Effects of basic fibroblast growth factor on ischemic gut and liver injuries

AIMS To explore the possible effects of basic fibrob- last growth factor (bFGF) on ischemic gut and liver in- juries after trauma. METHODS Animal model of super mesenteric artery (SMA) occlusion was used in this study. Seventy-two Wistar rats were divided into three groups of 24 rats each. Each animal in group 1 (bFGF treated) was in- jected with 4 μg of bFGF in 0.15 ml of normal saline solution containing 0.1%(w/v) heparin through the jugular vein at the onset of reperfusion. Animals in group 2 (saline treated) received the same vehicle, but without bFGF. Group 3 (sham-operated) ani- mals were treated with the same operations,but without SMA occlusion. Liver function parameters, serum TNFα,bacterial examination and pathological study were used to evaluate the results. RESULTS In group 1,the amounts of ALT and AST and serum TNFα were reduced significantly at 6,24 and 48 hours as compared with group 2. Bacterial ex- amination showed that the bacterial translocation from gut to liver,spleen and MLN in group 1 was much lower than that in group 2. The pathological results support the concept of significant protecting effects of bFGF. CONCLUSIONS Venous administration of bFGF may help reduce gut and liver injuries after ischemia and reperfusion. Its mechanism of action may involve the mitogenic and non-mitogenic effects of bFGF.

Inhibition of CXCR4 activity with AMD3100 decreases invasion of human colorectal cancer cells in vitro

AIM: To investigate the effect and mechanism of blockade of the CXC chemokine receptor-4 (CXCR4) signaling pathway by AMD3100, a small non-peptide CXCR4 inhibitor, on invasion and metastasis of colorectal cancer cells in vitro. METHODS: Human colorectal cancer cell line SW480 was treated with AMD3100 at different final concentrations. 3-(4,5-dimethylthiazole-2-yl)-2.5-dipheny-ltetrazolium bromide (MTT) assay was used to detect the effect of AMD3100 on cell proliferation. The invasion ability of SW480 cells was determined by cell invasion assay kit. In the presence of AMD3100, the CXCL12-mediated migratory response of SW480 cells was tested by classical chemotaxis assays. RT-PCR analysis and Western blotting were used to detect the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in SW480 cells. RESULTS: Cell viability was significantly suppressed by AMD3100 in a dose-dependent manner. AMD3100 (100 and 1000 ng/mL) significantly inhibited the invasion ability of SW480 cells. Treatment with AMD3100 markedly reduced the expression of VEGF and MMP-9 but not MMP-2 in SW480 cells. CONCLUSION: The CXCL12/CXCR4 system is an important mediator of proliferation and invasion of CXCR4-expressing colorectal cancer cells. AMD3100 inhibited invasion and metastasis activity of the colorectalcancer cell line SW480 through down-regulation of VEGF and MMP-9 expression.

Overexpression of connective tissue growth factor WISP-1 in Chinese primary rectal cancer patients

AIM： To clarify the expression change of Wnt-induced secreted protein-1 （WISP-l） in human rectal cancer and to determine whether it is correlated with invasion and metastasis of human rectal cancer.METHODS： Eighty-six paired samples of rectal cancer and surgically resected distant normal rectal tissue were collected and allocated into cancer group and control group respectively. WISP-1 mRNA was detected by relative quantitative real-time RT-PCR and WISP-1 protein was examined by immunohistochemical staining.RESULTS： WISP-1 gene overexpression was found in 65% （56/86） primary rectal cancers, 2-30 times that of the level in normal matched rectal tissues （P = 0.001）. The mRNA expression level was correlated with Duke＇s staging, histological differentiation grade and lymph node status. The WISP-1 protein expression was in accordance with mRNA expression level. The positive degree of immunohistochemical staining in the cancer group （1.40±0.35） was different from that in control group （1.04± 0.08, P 〈 0.001）. Moreover, in cancer group the positive staining degree in high-level mRNA cancers （1.46 ±0.37, n = 56） was higher than that in low-level mRNA （1.28 ± 0.28, n = 30, P = 0.018）.CONCLUSION： Aberrant levels of WISP-1 expression may play a role in rectal tumorigenesis. WISP-1 may be used as a specific clinical diagnosis and prognosis marker in rectal cancer.

