Ping-Pin Zheng

Identification of relevant prognostic histopathologic features in 69 intracranial ependymomas, excluding myxopapillary ependymomas and subependymomas

The results of attempts to identify histopathologic parameters that contribute to the clinical outcome of patients with ependymomas have been controversial. This may be due to the relative rareness of ependymomas. Furthermore, in many investigations, myxopapillary ependymomas and subependymomas were included and may have confounded results, because those tumors should be considered clinicopathologic entities distinct from the other ependymomas.

MALDI-TOF Mass Spectrometry Analysis of Cerebrospinal Fluid Tryptic Peptide Profiles to Diagnose Leptomeningeal Metastases in Patients with Breast Cancer

Leptomeningeal metastasis (LM) is a devastating complication that occurs in 5% of patients with breast cancer. Early diagnosis and initiation of treatment are essential to prevent neurological deterioration. However, early diagnosis of LM remains challenging because 25% of cerebrospinal fluid (CSF) samples produce false-negative results at first cytological examination. We developed a new, MS-based method to investigate the protein expression patterns present in the CSF from patients with breast cancer with and without LM. CSF samples from 106 patients with active breast cancer (54 with LM and 52 without LM) and 45 control subjects were digested with trypsin. The resulting peptides were measured by MALDI-TOF MS. Then, the mass spectra were analyzed and compared between patient groups using newly developed bioinformatics tools. A total of 895 possible peak positions was detected, and 164 of these peaks discriminated between the patient groups (Kruskal-Wallis, p < 0.01). The discriminatory masses were clustered, and a classifier was built to distinguish patients with breast cancer with and without LM. After bootstrap validation, the classifier had a maximum accuracy of 77% with a sensitivity of 79% and a specificity of 76%. Direct MALDI-TOF analysis of tryptic digests of CSF gives reproducible peptide profiles that can assist in diagnosing LM in patients with breast cancer. The same method can be used to develop diagnostic assays for other neurological disorders.

Increased levels of circulating endothelial progenitor cells and circulating endothelial nitric oxide synthase in patients with gliomas

Gliomas are among the highest vascularized tumors. We hypothesized that patients with gliomas have increased levels of circulating endothelial progenitor cells (EPCs) and circulating endothelial nitric oxide synthase (eNOS).

Low-Molecular Weight Caldesmon as a Potential Serum Marker for Glioma

Purpose: Testing the feasibility of using the serum low-molecular weight caldesmon (l-CaD) level as a serum marker for the presence of glioma. Experimental Design: Within a total of 230 serum samples, the l-CaD level was measured in healthy volunteers (30), patients with gliomas (57), nonglial intracranial tumors (107), and nontumor neurologic diseases (36) by ELISA. The specificity of the assay was monitored by combination of immunoprecipitation and immunoblotting. Results: The serum level of l-CaD is significantly higher in the group of glioma patients as compared with any of the other groups (P < 0.001). The cutoff value of 45 yields optimal sensitivity and specificity of the assay (91% and 84%, respectively; area under the curve score = 0.91). The specificity of ELISA was confirmed by the immunoprecipitation/immunoblotting control experiments. There were no significant differences in serum l-CaD levels between patients with low- or high-grade gliomas. Conclusions: The serum l-CaD level as determined by ELISA is a good discriminator between glioma patients versus patients with other intracranial tumors, other neurologic diseases, and healthy people. Prospective studies are required to test the contribution of the assay in making the diagnosis of glioma, or its feasibility for monitoring the tumor during treatment.

Circulating glioma biomarkers

Validated biomarkers for patients suffering from gliomas are urgently needed for standardizing measurements of the effects of treatment in daily clinical practice and trials. Circulating body fluids offer easily accessible sources for such markers. This review highlights various categories of tumor-associated circulating biomarkers identified in blood and cerebrospinal fluid of glioma patients, including circulating tumor cells, exosomes, nucleic acids, proteins, and oncometabolites. The validation and potential clinical utility of these biomarkers is briefly discussed. Although many candidate circulating protein biomarkers were reported, none of these have reached the required validation to be introduced for clinical practice. Recent developments in tracing circulating tumor cells and their derivatives as exosomes and circulating nuclear acids may become more successful in providing useful biomarkers. It is to be expected that current technical developments will contribute to the finding and validation of circulating biomarkers.

Glut1/SLC2A1 is crucial for the development of the blood-brain barrier in vivo

The overall permeability of the blood‐brain barrier (BBB) is regulated by specialized cerebral endothelial cells and their junctional complexes, consisting of adherens junctions (AJs) and tight junctions (TJs). Among the members of the glucose transporters (Glut), Glut1 is a unique molecule expressed in the cerebral endothelial cells. Glut1 and the junctional proteins are concomitantly downregulated in situations in which breakdown of the BBB has taken place. We hypothesized that the expression of Glut1 may play a significant role in the development of the cerebral microvasculature with BBB properties. To date, there is no information on the role of Glut1 during the development of BBB. In the present study, the in vivo effects of Glut1 knockdown on the cerebral vascular development were investigated.

