Hydrosilylation reaction of olefins: recent advances and perspectives

This review focuses on the recent development of efficient, selective, and cheaper hydrosilylation catalyst systems appearing in the last decade.

Epigenetic silencing of microRNA-373 to epithelial-mesenchymal transition in non-small cell lung cancer through IRAK2 and LAMP1 axes

The role of microRNAs (miRNAs) in carcinogenesis as tumor suppressors or oncogenes has been widely reported. Epigenetic change is one of the mechanisms of transcriptional silencing of miRNAs in cancer. To identify lung cancer-related miRNAs that are mediated by histone modification, we conducted microarray analysis in the Calu-6 non-small cell lung cancer (NSCLC) cell line after treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor. The expression level of miR-373 was enhanced by SAHA treatment in this cell line by microarray and the following quantitative RT-PCR analyses. Treatment with another HDAC inhibitor, Trichostatin A, restored the levels of miR-373 expression in A549 and Calu-6 cells, while demethylation drug treatment did not. Importantly, miR-373 was found to be down-regulated in NSCLC tissues and cell lines. Transfection of miR-373 into A549 and Calu-6 cells attenuated cell proliferation, migration, and invasion and reduced the expression of mesenchymal markers. Additional microarray analysis of miR-373-transfected cells and computational predictions identified IRAK2 and LAMP1 as targets of miR-373. Knockdown of these two genes showed similar biological effects to those of miR-373 overexpression. In clinical samples, overexpression of IRAK2 correlated with decreased disease-free survival of patients with non-adenocarcinoma. In conclusion, we found that miR-373 is silenced by histone modification in lung cancer cells and identified its function as a tumor suppressor and negative regulator of the mesenchymal phenotype through downstream IRAK2 and LAMP1 target genes.

CD49f(high) cells retain sphere-forming and tumor-initiating activities in human gastric tumors

Identification of gastric tumor-initiating cells (TICs) is essential to explore new therapies for gastric cancer patients. There are reports that gastric TICs can be identified using the cell surface marker CD44 and that they form floating spheres in culture, but we could not obtain consistent results with our patient-derived tumor xenograft (PDTX) cells. We thus searched for another marker for gastric TICs, and found that CD49f(high) cells from newly-dissected gastric cancers formed tumors with histological features of parental ones while CD49f(low) cells did not when subcutaneously injected into immunodeficient mice. These results indicate that CD49f, a subunit of laminin receptors, is a promising marker for human gastric TICs. We established a primary culture system for PDTX cells where only CD49f(high) cells could grow on extracellular matrix (ECM) to form ECM-attaching spheres. When injected into immunodeficient mice, these CD49f(high) sphere cells formed tumors with histological features of parental ones, indicating that only TICs could grow in the culture system. Using this system, we found that some sphere-forming TICs were more resistant than gastric tumor cell lines to chemotherapeutic agents, including doxorubicin, 5-fluorouracil and doxifluridine. There was a patient-dependent difference in the tumorigenicity of sphere-forming TICs and their response to anti-tumor drugs. These results suggest that ECM plays an essential role for the growth of TICs, and that this culture system will be useful to find new drugs targeting gastric TICs.

Circulating microRNAs as biomarkers for early detection of diffuse-type gastric cancer using a mouse model

Background:

Diffuse-type gastric cancer (DGC) exhibits rapid disease progression and a poor prognosis. There are no effective serum biomarkers for early detection of DGC. We have established an E-cadherin/p53 double conditional knockout (DCKO) mouse line that recapitulates human DGC morphologically and molecularly. In this study we tried to identify circulating microRNAs (miRNAs) as non-invasive biomarkers for DGC diagnosis using DCKO mice.

Methods:

We performed miRNA microarray and quantitative reverse transcription–PCR analyses of tissue and serum samples from DCKO mice with DGC and age-matched littermate controls.

Results:

Comparative analyses showed that mouse and human primary gastric cancers have similar miRNA expression patterns. Next, we selected some candidate miRNAs highly expressed in sera and cancer tissues of DCKO mice for further evaluation. TaqMan quantitative RT–PCR analyses indicated that four of them, miR-103, miR-107, miR-194 and miR-210, were significantly upregulated in sera of both early and advanced-stage DGC-bearing mice compared with in corresponding controls. Receiver-operating characteristic curve analyses demonstrated that these four miRNAs can discriminate DGC-positive cases from normal ones with high sensitivity and specificity.