Treatment of metastatic colorectal carcinomas by systemic inhibition of vascular endothelial growth factor signaling in mice

AIM： Tumor angiogenesis has been shown to be promoted by vascular endothelial growth factor （VEGF） via stimulating endothelial cell proliferation, migration, and survival. Blockade of VEGF signaling by different means has been demonstrated to result in reduced tumor growth and suppression of tumor angiogenesis in distinct tumor entities. Here, we tested a recombinant adenovirus, AdsFItl-3, that encodes an antagonistically acting fragment of the VEGF receptor 1 （Fit-l）, for systemic antitumor effects in pre-established subcutaneous CRC tumors in mice.METHODS： Murine colorectal carcinoma cells （CT26） were inoculated subcutaneously into Balb/c mice for in vivo studies. Tumor size and survival were determined. 293 cell line was used for propagation of the adenoviral vectors. Human lung cancer line A549 and human umbilical vein endothelial cells were transfected for in vitro experiments.RESULTS： Infection of tumor cells with AdsFlt1-3 resulted in protein secretion into cell supernatant, demonstrating correct vector function. As expected, the secreted sFlt1-3 protein had no direct effect on CT26 tumor cell proliferation in vitro, but endothelial cell function was inhibited by about 46% as compared to the AdLacZ control in a tube formation assay. When AdsFlt1-3 （5×10^9 PFU/animal） was applied to tumor bearing mice, we found a tumor inhibition by 72% at d 12 after treatment initiation, in spite of these antitumoral effects, the survival time was not improved. According to reduced intratumoral microvessel density in AdsFlt1-3-treated mice, the antitumor mechanism can be attributed to angiostatic vector effects. We did not detect increased systemic VEGF levels after AdsFlt1-3 treatment and liver toxicity was low as judged by serum alanine aminotransferase determination.CONCLUSION： In this study we confirmed the value of a systemic administration of AdsFItl-3 to block VEGF signaling as antitumor therapy in an experimental metastatic colorectal carcinoma model in mice.

KIT exon 11 codon 557/558 deletion/insertion mutations define a subset of gastrointestinal stromal tumors with malignant potential

AIM: To study the association of the frequency and pattern of KIT and PDGFRA mutations and clinicopathological factors in a group of patients with gastrointestinal stromal tumors (GIST). METHODS: Thirty patients with GIST were examined. Exons 9, 11, 13, and 17 of the KIT and exons 12 and 18 of the PDGFRA gene were analyzed for the presence of mutations by PCR amplification and direct sequencing. RESULTS: KIT or PDGFRA mutations were detected in 21 of the 30 patients (70%). Sixteen patients had mutations within KIT exon 11, three within KIT exon 9, and two within PDGFRA exon 18. GISTs with KIT exon 9 mutations were predominantly located in the small intestine, showed a spindle cell phenotype, and were assessed as potentially malignant. GISTs with KIT exon 11 mutations were located in the stomach and intestine, showed mainly a spindle cell phenotype, and were scored as potentially malignant (P < 0.05). Tumors with KIT exon 11 codon 557/558 deletion/insertion mutations were found to be associated with a potentially malignant clinical behaviour (P < 0.003). GISTs with PDGFRA mutations located in stomach showed a mixedcell phenotype and were classified as of very low or low moderate malignant potential. CONCLUSION: Determination of KIT and PDGFRA mutations should be additional parameters for the better prediction of GISTs clinical behaviour. Tumors with deletion/insertion mutations affecting codons 557/558 of the KIT gene seem to represent a distinct subset of malignant GISTs.

New approaches in angiogenic targeting for colorectal cancer

Colorectal carcinoma （CRC） is one of the leading causes of cancer death worldwide. In the last decade, the addition of irinotecan and oxaliplatin to standard fluorouracil-based chemotherapy regimens have set the new benchmark of survival for patients with metastatic CRC at approximately 20 too. Despite these advances in the management of CRC, there is a strong medical need for more effective and well-tolerated therapies. The dependence of tumor growth and metastasis on blood vessels makes angiogenesis a rational target for therapy. One of the major pathways involved in this process is the vascular endothelial growth factor （VEGF） and its receptors （VEGFR）. In 2004, the first agent targeting angiogenesis, bevacizumab （BV）, was approved as an adjunct to first-line cytotoxic treatment of metastatic CRC. The role of BV as part of adjuvant treatment and in combination with other targeted therapies is the subject of ongoing trials. However, BV is associated with an increase in the risk of arterial thromboembolic events, hypertension and gastrointestinal perforations and its use must be cautious. Novel VEGFR TK inhibitors with different ranges of nanomolar potencies, selectivities, and pharmacokinetic properties are entering phase 111 trials for the treatment of cancer. Conversely, one of these novel agents, vatalanib, has been shown not to confer survival benefit in first and second-line treatment of advanced CRC. The basis of these findings is being extensively evaluated. Ongoing and new well-designed trials will define the optimal clinical application of the actual antiangiogenic agents, and, on the other hand, intensive efforts in basic research will identify new agents with different antiangiogenic approaches for the treatment of CRC. In this review we discuss and highlight current and future approaches in angiogenic targeting for CRC.

