SAR131675 exhibits anticancer activity on human ovarian cancer cells through inhibition of VEGFR-3/ERK1/2/AKT signaling pathway

Vascular endothelial growth factor receptor-3 (VEGFR-3) is known to participate in tumorigenesis and lymphangiogenesis, and as such, has the potential to serve as a molecular target for cancer therapy. SAR131675 is a highly selective VEGFR-3 antagonist that has an inhibitive effect on lymphatic cell growth. However, the anticancer effects and underlying mechanisms of SAR131675 in ovarian cancer remain poorly understood. In this study, we investigated the pathological role of VEGFR-3, and the effects of SAR131675 on proliferation, cell cycle, migration, and apoptosis in ovarian cancer cells. Our results showed that the mRNA and protein of VEGFR-3 were expressed in OVCAR3 and SKOV3 ovarian cancer cells, and this receptor was activated following stimulation with 50 ng/ml VEGF-C Cys156Ser (VEGF-CS), a selective ligand for VEGFR-3. Enhancing VEGFR-3 phosphorylation by treatment of ovarian cancer cells with VEGF-CS resulted in increased levels of phosphorylated extracellular signal-regulated kinases 1/2 (ERK1/2) and AKT. Moreover, our data demonstrated that SAR131675 inhibited VEGF-CS-mediated proliferation, colony formation, and migration of cancer cells in a dose-dependent manner. In addition, inhibition of VEGFR-3 activation with SAR131675 significantly increased cell cycle arrest and promoted apoptosis in both OVCAR3 and SKOV3 cells. Mechanistically, SAR131675 effectively suppressed the VEGF-CS-induced phosphorylation of VEGFR-3 and its downstream effectors including activated ERK1/2 and AKT in ovarian cancer cells. Our results reveal an anticancer activity of SAR131675 on the growth and migration of ovarian cancer cells, which may be through inhibiting VEGFR-3/ERK1/2/AKT pathway. SAR131675 may serve as an effective targeted drug for ovarian cancer.

Morphometric image analysis of vascular endothelial growth factor receptor-3 in preeclamptic, HIV infected women

OBJECTIVE

To ascertain the expression of vascular endothelial growth factor receptor-3 (VEGFR-3) in placental conducting and exchange villi from normotensive, preeclamptic (PE) and antiretroviral treated pregnant women, using morphometric image analysis.

STUDY DESIGN

This study utilizes retrospectively collected, paraffin wax-embedded, placental samples (n = 90) that were immuno-stained for VEGFR-3. During selection of the retrospective study, women with chronic illnesses were filtered out, to exclusively allow for the examination of VEGFR-3 immuno-expression in HIV and preeclamptic women. The study population consisted of normotensive (n = 30) and preeclamptic (n = 60) groups which were further divided on the basis of HIV status (negative - and positive +), and early and late onset preeclampsia (EOPE and LOPE respectively). The resulting groups were as follows; N- (n = 15), N+ (n = 15), EOPE- (n = 15), EOPE+ (n = 15), LOPE- (n = 15) and LOPE+ (n = 15). Microscopic examination and morphometric image analysis were performed on the immuno-stained placental tissue samples.

RESULTS

Analysis on HIV status did not yield a significant difference in conducting (p =  0.3015) or exchange (p =  0.4535) villi, regardless of pregnancy type. The N vs. PE analysis showed a reduced immuno-expression of VEGFR-3 in both conducting (p =  0.0107) and exchange (p <  0.0001) villi. Results from a multiple group comparative analysis of N vs. EOPE vs. LOPE VEGFR-3 immuno-expression, showed a significant difference between the N vs. EOPE groups.

CONCLUSION

The results presented provide compelling evidence that HIV infection does not significantly alter angiogenesis in placental villi. PE however, has caused angiogenic dysregulation and trophoblast pathology was observed. We report a severe downregulation of VEGFR-3 in placental villi from EOPE woman, regardless of HIV status. Hence we suggest a future investigation into EOPE's aetiology and its downstream effects on pregnancy.

