Quantitative analysis of lymphangiogenic markers for predicting metastasis of human gastric carcinoma to lymph nodes. Int J Cancer. 2005;115:388-392. [PMID: 15688374 DOI: 10.1002/ijc.20859]

Dysregulation of Lymphatic Endothelial VEGFR3 Signaling in Disease

Vascular endothelial growth factor (VEGF) receptor 3 (VEGFR3), a receptor tyrosine kinase encoded by the FLT4 gene, plays a significant role in the morphogenesis and maintenance of lymphatic vessels. Under both normal and pathologic conditions, VEGF-C and VEGF-D bind VEGFR3 on the surface of lymphatic endothelial cells (LECs) and induce lymphatic proliferation, migration, and survival by activating intracellular PI3K-Akt and MAPK-ERK signaling pathways. Impaired lymphatic function and VEGFR3 signaling has been linked with a myriad of commonly encountered clinical conditions. This review provides a brief overview of intracellular VEGFR3 signaling in LECs and explores examples of dysregulated VEGFR3 signaling in various disease states, including (1) lymphedema, (2) tumor growth and metastasis, (3) obesity and metabolic syndrome, (4) organ transplant rejection, and (5) autoimmune disorders. A more complete understanding of the molecular mechanisms underlying the lymphatic pathology of each disease will allow for the development of novel strategies to treat these chronic and often debilitating illnesses.

Lymphatic vessel remodeling and invasion in pancreatic cancer progression

Background

The lymphatic system is involved in metastasis in pancreatic cancer progression. In cancer staging, lymphatic spread has been used to assess the invasiveness of tumor cells. However, from the endothelium's perspective, the analysis downplays the peri-lesional activities of lymphatic vessels. This unintended bias is largely due to the lack of 3-dimensional (3-D) tissue information to depict the lesion microstructure and vasculature in a global and integrated fashion.

Methods

We targeted the pancreas as the model organ to investigate lymphatic vessel remodeling in cancer lesion progression. Transparent pancreases were prepared by tissue clearing to facilitate deep-tissue, tile-scanning microscopy for 3-D lymphatic network imaging.

Findings

In human pancreatic ductal adenocarcinoma, we identify the close association between the pancreatic intraepithelial neoplasia (PanIN) lesions and the lymphatic network. In mouse models of PanIN (elastase-CreER;LSL-Kras^G12D and elastase-CreER;LSL-Kras^G12D;p53^+/−), the 3-D image data reveal the peri-lesional lymphangiogenesis, endothelial invagination, formation of the bridge/valve-like luminal tubules, vasodilation, and luminal invasion. In the orthotopic mouse model of pancreatic cancer, we identify the localized, graft-induced lymphangiogenesis and the peri- and intra-tumoral lymphatic vessel invasion.

Interpretation

The integrated view of duct lesions and vascular remodeling suggests an active role, rather than a passive target, of lymphatic vessels in the metastasis of pancreatic cancer. Our 3-D image data provide insights into the pancreatic cancer microenvironment and establish the technical and morphological foundation for systematic detection and 3-D analysis of lymphatic vessel invasion.

Fund

Taiwan Academia Sinica (AS-107-TP-L15 and AS-105-TP-B15), Ministry of Science and Technology (MOST 106-2321-B-001-048, 106-0210-01-15-02, 106-2321-B-002-034, and 106-2314-B-007-004-MY2), and Taiwan National Health Research Institutes (NHRI EX107-10524EI).

Classification of nodal stations in gastric cancer

The lymphatic drainage from the stomach is anatomically elaborate and it is very hard to predict the pattern of lymph node (LN) metastases from gastric cancer (GC). However, there are LN stations metastases that are more frequently observed depending on the tumor location. Furthermore, the incidence of metastasis to various regional LN stations depends on the depth of gastric-wall invasion. The Japanese Gastric Cancer Association (JGCA) classifies the regional LNs draining the stomach into 33 regional lymphatic stations. These are distinguished into three (N1-N3) groups with respect to the location of the primary tumor. The aim of this classification is to provide a common language for the clinical, surgical, and pathological description of GC.

Interleukin-8: A potent promoter of human lymphatic endothelial cell growth in gastric cancer

Lymphatic metastasis is a major progression route of gastric cancer. Interleukin-8 (IL-8), as an inflammatory cytokine, is induced by Helicobacter pylori infection and is strongly associated with gastric cancer development and metastasis. The blood and lymphatic systems are similar in their function and gene expression profiles. It has been proposed that IL-8 activates angiogenesis. However, the direct role of IL-8 in lymphangiogenesis in gastric cancer remains unclear. We investigated the effect of IL-8 on the growth of human lymphatic endothelial cells (LECs). In addition, protein and mRNA expression of selected lymphangiogenesis markers was assessed in these cells. LECs were co-cultured with gastric cancer SGC7901 cells and exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1.0 ng/ml). The Cell Counting Kit-8 was used to evaluate LEC proliferation (cultured for 1-6 days). Then, protein (immunofluorescence and western blotting) and mRNA [quantitative transcription-polymerase chain reaction (qPCR)] levels were measured in samples obtained from the 24-h cultured cells, for lymphatic vessel endothelial hyaluronic acid receptor-1 (LYVE-1), vascular endothelial growth factor (VEGF)-C, VEGF-D and vascular endothelial growth factor receptor-3 (VEGFR-3). The data presented herein demonstrated that IL-8 promotes the proliferation of LECs and enhances the protein and mRNA expression of LYVE-1. Notably, IL-8 inhibited VEGF-C, VEGF-D and VEGFR-3 protein expression as well as VEGF-D and VEGFR-3 mRNA expression. These findings suggest that IL-8 may be a potent inducer of LECs, although this effect does not appear to involve the VEGF-C/VEGF-D and VEGFR-3 signaling pathway.

Anti-angiogenic therapies for advanced esophago-gastric cancer

Neo-vascularization is a vital process for tumor growth and development which involves the interaction between tumor cells and stromal endothelial cells through several growth factors and membranous receptors which ultimately activate pro-angiogenic intracellular signaling pathways. Inhibition of angiogenesis has become a standard treatment option for several tumor types including colorectal cancer, glioblastoma and ovarian cancer. In gastric cancer, the therapeutic role of anti-angiogenic agents is more controversial. Bevacizumab and ramucirumab, two monoclonal antibodies, which target vascular endothelial growth factor-A and vascular endothelial growth factor receptor-2, respectively, have been demonstrated antitumor activity in patients with tumors of the stomach or esophagogastric junction. However, especially for bevacizumab, this antitumor activity has not consistently translated into a survival advantage over standard treatment in randomized trials. In this article, we provide an overview of the role of angiogenesis in gastric cancer and discuss the results of clinical trials that investigated safety and effectiveness of antiangiogenic therapies in this disease. A review of the literature has been done using PubMed, ClinicalTrials.gov website and the ASCO Annual Meeting Library.

The clinical implication of cancer-associated microvasculature and fibroblast in advanced colorectal cancer patients with synchronous or metachronous metastases

BACKGROUND

We aimed to evaluate the clinical significance of microvessel density (MVD), lymphatic vessel density (LVD), and cancer-associated fibroblasts (CAFs) in relation to tumor location in advanced colorectal cancer (CRC).

METHODS

Using immunohistochemistry, we examined 181 advanced CRC patients for CD31 and D2-40 to measure MVD and LVD, respectively, α-smooth muscle actin (SMA) and desmin to identify CAFs, and PTEN to examine genetic changes of CAFs. To evaluate the regional heterogeneity of these properties, we examined tissue from four sites (the center and periphery of the primary cancer, a distant metastasis, and a lymph node metastasis) in each patient.