Dynamic change of epidermal growth factor in neonatal rat with intestine injury

AIM: To determine whether diminished levels of epidermal growth factor (EGF) were present in neo-natal rats with intestinal injury and related with the degree of intestinal injury, so we modeled a model in neo-natal rats of intestinal injury and to examine the dynamic levels of EGF on injury of intestine.METHODS: One-day-old Wistar rat pups received an intraperitoneally injection with 4 mg/kg lipopolysaccharide (LPS), followed by collection of ileum tissue at 1, 3, 6, 12,and 24 h following LPS administration. The ileum was for histological evaluation of NEC and for measurements of EGF using ABC-ELISA. The correlation between the degree of intestinal injury and levels of EGF was determined. RESULTS: The LPS-injected pups also showed a significant increase in injury scores at 1, 3, 6, 12, and 24 h [respectively, (1.08±0.61), (1.63±0.84), (1.95±0.72), (2.42±0.43)and (2.21±0.53)] vsthe control (0.12±0.17) (P＜0.01).EGF levels at 1, 3, 6, 12 h [respectively, (245.6±49.0), (221.4±39.0), (223.4±48.1), (246.0±46.6)] pg/mg were significantly loss than the control (275.6±50.4) pg/mg (P＜0.05). There was a significant negative correlation between the EGF levels and the grade of intestinal injury within 24 h (P＜0.05).CONCLUSION: Neo-natal rats with intestinal injury have significantly lower levels of ileum EGF. Reduced levels of this growth factor might be related to the pathogenesis of NEC.

Evaluation of malignancy using Ki-67,p53,EGFR and COX-2 expressions in gastrointestinal stromal tumors

AIM:To investigate the role of expressions of Ki-67, p53,epidermal growth factor receptor(EGFR)and cyclooxygenase-2(COX-2)in gastrointestinal stromal tumor(GIST)grading and prognosis. METHODS:Tumor tissue was collected retrospectively from 96 patients with GIST.Antibodies against Ki-67, p53,EGFR and COX-2 were used for immunohistochemical staining.Tumor grading was designated according to a consensus system and the staining was quantified in 3 categories for each antibody in the statistical analysis. RESULTS:The Ki-67 expression in GISTs was significantly associated with the size of the tumors,mitotic rate and the risk of malignancy(x2=15.51,P=0.02; x2=22.27,P<0.001;x2=20.05;P<0.001).The p53 expression was also significantly correlated with mitotic rate and the risk of malignancy(x2=9.92,P= 0.04;x2=9.97;P=0.04).Over-expression of Ki-67 was strongly correlated with poor survival(x2=10.44, P=0.006),but no correlation was found between the expression of p53,EGFR or COX-2 and survival. Multivariate analysis further demonstrated that Ki-67 expression(relative risk=15.78,95%CI:4.25-59.37) could be used as an independent prognostic value for GIST patients.Adjuvant imatinib therapy could improve clinical outcomes in the patients with high risk and intermediate risk of recurrence after complete tumor resections(median survival time:52 mo vs 37 mo, x2=7.618,P=0.006). CONCLUSION:Our results indicated that the expression of Ki-67 could be used as an independent prognostic factor for GIST patients.

