Ulm, Univ., Diss., 2008.

Marburg, Universiẗat, Diss., 2008.

Ulm, Univ. Diss., 2006.

Vascular endothelial growth factor (VEGF) is an endothelial cell mitogen involved in angiogenesis, the formation of new blood vessels. sFlt-1, a secreted form of the signal-transducing VEGF receptor Flt-1, can inhibit cellular responses to VEGF both in vitro and in vivo. sFlt-1 is generated by alternative pre-mRNA processing; removal of Flt-1 intron 13 by splicing produces the mRNA for transmembrane Flt-1, whereas cleavage/polyadenylation within this intron, preserving the exon 13/intron 13 junction, yields sFlt-1 mRNA. Despite the likely importance of sFlt-1 in VEGF signaling, little is known about the regulation of its expression. Previous studies using an Flt-1 minigene (pFIN13) revealed that intronic cleavage/polyadenylation signals can affect Flt-1 expression, and, conversely, that 3' intronic splice signals can affect sFlt-1 expression. The goal of present work was to test the hypothesis that splicing and cleavage/polyadenylation factors compete functionally on Flt-1 transcripts, by 1) assessing the influence of exon 13/14 splicing determinants on expression of Flt-1 RNA processing variants in a transfected cell model system; 2) determining the effects of altering the relative abundance of proteins principally involved in splicing or cleavage/polyadenylation; and 3) characterizing a previously-unknown splice variant, predicted to encode a novel sFlt-1 protein isoform, in cells overexpressing the spliceosomal RNA binding protein U2AF65. When the upstream exon in pFIN13 was decreased from 2135 to 309 bp, the sFlt-1:Flt-1 mRNA ratio decreased 8.9-fold and an aberrant 5'UTR/exon 14 splice decreased 60-fold, indicating that "exon definition" is a key parameter of successful Flt-1 RNA processing. Mutation of 5' or 3' intronic splice signals had little effect on Long sFlt-1:Total sFlt-1 mRNA ratio, suggesting that splicing and cleavage/polyadenylation factors may not compete physically for Flt-1 transcripts. Although co-transfection with RNA processing factor cDNAs did not generally produce the predicted pattern of effects on sFlt-1:Flt-1 mRNA ratio, a cryptic exon within intron 13 was revealed in cells overexpressing U2AF65. sFlt-1 protein apparently can be encoded by mRNAs either cleaved/polyadenylated within intron 13 or, surprisingly, by splicing of the cryptic exon "13b." Thus, the cellular decision to produce sFlt-1 or Flt-1 from a nascent RNA can no longer be viewed as a simple choice between cleavage/polyadenylation and splicing. / Ph. D.

Angiogenesis is not only essential for tumor growth but is also implicated in invasion of the cancer cells into the circulation, and growth of dormant micro-metastases into frank metastatic lesions. Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis as well as in solid tumors. It also has a role for VEGF in hematopoietic neoplasms; although has not been fully elucidated. This study will examine the VEGF secretary activity of malignant cells in the patients with hematologic malignancies. Supernatants of cell culture after 72 hours & 7th day were analyzed for VEGF value by ELISA method. The purposes of this study are to assay the VEGF activity and its correlation with disease prognosis in various hematological disorders; and to detect the VEGF autocrine activity of tumor cells in sequential culture without any stimulation in vitro. Results: our research samples were 75 specimens. The VEGF value was low in 13 cases of benign diseases, no obvious auto-secretary activity of those cells. There was no significant correlation between VEGF value and disease status in acute lymphoblastic leukemia; however, the cases were too small to had exact predict value (only 7 cases). In 17 Cases of malignant lymphoma, low D0 VEGF value (<300 pg) had good prognosis; those cases relapsed after treatment had high auto-secretary activity (high VEGF value of 7th culture day) and had bad disease prognosis, but there was no statistic significance. In 14 Cases of acute myelogenous leukemia, high D0 VEGF value (>150 pg) and high VEGF value of 7th culture day both presented bad disease outcome. In 16 cases of chronic myeloid leukemia (CML), low plasma VEGF level (D0<300pg) was all in chronic phase; all cases in accelerated phase (3 cases) and acute blastic crisis (5 cases) presented with high plasma VEGF level (>300pg). Patients with high plasma VEGF level had 70 % (7of 10) in worse disease status (P=0.010). Patients in chronic phase of CML had low VEGF auto-secretary activity and most of the blastic crisis patients were with high VEGF auto-secretary activity and also had bad prognosis. (P=0.248) Conclusion: although our study is a primary result, study cases are varied, but it still provide important information that VEGF has an important role in hematological malignancies. We will process further research of single and specific disease in the future to analyze the exact correlation of VEGF and hematological diseases.

