Gregory Kouraklis

Circulating VEGF levels in the serum of gastric cancer patients: Correlation with pathological variables, patient survival, and tumor surgery

ObjectiveTo evaluate the clinical usefulness of serum vascular endothelial growth factor (VEGF) levels in gastric cancer patients. Summary Background DataVascular endothelial growth factor plays an important role in the formation of new blood vessels involved in the growth and metastatic spread of solid tumors, but there is limited information regarding the clinical significance of serum VEGF levels in cancer patients. MethodsSerum VEGF concentrations were measured by an enzyme linked immunosorbent assay in 61 healthy controls and in 58 gastric cancer patients before surgery, and then again at 7 and 30 days after surgery. The association between preoperative serum VEGF levels, clinicopathological features and patient survival, and their changes following surgery were evaluated. ResultsSerum VEGF levels in gastric cancer patients were significantly higher than those in controls. There was a significant association between serum VEGF levels and disease stage, as well as invasion depth of the tumor and the presence of distant metastases. Serum VEGF levels decreased significantly after radical resection of the primary tumor and increased in patients with unresectable tumors. Multivariate regression analysis showed that serum VEGF level is an independent prognostic factor for survival. ConclusionsSerum VEGF levels in gastric patients are significantly higher compared with normal controls and correlate with local tumor extent, disease stage, and the presence of distant metastases. Preoperative serum VEGF concentration decreases significantly after radical resection of the primary tumor and is an independent prognostic factor for patient survival suggesting that determination of serum VEGF levels may be clinically useful.

Adenovirus-mediated expression of antisense MMP-9 in glioma cells inhibits tumor growth and invasion

Matrix metalloproteinase 9 (MMP-9) is known to play a major role in cell migration and invasion in both physiological and pathological processes. Our previous work has shown that increased MMP-9 levels are associated with human glioma tumor progression. In this study, we evaluated the ability of an adenovirus containing a 528 bp cDNA sequence in antisense orientation to the 5′ end of the human MMP-9 gene (Ad-MMP-9AS) to inhibit the invasiveness and migratory capacity of the human glioblastoma cell line SBN19 in in vitro and in vivo models. Infection of glioma cells with Ad-MMP-9AS reduced MMP-9 enzyme activity by approximately 90% compared with mock- or Ad-CMV-infected cells. Migration and invasion of glioblastoma cells infected with Ad-MMP-9AS were significantly inhibited relative to Ad-CMV-infected controls in spheroid and Matrigel assays. Intracranial injections of SNB19 cells infected with Ad-MMP-9AS did not produce tumors in nude mice. However, injecting the Ad-MMP-9AS construct into subcutaneous U87MG tumors in nude mice caused regression of tumor growth. These results support the theory that adenoviral-mediated delivery of the MMP-9 gene in the antisense orientation has therapeutic potential for treating gliomas.

Peroxisome Proliferator Activated Receptor-γ (PPAR-γ) Ligands and Angiogenesis

The peroxisome proliferator activated receptor (PPAR)-γ ligands have been initially described as important regulators of adipogenic differentiation and glucose homeostasis. Detailed studies in different tissues pointed to the roles of these ligands in cell proliferation and cancer, establishing their anticancer properties against a wide variety of neoplastic cells. The growth of any solid tumor depends on angiogenesis, as tumor vascularization is a vital process for tumor volume increase and its metastatic potential. Recently, the role of PPAR-γ ligands as potent angiogenesis modulators in vitro and in vivo, has been referred. This review takes into consideration the latest data concerning the participation of PPAR-γ ligands in the biological mechanisms underlying angiogenesis inhibition (important in anticancer therapy) and the controversy concerning angiogenesis induction (important in non-neoplastic diseases). As inhibition of angiogenesis represents one of the more promising, new approaches to anticancer therapy, PPAR-γ ligands in addition to their established role as tumor cell cycle modulators could be implicated in future strategies for cancer treatment.

