Influences of angiogenesis and lymphangiogenesis on cancerous invasion in experimentally induced tongue carcinoma

BACKGROUND: Although it is clear that dissemination via the blood system involves angiogenesis, it is uncertain whether tumors also induce lymphangiogenesis or simply invade existing peritumoral vessels. The purpose of this study was to elucidate changes in tumor blood and lymph vessels in cases involving the invasion of squamous cell carcinoma in the oral cavity, and its significance. Blood and lymph vessels densities in tongue carcinomas induced in hamsters were investigated. METHODS: Tongue cancer was induced by abrading the right margin of the tongue of each hamster with an endodontic barbed broach and subsequently applying 1.0% 9,10-dimenthl-1,2-benzanthracene (DMBA) dissolved in acetone, three times a week, at the same site. Fresh frozen sections were prepared and blood vessels stained blue by perfusion with Coomassie Brilliant Blue and lymph vessels stained brown for 5'-nucleotidase. The effects on the blood vessels and lymph vessels were observed. RESULTS: The results showed that blood and lymph vessel densities were greater in the advanced carcinoma tissues than in normal tissue. These were compared in terms of the mode of cancer invasion. As tumor invasion progressed, the blood vessel density decreased but lymph vessel density tended to be higher in high-degree tumor invasion than in low-degree tumor invasion. The expression of vascular endothelial growth factor-C was seen more frequently as tumor invasion progressed. CONCLUSIONS: The present findings indicated that angiogenesis and lymphangiogenesis are affected by cancerous invasion.     

Chy-3 mice are Vegfc haploinsufficient and exhibit defective dermal superficial to deep lymphatic transition and dermal lymphatic hypoplasia.

Recent advances in molecular lymphology and lymphatic phenotyping techniques in small animals offer new opportunities to delineate mutant mouse models. Chy-3 mutant mice were originally named for their chylous ascites, but the underlying lymphatic disorder was not defined. We now re-examined these mice and applied advanced genotyping and lymphatic phenotyping techniques to pinpoint the specific lymphatic defect in this mouse model. We demonstrated that Chy-3 mice carry a large chromosomal deletion that includes Vegfc and narrowed this region by monitoring the heterozygosity of genetic markers. We found that Chy-3 mice not only exhibited chylous ascites but also lymphedema of the hind paws and, in approximately half of the males, lymphedema of the penis. Visual lymphangiography and immunofluorescence staining showed a hypoplastic dermal lymphatic network, whereas the blood vasculature appeared unaffected. This hypoplastic lymphatic network was functional, and all adult Chy-3 mice exhibited a lateral lymphatic pathway directly connecting the inguinal to the axillary lymph node. The dermal superficial to deep lymphatic connections in upper limbs and in all cervical regions were intact and functionally drained the upper body. Lymphatic tracer was not transported from the dermal to the deep truncal lymphatic system in the lower limbs, even though the deep lymphatic vessels and nodes were present and patent. These findings further delineate the lymphatic phenotype of Chy-3 mice, identify a collateral lymph drainage pathway previously undescribed in other genetic models of lymphedema, and demonstrate a predilection for lymphatic abnormalities of the lower limbs.     

Expression of vascular endothelial growth factor receptor 3 in blood and lymphatic vessels of lung adenocarcinoma