Conclusion:

These observations suggest that this mouse model of DGC is useful for identifying serum biomarkers, and we found circulating miRNAs that can accurately detect DGC at an early stage.

Synergistic tumour suppressor activity of E-cadherin and p53 in a conditional mouse model for metastatic diffuse-type gastric cancer

BACKGROUND

Gastric cancer is the second most frequent cause of death from cancer in the world, diffuse-type gastric cancer (DGC) exhibiting a poor prognosis. Germline mutations of CDH1, encoding E-cadherin, have been reported in hereditary DGC, and genetic and/or epigenetic alterations of CDH1 are frequently detected in sporadic DGC. Genetic alterations of TP53 are also frequently found in DGC. To examine the synergistic effect of the loss of E-cadherin and p53 on gastric carcinogenesis, a mouse line was established in which E-cadherin and p53 are specifically inactivated in the stomach parietal cell lineage.

METHODS

Atp4b-Cre mice were crossed with Cdh1(loxP/loxP) and Trp53(loxP/loxP) mice, and the gastric phenotype of Atp4b-Cre(+);Cdh1(loxP/loxP);Trp53(loxP/loxP) double conditional knockout (DCKO) mice was examined.

RESULTS

Non-polarised E-cadherin-negative parietal cells and proton pump-negative atypical foci were observed in DCKO mice. Intramucosal cancers and invasive cancers composed of poorly differentiated carcinoma cells and signet ring cells, histologically very similar to those in humans, were found from 6 to 9 months, respectively. Fatal DGC developed at 100% penetrance within a year, frequently metastasised to lymph nodes, and had tumourigenic activity in immunodeficient mice. Gene expression profiles of DGC in DCKO mice also resembled those of human DGC, and mesenchymal markers and epithelial-mesenchymal transition-related genes were highly expressed in mouse DGC as in human DGC.

CONCLUSION

This mouse line is the first genetically engineered mouse model of DGC and is very useful for clarifying the mechanism underlying gastric carcinogenesis, and provides a new approach to the treatment and prevention of DGC.

Mutation analysis of BRAF and KIT in circulating melanoma cells at the single cell level

Background:

The availability of molecular-targeted therapies for the treatment of melanoma has emphasised the need to identify mutations in target genes such as BRAF and KIT. Circulating tumour cells (CTC) are present in the peripheral blood of a significant proportion of cancer patients.

Methods:

High molecular weight melanoma-associated antigen (HMW-MAA) was used to isolate melanoma cells from peripheral blood as it is selectively expressed at high levels on melanomas. The HMW-MAA-positive cells were isolated using immunomagnetic beads. After removing CD45⁺ cells, CTC were identified by staining with MART-1- and gp100-specific antibodies (HMW-MAA⁺, CD45⁻, MART-1/gp100⁺). Single, isolated CTC were then subjected to BRAF and KIT mutational analysis.

Results:

CTC (HMW-MAA⁺, CD45⁻, MART-1/gp100⁺) were isolated from the blood of 11 patients and BRAF and KIT were sequenced in nine and four patients, respectively. The BRAF sequences identified in the CTC were inconsistent with those identified in autologous melanoma tumours in three patients and the KIT sequences were inconsistent in three patients. In addition, polyclonal BRAF mutations were identified in one patient and concomitant mutations in BRAF and KIT were identified in another patient.

Conclusion:

Melanoma cells show clonal heterogeneity. Therefore, CTC genotyping may be crucial for successful molecular-targeted therapy.

Acid inhibits TRPV4-mediated Ca²⁺ influx in mouse esophageal epithelial cells

BACKGROUND

The transient receptor potential vanilloid 4 (TRPV4), a thermo-sensitive stretch-activated cation channel, is expressed in the skin stratified squamous epithelium, contributing to the acquisition of barrier function. Similarly, functional TRPV4 may be located in the stratified squamous epithelial lining of the esophagus, being involved in the pathogenesis of gastroesophageal reflux disease (GERD). Here we investigated the expression of TRPV4 in the mouse esophageal epithelium.