RESULTS

MVD, LVD, and CAFs showed significant heterogeneity with respect to the tumor location. LVD was the greatest in the center of the primary cancers and the amount of CAFs was the lowest in distant metastases. In distant metastases, those from the lung had higher LVD and MVD, but fewer CAFs than those from the liver, peritoneum, or ovary. Patients with low MVD and LVD in the center of the primary cancer had worse outcomes and patients with few CAFs in distant metastases and in the primary tumor had a lower survival rate. PTEN expression in CAFs in distant metastases was lost in 11 of 181 CRC patients (6.1%), which was associated with a worse prognosis.

CONCLUSIONS

The microenvironment, including cancer-associated microvasculature and fibroblasts, is heterogeneous with respect to the tumor location in CRC patients. Therefore, heterogeneity of microenvironments should be taken into account when managing CRC patients.

TGF-β1 promotes lymphangiogenesis during peritoneal fibrosis

Peritoneal fibrosis (PF) causes ultrafiltration failure (UFF) and is a complicating factor in long-term peritoneal dialysis. Lymphatic reabsorption also may contribute to UFF, but little is known about lymphangiogenesis in patients with UFF and peritonitis. We studied the role of the lymphangiogenesis mediator vascular endothelial growth factor-C (VEGF-C) in human dialysate effluents, peritoneal tissues, and peritoneal mesothelial cells (HPMCs). Dialysate VEGF-C concentration correlated positively with the dialysate-to-plasma ratio of creatinine (D/P Cr) and the dialysate TGF-β1 concentration. Peritoneal tissue from patients with UFF expressed higher levels of VEGF-C, lymphatic endothelial hyaluronan receptor-1 (LYVE-1), and podoplanin mRNA and contained more lymphatic vessels than tissue from patients without UFF. Furthermore, mesothelial cell and macrophage expression of VEGF-C increased in the peritoneal membranes of patients with UFF and peritonitis. In cultured mesothelial cells, TGF-β1 upregulated the expression of VEGF-C mRNA and protein, and this upregulation was suppressed by a TGF-β type I receptor (TGFβR-I) inhibitor. TGF-β1-induced upregulation of VEGF-C mRNA expression in cultured HPMCs correlated with the D/P Cr of the patient from whom the HPMCs were derived (P<0.001). Moreover, treatment with a TGFβR-I inhibitor suppressed the enhanced lymphangiogenesis and VEGF-C expression associated with fibrosis in a rat model of PF. These results suggest that lymphangiogenesis associates with fibrosis through the TGF-β-VEGF-C pathway.

Chemokines, chemokine receptors and the gastrointestinal system

The biological properties of tumor cells are known to be regulated by a multitude of cytokines and growth factors, which include epidermal growth factor receptor agonists and members of the transforming growth factor β family. Furthermore, the recent explosion of research in the field of chemokine function as mediators of tumor progression has led to the possibility that these small, immunomodulatory proteins also play key roles in carcinogenesis and may, therefore, be potential targets for novel therapeutic approaches. In this review, we will summarize recently reported findings in chemokine biology with a focus on the gastrointestinal tract.

Signaling for lymphangiogenesis via VEGFR-3 is required for the early events of metastasis

Metastasis to regional lymph nodes is an important and early event in many tumors. Vascular endothelial growth factor-C (VEGF-C), VEGF-D and their receptor VEGFR-3, play a role in tumor spread via the lymphatics, although the timing of their involvement is not understood. In contrast, VEGFR-2, activated by VEGF-A, VEGF-C and VEGF-D, is a mediator of angiogenesis and drives primary tumor growth. We demonstrate the critical role for VEGFR-3, but not VEGFR-2, in the early events of metastasis. In a tumor model exhibiting both VEGF-D-dependent angiogenesis and lymphangiogenesis, an antibody to VEGFR-2 (DC101) was capable of inhibiting angiogenesis (79 % reduction in PECAM + blood vessels) and growth (93 % reduction in tumor volume). However, unlike an anti-VEGFR-3 Mab (mF4-31C1), DC101 was not capable of eliminating either tumor lymphangiogenesis or lymphogenous metastasis (60 % reduction of lymph node metastasis by DC101 vs 95 % by mF4-31C1). Early excision of the primary tumors demonstrated that VEGF-D-mediated tumor spread precedes angiogenesis-induced growth. Small but highly metastatic primary human breast cancers had significantly higher lymphatic vessel density (23.1 vessels/mm(2)) than size-matched (11.7) or larger non-metastatic tumors (12.4) thus supporting the importance of lymphatic vessels, as opposed to angiogenesis-mediated primary tumor growth, for nodal metastasis. These results suggest that lymphangiogenesis via VEGF-D is more critical than angiogenesis for nodal metastasis.

Serum vascular endothelial growth factor-C and lymphoangiogenesis are associated with the lymph node metastasis and prognosis of patients with colorectal cancer

BACKGROUND

The study aims to investigate the relationship among serum vascular endothelial growth factor (SVEGF-C), VEGF-C expression and lymph vessel density (LVD) in tumour tissue, and their influence to colorectal carcinoma (CRC).

METHODS

The SVEGF-C concentration of 110 patients with CRC and 40 healthy donors was examined by ELISA. The 110 tumour tissues and 40 normal colorectal specimens were examined by immunohistochemical staining (SP method) with VEGF-C and podoplanin (lymphatic vessel specific antibody). Kaplan–Meier survival analysis determined the influence on CRC prognosis.

RESULTS

CRC SVEGF-C level (889.0 ± 264.0 pg/mL) significantly exceeded (P = 0.000) the control level (373.2 ± 97.3 ng/L), and was significantly higher in T3, lymph node metastasis (LNM), distant metastasis, and pTNM groups III and IV. LNM prediction sensitivity, specificity, and accuracy of SVEGF-C were 85.7, 80.0 and 83.6%, respectively (875 pg/mL cut-off). VEGF-C expression was elevated in CRC versus control patients (P = 0.000), and was significantly related to LNM and pTNM stages III and IV. Mean LVD in CRC (6.3 ± 0.7/200 HP) significantly exceeded control mean (3.0 ± 0.7/200 HP) (P = 0.000). LVD was significantly higher in LNM and pTNM stages III and IV. SVEGF-C level was significantly higher in VEGF-C positive versus negative patients (P = 0.000), and was related to LVD (P = 0.009). Kaplan–Meier ranking of prognostic factors was SVEGF-C level (P = 0.000), VEGF-C expression (P = 0.001) and LVD (P = 0.012).

CONCLUSION

SVEGF-C level, VEGF-C and LVD are related to LNM and poor prognosis in patients with CRC. SVEGF-C may be a biomarker for LNM in CRC.

Transforming growth factor-β induces vascular endothelial growth factor-C expression leading to lymphangiogenesis in rat unilateral ureteral obstruction

Inflammation is recognized as an important contributor to lymphangiogenesis; however, in tubulointerstitial lesions in human chronic kidney diseases, this process is better correlated with the presence of myofibroblasts rather than macrophages. As little is known about the interaction between lymphangiogenesis and renal fibrosis, we utilized the rat unilateral ureteral obstruction model to analyze inflammation, fibrosis, lymphangiogenesis, and growth factor expression. Additionally, we determined the relationship between vascular endothelial growth factor-C (VEGF-C), an inducer of lymphangiogenesis, and the profibrotic factor, transforming growth factor-β1 (TGF-β1). The expression of both TGF-β1 and VEGF-C was detected in tubular epithelial and mononuclear cells, and gradually increased, peaking 14 days after ureteral obstruction. The kinetics and localization of VEGF-C were similar to those of TGF-β1, and the expression of these growth factors and lymphangiogenesis were linked with the progression of fibrosis. VEGF-C expression was upregulated by TGF-β1 in cultured proximal tubular epithelial cells, collecting duct cells, and macrophages. Both in vitro and in vivo, the induction of VEGF-C along with the overall appearance of lymphatics in vivo was specifically suppressed by the TGF-β type I receptor inhibitor LY364947. Thus, TGF-β1 induces VEGF-C expression, which leads to lymphangiogenesis.