Vascular endothelial growth factor receptor 3 (VEGFR-3) has been proposed as a marker for lymphatic endothelial cells. This study investigated the expression of VEGFR-3 in the tumour vessels of lung adenocarcinoma and evaluated whether VEGFR-3 staining was useful for identifying lymphatic vessels within the tumour stroma. It also explored whether active growth of lymphatic vessels occurred in lung adenocarcinoma. Formalin-fixed, paraffin-embedded specimens obtained from 60 cases of lung adenocarcinoma, including five cases of pure bronchiolo-alveolar carcinoma (BAC) without stromal, vascular, and pleural invasion, were examined. No VEGFR-3-positive vessels were observed in pure BAC, but varying numbers of VEGFR-3-positive vessels were found in 39 of 55 (70.9%) invasive adenocarcinomas. A comparison of serial sections stained for VEGFR-3, CD31, and laminin-1 showed that most of the VEGFR-3-positive vessels appeared to be blood vessels (CD31-positive, laminin-1-positive), but some had the characteristics of lymphatic vessels (variable staining for CD31, little or no staining for laminin-1). VEGFR-3 staining highlighted lymphatic invasion by cancer cells; this invasion could not be detected by CD31 or haematoxylin and eosin (H&E) staining. Active growth of lymphatic vessels (as indicated by nuclear Ki-67 labelling of the endothelium) was observed in five tumours, four of which showed a high level of lymphatic invasion by cancer cells. It was concluded that VEGFR-3 immunostaining did not discriminate clearly between vascular and lymphatic endothelial cells, since expression of VEGFR-3 can be up-regulated in tumour blood vessels. However, VEGFR-3 staining combined with laminin-1 and CD31 staining would be useful for identifying lymphatic vessels and their invasion by tumour cells in a more objective way. Finally, proliferation of lymphatic endothelial cells may occur in association with lymphatic invasion by cancer cells.     

Lymphatic endothelial cell identity is reversible and its maintenance requires Prox1 activity

The activity of the homeobox gene Prox1 is necessary and sufficient for venous blood endothelial cells (BECs) to acquire a lymphatic endothelial cell (LEC) fate. We determined that the differentiated LEC phenotype is a plastic, reprogrammable condition that depends on constant Prox1 activity for its maintenance. We show that conditional down-regulation of Prox1 during embryonic, postnatal, or adult stages is sufficient to reprogram LECs into BECs. Consequently, the identity of the mutant lymphatic vessels is also partially reprogrammed as they acquire some features typical of the blood vasculature. siRNA-mediated down-regulation of Prox1 in LECs in culture demonstrates that reprogramming of LECs into BECs is a Prox1-dependent, cell-autonomous process. We propose that Prox1 acts as a binary switch that suppresses BEC identity and promotes and maintains LEC identity; switching off Prox1 activity is sufficient to initiate a reprogramming cascade leading to the dedifferentiation of LECs into BECs. Therefore, LECs are one of the few differentiated cell types that require constant expression of a certain gene to maintain their phenotypic identity.     

Similarities and differences of human and experimental mouse lymphangiomas.

Lymphangioma is a disfiguring malformation of early childhood. A mouse lymphangioma model has been established by injecting Freund's incomplete adjuvant (FIA) intraperitoneally, but has not been compared with the human disease. We show that, in accordance with studies from the 1960s, the mouse model represents an oil-granuloma, made up of CD45-positive leukocytes and invaded by blood and lymph vessels. Several markers of lymphatic endothelial cells are expressed in both mouse and human, like CD31, Prox1, podoplanin, and Lyve-1. However, the human disease affects all parts of the lymphovascular tree. We observed convolutes of lymphatic capillaries, irregularly formed collectors with signs of disintegration, and large lymph cysts. We observed VEGFR-2 and -3 expression in both blood vessels and lymphatics of the patients, whereas in mouse VEGFR-2 was confined to activated blood vessels. The experimental mouse FIA model represents a vascularized oil-granuloma rather than a lymphangioma and reflects the complexity of human lymphangioma only partially.     

VEGF stimulates lymphangiogenesis in colorectal cancer and the treatment via anti-lymphangiogenesis

Lymph node metastasis is the most common and basic way in the extending of colorectal tumor. It is an important reason for the difficulty of curing the tumor and the tumor's high mortality. And it is also an important factor that effects surgery treatment. Vascular endothelial growth factor( VEGF) family is a group of factors which specificly act on endothelial cell. VEGF has been shown to be an important regulator of tumour angiogenesis.but its effect on lymphan-giogenesis is not so clear. In this review, we discussed VEGF's effect on lymphangiogenesis, the colorectal microenviron-ment's effect on the factors expression and the therapeutics via antilymphangiogenesis by inhibiting VEGFR-3 signaling.     