METHODS

TRPV4 expression at the mRNA and protein levels was examined by reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemistry. A calcium imaging technique and ATP assay were used to evaluate the functionality of TRPV4 in freshly isolated esophageal epithelial cells.

KEY RESULTS

Transcripts and proteins encoding TRPV4 were colocalized in the basal and intermediate layers of the esophageal epithelium. Both 4α-phorbol 12,13- didecanoate (4α-PDD), a selective agonist for TRPV4, and hypo-osmolar solution (160 mOsm) elevated the intracellular calcium concentration ([Ca(2+) ](i) ) in a subset of the isolated cells (70%). These [Ca(2+) ](i) increases were potently inhibited by ruthenium red (RuR), a TRPV4 channel antagonist, and were suppressed by extracellular protons (pH 5.0). Finally, application of 4α-PDD evoked ATP release in primary esophageal epithelial cells.

CONCLUSIONS & INFERENCES

Acid-sensitive TRPV4 channels were mainly expressed in the esophageal epithelial cells of the basal and intermediate layers. Direct exposure of TRPV4-expressing cells to gastric acid, as would occur in cases of GERD, could influence their cellular functions, possibly aggravating the disease state.

CD133 is a marker of gland-forming cells in gastric tumors and Sox17 is involved in its regulation

CD133 is a universal marker of tissue stem/progenitor cells as well as cancer stem cells, but its physiological significance remains to be elucidated. Here we examined the relationship between expression of CD133 and features of gastric epithelial cells, and found that CD133-positive (CD133[+]) tumor cell lines formed well-differentiated tumors while CD133-negative (CD133[-]) lines formed poorly differentiated ones when subcutaneously injected into nude mice. We also found that CD133(+) and CD133(-) cell populations co-existed in some cell lines. FACS analysis showed that CD133(+) cells were mother cells because CD133(+) cells formed both CD133(+) and CD133(-) cells, but CD133(-) cells did not form CD133(+) cells. In these cell lines, CD133(+) cells formed well-differentiated tumors while CD133(-) cells formed poorly differentiated ones. In human gastric cancers, CD133 was exclusively expressed on the luminal surface membrane of gland-forming cells, and it was never found on poorly differentiated diffuse-type cells. Considering that poorly differentiated tumors often develop from well-differentiated tumors during tumor progression, these results suggest that loss of expression of CD133 might be related to gastric tumor progression. Microarray analysis showed that CD133(+) cells specifically expressed Sox17, a tumor suppressor in gastric carcinogenesis. Forced expression of SOX17 induced expression of CD133 in CD133(-) cells, and reduction of SOX17 caused by siRNA in CD133(+) cells induced a reduction in the level of CD133. These results indicate that Sox17 might be a key transcription factor controlling CD133 expression, and that it might also play a role in the control of gastric tumor progression.

MicroRNA-126 inhibits SOX2 expression and contributes to gastric carcinogenesis

Background

SRY (sex-determining region Y)-box 2 (SOX2) is a crucial transcription factor for the maintenance of embryonic stem cell pluripotency and the determination of cell fate. Previously, we demonstrated that SOX2 plays important roles in growth inhibition through cell cycle arrest and apoptosis, and that SOX2 expression is frequently down-regulated in gastric cancers. However, the mechanisms underlying loss of SOX2 expression and its target genes involved in gastric carcinogenesis remain largely unknown. Here, we assessed whether microRNAs (miRNAs) regulate SOX2 expression in gastric cancers. Furthermore, we attempted to find downstream target genes of SOX2 contributing to gastric carcinogenesis.

Methodology/Principal Findings

We performed in silico analysis and focused on miRNA-126 (miR-126) as a potential SOX2 regulator. Gain- and loss-of function experiments and luciferase assays revealed that miR-126 inhibited SOX2 expression by targeting two binding sites in the 3′-untranslated region (3′-UTR) of SOX2 mRNA in multiple cell lines. In addition, miR-126 was highly expressed in some cultured and primary gastric cancer cells with low SOX2 protein levels. Furthermore, exogenous miR-126 over-expression as well as siRNA-mediated knockdown of SOX2 significantly enhanced the anchorage-dependent and -independent growth of gastric cancer cell lines. We next performed microarray analysis after SOX2 over-expression in a gastric cancer cell line, and found that expression of the placenta-specific 1 (PLAC1) gene was significantly down-regulated by SOX2 over-expression. siRNA- and miR-126-mediated SOX2 knockdown experiments revealed that miR-126 positively regulated PLAC1 expression through suppression of SOX2 expression in gastric cancer cells.

