FCH, 0.708 (0.512-0.904) and 0.139 (-0.236 to 0.513) for the Naranjo algorithm, and 0.50 (0.284-0.716) and 0.326 (0.110-0.541) for the WHO-UMC scale, respectively. CONCLUSION: Our findings suggest the utility of the ACAD-FCH when assessing death cases with intracranial haemorrhage. However, larger studies including intra-rater assessments are warranted for further validation of this algorithm.

Identification of a suppressive mechanism for Hedgehog signaling through a novel interaction of Gli with 14-3-3.

Gli transcription factors are central effectors of Hedgehog signaling in development and tumorigenesis. Using a tandem affinity purification (TAP) strategy and mass spectrometry, we have found that Gli1 interacts with 14-3-3epsilon, and that Gli2 and Gli3 also bind to 14-3-3epsilon through homologous sites. This interaction depends on their phosphorylation, and cAMP-dependent protein kinase (PKA), a known negative regulator of Hedgehog signaling serves as a responsible kinase. A Gli2 mutant engineered to eliminate this interaction exhibited increased transcriptional activity (2 approximately 3x). Transcriptional repression by 14-3-3 binding was also observed with Gli3, when its N-terminal repressor domain was deleted. The phosphorylation sites responsible for the binding to 14-3-3 are distinct from those required for proteolysis, the known mechanism for PKA-induced repression of Hh signaling. Our data propose a novel mechanism in which PKA down-regulates Hedgehog signaling by promoting the interaction between Gli and 14-3-3 as well as proteolysis. Given the certain neuronal or malignant disorders in human caused by the abnormality of 17p13 encompassing 14-3-3epsilon overlap with increased Hh signaling, the Gli-14-3-3 interaction may have pathological significance for those human diseases.

Reduced expression of RAS protein activator like-1 in gastric cancer.

RAS signaling is frequently deregulated in human neoplasms. However, RAS mutations have been found in only a small proportion of human gastric cancers, implicating other mechanisms in the activation of RAS signaling in gastric tumorigenesis. We have previously reported that decreased expression of RAS protein activator like-1 (RASAL1), a member of the RAS-GTPase-activating proteins that switch off RAS activity, contributes to colon tumor progression. In our study, we explored the involvement of decreased RASAL1 expression in gastric tumorigenesis. RASAL1 expression was reduced in 6 of 10 gastric cancer cell lines examined by immunoblotting. Knockdown of RASAL1 increased mitogen-activated protein kinase signaling in response to growth factor stimulation, and the forced expression of RASAL1 reduced proliferation of gastric cancer cells. Immunohistochemical analyses in primary gastric tumors showed that RASAL1 expression was reduced in 23 of 48 (48%) of the gastric cancers but in none of the adenomas (0/10). Methylation of the RASAL1 promoter region and loss of heterozygosity (LOH) at the RASAL1 locus were examined to investigate the causes of RASAL1 silencing. All cell lines with reduced RASAL1 had RASAL1 methylation, and two had LOH. In primary gastric cancers, methylation or LOH was detected in 50% (6/12) of those with reduced RASAL1. Furthermore, RASAL1 expression was restored in some cell lines by histone deacetylase inhibitor treatment. Our findings demonstrate that reduced RASAL1 expression, partly due to genetic and epigenetic changes, contributes to gastric carcinogenesis, and also re-emphasize the importance of RAS signaling in gastric cancer development.

Altered composition of fatty acids exacerbates hepatotumorigenesis during activation of the phosphatidylinositol 3-kinase pathway.