Increased expression of vascular endothelial growth factor-C and vascular endothelial growth factor receptor-3 after pilocarpine-induced status epilepticus in mice

Vascular endothelial growth factor (VEGF)-C and its receptor, vascular endothelial growth factor receptor (VEGFR)-3, are responsible for lymphangiogenesis in both embryos and adults. In epilepsy, the expression of VEGF-C and VEGFR-3 was significantly upregulated in the human brains affected with temporal lobe epilepsy. Moreover, pharmacologic inhibition of VEGF receptors after acute seizures could suppress the generation of spontaneous recurrent seizures, suggesting a critical role of VEGF-related signaling in epilepsy. Therefore, in the present study, the spatiotemporal expression of VEGF-C and VEGFR-3 against pilocarpine-induced status epilepticus (SE) was investigated in C57BL/6N mice using immunohistochemistry. At 1 day after SE, hippocampal astrocytes and microglia were activated. Pyramidal neuronal death was observed at 4 days after SE. In the subpyramidal zone, VEGF-C expression gradually increased and peaked at 7 days after SE, while VEGFR-3 was significantly upregulated at 4 days after SE and began to decrease at 7 days after SE. Most VEGF-C/VEGFR-3-expressing cells were pyramidal neurons, but VEGF-C was also observed in some astrocytes in sham-manipulated animals. However, at 4 days and 7 days after SE, both VEGFR-3 and VEGF-C immunoreactivities were observed mainly in astrocytes and in some microglia of the stratum radiatum and lacunosum-moleculare of the hippocampus, respectively. These data indicate that VEGF-C and VEGFR-3 can be upregulated in hippocampal astrocytes and microglia after pilocarpine-induced SE, providing basic information about VEGF-C and VEGFR-3 expression patterns following acute seizures.

Lymphangiogenesis: fuel, smoke, or extinguisher of inflammation's fire?

Lymphangiogenesis is a recognized hallmark of inflammatory processes in tissues and organs as diverse as the skin, heart, bowel, and airways. In clinical and animal models wherein the signaling processes of lymphangiogenesis are manipulated, most studies demonstrate that an expanded lymphatic vasculature is necessary for the resolution of inflammation. The fundamental roles that lymphatics play in fluid clearance and immune cell trafficking from the periphery make these results seemingly obvious as a mechanism of alleviating locally inflamed environments: the lymphatics are simply providing a drain. Depending on the tissue site, lymphangiogenic mechanism, or induction timeframe, however, evidence shows that inflammation-associated lymphangiogenesis (IAL) may worsen the pathology. Recent studies have identified lymphatic endothelial cells themselves to be local regulators of immune cell activity and its consequential phenotypes - a more active role in inflammation regulation than previously thought. Indeed, results focusing on the immunocentric roles of peripheral lymphatic function have revealed that the basic drainage task of lymphatic vessels is a complex balance of locally processed and transported antigens as well as interstitial cytokine and immune cell signaling: an interplay that likely defines the function of IAL. This review will summarize the latest findings on how IAL impacts a series of disease states in various tissues in both preclinical models and clinical studies. This discussion will serve to highlight some emerging areas of lymphatic research in an attempt to answer the question relevant to an array of scientists and clinicians of whether IAL helps to fuel or extinguish inflammation. Impact statement Inflammatory progression is present in acute and chronic tissue pathologies throughout the body. Lymphatic vessels play physiological roles relevant to all medical fields as important regulators of fluid balance, immune cell trafficking, and immune identity. Lymphangiogenesis is often concurrent with inflammation and can potentially aide or worsen disease progression. How new lymphatic vessels impact inflammation and by which mechanism is an important consideration in current and future clinical therapies targeting inflammation and/or vasculogenesis. This review identifies, across a range of tissue-specific pathologies, the current understanding of inflammation-associated lymphangiogenesis in the progression or resolution of inflammation.

SiRNA-mediated silencing of VEGFR-3 reduces proliferation, adhesion and migration of colorectal cancer cells

AIM: To investigate the effect of transfection with an adenovirus vector expressing short interfering RNA (siRNA) targeting vascular endothelial growth factor receptor-3 (VEGFR-3) on cell proliferation, adhesion and migration in colorectal cancer cell line LoVo.

METHODS: An adenovirus vector expressing siRNA targeting VEGFR-3 was constructed and transfected into LoVo cells. The expression of VEGFR-3 was detected by RT-PCR and Western blot. Cell proliferation and migration were detected by MTT assay and Transwell assay, respectively.

RESULTS: The expression of VEGFR-3 mRNA and protein was significantly decreased after transfection with the recombinant adenovirus (P < 0.05), compared with the blank control group and negative control group. The proliferation, adhesion and migration of LoVo cells were significantly decreased after transfection with the recombinant adenovirus (P < 0.05).

CONCLUSION: SiRNA-mediated silencing of VEGFR-3 inhibits the proliferation, adhesion and migration of LoVo cells.