Prognostic significance of BMP and activin membrane-bound inhibitor in colorectal cancer

AIM： To investigate the clinical significance of BMP and activin membrane-bound inhibitor （BAMBI） which is a pseudoreceptor of transforming growth factorbeta （TGF-β） type 1 receptors and acts as a negative regulator of TGF-β signaling and expression aberrantly elevated in colorectal cancers （CRCs）. We studied BAMBI expression in CRCs. METHODS： We studied BAMBI expression in 183 surgically resected CRCs by immunochemical and immunoblotting analyses using a generated monoclonal anti-BAMBI antibody. Commercially available anti-β- catenin and anti-p53 antibodies were also applied for immunochemical analyses as a comparison control.RESULTS： Immunohistochemical analysis revealed that BAMBI expression was observed in 148 （80.8%）, and strong BAMBI expression was observed in 46% of the CRCs. Strong BAMBI expression was positively correlated with histological type, depth of invasion, lymph node metastases, and tumor node metastasis （TNM） stage （P 〈 0.05）. Clear associations were found between BAMBI and β-catenin （P = 0.035） and p53 （P =0.049） expression. In curatively resected CRC, 5-year recurrence-free survival was 51.9% （P = 0.037） for strong BAMBI expression compared to 79.8% for weak BAMBI expression. In the Cox＇s multivariate analysis, lymph node metastases （relative risk 6.685; P 〈 0.001） and depth of invasion （RR 14.0; P = 0.013） were significant indicators for recurrence, and strong BAMBI expression （RR 2.26; P = 0.057） tended to be significant. CONCLUSION： BAMBI was linked to a potentially aggressive tumor phenotype and predicted tumor recurrence and cancer-related death in CRC. BAMBI expression might be applicable in the routine clinical setting of CRC.

Primary multiple extragastrointestinal stromal tumors of the omentum with different mutations of c-kit gene

The author reports a very rare case of sporadic primary multiple extragastrointestinal stromal tumors (EGISTs) of the omentum associated with different mutations of the exon 11 of the c-kit gene in a 75-year-old man with gastric cancer. During an operation for the cancer, two solid tumors (10 mm and 8 mm) were found in the omentum. Both tumors consisted of cellular spindle cells. Mitotic figures were two and three per 50 high power fields. The tumor cells were positive for KIT, CD34 and vimentin, but negative for desmin, S100 protein, α-smooth muscle actin and p53 protein. Ki67 labeling was 2% and 3%. The larger EGIST showed a deletion of codons 552-558 of exon 11 of the c-kit gene, while the smaller EGIST had a point mutation at codon 559 (GTT←GAT) in exon 11 of the c-kit gene. Exons 9, 13, and 17 of the c-kit gene, and exons 12 and 18 of the platelet derived growth factor receptor α genes showed no mutations. The case shows that sporadic multiple EGISTs can occur in the omentum.

Transforming growth factor beta can be a parameter of aggressiveness of pT1 colorectal cancer

AIM: To evaluate the significance of transforming growth factor beta (TGF β) expression, in correlation with histopathological parameters, at the front of invasion in T1 colorectal cancer (CRC) and presence of metastases. METHODS: TGF p immunohistochemical expression was studied in 34 specimens of colorectal adenocarcinomas (pT1). A three-step avidin-biotinylated immuno-peroxidase (ABCu-NCL) staining technique was performed on 4-μm paraffin-embedded tissue sections with a monoclonal antibody to TGF β (Novocastra, NCL-TGFB, clone TGFB 17, dilution 1:40). RESULTS: Seventeen (50%) out of 34 lesions were positive for TGF p expression. The TGF β-positive rate in patients with vascular invasion was significantly higher than in those without vascular invasion (11/14 cases, P<0.01, P= 0.005). The TGF p-positive rate was observed in 91.7% of patients with presence of tumor budding at the front of invasion (11/12 cases, P<0.01, P= 0.0003). A statistically significant correlation was found between the presence of lymph node metastases and positive expression of TGF β (14/16 cases, P<0.01, P= 0.0001). We also observed that the TGF β-positive rates in groups with distant and non-distant metastases were 92.8% and 20% respectively, and a significant correlation between TGF β expression and distant metastasis was shown (P<0.01, P= 0.00003). CONCLUSION: The evaluation of TGF β expression of protein in association with histological parameters can be used as a parameter of the aggressiveness of pT1 CRC.