Differential expression of Hela-type caldesmon in tumour neovascularization: a new marker of angiogenic endothelial cells

Caldesmon (CaD) is a major actomyosin‐binding protein found in various cell types. There are at least two high‐molecular‐weight isoforms (h‐CaD) and four low‐molecular‐weight isoforms (l‐CaD) produced by alternative splicing. The alternatively spliced variants of the l‐CaD class are further differentiated by inclusion (Hela l‐CaD) or exclusion (WI‐38 l‐CaD) of exon 1. Currently, nothing is known about differential expression of the Hela l‐CaD in tumour neovascularization. In a previous study, expression of the Hela‐type transcripts was found in glioma blood vessels but not in the normal cerebral vasculature. To investigate whether the differentially expressed transcripts are translated into protein, a specific antibody against the peptide encoded by exon 1 was raised. Initially, exclusive expression of the protein in glioma vasculature was confirmed. To determine further whether these findings are generalizable to neovascularization in a wide variety of other tumour types, a large cohort of cancers derived from various organs, including breast, lung, kidney, colon, stomach, ovary, uterus, prostate, thyroid, liver, giving a total of 180 cases, were examined. Expression of the Hela l‐CaD was restricted to tumour vasculature and was not found in normal blood vessels. Hela l‐CaD was preferentially expressed in the early stage of tumour neovascularization and the Hela l‐CaD+ endothelial cells (ECs) were frequently enlarged, multinucleated, and developed elongated cell projections or free fragments of cytoplasm, correlating with the features of motile cells. In the Hela l‐CaD+ ECs, disassembly of focal adhesion and the formation of podosome‐like structures was observed. Therefore, the findings support the notion that quiescent ECs undergo activation of motility, necessary for ubiquitous tumour‐associated neovascularization. The data indicate that Hela l‐CaD can be considered as a marker for angiogenic ECs during the early stages of tumour neovascularization. Copyright

A crucial role of caldesmon in vascular development in vivo

AIMS We explored the in vivo effects of knockdown of caldesmon on vascular development in zebrafish. METHODS AND RESULTS We investigated the effects of caldesmon knockdown on the vascular development in a zebrafish model with special attention for the trunk and head vessels including the aortic arches. We examined the developing fishes at various time points. The vascular abnormalities observed in the caldesmon morphants were morphologically and functionally characterized in detail in fixed and living embryos. The knockdown of caldesmon caused serious defects in vasculogenesis and angiogenesis in zebrafish morphants, and the vascular integrity and blood circulation were concomitantly impaired. CONCLUSION The data provide the first functional assessment of the role of caldesmon in vascular development in vivo, indicating that this molecule plays a crucial role in vasculogenesis and angiogenesis in vivo. Interfering with caldesmon opens new therapeutic avenues for anti-angiogenesis in cancer and ischaemic cardiovascular disease.

Hela l-CaD is implicated in the migration of endothelial cells/endothelial progenitor cells in human neoplasms.

Caldesmon (CaD) is a major actin-binding protein distributed in a variety of cell types. No functional differences among the isoforms in in vitro studies were found so far. In a previous study we found that the low molecular caldesmon isoform (Hela l-CaD) is expressed in endothelial cells (ECs)/endothelial progenitor cells (EPCs) in tumor vasculature of various human tumors. Activation of cell motility is necessary for the navigation of the tip ECs during angiogenesis, and migration of EPCs from the bone marrow during vasculogenesis. In the present study we searched for features of motility and the intracellular expression sites of Hela l-CaD in ECs/EPCs of various human tumors under histologically preserved microenviroment. We discovered a variety of motility-related cell protrusions like filopodia, microspikes, lamellipodia, podosomes, membrane blebs and membrane ruffles in the activated ECs/EPCs. Hela l-CaD appeared to be invariably expressed in the subregions of these cell protrusions. The findings suggest that Hela l-CaD is implicated in the migration of ECs/EPC in human neoplasms where they contribute to tumor vasculogenesis and angiogenesis.

Proteomics in primary brain tumors.

Genomic damage present in tumors may lead to abnormal or altered expression of proteins. Some of the findings of genetic explorations of brain tumors have had their impact on making the diagnosis or are important with respect to therapeutic decisions. The identification of individual proteins or clusters of proteins expressed in neoplastic tissues potentially may have an even more important relevance for making the diagnosis, prognosis and treatment outcome. Diverse posttranslational modifications of proteins may be linked to neoplastic lineage or stage. For the rapidly developing fields of proteomics and its integration with genomics and transcriptomics (by now called operomics) the application of bioinformatics is crucial. This review addresses the nascent field of proteomics and its diagnostic potential in the feld of primary brain tumors. Various technical approaches to separate and identify proteins are described, including the most recent developments in the analytical proteomic technology.