Targeting the C-terminal focal adhesion kinase scaffold in pancreatic cancer

Preliminary studies in our laboratory have demonstrated the importance of both the NH2 and COOH terminus scaffolding functions of focal adhesion kinase (FAK). Here, we describe a new small molecule inhibitor, C10, that targets the FAK C-terminus scaffold. C10 showed marked selectivity for cells overexpressing VEGFR3 when tested in isogenic cell lines, MCF7 and MCF7-VEGFR3. C10 preferentially inhibited pancreatic tumor growth in vivo in cells with high FAK-Y925 and VEGFR3 expression. Treatment with C10 led to a significant inhibition in endothelial cell proliferation and tumor endothelial and lymphatic vessel density and decrease in interstitial fluid pressure. These results highlight the underlying importance of targeting the FAK scaffold to treat human cancers.

Design, synthesis, and biological evaluation of novel FAK scaffold inhibitors targeting the FAK-VEGFR3 protein-protein interaction

Focal adhesion kinase (FAK) and vascular endothelial growth factor receptor 3 (VEGFR3) are tyrosine kinases, which function as key modulators of survival and metastasis signals in cancer cells. Previously, we reported that small molecule chlorpyramine hydrochloride (C4) specifically targets the interaction between FAK and VEGFR3 and exhibits anti-tumor efficacy. In this study, we designed and synthesized a series of 1 (C4) analogs on the basis of structure activity relationship and molecular modeling. The resulting new compounds were evaluated for their binding to the FAT domain of FAK and anti-cancer activity. Amongst all tested analogs, compound 29 augmented anti-proliferative activity in multiple cancer cell lines with stronger binding to the FAT domain of FAK and disrupted the FAK-VEGFR3 interaction. In conclusion, we hope that this work will contribute to further studies of more potent and selective FAK-VEGFR3 protein-protein interaction inhibitors.

Response letter regarding the interpretation of gene expression data

This is a response letter to Verna E’s comments regarding our previous manuscript published last year in the World Journal of Gastroenterology entitled “Relationship between LYVE-1, VEGFR-3 and CD44 gene expressions and lymphatic metastasis in gastric cancer”, which evaluated the relationship between these expression levels and clinicopathological parameters (Ozmen F et al, World J Gastroenterology 2011; 17: 3220-3228). The mean values for lymphatic vessel endothelial hyaluronan receptor-1, CD44 and vascular endothelial growth factor receptor-3 expression (represented as 2^-ΔΔCt) were 1.13, 1.24 and 1.17, respectively, suggesting an increase in gene expression in tumor tissue compared to normal tissue. Despite the increase in gene expression in the cancer tissues (2^-ΔΔCt > 1), only some of the results reached statistical significance, which was thoroughly discussed in our paper. In the present letter, we report that his comments are flawed and result in confusion. Therefore, we herein provide more explanation regarding gene expression in gastric cancer. We hope that this letter will address Verna E’s misunderstandings.

Relationship between LYVE-1, VEGFR-3 and CD44 gene expressions and lymphatic metastasis in gastric cancer

AIM: To investigate the expression levels of lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), vascular endothelial growth factor receptor-3 (VEGFR-3) and CD44 genes and the relationship between their levels and clinicopathological parameters in gastric cancer.

METHODS: Tissue samples were obtained from 33 patients (8 females) with gastric cancer. mRNA levels of LYVE-1, VEGFR-3 and CD44 in normal and tumor tissues were quantitatively measured using real time polymerase chain reaction. The results were correlated with lymph node metastasis, histological type and differentiation of the tumor, T-stage, and presence of vascular, perineural and lymphatic invasions. The distribution of molecules in the tissue was evaluated using immunohistochemistry.

RESULTS: LYVE-1, CD44 and VEGFR-3 gene expression levels were significantly higher in gastric cancer than in normal tissue. While there was no correlation between gene expressions and clinicopathologic features such as histologic type, differentiation and stage, gene expression levels were found to be increased in conjunction with positive lymph node/total lymph node ratio and the presence of perineural invasion. A significant correlation was also found between LYVE-1 and CD44 over-expressions and perineural invasion and lymph node positivity in gastric cancers. When the distribution of LYVE-1 antibody-stained lymphatic vessels in tissue was evaluated, lymphatic vessels were located intra-tumorally in 13% and peri-tumorally in 27% of the patients. Moreover, lymph node metastases were also positive in all patients with LYVE-1-staining.

CONCLUSION: LYVE-1, VEGFR-3 and CD44 all play an important role in lymphangiogenesis, invasion and metastasis. LYVE-1 is a perfectly reliable lymphatic vessel marker and useful for immunohistochemistry.

Serum VEGFR-3 and survival of advanced gastric cancer patients treated with FOLFOX

AIM: To explore if vascular endothelial growth factor receptor-3 (VEGFR-3) and carcinoembryonic antigen (CEA) can predict overall survival in advanced gastric cancer.

