Biomedical subjects

Theodore Fotsis

Publications and source records attributed to Theodore Fotsis.

10 recordsLinked to original sources

PubMed2005

Matrix metalloproteinases in carcinoma of unknown primary.

BACKGROUND: The purpose was to study proteolysis-related molecules, matrix metalloproteinase-2 (MMP-2) and MMP-9 and tissue inhibitor of metalloproteinases-1 (TIMP-1), in carcinoma of unknown primary (CUP). METHODS: Paraffin-embedded tumor material from 75 patients diagnosed with CUP was used. Tumor histologies were adenocarcinoma (77%), undifferentiated carcinoma (19%), and squamous cell carcinoma (4%) and patients were categorized into favorable (62%) and unfavorable (38%) subsets. The tissue expression of MMP-2, MMP-9, and TIMP-1 was assessed by use of specific monoclonal antibodies and evaluated by means of a visual staining score. The expression of molecules studied was analyzed against clinicopathological data. RESULTS: MMP-2 was found expressed in 69% (strong expression in 49%), MMP-9 in 49% (strong in 36%), and TIMP-1 in 79% (strong in 44%) of studied cases. The expression of MMP-2 correlated positively with MMP-9. TIMP-1 was significantly higher in unfavorable compared with favorable tumors and was associated with a shorter survival of patients (7.5 vs. 12 mos). No other associations were detected. CONCLUSIONS: MMP-2, MMP-9, and TIMP-1 are widely expressed in CUP, suggesting an essential role of proteolysis in these tumors. TIMP-1 may be considered a possible marker of poor prognosis in CUP patients.

Adult↗

PubMed2005

Angiogenesis in cancer of unknown primary: clinicopathological study of CD34, VEGF and TSP-1.

BACKGROUND: Cancer of unknown primary remains a mallignancy of elusive biology and grim prognosis that lacks effective therapeutic options. We investigated angiogenesis in cancer of unknown primary to expand our knowledge on the biology of these tumors and identify potential therapeutic targets. METHODS: Paraffin embedded archival material from 81 patients diagnosed with CUP was used. Tumor histology was adenocarcinoma (77%), undifferentiated carcinoma (18%) and squamous cell carcinoma (5%). The tissue expression of CD34, VEGF and TSP-1 was assessed immunohistochemically by use of specific monoclonal antibodies and was analyzed against clinicopathological data. RESULTS: VEGF expression was detected in all cases and was strong in 83%. Stromal expression of TSP-1 was seen in 80% of cases and was strong in 20%. The expression of both proteins was not associated with any clinical or pathological parameters. Tumor MVD was higher in tumors classified as unfavorable compared to more favorable and was positively associated with VEGF and negatively with TSP-1. CONCLUSION: Angiogenesis is very active and expression of VEGF is almost universal in cancers of unknown primary. These findings support the clinical investigation of VEGF targeted therapy in this clinical setting.

Adenocarcinoma↗

PubMed2005

Activin A suppresses neuroblastoma xenograft tumor growth via antimitotic and antiangiogenic mechanisms.

The tumor suppressor function of activin A, together with our findings that activin A is an inhibitor of angiogenesis, which is down-regulated by the N-MYC oncogene, prompted us to investigate in more detail its role in the malignant transformation process of neuroblastomas. Indeed, neuroblastoma cells with restored activin A expression exhibited a diminished proliferation rate and formed smaller xenograft tumors with reduced vascularity, whereas lung metastasis rate remained unchanged. In agreement with the decreased vascularity of the xenograft tumors, activin A inhibited several crucial angiogenic responses of cultured endothelial cells, such as proteolytic activity, migration, and proliferation. Endothelial cell proliferation, activin A, or its constitutively active activin receptor-like kinase 4 receptor (ALK4T206D), increased the expression of CDKN1A (p21), CDKN2B (p15), and CDKN1B (p27) CDK inhibitors and down-regulated the expression of vascular endothelial growth factor receptor-2, the receptor of a key angiogenic factor in cancer. The constitutively active forms of SMAD2 and SMAD3 were both capable of inhibiting endothelial cell proliferation, whereas the dominant-negative forms of SMAD3 and SMAD4 released the inhibitory effect of activin A on endothelial cell proliferation by only 20%. Thus, the effects of activin A on endothelial cell proliferation seem to be conveyed via the ALK4/SMAD2-SMAD3 pathways, however, non-SMAD cascades may also contribute. These results provide novel information regarding the role of activin A in the malignant transformation process of neuroblastomas and the molecular mechanisms involved in regulating angiogenesis thereof.

Activin Receptors↗

PubMed2005

An isotope dilution gas chromatographic-mass spectrometric method for the simultaneous assay of estrogens and phytoestrogens in urine.