Modulation of cystatin C expression impairs the invasive and tumorigenic potential of human glioblastoma cells

Increases in the abundance of cathepsin B transcript and protein with increased tumor grade and changes in subcellular localization and activity of this enzyme. We observed progressive reductions in levels of the protease inhibitor cystatin C, an inhibitor of cathepsin B with corresponding increases in the malignancy of glioma cell lines, implying an inverse correlation between cystatin C and tumor grade. To investigate the role of cystatin C in the invasion of brain tumor cells, we stably transfected SNB19 glioblastoma cells with either a 0.4-kb cDNA construct of human cystatin C in the sense orientation or an empty vector. Clones expressing sense-cystatin C cDNA had higher cystatin C mRNA and protein levels than did control cells. Sense-transfected cells were also markedly less invasive than control cells in a Matrigel invasion assay and in a coculture assay of SNB19 spheroids and fetal rat brain aggregates. Finally, the sense-transfected cells did not form tumors in nude mice upon intracerebral injection. These results strongly implicate cystatin C in the invasiveness of human glioblastoma cells and suggest that sense transcripts of cystatin C may prove useful in cancer therapy.

Current treatment for colorectal liver metastases

Surgical resection offers the best opportunity for survival in patients with colorectal cancer metastatic to the liver, with five-year survival rates up to 58% in selected cases. However, only a minority are resectable at the time of diagnosis. Continuous research in this field aims at increasing the percentage of patients eligible for resection, refining the indications and contraindications for surgery, and improving overall survival. The use of surgical innovations, such as staged resection, portal vein embolization, and repeat resection has allowed higher resection rates in patients with bilobar disease. The use of neoadjuvant chemotherapy allows up to 38% of patients previously considered unresectable to be significantly downstaged and eligible for hepatic resection. Ablative techniques have gained wide acceptance as an adjunct to surgical resection and in the management of patients who are not surgical candidates. Current management of colorectal liver metastases requires a multidisciplinary approach, which should be individualized in each case.

Replication protein A is an independent prognostic indicator with potential therapeutic implications in colon cancer

Replication protein A (RPA), a component of the origin recognition complex, is required for stabilization of single-stranded DNA at early and later stages of DNA replication being thus critical for eukaryotic DNA replication. Experimental studies in colon cancer cell lines have shown that RPA protein may be the target of cytotoxins designed to inhibit cellular proliferation. This is the first study to investigate the expression of RPA1 and RPA2 subunits of RPA protein and assess their prognostic value in colon cancer patients. We analyzed immunohistochemically the expression of RPA1 and RPA2 proteins in a series of 130 colon cancer resection specimens in relation to conventional clinicopathological parameters and patients’ survival. Statistical significant positive associations emerged between: (a) RPA1 and RPA2 protein expressions (P=0.0001), (b) RPA1 and RPA2 labelling indices (LIs) and advanced stage of the disease (P=0.001 and 0.003, respectively), (c) RPA1 and RPA2 LIs and the presence of lymph node metastasis (P=0.002 and 0.004, respectively), (d) RPA1 LI and the number of infiltrated lymph nodes (P=0.021), (e) RPA2 LI and histological grade of carcinomas (P=0.05). Moreover, a statistical significant higher RPA1 LI was observed in the metastatic sites compared to the original ones (P=0.012). RPA1 and RPA2 protein expression associated with adverse patients’ outcome in both univariate (log rank test: P<0.00001 and 0.00001, respectively) and multivariate (Cox model: P=0.092 and 0.0001, respectively) statistical analysis. Statistical significant differences according to the expression of RPA1 and RPA2 proteins were also noticed in the survival of stage II (P<0.00001 and 0.0016, respectively) and stage III (P=0.0029 and 0.0079, respectively) patients. In conclusion, RPA1 and RPA2 proteins appear to be useful prognostic indicators in colon cancer patients and attractive therapeutic targets for regulation by tumor suppressors or other proteins involved in the control of cell proliferation.