METHODS: VEGFR-3 level was assessed by enzyme-linked immunosorbent assay, and CEA was assessed by chemiluminescence immunoassay in the sera of 81 advanced gastric cancer patients before treatment with oxaliplatin plus 5-fluorouracil and folinic acid.

RESULTS: Median survival time in patients with a low serum VEGFR-3 level was significantly longer than in those with a higher VEGFR-3 level (15.4 mo vs 7.7 mo, P < 0.001). Patients with a low CEA level had a longer survival than those with a higher CEA level (15.8 mo vs 8.6 mo, P < 0.001). Thirty-nine patients with low VEGFR-3 and low CEA levels had a median survival of 19.7 mo (P = 0.0006). The hazard ratio for patients with a high VEGFR-3 level was 2.443 (P = 0.002).

CONCLUSION: High serum VEGFR-3 level is correlated significantly with poor survival. In patients with a high serum level of VEGFR-3, alternative chemotherapy regimens should be considered.

Expression of VEGF-C, VEGFR-3, CD105 and CD68 protein in esophageal squamous cell carcinoma and their significance

AIM: To explore the expression of VEGF-C, VEGFR-3, CD105, CD68 protein and their correlation with lymphatic and vascular metastasis in esophageal squamous cell carcinoma (ESCC).

METHODS: Immunohistochemical SP method was used to detect the expression of VEGF-C, VEGFR-3, CD105 and CD68 protein in 50 cases of esophageal squamous cell carcinoma, 19 cases of adjacent atypical hyperplasia epithelium and 50 cases of normal esophageal epithelium. Relationship between expression of proteins and clinical biology of ESCC was investigated.

RESULTS: The expression rates of VEGF-C, VEGFR-3, CD105 and CD68 protein decreased by turns in carcinoma, adjacent atypical hyperplasia epithelium and normal esophageal epithelium specimens (VEGF-C: 82.0%, 47.4%, 26.0%; VEGFR-3: 72.0%, 36.8%, 18.0%; CD105: 30.53 ± 7.42, 0, 0; CD68: 50.89 ± 10.36, 14.10 ± 3.59, 11.30 ± 3.72). There was a significant statistic difference among the groups (P < 0.05). The expression of VEGF-C, CD105 and CD68 protein was closely correlated with the TNM grade, infiltrative depth and lymphatic metastasis in esophageal squamous cell carcinoma (all P < 0.05). The expression of VEGFR-3 protein was closely correlated with the lymphatic metastasis in esophageal squamous cell carcinoma (all P < 0.05). The expression of VEGF-C protein had positive correlation with the expression of VEGFR-3 (P < 0.01). There were statistically significant differences among positive and negative expression of VEGF-C and VEGFR-3 groups, and TAMs count and positive expression of CD105 blood vessel groups (P < 0.05).

CONCLUSION: VEGF-C, VEGFR-3, CD105 and CD68 protein play important roles in the infiltration, vascular metastasis and carcinogenesis in esophageal carcinoma. Joint detection of VEGF-C, VEGFR-3, CD105 and CD68 protein is expected to be one of molecular index in the early diagnosis, prognostic judgment and vascular metastasis of esophageal squamous cell carcinoma, offering an objective and reliable parameter for the clinic immune therapy and anti-lymphatic metastasis treatment.

Ex vivo inhibitory effects of VEGFR-3 siRNA on growth of human colon cancer cells

AIM: To construct small interfering RNA (siRNA) expression vector (psiRNA-VEGFR-3) targeting vascular endothelial growth factor receptor-3 (VEGFR-3) gene and to investigate effects of psiRNA-VEGFR-3 on suppressing the VEGFR-3 gene expression in human colon cancer cell lines.

METHODS: Three pairs of 19 bp reverse repeated sequence targeting VEGFR-3 mRNA spaced by 9 bp nucleotide were designed and synthesized, through directional cloning plasmid pSUPER to construct siRNA eukaryotic expression vector. LoVo cells were transfected with psiRNA-VEGFR-3 vectors by lipofectamine 2000. The expression of VEGFR-3 mRNA was detected by semi-quantitative real time PCR. MTT assay was used to measure cell growth and flow cytometry was used to analyze apoptosis.

RESULTS: The VEGFR-3 siRNA expression vector was constructed successfully; psiRNA-VEGFR-3 significantly inhibited VEGFR-3 expression in LoVo cells. Transfected psiRNA-VEGFR-3 markedly inhibited cell growth, and induced apoptosis in LoVo cells.

CONCLUSION: psiRNA-VEGFR-3 vectors can initiate RNA interference, downreguate expression of VEGFR-3 gene, which can inhibit cell proliferation and induce cell apoptosis.