Lymphangiogenesis and biological behavior in pancreatic carcinoma and other pancreatic tumors

Lymphatic vessels in primary tumor tissue play an important role in lymphatic metastasis. Lymphatic metastasis of malignant neoplasms is significantly related to prognosis, influencing both recurrence and survival. The aim of this study was to investigate the correlation of intra-tumoral lymphatic vessel density (iLVD) and peri-tumoral lymphatic vessel density (pLVD) with biological behavior and prognostic parameters in pancreatic carcinoma (PC) and other pancreatic tumors. Lymphangiogenesis was examined using the D2-40 monoclonal antibody in 33 cases of PC, 7 neuroendocrine tumors of the pancreas (NETP), 7 solid pseudopapillary tumors of the pancreas (SPTP) and 3 cystadenomas of the pancreas (CP). Positively-stained microvessels were counted at magnification ×400 in dense lymphatic vascular foci (hotspots). The LVD of PC was compared to 3 other pancreatic tumors. The relationships among the LVD, the extent of differentiation, lymphatic invasion, lymph node metastasis and other clinicopathological parameters of PC were analyzed. There was no difference in the iLVD among PC, NETP, SPTP and CP. The pLVD of NETP was markedly higher than that of PC, SPTP and CP. The pLVD of PC was significantly higher than that of SPTP and CP, but there was no difference between SPTP and CP. The pLVD of PC was significantly associated with the extent of differentiation, lymphatic invasion and lymph node metastasis, whereas it was not associated with age, gender, tumor size, tumor location and peri-pancreatic invasion. The iLVD of PC was not correlated with these clinicopathological parameters. There was no difference in iLVD and no marked difference in pLVD among the pancreatic tumors. Detection of pLVD is of greater importance than detecting iLVD in these pancreatic tumors, as pLVD can be utilized for the prediction of lymph node metastasis, thus aiding in the evaluation of patient prognosis.

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.

Lymphatic endothelial cell-secreted CXCL1 stimulates lymphangiogenesis and metastasis of gastric cancer

Lymph node metastasis is a significant factor in gastric cancer prognosis. It is well known that cancer cells secrete lymphangiogenic factors, thereby promoting lymphangiogenesis. However, the effects of lymphatic endothelial cell (LEC)-secreted factors on the process of lymphangiogenesis and tumor cell metastasis remain unclear. We established an animal model and successfully isolated LECs from afferent lymph vessels of sentinel lymph nodes (SLNs) in animal models. A microarray analysis was performed to characterize gene expression profile in afferent LECs induced by metastatic cancer cells. There were significant differences in 846 genes between normal LECs and LECs with lymph node metastasis. Among these genes, we found that expression of CXCL1 was upregulated, which was confirmed by quantitative reverse-transcriptase polymerase chain reaction. In a coculture system, gastric cancer cells induced CXCL1 secretion from LECs, which was associated with the NF-κB pathway. CXCL1 stimulated LECs migration and tube formation involving FAK-ERK1/2-RhoA activation and reorganization of F-actin. In human gastric cancer specimens, CXCR2 expression was positively correlated with TNM (Tumor, node, metastasis) stage and lymphatic vessel density. These results suggested that LECs of afferent SLNs had specific expression profiles, which were distinct from those of normal lymphatic vessels and appeared to promote metastasis. The expression pattern described in our study, including CXCL1 in LECs and its receptor CXCR2 in cancer cells, offers a promising therapeutic target for gastric cancer.

Lymph node metastasis of gastric cancer

Despite a decrease in incidence in recent decades, gastric cancer is still one of the most common causes of cancer death worldwide [1]. In areas without screening for gastric cancer, it is diagnosed late and has a high frequency of nodal involvement [1]. Even in early gastric cancer (EGC), the incidence of lymph node (LN) metastasis exceeds 10%; it was reported to be 14.1% overall and was 4.8 to 23.6% depending on cancer depth [2]. It is important to evaluate LN status preoperatively for proper treatment strategy; however, sufficient results are not being obtained using various modalities. Surgery is the only effective intervention for cure or long-term survival. It is possible to cure local disease without distant metastasis by gastrectomy and LN dissection. However, there is no survival benefit from surgery for systemic disease with distant metastasis such as para-aortic lymph node metastasis [3]. Therefore, whether the disease is local or systemic is an important prognostic indicator for gastric cancer, and the debate continues over the importance of extended lymphadenectomy for gastric cancer. The concept of micro-metastasis has been described as a prognostic factor [4-9], and the biological mechanisms of LN metastasis are currently under study [10-12]. In this article, we review the status of LN metastasis including its molecular mechanisms and evaluate LN dissection for the treatment of gastric cancer.

Serum vascular endothelial growth factor-D levels correlate with cervical lymph node metastases in papillary thyroid carcinoma

The aim of this multicenter study was to evaluate the clinical relevance of serum vascular endothelial growth factor-D (VEGF-D) in papillary thyroid carcinoma (PTC). This prospective study consisted of 74 patients with primary PTC and 15 patients with benign thyroid nodules treated from 2008 to 2009. VEGF-D concentration was compared with patient clinicopathologic features and lymph node metastases. There was no significant difference in mean serum VEGF-D levels between the PTC and benign thyroid nodule groups. Within the PTC group, serum VEGF-D levels were significantly higher in patients with lymph node metastases than in patients without metastases (241.92 vs. 213.89 pg/ml, respectively; P = 0.035). Receiver operating characteristic curve analysis revealed that preoperative serum VEGF-D levels were predictive of lymph node metastases in the patients >45 years. Serum VEGF-D level that was correlated with the presence of cervical lymph node metastases in PTC patients might be a useful prognostic indicator.

The effect of the expression of vascular endothelial growth factor (VEGF)-C and VEGF receptor-3 on the clinical outcome in patients with gastric carcinoma

AIMS

We aimed to investigate the relationship among VEGF-C/VEGFR-3 expression, lymphatic metastasis and patient prognosis in gastric carcinoma.

MATERIAL AND METHODS

VEGF-C and VEGFR-3 expression in gastric carcinoma tissues obtained from 204 patients who underwent curative gastrectomy (105 cases presented with lymph node metastasis and 99 cases without metastasis) was examined immunohistochemically. There was no significant difference in the other clinicopathologic variables except for postoperative pathological tumor stage (pT) and TNM stage between the two groups. The results were statistically processed.

RESULTS

The results showed that VEGF-C was located mainly in the cytoplasm of tumor cells and VEGFR-3 was found predominantly in the endothelium of lymphatic vessels. VEGF-C and VEGFR-3 expression was more frequent in gastric carcinoma tissues than that in normal gastric tissues, 54.90% and 35.29% respectively, which revealed that the expression of VEGF-C and VEGFR-3 was significantly stronger in patients with lymph node metastasis than in those without metastasis. Patients who had positive staining for VEGF-C showed significantly less favorable survival rates compared with patients who had negative staining for VEGF-C. The survival rates of patients who had positive staining for VEGFR-3 also were significantly lower compared with patients who had negative staining for VEGFR-3. Patients who had positive staining for both VEGF-C and VEGFR-3 exhibited the most unfavorable prognosis. Multivariate analysis demonstrated that the expression of VEGF-C and VEGFR-3 was an independent prognostic determinant. In addition, faint to moderate VEGF-C expression was detected in normal gastric epithelial cells (18/204, 8.9%).

CONCLUSIONS

VEGF-C and VEGFR-3 expression could serve as a prognostic biomarker in patients with gastric carcinoma.