BACKGROUND & AIMS: Some clinical findings have suggested that systemic metabolic disorders accelerate in vivo tumor progression. Deregulation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway is implicated in both metabolic dysfunction and carcinogenesis in humans; however, it remains unknown whether the altered metabolic status caused by abnormal activation of the pathway is linked to the protumorigenic effect. METHODS: We established hepatocyte-specific Pik3ca transgenic (Tg) mice harboring N1068fs*4 mutation. RESULTS: The Tg mice exhibited hepatic steatosis and tumor development. PPARγ-dependent lipogenesis was accelerated in the Tg liver, and the abnormal profile of accumulated fatty acid (FA) composition was observed in the tumors of Tg livers. In addition, the Akt/mTOR pathway was highly activated in the tumors, and in turn, the expression of tumor suppressor genes including Pten, Xpo4, and Dlc1 decreased. Interestingly, we found that the suppression of those genes and the enhanced in vitro colony formation were induced in the immortalized hepatocytes by the treatment with oleic acid (OA), which is one of the FAs that accumulated in tumors. CONCLUSIONS: Our data suggest that the unusual FA accumulation has a possible role in promoting in vivo hepato-tumorigenesis under constitutive activation of the PI3K pathway. The Pik3ca Tg mice might help to elucidate molecular mechanisms by which metabolic dysfunction contributes to in vivo tumor progression.

Surveillance of small intestinal abnormalities in patients with hepatocellular carcinoma: a prospective capsule endoscopy study.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) sometimes suffer from obscure gastrointestinal bleeding. Portal hypertension (PH), common in cirrhosis, induces esophagogastric varices. Because of the location, PH also may influence mucosal abnormalities in the small intestine. The objective of this study is to estimate the prevalence of small intestinal mucosal abnormalities in HCC patients using capsule endoscopy (CE). PATIENTS AND METHODS: We prospectively conducted CE in HCC patients, and analyzed the findings in relation to hepatic function, the number and size of HCC tumor and findings obtained by conventional endoscopy. RESULTS: Thirty-six patients (aged 66.7 ± 7.5 years, 29 men) underwent CE. Abnormal findings in the small bowel were found in 16 patients (44%), angioectasias in eight patients (22%), erosions in five (14%), varices in four (11%), polyps in four (11%), and submucosal tumor in one (3%). The patients with angioectasia had a larger spleen index than the no abnormal lesions group (85.4 ± 15.8 vs 59.0 ± 24.4, P = 0.02). The former group had been more frequently treated for esophageal varices endoscopically (62% vs 15%, P = 0.02). Large HCC nodules seemed more common in the patients with angioectasia than subjects without abnormal lesions (38% vs 5%, P = 0.06). Small intestinal varices also seemed to have a positive association with large HCC. During the follow up after CE, one patient with small intestinal polyps suffered from obscure gastrointestinal bleeding. CONCLUSIONS: CE revealed that HCC patients frequently have small intestinal mucosal lesions. In particular, small intestinal angioectasia, which may cause obscure gastrointestinal bleeding, seems to be associated with portal hypertension.

Macroscopic morphologic subtypes of laterally spreading colorectal tumors showing distinct molecular alterations.

Recent advances in colonoscopic techniques have resulted in more frequent detection of superficial-type colorectal tumors, that is, laterally spreading tumors (LSTs), although little is known about the characteristic clinical features and genetic alterations of LSTs. To elucidate the molecular characteristics of LSTs, genetic alterations in the KRAS, BRAF and PIK3CA genes and abnormal expression of the p53, beta-catenin and MYC proteins were analyzed using direct DNA sequencing and immunohistochemistry for 50 protruded-type tumors (Protruded), 35 granular-type LSTs (LST-G) and 19 nongranular-type LSTs (LST-NG). In addition, loss of heterozygosity (LOH) close to the adenomatous polyposis coli (APC) gene (5q21) was examined in these tumors. In univariate analyses, significant differences were noted in the percentages with KRAS mutations (Protruded, LST-G, LST-NG = 30.0%, 54.3%, 21.1%, respectively, p = 0.0156), nuclear accumulation of beta-catenin (Protruded, LST-G, LST-NG = 50.0%, 37.1%, 68.4%, respectively, p = 0.0267), expression of MYC (Protruded, LST-G, LST-NG = 26.0%, 17.1%, 42.1%, respectively, p = 0.0456) and LOH at the APC gene locus (Protruded, LST-G, LST-NG = 22.0%, 20.0%, 47.4%, respectively, p = 0.0302). Multivariate analysis demonstrated that the macroscopic subtype of LST was significantly associated with KRAS mutation (for LST-NG: odds ratio [OR] 0.23, 95% CI 0.06-0.90) and nuclear accumulation of beta-catenin (for LST-NG: OR 4.05, 95% CI 1.11-14.8). Our data revealed that the 2 subtypes of LST have different molecular characteristics, suggesting that 2 or more different molecular mechanisms result in colorectal tumors with a similar growth pattern.