Acid fibroblast growth factor reduces rat intestinal mucosal damage caused by ischemia-reperfusion insult

AIM： To detect the effects of acid fibroblast growth factor （aFGF） on apoptosis and proliferation of intestinal epithelial cells in differentiation or proliferation status to explore the protective mechanisms of aFGF. METHODS： Wistar rats were randomly divided into sham-operated control group （C, n = 6）, intestinal ischemia group （I, n = 6）, aFGF treatment group （A, n =48） and intestinal ischemia-reperfusion group （R, n =48）. Apoptosis of intestinal mucosal cells was determined with terminal deoxynucleotidyl transferasemediated dUTP-biotin nick-end labeling （TUNEL） technique. Proliferating cell nuclear antigen （PCNA） protein expression and distribution were detected with immunohistochemical method. Plasma levels of D-lactate were determined with modified Brandts method. RESULTS： In A group, administration of exogenous aFGF could improve intestinal histological structure and decrease plasma D-lactate levels at 2-12 h after the reperfusion compared with R group. The apoptotic rates and PCNA protein expressions were not increased until 2 h after reperfusion and were maximal at 12 h. After reperfusion for 2-12 h, the apoptotic rates were gradually augmented along the length of jejunal crypt-villus units. Administration of aFGF could significantly reduce the apoptotic response at 2-12 h after reperfusion （P〈0.05）. Apoptosis rates in villus and crypt epithelial cells in A group at 12 h after reperfusion were （62.5±5.5）% and （73.2±18.6）% of those in R group, respectively. Treatment of aFGF could apparently induce protein expression of PCNA in intestinal mucosal cells of A group compared with R group during 2-22 h after reperfusion （P〈0.05）. There were approximately 1.3- and 1.5-times increments of PCNA expression levels in villus and crypt cells in A group at 12 h after reperfusion compared with R group, respectively. CONCLUSION： Intestinal I/R insult could lead to histological structure change and apoptotic rate increment. The protective effects of aFGF against ischernia/reperfusion in rat intestinal rnucosa might be partially due to its ability to inhibit ischernia/reperfusioninduced apoptosis and to promote cell proliferation of crypt cells and villus epithelial cells.

Association of overexpression of TIF1γ with colorectal carcinogenesis and advanced colorectal adenocarcinoma

AIM:To determine the expression and clinical significance of transcriptional intermediary factor 1 gamma (TIF1γ),Smad4 and transforming growth factor-beta (TGFβR) across a spectrum representing colorectal cancer (CRC) development.METHODS:Tissue microarrays were prepared from archival paraffin embedded tissue,including 51 colorectal carcinomas,25 tubular adenomas (TA) and 26 HPs,each with matched normal colonic epithelium.Immunohistochemistry was performed using antibodies against TIF1γ,Smad4 and TGFβ RⅡ.The levels of expression were scored semi-quantitatively (score 0-3 or loss and retention for Smad4).RESULTS:Overexpression of TIF1γ was detected in 5/26 (19%) HP;however,it was seen in a significantly higher proportion of neoplasms,15/25 (60%) TAs and 24/51 (47%) CRCs (P<0.05).Normal colonic mucosa,HP,and TAs showed strong Smad4 expression,while its expression was absent in 22/51 (43%) CRCs.Over-expression of TGFβ RⅡ was more commonly seen in neoplasms,13/25 (52%) TAs and 29/51 (57%) CRCs compared to 9/26 (35%) HP (P<0.05).Furthermore,there was a correlation between TIF1γ overexpression and Smad4 loss in CRC (Kendall tau rank correlation value=0.35,P<0.05).The levels of TIF1γ overexpression were significantly higher in stage Ⅲ than in stage Ⅰ and Ⅱ CRC (P<0.05).CONCLUSION:The findings suggest that over-expression of TIF1γ occurs in early stages of colorectal carcinogenesis,is inversely related with Smad4 loss,and may be a prognostic indicator for poor outcome.

Metastasis-associated protein 1 induces VEGF-C and facilitates lymphangiogenesis in colorectal cancer

AIM:To study the correlation between high metastasisassociated protein 1(MTA1)expression and lymphangiogenesis in colorectal cancer(CRC)and its role in production of vascular endothelial growth factor-C(VEGF-C). METHODS:Impact of high MTA1 and VEGF-C expression levels on disease progression and lymphovasculardensity(LVD,D2-40-immunolabeled)in 81 cases of human CRC was evaluated by immunohistochemistry. VEGF-C mRNA and protein expressions in human LoVo and HCT116 cell lines were detected by real-time polymerase chain reaction and Western blotting,respectively,with a stable expression vector or siRNA. RESULTS:The elevated MTA1 and VEGF-C expression levels were correlated with lymph node metastasis and Dukes stages(P<0.05).Additionally,high MTA1 expression level was correlated with a large tumor size(P< 0.05).A significant correlation was found between MTA1 and VEGF-C protein expressions in tumor cells(r=0.371, P<0.05).Similar to the VEGF-C expression level,high MTA1 expression level was correlated with high LVD in CRC(P<0.05).Furthermore,over-expression of MTA1 significantly enhanced the VEGF-C mRNA and protein expression levels,whereas siRNAs-knocked down MTA1 decreased the VEGF-C expression level. CONCLUSION:MTA1,as a regulator of tumor-associated lymphangiogenesis,promotes lymphangiogenesis in CRC by mediating the VEGF-C expression.