The metabolism of endogenous estrogens is complicated and certain metabolic patterns may reflect an individual risk of estrogen-dependent diseases such as breast cancer. Since the 1960s we have been constantly involved in developing estrogen profiling methods, in the beginning using gas chromatography and later gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode (SIM) and finally utilizing isotope dilution (ID-GC-MS-SIM). The addition of the dietary phytoestrogens to the profile rendered the method even more complicated. The present work presents the final estrogen profile method for 15 endogenous estrogens, four lignans, seven isoflavonoids and coumestrol in one small urine sample (1/150th of a 24 h human urine sample, minimum 2.5-5 ml) with complete validation including investigations as to the precision, sensitivity, accuracy and specificity. The method does not include the minimal amounts of unconjugated estrogens in urine. It may also be used for animal (e.g. rat and mouse) urine using a minimum of 2 ml of usually pooled sample. Despite its complexity it was found to fulfill the reliability criteria, resulting in highly specific and accurate results.

Estrogens↗

PubMed2004

Luteolin inhibits vascular endothelial growth factor-induced angiogenesis; inhibition of endothelial cell survival and proliferation by targeting phosphatidylinositol 3'-kinase activity.

In an attempt to identify phytochemicals contributing to the well-documented preventive effect of plant-based diets on cancer incidence and mortality, we have previously shown that certain flavonoids inhibit in vitro angiogenesis. Here, we show that the flavonoid luteolin inhibited tumor growth and angiogenesis in a murine xenograft model. Furthermore, luteolin inhibited vascular endothelial growth factor (VEGF)-induced in vivo angiogenesis in the rabbit corneal assay. In agreement, luteolin inhibited both VEGF-induced survival and proliferation of human umbilical vein endothelial cells (HUVECs) with an IC(50) of about 5 mumol/L. Luteolin inhibited VEGF-induced phosphatidylinositol 3'-kinase (PI3K) activity in HUVECs, and this inhibition was critical for both the antisurvival and antimitotic affects of the compound. Indeed, luteolin abolished VEGF-induced activation of Akt, a downstream target of PI3K conveying both survival and mitotic downstream signals. Because overexpression of a constitutively active form of Akt rescued HUVECs only from the antisurvival effects of luteolin, the result indicated that luteolin targeted mainly the survival signals of the PI3K/Akt pathway. With regard to its antimitotic activity, luteolin inhibited VEGF-induced phosphorylation of p70 S6 kinase (S6K), a downstream effector of PI3K responsible for G(1) progression. Indeed, VEGF-induced proliferation of HUVECs was sensitive to rapamycin, an inhibitor of p70 S6K activation. Surprisingly, luteolin did not affect VEGF-induced phosphorylation of extracellular signal-regulated kinase 1/2 mitogen-activated protein kinases, a pathway that is considered important for the mitotic effects of VEGF. Thus, blockade of PI3K by luteolin was responsible for the inhibitory effects of the compound on VEGF-induced survival and proliferation of HUVECs. The antisurvival effects of luteolin were mediated via blockage of PI3K/Akt-dependent pathways, whereas inhibition of the PI3K/p70 S6K pathway mediated the antimitotic effects of the compound.

Angiogenesis Inhibitors↗

PubMed2004

Decrease of heat shock protein levels and cell populations by wine phenolic extracts.

The effect of red and white wine total extracts and phenolic fractions on heat shock protein (Hsp) levels in tumor cells and on tumor and endothelial cell populations in vitro has been investigated. Total extracts of red wines decreased Hsp70 and Hsp27 levels and the numbers of tumor and endothelial cells. Several red and white wine fractions significantly decreased Hsp27 levels, and some of them had also an effect on Hsp70 levels. A red wine fraction rich in polymeric flavanols and a white wine one rich in phenolic acids, flavonols, and tyrosol strongly lowered Hsp27 levels. Some red and white wine fractions strongly reduced tumor cell numbers, whereas most of them decreased endothelial cell numbers to variable extents. The present results indicate that wine phenolics decrease Hsp levels in tumor cells and tumor and endothelial cell populations. These properties may be important in the potent anticarcinogenic action of wine phenolics.

Animals↗

PubMed2002

N-myc oncogene overexpression down-regulates IL-6; evidence that IL-6 inhibits angiogenesis and suppresses neuroblastoma tumor growth.