Potential role for vascular endothelial growth factor-D as an autocrine factor for human gastric carcinoma cells

Vascular endothelial growth factor (VEGF)-D induces lymphangiogenesis by activating VEGF receptor (VEGFR)-3, which is expressed mainly by lymphatic endothelial cells. VEGFR-3 has also been detected in several types of malignant cells, but the significance of VEGFR-3 expression by malignant cells remains unclear. We examined the expression and function of VEGF-D/VEGFR-3 in human gastric carcinoma cells. Expression of VEGF-D and VEGFR-3 was analyzed in three human gastric carcinoma cell lines and 29 surgical specimens. cDNA microarray analysis was used to examine the effect of VEGF-D on the expression of genes associated with disease progression in VEGFR-3-expressing KKLS cells. VEGF-D-transfected cells and control cells were transplanted into the gastric wall of nude mice. In 10 of the 29 (34%) gastric carcinoma specimens and two of the three cell lines, cancer cells expressed both VEGF-D and VEGFR-3. In vitro treatment of KKLS cells with exogenous VEGF-D increased expression of cyclin D1 and Bcl-2 and stimulated cell proliferation. VEGF-D transfection into KKLS cells resulted in stimulation of angiogenesis, lymphangiogenesis, and cell proliferation, and in inhibition of apoptosis. VEGF-D may participate in the progression of human gastric carcinoma by acting via autocrine and paracrine mechanisms.

Lymphatic vessel density as a predictor of lymph node metastasis and its relationship with prognosis in urothelial carcinoma of the bladder

OBJECTIVE

• To determine the correlation of lymphatic vessel density (LVD) with lymph node metastasis (LNM), investigate the impact of vascular endothelial growth factor (VEGF)-C mRNA expression on LVD, and evaluate the impact of LVD on prognosis of bladder urothelial carcinoma (BUC).

PATIENTS AND METHODS

• In 56 samples of BUC, the lymphatic vessels were immunostained with polyclonal antibodies against VEGF receptor 3 (VEGFR-3). LVD was evaluated in both intratumoural and peritumoural tissues. • The expression level of VEGF-C mRNA was assessed by reverse transcriptase-polymerase chain reaction. • The correlation of LVD with VEGF-C mRNA and other clinicopathological parameters was also investigated.

RESULTS

• VEGFR-3 was expressed in lymphatic vessel endothelial cytoplasm. As the expression level of VEGF-C became higher, the intratumoural and peritumoural LVD increased significantly (P < 0.05). • At the same time, increased intratumoural and peritumoural LVD also presented in patients with lymphatic vessel invasion and LNM of BUC (P < 0.05). • In addition, increased peritumoural LVD and LNM predicted a poor recurrence-free survival (P < 0.05).

CONCLUSIONS

• It is suggested that in BUC, VEGF-C expression may contribute to lymphangiogenesis. • Patients with high peritumoural LVD and LNM tend to have a poor prognosis. • Inhibition of the blocking VEGF-C/VEGFR-3 pathway may attenuate lymphangiogenesis and represent a new target for investigational treatment of urothelial carcinoma of the bladder.

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.

Study on lymph node metastasis correlated to lymphangiogenesis, lymphatic vessel invasion, and lymph node micrometastasis in gastric cancer

BACKGROUND

This study aimed to evaluate the clinical significance of lymphangiogenesis, lymph vessel invasion (LVI), and lymph node (LN) micrometastasis (LNMM) in patients with gastric cancer.

METHODS

The influences of the expression levels of LVI, lymph vessel density (LVD) by D2-40 immunohistochemical (IHC) staining (n=68), LNMM (including CK 20 and CK pan immunostainings, n=51) on the clinicopathologic profiles and the prognosis were analyzed.

RESULTS

The higher positive rate of LVI-IHC was related to deeper invasion (P=0.044), later TNM stage (P=0.003), and more extensive LN metastasis (LNM, P=0.000). The level of LVD was significantly associated with venous invasion (P=0.037), later TNM stage (P=0.020), positive LVI-HE (P=0.040), positive LVI-IHC status (P=0.001), and severer LNM (P=0.001). Better prognosis in LVI negative group than LVI positive group has been identified. The survival rate of the group with LVD≥15/field was significantly lower than that in the group with LVD≤14/field (P=0.032). Invasion depth, N stage, LNM, blood vessel invasion, or LVI was respectively an independent prognostic factor to 3-y survival rate. The incidence of patients with LNM and metastasized LNs increased respectively from 74.5% (38/51) by HE staining to 88.2% (45/51) by CK immunostaining and from 32.0% (253/791) to 41.5% (328/791) (P=0.001). The increment of LNMM was correlated to larger tumor diameter (P=0.001), deeper invasion (P=0.018), LNM (P=0.001) and later TNM stage (P=0.012), positive LVI (P=0.04). Meanwhile, the evaluation on LNMM revealed the migration of LN stage (N(0)→N(1) in seven patients, N(1)→N(2) in six patients, and N(2)→N(3) in one patient), and TNM stage (I(b)→II in four patients, II→III(a) in 4 patients, III(a)→III(b) in 3 patients, and III(b)→IV in one patient). Survival analysis demonstrated that better prognosis in patients without LNM and/or LNMM.

CONCLUSION

Our immunohistochemical analyses using antibodies of D2-40 and CK, including both CK 20 and CK pan, detected a higher incidence of LVIs and LNMs in gastric cancer specimens. This study shows close correlations among lymphangiogenesis related factors, such as LVI, LVD, and LNMM, and patients' prognosis after surgery. Therefore, immunohistochemical evaluations of these factors could be used for the accurate determination of tumor aggressiveness.

Effects of VEGFR-3 phosphorylation inhibitor on lymph node metastasis in an orthotopic diffuse-type gastric carcinoma model

BACKGROUND

Vascular endothelial growth factor receptor-3 (VEGFR-3) signalling mediates lymphangiogenesis and lymphatic invasion; however, the effect of VEGFR-3 inhibition on the lymph node (LN) metastasis remains unclear. The aim of this study is to clarify the benefit of a VEGFR-3 inhibitor Ki23057 for LN metastasis.

METHODS

Ki23057 was administered orally to gastric cancer models created by orthotopic inoculation of diffuse-type gastric cancer cells, OCUM-2MLN. The effects of Ki23057 on lymphatic vessel invasion, lymphatic vessel density, and VEGFR-3 phosphorylation were examined by immunostaining or immunoblotting.

RESULTS

Ki23057 inhibited the autophosphorylation of VEGFR-3, with IC50 values of 4.3 nM in the cell-free kinase assay. Murine gastric cancer models created by the orthotopic inoculation of OCUM-2MLN cells showed the diffusely infiltrating growth and frequently developed LN metastasis. The oral administration of Ki23057 significantly (P<0.01) reduced the size of orthotopic tumours and the number of the metastatic LN in gastric cancer models. The degree of lymphatic invasion and lymphangiogenesis was significantly (P<0.05) lower in the gastric tumours treated by Ki23057. Ki23057 inhibited the phosphorylation of VEGFR-3 of lymphatic endothelial cells in gastric tumours.

CONCLUSION

The inhibition of lymphangiogenesis targeting VEGFR-3 phosphorylation is a therapeutic strategy for inhibiting LN metastasis of diffuse-type gastric cancer.

Increased intratumoral lymphatic vessel density correlates with lymph node metastasis in early gastric carcinoma

BACKGROUND

Prediction of lymph node metastasis in early gastric carcinoma (EGC) is important for management and follow-up of EGC patients. Increased lymphangiogenesis has been suggested to correlate with lymphatic invasion and lymph node metastasis in various tumors.

METHODS

Lymphatic vessel density (LVD) and microvessel density (MVD) of 141 EGCs were determined by double immunohistochemical staining for D2-40 and CD31. The mean values of three to five hotspots were calculated in intratumoral and peritumoral areas in digital images.