Hypoxia-inducible factor 1 alpha and vascular endothelial growth factor overexpression in ischemic colitis

AIM: To examine the etiology and pathophysiology in human ischemic colitis from the viewpoint of ischemic factors such as hypoxia-inducible factor 1 alpha (HIF-1 alpha and vascular endothelial growth factor (VEGF). METHODS: Thirteen patients with ischemic colitis and 21 normal controls underwent colonoscopy. The follow-up colonoscopy was performed in 8 patients at 7 to 10 d after the occurrence of ischemic colitis. Biopsy samples were subjected to real-time RT-PCR and immunohistochemistry to detect the expression of HIF-1 alpha and VEGF. RESULTS: HIF-1 alpha and VEGF expression were found in the normal colon tissues by RT-PCR and immunohistochemistry. HIF-1 alpha and VEGF were overexpressed in the lesions of ischemic colitis. Overexpressed HIF-1 alpha and VEGF RNA quickly decreased to the normal level in the scar regions at 7 to 10 d after the occurrence of ischemic colitis. CONCLUSION: Constant expression of HIF-1 alpha and VEGF in normal human colon tissue suggested that HIF-1 alpha and VEGF play an important role in maintaining tissue integrity. We confirmed the ischemic crisis in ischemic colitis at the molecular level, demonstrating overexpression of HIF-1 alpha and VEGF in ischemic lesions. These ischemic factors may play an important role in the pathophysiology of ischemic colitis.

Production of Human Epidermal Growth Factor in Fed-batch Culture of Acetate-tolerant Escherichia coli

An acetate-tolerant mutant of Escherichia coli DH5α, DA19, was used for secretory production of human epidermal growth factor （hEGF） whose expression was under the control of phoA promoter. The recombinant cells were cultured in a chemically defined medium, and glucose was added at different specific provision rates during the growth and expression phases. It was found that pH had a significant effect on the extracellular hEGF production. The extracellular hEGF concentration was 75.5mg·L^-1, 5.2-fold of the level reached at pH 7.0, even though more acetate was produced. Nitrogen source was limited in the later growth phase. Supplementation of ammonium promoted the consumption of phosphate and reduced the time to exhaust phosphate, but the extracellular hEGF production was similar to that without supplementation of ammonium.

Tyrosine kinase of insulin-like growth factor receptor as target for novel treatment and prevention strategies of colorectal cancer

AIM： To investigate the antineoplastic potency of the novel insulin-like growth factor 1 receptor （IGF-1R） tyrosine kinase inhibitor （TKI） NVP-AEW541 in cell lines and primary cell cultures of human colorectal cancer （CRC）. METHODS： Cells of primary colorectal carcinomas were from 8 patients. Immunostaining and crystal violet staining were used for analysis of growth factor receptor protein expression and detection of cell number changes, respectively. Cytotoxicity was determined by measuring the release of the cytoplasmic enzyme lactate dehydrogenase （LDH）. The proportion of apoptotic cells was determined by quantifying the percentage of sub-G1 （hypodiploid） cells. Cell cycle status reflected by the DNA content of the nuclei was detected by flow cytometry. RESULTS： NVP-AEW541 dose-dependently inhibited the proliferation of colorectal carcinoma cell lines and primary cell cultures by inducing apoptosis and cell cycle arrest. Apoptosis was characterized by caspase-3 activation and nuclear degradation. Cell cycle was arrested at the G1/S checkpoint. The NVP-AEW541-mediated cell cycle-related signaling involved the inactivation of Akt and extracellular signal-regulated kinase （ERK） 1/2, the upregulation of the cyclin-dependent kinase inhibitors p21^waf1/CIP1 and p27^kjp1, and the downregulation of the cell cycle promoter cyclin D1. Moreover, BAX was upregulated during NVP-AEW541-induced apoptosis, whereas Bcl-2 was downregulated. Measurement of LDH release showed that the antineoplastic effect of NVP-AEW541 was not due to general cytotoxicity of the compound. However, augmented antineoplastic effects were observed in combination treatments of NVP-AEW541 with either 5-FU, or the EGFR-antibody cetuximab, or the HMG-CoA-reductase inhibitor fluvastatin. CONCLUSION： IGF-1R-TK inhibition is a promising novel approach for either monoor combination treatment strategies of colorectal carcinoma and even for CRC chemoprevention.