Prognostic significance of genetic alterations detected by high-density single nucleotide polymorphism array in gastric cancer.

We sought to identify genomic changes that could be useful for clinical application, focusing on chromosomal instability and using a high-density single nucleotide polymorphism (SNP) array. We analyzed 34 gastric cancer cell lines for areas of DNA that exhibited copy number changes using the Affymetrix GeneChip Human Mapping 50 K Arrays. The results obtained with the cell lines were verified in 42 gastric cancer tissues using genomic PCR, quantitative real-time PCR, and loss of heterozygosity (LOH) analyses. Twenty-six local homozygous deletion regions, including 13 novel loci, and 31 recurrent high-grade gain regions, encompassing 14 novel loci, were found in the gastric cancer cell lines. Among the genes detected for high-grade gain in the cell lines, MYC, PAK1, and ITGB4BP showed copy number gain in more than 40% of gastric cancer tissues. LOH of AB051467, PTPRD, A2BP1, and C20orf133 was detected in more than 35% of gastric cancer tissues. The number of LOH was significantly greater in tumors with lymph node metastasis. In the early stage, the prognosis of patients with LOH of less than two genes was significantly better than that of those with LOH of two genes or more. Using high-density SNP arrays, we identified several novel and minute genomic alterations. LOH of four genes could be useful for prediction of lymph node metastasis and prognosis in early stage gastric cancers.

Decreased expression of the RAS-GTPase activating protein RASAL1 is associated with colorectal tumor progression.

BACKGROUND & AIMS: Although colorectal cancer (CRC) progression has been associated with alterations in KRAS and RAS signaling, not all CRC cells have KRAS gene mutations. RAS activity is modulated by RAS-GTPase-activating proteins (RASGAPs), so we investigated the role of RASGAPs in CRC progression. METHODS: The level of RASGAP expression in CRC cells was analyzed using quantitative real-time polymerase chain reaction. The expression of the RAS protein activator like-1 (RASAL1) was examined in clinical colorectal neoplasms using immunohistochemistry. The clinicopathologic (age, sex, and tumor site and grade) and molecular (KRAS gene mutation, as well as CTNNB1 and TP53 expression patterns) factors that could affect RASAL1 expression were examined. RESULTS: Of 12 RASGAPs examined, expression levels of only RASAL1 decreased in CRC cells; RASAL1 expression decreased in most CRC cells with wild-type KRAS gene but rarely in those with mutant KRAS gene. A transfection assay showed that RASAL1 repressed RAS/mitogen-activated protein kinase signaling in response to growth factor stimulation and reduced proliferation of CRC cells that contained wild-type KRAS gene. RASAL1 expression was detected in 46.9% (30/64) of adenocarcinoma, 17.4% (8/46) of large adenoma, and no (0/42) small adenoma samples. RASAL1 expression levels were correlated with the presence of wild-type KRAS gene in CRC tumor samples (P= .0010), distal location (P= .0066), and abnormal expression of TP53 (P= .0208). CONCLUSIONS: RASAL1 expression is reduced in CRC cells that contain wild-type KRAS gene. Reductions in RASAL1 expression were detected more frequently in advanced lesions than in small adenomas, suggesting that RASAL1 functions in the progression of benign colonic neoplasms.

Regulation of the hedgehog signaling by the mitogen-activated protein kinase cascade in gastric cancer.