RESULTS

The mean value of intratumoral LVD in a lymph-node-positive EGC group was 28.24/field, which was significantly higher than in a lymph-node-negative EGC group (19.43/field, P = 0.005). Peritumoral LVD, intratumoral MVD, and peritumoral MVD did not correlate with lymph node metastasis in EGCs (P > 0.05). Intratumoral LVD did not show significant differences according to lymphatic invasion and differentiation, which were positive predictors for lymph node metastasis in EGC. Using multivariate logistic regression, intratumoral LVD was an independent factor, with the above two factors and depth of invasion, for the prediction of lymph node metastasis in EGC with a relative risk of 3.570 in high-intratumoral-LVD group compared with low-intratumoral-LVD group (P = 0.022).

CONCLUSION

Intratumoral LVD may be a useful, independent predictor for lymph node metastasis, especially in combination with previously established predictors in EGC.

The Clinicopathological Significance of Tissue Levels of Hypoxia-Inducible Factor-1α and Vascular Endothelial Growth Factor in Gastric Cancer

Background/Aims

Hypoxia-inducible factor-1α (HIF-1α) is a mediator of tumor progression. Vascular endothelial growth factor (VEGF) is the most potent angiogenic factor known to be induced by HIF-1α. We investigated the clinicopathological significance of HIF-1α and VEGF levels in biopsied gastric cancer tissue.

Methods

Endoscopic biopsy specimens from 67 patients with gastric carcinoma who underwent surgery were available for this study. Semiquantitative RT-PCR was applied to biopsied tumors and normal tissues to determine the expressions of HIF-1α and VEGF. The expression levels of HIF-1α and VEGF were evaluated using the tumor:normal (T/N) ratios of HIF-1α and VEGF mRNA. The clinicopathological variables were reviewed retrospectively.

Results

The T/N ratios of HIF-1α mRNA showed significant correlation with lymph-node metastases, distant metastases, stage, and recurrence within 3 years (p<0.05). The T/N ratios of VEGF mRNA showed significant correlation with lymph-node metastases and distant metastases (p<0.05). There was a significant correlation between the T/N ratios of HIF-1α and VEGF mRNA (r=0.72, p<0.01).

Conclusions

The increased expression of HIF-1α and VEGF mRNA could reflect aggressive tumor behavior, including the recurrence of gastric cancer. Examination of HIF-1α mRNA in biopsy specimens by RT-PCR assay might provide useful preoperative information on tumor aggressiveness.

Histopathological predictor for regional lymph node metastasis in gastric cancer

Regional lymph node metastasis in gastric cancer is a definitive indicator of the patient's prognosis. The goal of this study was to identify the predictors for lymph node metastasis among all the possible histopathological parameters, especially by conducting an objective discrimination of the lymphatic and blood vessels. A total of 210 resected primary gastric cancers with or without lymph node metastasis were evaluated based on the conventional histopathological parameters together with immunohistochemistry using antisera-recognizing lymphatic endothelial hyaluronan receptor-1 (LYVE-1), von Willebrand factor, and lymphangiogenesis promoter vascular endothelial growth factor-C (VEGF-C) antibodies. A multivariate regression analyses of the results indicated that only lymphatic invasion was a significant independent predictor of lymph node metastasis at any stage of cancer invasion. VEGF-C expression was partially related to lymph node metastasis in early gastric cancer. The identification of lymphatic invasion by LYVE-1 antibody is therefore useful to predict regional lymph node metastasis in gastric cancer.

Correlation of vascular endothelial growth factor-D expression and VEGFR-3-positive vessel density with lymph node metastasis in gastric carcinoma

Lymph node metastasis is an important prognostic factor in gastric cancer. Vascular endothelial growth factor-D (VEGF-D) is a lymphangiogenic growth factor that activates VEGF receptor (VEGFR)-3, a receptor expressed in the lymphatic endothelium. We investigated the clinical value of VEGF-D expression and VEGFR-3 positive vessel density in gastric carcinoma with regard to lymphangiogenesis. Immunohistochemical staining was used to determine the expression of VEGF-D and VEGFR- 3 in specimens from 104 cases of resected gastric cancer. VEGF-D expression was observed in 62.5% of the gastric cancers and in 9.6% of the non-neoplastic gastric tissue. The VEGFR-3-positive vessel density was significantly greater in the VEGFD positive group than the negative group. VEGF-D expression was significantly associated with lymph node metastasis, increased serum CEA levels, and the nonsignet ring cell type. The VEGFR-3-positive vessel density was correlated with tumor size, lymphatic invasion, and lymph node metastasis. The VEGF-D expression and high VEGFR-3-positive vessel density were significant poor prognostic factors for relapse-free survival. These results suggest that VEGF-D and VEGFR-3-positive vessel density are potential molecular markers that predict lymphatic involvement in gastric carcinoma.

Tumor lymphangiogenesis and melanoma metastasis

Malignant melanomas of the skin primarily metastasize to lymph nodes, and the detection of sentinel lymph node metastases serves as an important prognostic parameter. There is now compelling evidence that melanomas can induce lymphangiogenesis (growth of lymphatic vessels), mainly at the tumor-stroma interface, and that the level of tumor lymphangiogenesis is correlated with the incidence of sentinel lymph node metastases and with disease-free survival. Thus, tumor lymphangiogenesis can serve as a novel prognostic predictor in melanoma. Vascular endothelial growth factor (VEGF)-C, released by melanoma cells and by tumor-associated macrophages, likely represents the major lymphangiogenic factor in melanoma, although other members of the VEGF family might also be involved. The recent discovery that tumors can induce a premetastatic niche, by inducing lymphatic vessel growth in sentinel lymph nodes even before metastasis, and that lymph node lymphangiogenesis enhances metastatic spread, indicates that activated lymphatic vessels represent novel targets for the detection and/or therapy of melanoma metastases.

Circulating lymphangiogenic growth factors in gastrointestinal solid tumors, could they be of any clinical significance?

Metastasis is the principal cause of cancer mortality, with the lymphatic system being the first route of tumor dissemination. The glycoproteins VEGF-C and VEGF-D are members of the vascular endothelial growth factor (VEGF) family, whose role has been recently recognized as lymphatic system regulators during embryogenesis and in pathological processes such as inflammation, lymphatic system disorders and malignant tumor metastasis. They are ligands for the VEGFR-3 receptor on the membrane of the lymphatic endothelial cell, resulting in dilatation of existing lymphatic vessels as well as in vegetation of new ones (lymphangiogenesis). Their determination is feasible in the circulating blood by immunoabsorption and in the tissue specimen by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR). Experimental and clinicopathological studies have linked the VEGF-C, VEGF-D/VEGFR3 axis to lymphatic spread as well as to the clinical outcome in several human solid tumors. The majority of these data are derived from surgical specimens and malignant cell series, rendering their clinical application questionable, due to subjectivity factors and post-treatment quantification. In an effort to overcome these drawbacks, an alternative method of immunodetection of the circulating levels of these molecules has been used in studies on gastric, esophageal and colorectal cancer. Their results denote that quantification of VEGF-C and VEGF-D in blood samples could serve as lymph node metastasis predictive biomarkers and contribute to preoperative staging of gastrointestinal malignancies.

Helicobacter pylori-associated gastritis is related to babA2 expression without heterogeneity of the 3' region of the cagA genotype in gastric biopsy specimens

BACKGROUND

Cytotoxin-associated gene A (cagA) is the major virulence factor of Helicobacter pylori strains and affects the clinical outcome of patients. Blood group antigen binding adhesin (BabA) helps the strains adhere to the epithelial cell layer and is the most important adhesin of H. pylori.