Is diabetes a causal agent for colorectal cancer? Pathophysiological and molecular mechanisms

The possible relationship between diabetes mellitus (DM) and colorectal cancer (CRC), concerning pathophysiological and molecular mechanisms is highlighted in this review. The most recent and complete articles and developments in this particular field were thoroughly reviewed. Common risk factors, such as obesity, sedentary lifestyle, and Western diet between DM and CRC, led to the theory that DM might be a causal agent for CRC development. Various studies have connected type 2 DM and CRC, either proximal or distal, in both sexes. Additionally, chronic insulin treatment has been linked with increased colorectal tumor risk among type 2 diabetic patients. Interestingly, elevated hemoglobin A1c has been proven to be an independent predictor of aggressive clinical behavior in CRC patients. These mechanisms include the insulin-like growth factor-hyperinsulinemia theory and the participation of oncogenic intracellular signaling pathways. Furthermore, it has been proposed that Cox-2 inhibitors might have a role in decreasing the incidence of CRC. Finally, the use of statins to reduce the risk for colon cancer in patients with diabetes has remained controversial. Diabetic patients over 50 should receive counseling regarding their elevated risk for CRC, and screening colonoscopy should be recommended before initiating insulin therapy. However, there are no current guidelines, and this strategy is not yet applicable to some countries, as the corresponding risk would not allow screening colonoscopy to be adopted. There is strong evidence to indicate that DM is a causal agent for CRC development. This conclusion provides new impetus for re-evaluating CRC screening worldwide.

Molecular basis of the potential of mesalazine to prevent colorectal cancer

Patients with ulcerative colitis (UC) and Crohn's disease (CD) are at increased risk for developing colorectal cancer (CRC), and this is believed to be a result of chronic inflammation. Although conclusive evidence is still missing, both epidemiological and experimental observations suggest that certain drugs used to treat inflammation, such as mesalazine, can reduce the incidence of colitis-associated CRC. Therefore, in recent years, several studies have been conducted to dissect the mechanisms by which mesalazine interferes with CRC cell growth and survival. This review summarizes the current information on the molecular mechanisms that underlie the antineoplastic action of mesalazine.

Interleukin-24 is correlated with differentiation and lymph node numbers in rectal cancer

AIM:To assess the significance of interleukin(IL)-24 and vascular endothelial growth factor(VEGF)expression in lymph-node-positive rectal cancer. METHODS:Between 1998 and 2005,90 rectal adenocarcinoma patients with lymph node involvement were enrolled.All patients received radical surgery and postoperative pelvic chemoradiotherapy of 50.4-54.0 Gy.Chemotherapy of 5-fluorouracil and leucovorin or levamisole was given intravenously during the first and last week of radiotherapy,and then monthly for about 6 mo.Expression of IL-24 and VEGF was evaluated by immunohistochemical staining of surgical specimens, and their relations with patient characteristics and survival were analyzed.The median follow-up of surviving patients was 73 mo(range:52-122 mo). RESULTS:IL-24 expression was found in 81 out of 90 patients;31 showed weak intensity and 50 showedstrong intensity.VEGF expression was found in 64 out of 90 patients.Negative and weak intensities of IL-24 expression were classified as negative expression for analysis.IL-24 expression was significantly reduced in poorly differentiated tumors in comparison with well or moderately differentiated tumors(P=0.004),N2b to earlier N stages(P=0.016),and stageⅢc to stageⅢ a orⅢb(P=0.028).The number of involved lymph nodes was also significantly reduced in IL-24-positive patients in comparison with IL-24-negative ones. There was no correlation between VEGF expression and patient characteristics.Expression of IL-24 and VEGF was not correlated with survival,but N stage and stages were significantly correlated with survival. CONCLUSION:IL-24 expression was significantly correlated with histological differentiation,and inversely correlated with the degree of lymph node involvement in stageⅢrectal cancer.