胃癌淋巴管生成与淋巴管密度的相关性研究

胃癌的发病率日益增加,而淋巴转移是导致患者最终死亡的重要原因之一.血管内皮生长因子C(VEGF-C)、血管内皮生长因子D(VEGF-D)与其特异性的受体血管内皮生长因子受体3(VEGFR-3)结合能够促进淋巴管生成,并促进淋巴管转移,并且与肿瘤的淋巴管密度密切相关.近年来对于胃癌的淋巴管的研究正在开展,本文就胃癌淋巴管生成机制、淋巴管生成与淋巴管密度关系的最新研究进展以及此项研究的临床意义加以综述.     

胰腺癌淋巴管生成及其与生物学行为关系

目的研究胰腺癌淋巴管生成的机制、分布特征及其与胰腺癌临床病理学的关系。方法应用免疫组化双标记方法检测42例胰腺癌和12例癌旁胰腺组织中血管内皮生长因子-C（VEGF—C）及肾小球足突细胞黏蛋白（Podoplanin）的表达。结果42例胰腺癌组织VEGF—C阳性率为61．9％,12例癌旁胰腺组织中VEGF—C阳性表达率为58．3％,两者差异无显著性（x^2=0．050,P〉0．05）。VEGF-C阳性率与胰腺癌的淋巴结转移有密切关系（x^2=4．822,P〈0．05）,而与胰腺癌大小、组织学分级、神经浸润及临床病理分期无关（P〉0．05）。胰腺癌组织中可见明确的Podoplanin阳性淋巴管,其数目和分布具有明确的异质性。肿瘤边缘组织中淋巴管数最多,其次为肿瘤表浅部,而肿瘤中心区最少;在形态上,肿瘤边缘可以见到较多管腔扩张的淋巴管,而肿瘤中心及表浅淋巴管多为闭锁的条索状或点状。癌旁胰腺中Podoplanin阳性淋巴管分布在呈慢性炎症的胰腺组织周围,多数呈扩张状态。42例胰腺癌组织中LVD为7．67±1．25,12例癌旁胰腺组织中LVD为7．85±0．93,二者差别无显著性（t=0．639,P〉0．05）。胰腺癌组织中LVD与淋巴结转移及临床病理分期有关（t=7．076,6．803,P〈0．01）,而与胰腺癌大小、组织学分级和神经浸润无关（P〉0．05）。胰腺癌组织中VEGF-C的表达与LVD间呈正相关性（r=0．509,P〈0．05）。结论胰腺癌及癌旁胰腺组织中VEGF—C高表达,促进淋巴管增生,可能是临床上胰腺癌早期发生淋巴结转移的重要机制之一。     

舌癌的淋巴管生成与颈部淋巴结转移

目的：探讨人舌鳞癌淋巴管生成与颈淋巴结转移的关系。方法：采用淋巴管内皮透明质酸受体-1（lymphatic vessel endothelial HA receptor-1,LYVE-1）为淋巴内皮标记物,对照血管标记物CD34和CD105进行免疫组织化学染色,光镜下计数依次获得肿瘤间质淋巴管密度、肿瘤间质淋巴管开放面积、癌巢内淋巴管密度、肿瘤间质血管密度及癌巢内血管密度等指标。结果：舌鳞癌肿瘤间质淋巴管密度（5.66±2.34）与正常舌组织淋巴管密度（3.18±0.88）比较差别有统计学意义（P〈0.001）。肿瘤间质、癌巢内血管和淋巴管密度及肿瘤间质淋巴管开放面积在病理证实淋巴结转移组和淋巴结未转移组间有明显差异。结论：肿瘤间质、癌巢内淋巴管密度和血管密度,以及肿瘤间质淋巴管开放面积等指标各自与颈淋巴结转移有相关性;肿瘤间质淋巴管密度升高是颈淋巴结转移首位风险因素。