OBJECTIVES

We tried to study the association between the status of babA2 and cagA in H. pylori strains and histological gastritis. methods: Thirty-six patients were included. RNA was extracted from two frozen biopsy samples of the antrum and corpus, respectively, and cagA/babA2 genotypes were analyzed with reverse transcription polymerase chain reaction and direct sequencing. Two gastric specimens of the antrum and corpus, respectively, were also stained with hematoxylin and eosin to analyze H. pylori-related gastritis.

RESULTS

In the antrum, 56% of the specimens were babA2 positive and in the corpus 53%. The gastritis scores of activity and inflammation were associated with the presence of babA2 in antrum specimens but not in corpus specimens. cagA gene encoding in the CagA EPIYA-D region was detected in all samples, and the sequence was completely identical between those from the gastric corpus and antrum.

CONCLUSION

babA2 expression is heterogeneous and correlated with the extent of gastritis in the antrum, but not in the corpus, whereas cagA shows a monotonous genotype.

Inhibition of cyclooxygenase-2 suppresses lymph node metastasis via reduction of lymphangiogenesis

Cyclooxygenase-2 (COX-2) inhibitor has been reported to suppress tumor progression. However, it is unclear whether this inhibitor can also prevent lymphatic metastasis. To determine the effects of COX-2 inhibitor on lymphatic metastasis, etodolac, a COX-2 inhibitor, was given p.o. to mice bearing orthotopic xenografts or with carcinomatous peritonitis induced with a highly metastatic human diffuse-type gastric carcinoma cell line, OCUM-2MLN. Tumor lymphangiogenesis was significantly decreased in etodolac-treated mice compared with control mice. Consistent with this decrease in lymphangiogenesis, the total weight of metastatic lymph nodes was less in etodolac-treated mice than in control mice. Immunohistochemical analysis revealed that the major source of vascular endothelial growth factor-C (VEGF-C) and VEGF-D was F4/80-positive macrophages in our models. The mRNA levels of VEGF-C in mouse macrophage-like RAW264.7 cells, as well as those in tumor tissues, were suppressed by etodolac. The growth of human dermal lymphatic microvascular endothelial cells was also suppressed by etodolac. Supporting these findings, etodolac also inhibited lymphangiogenesis in a model of chronic aseptic peritonitis, suggesting that COX-2 can enhance lymphangiogenesis in the absence of cancer cells. Our findings suggest that COX-2 inhibitor may be useful for prophylaxis of lymph node metastasis by reducing macrophage-mediated tumor lymphangiogenesis.

Expression patterns of lymphangiogenic and angiogenic factors in a model of breast ductal carcinoma in situ

BACKGROUND

Foci of invasion are found in greater than 20% of excised specimens of breast ductal carcinoma in situ (DCIS). Since lymphangiogenesis markers are associated with the potential for increased lymph node metastasis, the purpose of the current study was to determine expression of lymphangiogenesis molecular markers in a model of aggressive DCIS.

METHODS

From the MCF10A xenograft model, comedo type MCF10DCIS.com cells, premalignant MCF10AT, and invasive MCF10CA1a.cl1 cells were tested. Invasion was tested by Matrigel invasion assays (Becton-Dickinson, Bedford, MA). Gene expression was determined by reverse transcriptase-polymerase chain reaction and protein expression by immunoblot, normalized to beta-actin.

RESULTS

MCF10DCIS.com cells were 4-fold more invasive than MCF10AT cells (P < .01), and expressed several-fold more mRNA and protein than MCF10AT and MCF10CA1a.cl1 cells for vascular endothelial growth factor C, vascular endothelial growth factor D, and lymphatic vessel endothelial hyaluronan receptor 1 (P < .01).

CONCLUSIONS

A subset of comedo-type DCIS cells are invasive, and expression of lymphangiogenesis markers is greater at the mRNA and protein levels than by invasive cancer cells (P < .01). These additional molecular markers may characterize aggressive DCIS more precisely.

Immunohistochemical molecular markers as predictors of curability of endoscopically resected submucosal colorectal cancer

AIM: To clarify the usefulness of immunohistochemical molecular markers in predicting lymph node metastasis of submucosal colorectal cancer.

METHODS: We examined microvessel density, lymphatic vessel density, the Ki-67 labeling index, expression of MUC1 and Matrix metalloproteinase-7 (MMP-7) in tumor cells, and expression of cathepsin D in stromal cells at the invasive front by immunostaining of samples resected from 214 patients with submucosal colorectal cancer. Pathologic features were assessed on hematoxylin-eosin-stained samples. We evaluated the relations between clinicopathologic/immunohistochemical features and lymph node metastasis.

RESULTS: Lesions of the superficial type, with an unfavorable histologic grade, budding, lymphatic involvement, high microvessel density (≥ 40), high lymphatic vessel density (≥ 9), high Ki-67 labeling index (≥ 42), and positivity of MUC1, cathepsin D, and MMP-7 showed a significantly high incidence of lymph node metastasis. Multivariate analysis revealed that high microvessel density, unfavorable histologic grade, cathepsin D positivity, high lymphatic vessel density, superficial type, budding, and MUC1 positivity were independent risk factors for lymph node metastasis. A combined examination with four independent immunohistochemical markers (microvessel density, cathepsin D, lymphatic vessel density, and MUC1) revealed that all lesions that were negative for all markers or positive for only one marker were negative for lymph node metastasis.

CONCLUSION: Analysis of a combination of immuno-histochemical molecular markers in endoscopically resected specimens of submucosal colorectal cancer allows prediction of curability regardless of the pathologic features visible of hematoxylin-eosin-stained sections.

VEGF-C and VEGF-A synergistically enhance lymph node metastasis of gastric cancer

PURPOSE

Vascular endothelial growth factor C (VEGF-C) is the most important molecule in lymphangiogenesis and its relationship with lymph node metastasis has attracted considerable interest. We investigated the relationship of VEGF-C or VEGF-A with clinicopathological factors in gastric cancer patients.

METHODS

Eighty gastric cancer patients who underwent gastric resection were analyzed immunohistochemically for expression of VEGF-C and VEGF-A protein.

RESULTS

Positive immunoreactivity of VEGF-C and VEGF-A was observed in 75 (93.8%) and 41 (51.3%) patients, respectively. VEGF-A expression was significantly correlated with tumor differentiation (p=0.0017) and vascular invasion (p=0.0004). And positive relationship of VEGF-C expression was only demonstrated with tumor differentiation (p=0.0168). Interestingly, however, the frequency of lymph node metastasis was significantly higher in the patients with expression of both VEGF-C and VEGF-A (strong positive expression, p=0.036). Furthermore, the expression of both was also significantly correlated with depth of tumor invasion, tumor differentiation, lymphatic invasion, and vascular invasion.

CONCLUSION

The present results suggest that strong expression of VEGF-A in addition to VEGF-C expression is essential in lymph node metastasis, presumably because enhanced metastatic potential including lymphangiogenesis induced by both VEGF-A and VEGF-C is vital in lymph node metastasis of gastric cancer.

Construction and expression of small interfering RNA vector targeting on vascular endothelial growth factor-C

AIM: To clone the recombinant plasmid affecting vascular endothelial growth factor-C (VEGF-C) gene transcription by RNA interference and observe VEGF-C expression in human gastric cancer cell.

METHODS: Two DNA sequences containing small hairpin structure were designed and synthesized. The complement form was obtained by annealing and then cloned into vector pSilencer3.1-H1. The recombinant plasmid was transformed into strain DH5α. After amplification and purification, the target plasmid, identified by restriction enzyme, was obtained sequenced. Finally, gastric carcinoma cell line SGC-7901 was transfected with the plasmid, and the protein expression of VEGF-C was detected by Western blot.