Angiogenesis is an indispensable prerequisite for the progression and metastasis of solid malignancies. Tumor angiogenesis appears to be governed by alterations of tumor suppressor or oncogenes operant in a broad range of tumors. We have addressed this issue in neuroblastoma, a malignancy characterized by the near-exclusive amplification and overexpression of the N-Myc oncogene. Here, we report that N-Myc overexpression results in down-regulation of interleukin-6 (IL-6) and that IL-6 is an inhibitor of endothelial cell proliferation and VEGF-induced rabbit corneal angiogenesis. STAT3 is instrumental for IL-6 activity as infection with adenoviruses expressing a phosphorylation deficient STAT3 mutant renders endothelial cells insensitive to the antiproliferative action of IL-6. Finally, though IL-6 does not influence neuroblastoma cell growth, IL-6-expressing xenograft tumors in mice exhibit reduced neovascularization and suppressed growth. Our data shed new light on the mechanisms by which N-myc oncogene amplification enhances the malignant phenotype in neuroblastomas.

Angiogenesis Inhibitors↗

PubMed2002

Luteolin reduces lipopolysaccharide-induced lethal toxicity and expression of proinflammatory molecules in mice.

Luteolin is a flavonoid that has been shown to reduce proinflammatory molecule expression in vitro. In the present study, we have tested the ability of luteolin to inhibit lipopolysaccharide (LPS)- induced lethal toxicity and proinflammatory molecule expression in vivo. Mice receiving LPS (Salmonella enteriditis LPS, 32 mg/kg, intraperitoneally) exhibited high mortality with only 4.1% of the animals surviving seven days after the LPS challenge. On the contrary, mice that had received luteolin (0.2 mg/kg, intraperitoneally) before LPS showed an increased survival rate with 48% remaining alive on Day 7. To investigate the mechanism by which luteolin affords protection against LPS toxicity we measured intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor-alpha (TNF-alpha) production in response to LPS in the presence or absence of luteolin pretreatment. Treatment of animals with LPS increased serum TNF-alpha levels in a time-dependent manner. The increase in peak serum TNF-alpha levels was sensitive to luteolin pretreatment. Luteolin pretreatment also reduced LPS-stimulated ICAM-1 expression in the liver and abolished leukocyte infiltration in the liver and lung. We conclude that luteolin protects against LPS-induced lethal toxicity, possibly by inhibiting proinflammatory molecule (TNF-alpha, ICAM-1) expression in vivo and reducing leukocyte infiltration in tissues.

Analysis of Variance↗

PubMed2002

Early endosomal regulation of Smad-dependent signaling in endothelial cells.

Transforming growth factor beta (TGFbeta) receptors require SARA for phosphorylation of the downstream transducing Smad proteins. SARA, a FYVE finger protein, binds to membrane lipids suggesting that activated receptors may interact with downstream signaling molecules at discrete endocytic locations. In the present study, we reveal a critical role for the early endocytic compartment in regulating Smad-dependent signaling. Not only is SARA localized on early endosomes, but also its minimal FYVE finger sequence is sufficient for early endosomal targeting. Expression of a SARA mutant protein lacking the FYVE finger inhibits downstream activin A signaling in endothelial cells. Moreover, a dominant-negative mutant of Rab5, a crucial protein for early endosome dynamics, causes phosphorylation and nuclear translocation of Smads leading to constitutive (i.e. ligand independent) transcriptional activation of a Smad-dependent promoter in endothelial cells. As inhibition of endocytosis using the K44A negative mutant of dynamin and RN-tre did not lead to activation of Smad-dependent transcription, the effects of the dominant-negative Rab5 are likely to be a consequence of altered membrane trafficking of constitutively formed TGFbeta/activin type I/II receptor complexes at the level of early endosomes. The results suggest an important interconnection between early endosomal dynamics and TGFbeta/activin signal transduction pathways.

Animals↗

PubMed2002

N-myc oncogene overexpression down-regulates leukemia inhibitory factor in neuroblastoma.

Amplification of N-myc oncogene is a frequent event in advanced stages of human neuroblastoma and correlates with poor prognosis and enhanced neovascularization. Angiogenesis is an indispensable prerequisite for the progression and metastasis of solid malignancies, which is modulated by tumor suppressors and oncogenes. We have addressed the possibility that N-myc oncogene might regulate angiogenesis in neuroblastoma. Here, we report that experimental N-Myc overexpression results in down-regulation of leukemia inhibitory factor (LIF), a modulator of endothelial cell proliferation. Reporter assays using the LIF promoter and a series of N-Myc mutants clearly demonstrated that down-regulation of the LIF promoter was independent of Myc/Max interaction and required a contiguous N-terminal N-Myc domain. STAT3, a downstream signal transducer, was essential for LIF activity as infection with adenoviruses expressing a phosphorylation-deficient STAT3 mutant rendered endothelial cells insensitive to the antiproliferative action of LIF. LIF did not influence neuroblastoma cell proliferation suggesting that, at least in the context of neuroblastoma, LIF is involved in paracrine rather than autocrine interactions. Our data shed light on the mechanisms by which N-myc oncogene amplification enhances the malignant phenotype in neuroblastoma.

Cell Division↗