The hedgehog and mitogen-activated protein kinase (MAPK) signaling pathways regulate growth in many tumors, suggesting cooperation between these two pathways in the regulation of cell proliferation. However, interactions between these pathways have not been extensively studied. We assessed cross-talk between hedgehog and MAPK signaling in the regulation of cell proliferation in gastric cancer. We showed that PTCH expression was significantly correlated with extracellular signal-regulated kinase (ERK) 1/2 phosphorylation (P = 0.016) as well as SHH expression (P = 0.034) in the 35 gastric cancers assessed by immunohistochemistry. Indeed, MAPK signaling increased the GLI transcriptional activity and induced the expression of hedgehog target genes in gastric cancer cells. The inductive effect of activated KRAS and mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) 1 was blocked by the suppressor of fused (SUFU), indicating that MAPK signaling regulates GLI activity via a SUFU-independent process. Moreover, the deletion of the NH2-terminal domain of GLI1 gene resulted in reduced response to MEK1 stimulation. Our results suggest that the KRAS-MEK-ERK cascade has a positive regulatory role in GLI transcriptional activity in gastric cancer.

Down-regulation of hedgehog-interacting protein through genetic and epigenetic alterations in human hepatocellular carcinoma.

PURPOSE: Hedgehog (Hh) signaling is activated in several cancers. However, the mechanisms of Hh signaling activation in hepatocellular carcinoma (HCC) have not been fully elucidated. We analyzed the involvement of Hh-interacting protein (HHIP) gene, a negative regulator of Hh signaling, in HCC. EXPERIMENTAL DESIGN: Glioma-associated oncogene homologue (Gli) reporter assay, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, and quantitative real-time reverse transcription-PCR for the target genes of the Hh signals were performed in HHIP stably expressing hepatoma cells. Quantitative real-time PCR for HHIP was performed in hepatoma cells and 36 HCC tissues. The methylation status of hepatoma cells and HCC tissues was also analyzed by sodium bisulfite sequencing, demethylation assay, and quantitative real-time methylation-specific PCR. Loss of heterozygosity (LOH) analysis was also performed in HCC tissues. RESULTS: HHIP overexpression induced significant reductions of Gli reporter activity, cell viability, and transcription of the target genes of the Hh signals. HHIP was hypermethylated and transcriptionally down-regulated in a subset of hepatoma cells. Treatment with a demethylating agent led to the HHIP DNA demethylation and restoration of HHIP transcription. HHIP transcription was also down-regulated in the majority of HCC tissues, and more than half of HCC tissues exhibited HHIP hypermethylation. The HHIP transcription level in HHIP-methylated HCC tissues was significantly lower than in HHIP-unmethylated HCC tissues. More than 30% of HCC tissues showed LOH at the HHIP locus. CONCLUSIONS: The down-regulation of HHIP transcription is due to DNA hypermethylation and/or LOH, and Hh signal activation through the inactivation of HHIP may be implicated in the pathogenesis of human HCC.

Integrated analysis of copy number alterations and loss of heterozygosity in human pancreatic cancer using a high-resolution, single nucleotide polymorphism array.

OBJECTIVE: To chart molecular genetic events in pancreatic cancer. METHODS: We analyzed genome-wide copy number alterations and loss of heterozygosity (LOH) in 25 established pancreatic cancer cell lines using a high-density single nucleotide polymorphism (SNP) array. We verified the data using genomic PCR and applied them to clinical samples. RESULTS: Twenty-six homozygous deletion regions were detected in at least 1 cell line and LOH was found at 9p, 18q, 17p, 8p, 13q, 6q, 3p, 6p, 22q, 9q and 12q with high frequency (>50%), consistent with a previous study. Moreover, we found 23 amplified regions in at least 2 cell lines, including 8 unreported loci. We then examined representative genes at the 8 amplified loci in matched pairs of pancreatic cancer and normal tissues. The amplification was detected in 1 (7.1%) to 5 (35.7%) of 14 microdissected tissue specimens. CONCLUSION: Using high-resolution SNP arrays, we studied genome-wide copy number alterations and LOH simultaneously. We identified several novel and minute genomic amplifications, which contained candidate oncogenes in human pancreatic cancers.

Rapid detection of the hepatitis B virus YMDD mutant using TaqMan-minor groove binder probes.