Conclusions

Taken together, our results indicate that miR-126 is a novel miRNA that targets SOX2, and PLAC1 may be a novel downstream target gene of SOX2 in gastric cancer cells. These findings suggest that aberrant over-expression of miR-126 and consequent SOX2 down-regulation may contribute to gastric carcinogenesis.

Involvement of epigenetically silenced microRNA-181c in gastric carcinogenesis

Aberrant expression of microRNA (miRNA) has been reported in various cancers. To clarify the role of miRNA in gastric carcinogenesis, we performed miRNA microarray analysis and investigated expression changes of miRNAs in a 5-aza-2'-deoxycytidine (5-aza-CdR)-treated gastric cancer cell line, KATO-III. On microarray analysis, five miRNAs were found to be upregulated (>3-fold) after 5-aza-CdR treatment compared with untreated cells. Among them, miR-181c and miR-432AS exhibited CpG islands in their upstream sequences on computational analysis, and their upregulation was verified by reverse transcription-polymerase chain reaction analyses. In particular, miR-181c upregulation was found not only in KATO-III but also in two other gastric and one colorectal cancer cell line with 5-aza-CdR treatment. Decreased expression of miR-181c was observed in 9 of 16 primary gastric carcinoma (GC) cases compared with the corresponding non-cancerous stomach tissues. Hypermethylation signals in the upstream region of miR-181c were observed in some cultured and primary GC cells with negative or low miR-181c expression. Transfection of the precursor miR-181c molecule induced decreased growth of two gastric cancer cell lines, KATO-III and MKN45. As for targets of miR-181c, oncogenic NOTCH4 and KRAS were identified by complementary DNA microarray analysis after precursor miR-181c molecule transfection, computational searches of miRNA target databases and reporter assaying using the 3'-untranslated regions of the two genes. These results indicate that miR-181c may be silenced through methylation and play important roles in gastric carcinogenesis through its target genes, such as NOTCH4 and KRAS.

Podoplanin is a potential marker for the diagnosis of ependymoma: a comparative study with epithelial membrane antigen (EMA)

Podoplanin is a mucin-type transmembrane sialoglycoprotein that is characteristically expressed in lymphatic endothelia. It is also expressed in the ependyma of the central nervous system as well as in ependymomas. Particularly, membrane-bound structures along the luminal surface, ring-like structures, and dot-like structures in the cytoplasm, all of which were originally reported for epithelial membrane antigen (EMA) immunohistochemistry in ependymoma, were also reported for podoplanin immunohistochemistry in ependymoma. This study was undertaken to evaluate podoplanin as compared with EMA as a marker of ependymoma. A total of 16 ependymomas (WHO Grade (G) II, 9 cases; GIII, 4; myxopapillary, 2; GIII clear cell, (1) were immunohistochemically studied using antibodies against podoplanin (clones D2-40 and NZ-1) as well as an antibody against EMA (clone E29). In all cases, D2-40 and NZ-1 excellently labeled linear signals along the luminal surface of ependymal canals/rosettes, dot-like structures, and/or ringlike structures, as did E29. These structures were generally more abundant in GII ependymomas than in GIII ependymomas. A semiquantitative analysis between the immunopositive structures of D2-40 or NZ-1 and E29 was conducted with a focus on the dot-like structures and the ring-like structures in the cases of GII and GIII ependymoma. The result showed that there was no statistical difference between D2-40 or NZ-1 and E29. Our study suggests that podoplanin is a potential marker for the diagnosis of ependymoma that corresponds to EMA. Anti-podoplanin antibodies and anti-EMA antibodies could cooperate with each other for the diagnostic immunohistochemistry of ependymoma.

A clinical study of Henoch-Schönlein Purpura associated with malignancy

BACKGROUND

Malignancy has been reported as a causative factor of cutaneous vasculitis, although only two retrospective epidemiological studies have analysed the association between Henoch-Schönlein purpura (HSP) and malignancy to date.