RESULTS: After enzyme digestion and sequencing, the VEGF-C siRNA expression vector was successfully constructed. Western blot analysis showed that the protein expression of VEGF-C was markedly decreased after transfection, especially in the cells transfected with pSilencer3.1-VEGF-C1, and the inhibitory rate was 81.2%, significantly different from that in the negative control group (P < 0.05).

CONCLUSION: The recombinant plasmid containing VEGF-C siRNA is successfully constructed. RNAi may continually and stably suppress VEGF-C protein expression, which is a potential approach for tumor gene therapy.

Rapamycin, a specific inhibitor of the mammalian target of rapamycin, suppresses lymphangiogenesis and lymphatic metastasis

Tumor lymphangiogenesis is now known to play a causal role in lymph node metastasis, and thus its inhibition would have great significance for the prevention of lymph node metastasis in cancer therapy. VEGF-C has recently been identified as a key molecule that involved in tumor lymphangiogenesis and lymphatic metastasis. However, the expressional regulation of VEGF-C is not fully understood. We investigated the role of mTOR, which is a downstream kinase of the phosphatidylinositol 3-kinase/Akt pathway, and the MAPK family (MEK1/2, p38, and JNK) in the regulation of VEGF-C and VEGF-A expression in B13LM cells, a lymphatic metastasis-prone pancreatic tumor cell line. We also investigated the antilymphangiogenic effect of rapamycin, a specific inhibitor of mTOR in vivo using male BALB/c nu/nu mice. VEGF-C expression was inhibited by the inhibitors for mTOR, p38, and JNK, but not by the inhibitor for MEK1/2, whereas VEGF-A expression was inhibited by all four of these inhibitors. The serum starvation-induced expression of VEGF-C was inhibited by rapamycin, whereas that of VEGF-A was incompletely inhibited. The metastatic experiment in vivo demonstrated that the number and the area of lymphatic vessels in the primary tumors were significantly decreased by rapamycin. Finally, the lymph node metastasis was significantly suppressed in rapamycin-treated mice. Our results suggest that mTOR, p38, and JNK play important roles in VEGF-C expression, and that rapamycin has an antilymphangiogentic effect and exerts the expected inhibition of lymphatic metastasis.

Vascular endothelial growth factors C and D represent novel prognostic markers in colorectal carcinoma using quantitative image analysis

BACKGROUND/AIMS

Vascular endothelial growth factor C (VEGF-C) and vascular endothelial growth factor D (VEGF-D) are potent lymphangiogenic and angiogenetic mediators in many kinds of tumors. However, the exact impacts of VEGF-C and VEGF-D on the prognosis of colorectal cancer (CRC) remain elusive. The aims of this study were to demonstrate the expression of VEGF-C and VEGF-D and to correlate their expression levels with clinicopathological factors and long-term survival in patients with CRC.

PATIENTS AND METHODS

Between January 1996 and January 1998, 69 patients with pathologically confirmed CRC who received routine follow-up at the Ruijin Hospital were included in this study. VEGF-C and VEGF-D protein expression and microvessel density of 69 surgical specimens were assessed by immunohistochemistry, with 20 samples of normal colorectal tissues as controls. All patients were followed up for 108 months or until death. The Immunohistochemical stains were quantified and analyzed by means of a Zeiss Axioplan 2 imaging analysis system.

RESULTS

The protein expression of VEGF-C and VEGF-D in tumor tissues was much higher than that in normal colorectal tissues (p < 0.01). The VEGF-C expression significantly correlated with lymph node metastasis (p = 0.011) and clinical stages of CRC (p < 0.01). The VEGF-D expression correlated with patient ages (p = 0.013), depth of tumor invasion (p = 0.013), and lymph node metastasis (p = 0.028). The expression of VEGF-C and VEGF-D was significantly correlated with the microvessel density. Both overall survival and disease-free survival at 108 months were significantly lower in the CRC patients with a high VEGF-C and/or a high VEGF-D expression, and the patients with a high expression of both VEGF-C and VEGF-D had the shortest overall survival and disease-free survival when compared with other patients.

CONCLUSION

The VEGF-C or VEGF-D expression was significantly correlated with lymph node metastasis and long-term prognosis and could be applied as prognostic markers in CRC.

DNA demethylation of vascular endothelial growth factor-C is associated with gene expression and its possible involvement of lymphangiogenesis in gastric cancer

Previous studies have indicated that lymphangiogenesis in solid tumors is associated with lymphatic metastasis. Overexpression of Vascular endothelial growth factor (VEGF)-C plays a major role in lymphangiogenesis in cancers. In the present study, DNA methylation and expression of the VEGF-C gene was investigated in gastric cancer (GC). Four GC cell lines (MKN-45, MKN-74, HSC-39 and HSC-43) showed no expression of VEGF-C, and the VEGF-C gene was found to be methylated in these cells. In contrast, 7 GC cell lines (MKN-1, MKN-7, MKN-28, TMK-1, KATO-III, SH101-P4 and HSC-44PE) expressed VEGF-C, and the VEGF-C gene was found to be unmethylated in these cell lines. In addition, expression of VEGF-C mRNA was retrieved by treatment with a demethylating agent, Aza-2'-deoxycytidine. In GC tissue samples, bisulfite DNA sequencing analysis revealed that VEGF-C was not methylated in 9 (29.0%) of 31 GC samples, whereas demethylation was not observed in corresponding non-neoplastic mucosa samples. Overexpression of VEGF-C mRNA was observed in 16 (51.6%) of 31 GC samples by quantitative reverse transcription-polymerase chain reaction. Of the 9 GC cases with VEGF-C demethylation, 8 (88.9%) overexpressed VEGF-C. In contrast, of the 22 GC cases without VEGF-C demethylation, 8 (36.4%) overexpressed VEGF-C (p = 0.0155). Furthermore, lymphatic vessel density determined by immunostaining of podoplanin in GC tissues was associated with overexpression of VEGF-C (p < 0.0001). These results suggest that demethylation and activation of the VEGF-C gene is likely involved in lymphangiogenesis in GC.

Association of serum vascular endothelial growth factor-C and lymphatic vessel density with lymph node metastasis and prognosis of patients with gastric cancer

AIM: To investigate whether serum vascular endothelial growth factor-C (SVEGF-C), VEGF-C, and lymphatic vessel density (LVD) in tumor tissues are related to lymph node metastasis (LNM) and prognosis in gastric cancer.

METHODS: SVEGF-C levels of 80 gastric cancer patients and 20 healthy donors were examined using ELISA. VEGF-C expression and LVD were examined using immunohistochemical staining. Kaplan-Meier survival analysis was performed to determine their influence on the prognosis of the patients.

RESULTS: The SVEGF-C level in gastric cancer patients (595.9 ± 201.0 ng/L) was significantly higher (P = 0.000) than controls (360.0 ± 97.4 ng/L). Both SVEGF-C and LVD were significantly higher in poorly differentiated adenocarcinomas, T3 and T4, LNM, distant metastasis, and pTNM groups III and IV (P = 0.000). The sensitivity and specificity of SVEGF-C for predicting LNM were 82.8% and 81.8%, respectively (cut-off = 542.5 ng/L). The positive expression rate of VEGF-C was significantly higher in cancerous than in normal tissues (65% vs 20%; P = 0.001). VEGF-C expression up-regulation was significantly related to differentiation, depth of invasion, LNM, distant metastasis, and pTNM stage (P = 0.000). LVD was 10.7 ± 3.1/200 HP in the experimental group vs 4.9 ± 1.3/200 HP in controls (P = 0.000); LVD in cancerous tissues with and without LNM was 12.0 ± 2.7/200 HP vs 7.6 ± 0.5/200 HP, respectively (P = 0.000). SVEGF-C and LVD were significantly higher in VEGF-C positive than in negative patients (P = 0.000); SVEGF-C level was related to LVD (P = 0.000). Kaplan-Meier survival analysis factors predicating poor prognosis were: SVEGF-C level (P = 0.001), VEGF-C expression and LVD (both P = 0.000).