BACKGROUND: TaqMan-minor groove binder (MGB) probes were used in a real-time PCR-based assay for the rapid and accurate detection of hepatitis B virus (HBV) YMDD mutants. METHODS: TaqMan-MGB probes were designed to distinguish between wild-type (YMDD) and mutant (YVDD and YIDD) strains of HBV. The detection limit and sensitivity of the assay were determined using a dilution series of a mixture of wild-type and mutant plasmids. Serum samples collected from four patients with chronic mutant HBV infections during lamivudine therapy were analyzed using this method. RESULTS: The detection limit for YVDD and YIDD was 10 and 50 copies, respectively, whereas the sensitivity was 10% within a mixed virus population. In the clinical samples, mutant strains of HBV could be detected at levels <2.6 log copies/ml of HBV DNA. While 15 of the 21 samples tested by this method were positive for the YMDD mutant, direct sequencing and a reverse hybridization line probe assay (INNO-LiPA HBV DR v2) detected the mutant strain in only 11 and 9 samples, respectively. Moreover, the data for 6 samples analyzed by TA cloning were fully consistent with our TaqMan PCR results. CONCLUSIONS: We successfully established a sensitive and accurate assay for the YMDD mutant of HBV. This method may be useful for monitoring patients treated with lamivudine.

Dysregulated expression of stem cell factor Bmi1 in precancerous lesions of the gastrointestinal tract.

PURPOSE: It is important to identify the definitive molecular switches involved in the malignant transformation of premalignant tissues. Cellular senescence is a specific characteristic of precancerous tissues, but not of cancers, which might reflect tumorigenesis-protecting mechanisms in premalignant lesions. Polycomb protein Bmi1, which is a potent negative regulator of the p16INK4 gene, suppresses senescence in primary cells and is overexpressed in various cancers. We hypothesized that Bmi1 expression would also be dysregulated in precancerous lesions in human digestive precancerous tissues. EXPERIMENTAL DESIGN: Bmi1 expression was investigated in cancerous and precancerous tissues of the digestive tract. The expression of p16, beta-catenin, and Gli1 and the in vivo methylation status of the p16 gene were also analyzed in serial sections of colonic precancerous lesions. RESULTS: Bmi1 was clearly overexpressed across a broad spectrum of gastrointestinal cancers, and the expression of Bmi1 increased in a manner that reflected the pathologic malignant features of precancerous colonic tissues (low-grade dysplasia, 12.9 +/- 2.0%; high-grade dysplasia, 82.9 +/- 1.6%; cancer, 87.5 +/- 2.4%). p16 was also strongly expressed in high-grade dysplasia, but not in cancers. p16 promoter methylation was detected only in some Bmi1-positive neoplastic cells. CONCLUSIONS: Bmi1 overexpression was correlated with the malignant grades of human digestive precancerous tissues, which suggests that advanced Bmi1 dysregulation might predict malignant progression. The abnormal Bmi1 expression might link to malignant transformation via the disturbance of orderly histone modification.

Single small-interfering RNA expression vector for silencing multiple transforming growth factor-beta pathway components.

Although RNA interference (RNAi) is a popular technique, no method for simultaneous silencing of multiple targets by small-hairpin RNA (shRNA)-expressing RNAi vectors has yet been established. Although gene silencing can be achieved by synthetic small-interfering RNA (siRNA) duplexes, the approach is transient and largely dependent on the transfection efficiency of the host cell. We offer a solution: a simple, restriction enzyme-generated stable RNAi technique that can efficiently silence multiple targets with a single RNAi vector and a single selection marker. In this study, we succeeded in simultaneous stable knockdown of transforming growth factor beta (TGF-beta) pathway-related Smads--Smad2, Smad3 and Smad4--at the cellular level. We observed distinct phenotypic changes in TGF-beta-dependent cellular functions such as invasion, wound healing and apoptosis. This method is best suited for an analysis of complex signal transduction pathways in which silencing of a single gene cannot account for the whole process.

Functional analysis of PIK3CA gene mutations in human colorectal cancer.