OBJECTIVE

To analyse the association between adult HSP and malignancy.

METHODS

We retrospectively reviewed the medical records of patients and found 103 cases of HSP over the past 20 years. Fifty-three cases (aged > or = 41 years) were categorized to two groups including 'with malignancy' or 'without malignancy', so that we could analyse the differences of clinical features between them. We also compared our study to previous reports.

RESULTS

Twenty-three cases out of 53 patients exhibited underlying malignant tumours. We focused on nine patients in which malignant tumours were thought to be strongly associated. Seven of nine patients exhibited new metastatic lesions or died due to underlying cancer within 1-32 months.

CONCLUSIONS

An association between HSP and malignant disease might have important diagnostic and pathophysiologic implications.

Methylation of the calcium channel-related gene, CACNA2D3, is frequent and a poor prognostic factor in gastric cancer

BACKGROUND & AIMS

The calcium channel voltage-dependent alpha2delta subunit consists of 4 genes, CACNA2D1 to CACNA2D4, of which CACNA2D2 and CACNA2D3 are located on 3p21.3 and 3p21.1, respectively. Here, we examined the relation between alpha2delta subunit gene alterations and gastric carcinogenesis.

METHODS

The expression and methylation status of the alpha2delta subunit genes were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and methylation-specific PCR in gastric cancers (GCs). The effects of CACNA2D3 expression were examined by cell proliferation and adhesion assays, and they predicted target gene alterations.

RESULTS

Aberrant methylation of CACNA2D1 and CACNA2D3 mostly corresponded to their expression status in GC cell lines. CACNA2D1/3 methylation was detected in 10 (12.5%) and 24 (30%) of the 80 GC cases, respectively, but no CACNA2D2 methylation was seen in 32 cases. CACNA2D3 methylation was more frequently found in diffuse type than in intestinal type (16/38 [42.1%] vs 8/42 [19.0%]; P = .025) GCs. Among the 53 patients with advanced GCs, patients with cancers showing CACNA2D3 methylation had a significantly shorter survival time than patients without this methylation (P = .003). Exogenous CACNA2D3 expression strongly inhibited cell growth and adhesion and up-regulated p21 and p27 expression in HEK-293T and NUGC4 cells. Inverse effects were seen by CACNA2D3 small interfering RNA treatment in the CACNA2D3-positive cell lines, indicating that CACNA2D3 may have tumor suppressive functions.

CONCLUSIONS

Loss of CACNA2D3 expression through aberrant promoter hypermethylation may contribute to gastric carcinogenesis, and CACNA2D3 methylation is a useful prognostic marker for patients with advanced GC.

Development of a measuring system of contact force during braille reading using an optical 6-axis force sensor

A system with an optical 6-axis force sensor was developed to measure contact force during braille reading. In using this system, we encountered two problems. One is a variability of output values depending on the contact point. This was solved by using two transformation techniques. The other is that subjects read braille in a different manner from the usual. We compared two manners of braille reading, one-handed vs two-handed, and found a small reduction in reading speed. Using this system, we collected data from four braille readers and quantitatively showed more minute contact force trajectories than those in earlier studies.

[The strategy to avoid malperfusion of vital organs during operation for acute aortic dissection; multi-monitoring and right brachial artery perfusion]

BACKGROUND

Malperfusion of vital organs is the most serious complication during cardiopulmonary bypass for acute aortic dissection.

METHOD

From 2001 to 2006, 40 patients underwent operation for acute type A aortic dissection. Right brachial artery perfusion was performed in 20 patients. From May 2005, transesophageal echocardiography and cerebral oxygenation measured by near infrared spectroscopy were continuously monitored during operation.

RESULTS

There were 3 in-hospital deaths and 3 brain infarction. Switching of blood flow during cardiopulmonary bypass occurred in 3 patients; 2 patients suffered from diffuse brain infarction while. in the other patient, switching of perfusion was detected at once by multi-monitoring and resolved by induction of right brachial artery perfusion.

CONCLUSION

Close monitoring of cerebral oxygenation by near infrared spectroscopy, transesophageal echocardiography and right brachial artery perfusion are effective in operation for acute aortic dissection.