Ghrelin: A potential therapeutic target for cancer

Ghrelin is a recently identified 28-amino-acid peptide, capable of stimulating pituitary growth hormone release in humans and other mammals. It is mainly secreted from the gastric mucosa, but it is also widely expressed in a variety of tissues, in both normal and malignant conditions. Ghrelin has a multiplicity of physiological functions in gastrointestinal, cardiovascular, pulmonary and immune system, and also exerts a variety of roles, from increasing food intake (orexigenic effect) to affecting cell proliferation. The actions of ghrelin are mediated by the ghrelin receptor, also known as the growth hormone secretagogue receptor (GHS-R). The purpose of this review is to provide an overview of the expression and putative role of ghrelin and its receptor in cancer. Ghrelin and its receptor are detected in tumor tissues, and evidence is emerging that ghrelin plays an autocrine/paracrine role in cancer and could serve as a diagnostic or prognostic tool or as therapeutic target.

Bacterial translocation, endotoxaemia and apoptosis following Pringle manoeuvre in rats ☆

BACKGROUND Intraoperative occlusion of the hepatoduodenal ligament (Pringle manoeuvre (Pm)) is often employed for the reduction of blood loss during liver surgery. No data exist to date on the effects of Pm on mucosal barrier dysfunction, systemic bacterial translocation (BT), endotoxaemia and apoptosis. MATERIALS AND METHODS Sixty-five male Wistar rats in three groups: I (n=25) controls, II (n=20) sham operation, III (n=20) occlusion of the hepatoduodenal ligament (Pm). Tissue samples from mesenteric lymph nodes (MLNs), liver, lungs and spleen were analysed after 30 min and at 24 h. Endotoxin was measured in portal and aortic blood and routine haematological and biochemical parameters were measured before and after Pm. RESULTS No differences were found in the blood parameters before and after Pm, but a significant increase in contaminated MLNs and liver was noted. All cultured bacteria were enteric in origin. Portal and aortic endotoxin were significantly increased. Overall the ileal architecture remained intact in all specimens studied and no significant pathology was observed. The ABC increased after Pm significantly (P<0.01). CONCLUSION Normothermic Pm of 30 min duration results in immediate and delayed gut barrier failure by significantly increasing BT and endotoxaemia which might be attributed to portal stasis leading to intestinal congestion as well as temporary liver ischaemia. Apoptosis increased significantly 30 min after performing the Pm.

Focal adhesion kinase expression is not a prognostic predictor in colon adenocarcinoma patients.

AIM Focal adhesion kinase (FAK) is an enzyme of the tyrosine kinase group linked to signaling pathways between cells and their extracellular matrix. FAK expression in tumor cells in vitro may correlate with their ability for invasion and metastasis. METHODS FAK protein expression was examined immunohistochemically in 80 cases of colon adenocarcinoma, and correlated with clinicopathological parameters; tumor proliferative capacity, reflected by Ki-67 antigen expression; and survival. RESULTS All tumor samples were FAK positive compared to normal colonic mucosa. FAK protein overexpression was seen in 32 out of 80 cases. FAK protein overexpression did not correlated with tumor histological grade, stage, Ki-67 positivity or survival. CONCLUSIONS Raised FAK protein expression was noted by immunohistochemistry in human colon carcinoma cases. The implication are discussed.

Ghrelin's role on gastrointestinal tract cancer

Ghrelin is a recently identified 28-amino-acid peptide, with pituitary growth hormone releasing activities in humans and other mammals. In mammals, ghrelin plays a variety of roles, including influence on food intake, gastric motility, and acid secretion of the gastrointestinal tract. It is mainly secreted from the stomach mucosa, but it is also expressed widely in other tissues - in normal and malignant conditions - and, therefore, ghrelin may exert such variable endocrine and paracrine effects, as autocrine and/or paracrine function in cancer. Ghrelins actions are mediated via its receptor, known as growth hormone secretagogue receptor (GHS-R), type 1a and 1b. Several endocrine and non-endocrine cancers, such as gastro-entero-pancreatic carcinoids, colorectal neoplasms, pituitary adenomas, pulmonary and thyroid tumours, as well as lung, breast, and pancreatic carcinomas express ghrelin at both mRNA and protein levels. In the current review, we summarise the available so far data with regard to: (a) the structure of the ghrelin molecule and its receptor; (b) its tissue contribution in physiologic and neoplasmatic conditions; and (c) ghrelins possible role in carcinogenesis; specifically, in the area of gastrointestinal tract cancer. The aim of the present study is to determine whether or not ghrelin promotes the proliferation rate of the gastrointestinal tract (GIT) tumours.