Mutations in the PIK3CA gene, which encodes the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), have been reported in human cancers, including colorectal cancer. Most of the mutations cluster at hotspots within the helical and kinase domains. Whereas H1047R, one of the hotspot mutants, is reported to have elevated lipid kinase activity, the functional consequences of other mutations have not been examined. In this study, we examined the effects of colon cancer-associated PIK3CA mutations on the lipid kinase activity in vitro, activation of the downstream targets Akt and p70S6K in vivo and NIH 3T3-transforming ability. Of eight mutations examined, all showed increased lipid kinase activity compared with wild-type p110alpha. All the mutants strongly activated Akt and p70S6K compared with wild-type p110alpha as determined by immunoblotting using phospho-specific antibodies. These mutants also induced morphologic changes, loss of contact inhibition, and anchorage-independent growth of NIH 3T3 cells. The hotspot mutations examined in this study, E542K, E545K, and H1047R, all had high enzymatic and transforming activities. These results show that almost all the colon cancer-associated PIK3CA mutations are functionally active so that they are likely to be involved in carcinogenesis.

Blockade of the stromal cell-derived factor-1/CXCR4 axis attenuates in vivo tumor growth by inhibiting angiogenesis in a vascular endothelial growth factor-independent manner.

The interaction between the chemokine receptor CXCR4 and its specific ligand, stromal cell-derived factor-1 (SDF-1/CXCL12), mediates several cellular functions. In cancer, SDF-1-positive or CXCR4-positive cells of various lineages are detected within tumor tissues. Recent intensive research has indicated the possibility that blocking CXCR4 could reduce the metastatic potential of cancer cells. Here, we show that the inhibition of the SDF-1/CXCR4 axis decreases the growth of s.c. gastrointestinal tumors through the suppression of tumor neoangiogenesis. The neutralization of CXCR4 suppressed the growth in vivo of tumors derived from mouse Colon38 and PancO2 cells, whereas it did not affect the growth of Colon38 and PancO2 cells in vitro. This attenuation of tumor growth was found to be independent of the expression of CXCR4 by the cancer cells themselves, because CXCR4 knocked-down Colon38 cells grew similarly to control cells. Furthermore, CD31-positive tumor capillaries were reduced to 45% (P < 0.001) and intratumor blood flows were decreased to 65% (P < 0.01) by blockade of CXCR4. The vascular endothelial growth factor (VEGF) concentration in the tumors was not affected by the neutralization of CXCR4. Taken together with the detection of CXCR4-positive endothelial cells in the tumor tissues, the findings suggest that the antiangiogenic effects of the blockade of CXCR4 are related to a reduction of the establishment of tumor endothelium independently of VEGF inhibition. Our data indicate that the SDF-1/CXCR4 pathway might be a general target for anticancer strategies and that blocking this system could be cooperatively effective in combination with other antiangiogenic therapies, such as blockade of VEGF.

p53-Independent negative regulation of p21/cyclin-dependent kinase-interacting protein 1 by the sonic hedgehog-glioma-associated oncogene 1 pathway in gastric carcinoma cells.

The activation of Hedgehog (Hh) signaling has been implicated in the growth of various tumor types, including gastric carcinoma. However, the precise mechanisms of Hh activation and suppression of tumor growth by the blockade of Hh signaling in gastric carcinoma cells remain unknown. The aim of this study was to elucidate the mechanism of abnormal Hh signaling and the key molecules contributing to dysregulated growth of gastric carcinoma. The Sonic hedgehog (Shh) ligand and its receptor Patched were expressed in all five gastric carcinoma cell lines examined (MKN1, MKN7, MKN45, MKN74, and AGS cells). The blockade of Hh signaling with anti-Shh antibody inhibited the growth of all five gastric carcinoma cell lines. Shh was overexpressed (mean, 12.8-fold) in 8 of 14 (57.0%) cancerous tissue samples from patients with gastric carcinoma as compared with expression in the surrounding noncancerous tissues. The disruption of glioma-associated oncogene 1 (Gli1) by small interfering RNA induced an increase in p21/cyclin-dependent kinase-interacting protein 1 (CIP1), interfered with the G1-S transition, and suppressed cell proliferation. The stimulation or inhibition of Hh signaling did not affect p53 activity and the induction of p21/CIP1 expression and the G1 arrest by inhibition of Hh signaling were not affected by the p53 status. These findings suggest that the overexpression of Shh contributes to constitutive Hh activation and that this signaling pathway negatively regulates p21/CIP1 through a Gli1-dependent and p53-independent mechanism in gastric carcinoma cells.