Ulm, Univ., Diss., 2008.

Universiẗat, Diss--Gießen, 2001.

Ulm, Univ., Diss., 2001.

Univ., Diss., 2010--Marburg.

Tumour development is dependent upon the formation of an adequate blood supply through angiogenesis. Vascular endothelial growth factor (VEGF) is one of the most potent and specific pro-angiogenic factors associated with tumour development. Vascular endothelial growth factor is elevated in dogs with a variety of neoplastic tumours and has been linked to an increased risk for metastasis and a poorer prognosis in several tumours. Spirocerca lupi (S. lupi) is a nematode of canids which infests the oesophagus where it forms a nodule. The oesophageal nodule can develop into a neoplastic tumour namely osteosarcoma, fibrosarcoma or anaplastic sarcoma. The pathogenesis of the neoplastic transformation is poorly understood. Diagnosis of neoplastic transformation can be challenging and is based on endoscopy-guided biopsies which are invasive, expensive and may yield non diagnostic samples. The aim of this prospective study was to determine if serum and plasma VEGF levels could be used to distinguish between neoplastic and non-neoplastic spirocercosis. Twenty four dogs were enrolled in the study, 9 with non-neoplastic, 9 with neoplastic spirocercosis, and 6 control dogs. Plasma and serum samples for VEGF analysis were collected at diagnosis. Measurement of VEGF was done using a canine VEGF Quantikine ELISA kit. Statistical analysis to compare the means of the VEGF concentrations between the groups was performed using the Kruskal-Wallis followed by the Dunn’s test. Significance was set at p<0.05 The median plasma VEGF concentration of the dogs with neoplastic spirocercosis 629pg/ml (range 282 – 2366) was higher than the median plasma VEGF concentrations of both the non-neoplastic 0pg/ml (range 0 – 716) and controls 0pg/ml (range 0 – 0) (p<0.001). The median serum VEGF concentration of the neoplastic dogs 69pg/ml (range 0 – 212) was higher than the serum VEGF concentrations in the non-neoplastic 0pg/ml (range 0 – 44.13) and control 0pg/ml (range 0 – 39.4) (p=0.001). Plasma VEGF at a cut off value of 250pg/ml was determined to have a sensitivity of 100%, specificity of 77.8%, a PPV of 81.8% and a NPV of 100% for determining neoplastic transformation. Serum VEGF at a cut off value of 25pg/ml was determined to have a sensitivity of 88.9%, specificity of 100%, a PPV of 100% and a NPV of 90% for determining neoplastic transformation. Both plasma and serum VEGF concentrations can be used to differentiate between non-neoplastic and neoplastic spirocercosis. Plasma VEGF concentrations were higher than serum VEGF concentrations, contrary to what is reported in literature. Both plasma and serum VEGF concentrations can, therefore, potentially be used for diagnosis of neoplastic vs. non-neoplastic cases in canine spirocercosis. There is a need to perform more studies to determine cut-off concentrations that would maximize the sensitivity and specificity for determining neoplastic transformation in canine spirocercosis as well as to determine the role of VEGF in the pathogenesis of the neoplastic transformation. Copyright / Dissertation (MMedVet)--University of Pretoria, 2012. / Companion Animal Clinical Studies / unrestricted