CONCLUSION: SVEGF-C level, VEGF-C and LVD are related to LNM and poor prognosis of patients with gastric cancer. SVEGF-C may be a biomarker for LNM in gastric cancer.

Lymphatic endothelial cells, tumor lymphangiogenesis and metastasis: New insights into intratumoral and peritumoral lymphatics

Lymphatic metastasis of tumor cells represents a series of extremely complex and sequential processes that include dissemination and invasion into surrounding stromal tissues from primary tumors, penetration into lymphatic walls and implantation in regional lymph nodes, and extravasation or proliferation in parenchyma of target organs. Recent developments in lymphatic biology and research, especially the application of unique molecular markers specific for lymphatic endothelial cells (LECs), LYVE-1, Prox-1 and podoplanin have provided exciting new insights into the tumor microenvironment and LEC-tumor cell interface. To date, established factors for determining the behavior and prognosis of primary tumors have been emphasized morphologically and physiologically, i.e., lymphatic impairment and vessel density, dysfunction of lymphatic valves, interstitial fluid pressure, as well as a series of lymphangiogenic growth factors including VEGF-C/-D, and other cytokines and chemokines. Increasing knowledge of the tumor biological significance in lymphatics within the tumors (intratumoral lymphatics, ITLs) and at the tumor periphery (peritumoral lymphatics, PTLs) has greatly promoted understanding of tumor access into the lymphatic system by inducing lymphangiogenesis or by co-opting preexisting lymphatics. Therefore, the targeting PTLs and ITLs, which have been proposed as an important route for antimetastatic approach, are deemed worthy of further study in various animal tumor models and human tumors.

Lymphatic microvessel density is an independent prognostic factor in colorectal cancer

PURPOSE

Although lymph node metastasis via lymphatic vessels often is related with an adverse outcome, it is not well known whether lymphatic spread to lymph node needs the development of the new lymphatic formation. In addition, the correlation between lymphangiogenesis and prognosis has not been well documented. This study was designed to assess the prognostic value of lymphangiogenesis and lymphatic vessel invasion in colorectal cancer.

METHODS

We examined 106 colorectal cancer specimens by immunostaining for podoplanin, lymphatic endothelial specific marker. We evaluated lymphangiogenesis, as measured by lymphatic microvessel density, and lymphatic vessel invasion. We next investigated the association of these two parameters with the clinicopathologic findings and prognosis.

RESULTS

A significant correlation was observed between high lymphatic microvessel density and positive lymphatic vessel invasion (P = 0.0003). Positive lymphatic vessel invasion was significantly associated with the presence of lymph node metastasis (P = 0.0071). The survival curves demonstrated that both high lymphatic microvessel density and positive lymphatic vessel invasion were correlated with an adverse outcome (P = 0.0004 and P = 0.009, respectively). In a univariate analysis, high lymphatic microvessel density and positive lymphatic vessel invasion were negatively associated with the overall survival (P = 0.0011 and P = 0.0118, respectively). Furthermore, high lymphatic microvessel density, but not lymphatic vessel invasion, correlated with a poor outcome in a multivariate analysis (P = 0.0114).

CONCLUSIONS

Our data suggested that lymphatic vessel invasion was related with lymph node metastasis and that both lymphatic microvessel density and lymphatic vessel invasion were related with an adverse outcome in colorectal cancer. Furthermore, lymphatic microvessel density may be a useful prognostic factor in colorectal cancer.

Quantitative analysis of lymphangiogenic markers in human gastroenteric tumor

BACKGROUND

Lymphatic spread of gastroenteric tumor cells to regional lymph nodes is one of the early events in metastatic cancers and is often associated with distant metastatic spread and poor prognosis. Expression levels of newly described lymphatic endothelial markers, LYVE-1, VEGF-C, VEGF-D and the VEGF receptors VEGFR-3 were assessed in our study.

METHODS

Paired (tumor and corresponding normal tissue) samples were obtained. The expression level of each factor was determined using RT-PCR and quantified by using a real-time quantitative PCR (RT-QPCR) technique, with respective cloned cDNA plasmids as internal standards.

RESULTS

The expression of VEGF-C and lymphatic endothelial marker VEGFR-3 was significantly greater in patients with lymph node metastasis than in those without metastasis, but no different expression level of VEGF-D and LYVE-1 was detected in both groups of patients. Lymphatic vessel density (LVD), which was assessed by immunohistochemistry for LYVE-1, was correlated with lymphangiogenesis factors and lymph node metastasis. Expression of VEGF-C and VEGFR-3 was significantly associated with higher peritumoral LVD than normal group, and LVD was found greater in the node-positive group than in the node-negative group.

CONCLUSIONS

These results indicate that quantitative analysis of lymphangiogenic marker VEGF-C and VEGFR-3 in gastroenteric specimens may be useful in predicting metastasis of gastroenteric cancer to regional lymph nodes, but the role of LYVE-1 in predicting metastasis of gastroenteric cancer requires further analysis.

Lymphatic vessel density at the site of deepest penetration as a predictor of lymph node metastasis in submucosal colorectal cancer

PURPOSE

Lymph node metastasis is an important factor that influences curability after endoscopic treatment of submucosal colorectal cancer. This study was designed to determine the usefulness of identification of lymphatic vessels by immunohistochemistry in predicting lymph node metastasis of submucosal colorectal cancer.

METHODS

Lymphatic involvement was assessed by hematoxylin and eosin staining and podoplanin immunostaining on samples resected from 268 patients with submucosal colorectal cancer. Lymphatic vessel density was estimated by two investigators by average count of three fields (x200) in the area of greatest number of podoplanin-positive capillaries at the site of deepest submucosal penetration. Relations with other clinicopathologic parameters also were investigated.

RESULTS

Lesions with high lymphatic vessel density (> or =9 vessels per field) showed a significantly greater incidence of lymph node metastasis than did those with low lymphatic vessel density (<9 vessels per field; 23.3 vs. 8.4 percent). By multivariate analysis, lymphatic vessel density was determined to be an independent risk factor for lymph node metastasis of submucosal colorectal cancer (P = 0.0044). Lymphatic vessel density also correlated with tumor budding and the degree of inflammation at the invasive front.

CONCLUSIONS

Identification of lymphatic vessels by podoplanin immunostaining provides objective and accurate evaluation of lymphatic involvement. Lymphatic vessel density at the site of deepest penetration is a useful predictor of lymph node metastasis of submucosal colorectal cancer.

Prognostic significance of vascular endothelial growth factor D in gastric carcinoma

The angiogenic factor called vascular endothelial growth factor (VEGF)-D is a ligand for VEGF receptor-2 (VEGFR-2/KDR) and receptor-3 (VEGFR-3/Flt-4). It is implicated in the development of lymphatic vessels and promotion of lymphatic metastasis. The purpose of this study was to investigate the prognostic significance of VEGF-D expression in patients with gastric carcinoma. We assessed the expression of VEGF-D in gastric carcinoma by immunohistochemistry on 143 consecutive patients' stored sections and evaluated the lymphatic vessel count (LVC) in tumors using the novel selective lymphatic endothelium marker D2-40. VEGF-D expression was observed in 55 (39%) tumor sections. The expression of VEGF-D correlated significantly with tumor size, T of the TNM classification, lymphatic and venous system invasion, LVC, lymph node metastasis, M of TNM, and pTNM stage. Multivariate analysis indicated that VEGF-D expression was an independent prognostic factor for both relapse-free survival (RFS) and overall survival (OS). Our data indicate the involvement of VEGF-D in tumor progression via lymphoangiogenic pathways. Practically, VEGF-D expression can be useful for predicting RFS and OS in patients with gastric carcinoma.