Polysaccharide-containing fraction from Artemisia argyi inhibits tumor cell-induced platelet aggregation by blocking interaction of podoplanin with C-type lectin-like receptor 2

Tumor cell-induced platelet aggregation (TCIPA) is a mechanism that involves the protection of tumor cells in the circulation and the promotion of tumor cell invasion and metastases. The C-type lectin-like receptor 2 (CLEC-2) that binds podoplanin (PDPN) is on the platelet surface and facilitates the TCIPA. Selective blockage of the PDPN-mediated platelet-tumor cell interaction is thereby a plausible strategy for inhibiting metastases. In a search for antagonists of PDPN- and tumor cell-induced platelet aggregation, traditional Chinese medicines were screened and it was found that the water extract of Artemisia argyi leaves selectively inhibited the PDPN-induced platelet aggregation. Bioactivity-guided fractionation analysis was performed for defining a polysaccharide-containing fraction (AAWAP) characterized by inhibition of PDPN activity and tumor cell-induced platelet aggregation. The pharmacological effects of AAWAP on PDPN-activated CLEC-2 signaling were determined by using Western blot and alpha screening analyses. AAWAP was non-toxic to the cells and platelets and it suppressed PDPN- and tumor cell-induced platelet aggregation by irreversibly blocking the interaction between PDPN and CLEC-2 in a dose-dependent manner. These findings indicate that AAWAP is an antagonist of the PDPN-CLEC-2 interaction. This action by AAWAP may result in the prevention of tumor cell metastases, and if so, could become an effective pharmacological agent in treating cancer patients.     

High podoplanin expression in cancer cells predicts lower incidence of nodal metastasis in patients with lung squamous cell carcinoma

Podoplanin is expressed in a variety of malignant cells, and is generally regarded as a factor promoting tumor progression in conventional studies. Conversely, a recent clinicopathological study has revealed that low podoplanin in cancer cells was correlated with poor prognosis of patients with stage IB lung squamous cell carcinoma (LSCC).We here evaluated the clinicopathological relationship between cancer-cell podoplanin expression and clinicopathological parameters in 40 cases of LSCC (stage I-III).Immunohistochemical podoplanin expression significantly correlated with N classification and pathological stage, but not with other clinicopathological parameters. Notably, all 16 cases with high podoplanin expression unexceptionally exhibited pathological N0 status. Cases without nodal metastasis showed a significantly higher podoplanin-positive score. Furthermore, patients with high podoplanin expression exhibited a significantly longer survival time and disease-free time.These findings suggest that immunohistochemical analysis for podoplanin may serve as a marker of risk of nodal metastasis and prognosis in patients with LSCC.     

LYVE-1及Podoplanin在小鼠Lewis肺癌模型肿瘤内表达情况的初步研究

目的 检测两种淋巴管标志物LYVE-1及Podoplanin在小鼠Lewis肺癌模型肿瘤中的表达,并比较其表达特异性.方法 建立小鼠Lewis肺癌肿瘤模型,检测LYVE-1、Podoplanin在肿瘤内淋巴管的表达,并利用CD34标记肿瘤内的毛细血管以便与淋巴管进行区分.结果 LYVE-1及Podoplanin染色结果并不完全重叠,Podoplanin阳性表达结果除与LYVE-1相同部分外,尚存在大量棕黄色条带状及阳性细胞结构染色,且CD34表达阴性.结论 LYVE-1较podoplanin对Lewis肺癌淋巴管的识别更为特异,背景更为清晰,与CD34联合应用可准确区分毛细淋巴管与毛细血管.     

D2-40 functions as an effective chondroid marker distinguishing true chondroid tumors from chordoma

Chordomas and low-grade chondrosarcomas of the central nervous system share many histological features, generating, at times, considerable diagnostic difficulty and, not infrequently, requiring immunohistochemical analysis for appropriate classification. While both chordomas and chondrosarcomas stain positively for S100, only chordomas typically express epithelial antigens like cytokeratins and epithelial membrane antigen. Positive or negative staining with these latter two markers currently represents the only immunohistochemical technique that effectively distinguishes chordomas from chondrosarcomas. A marker that is reliably positive in chondrosarcomas and negative in chordomas has, to date, not been reported. D2-40 is a monoclonal antibody initially developed against M2A, a fetal testis-related antigen now known as podoplanin (aggrus), which has been found to stain a diverse collection of both benign and malignant tissues. In this study, we systematically investigated D2-40 immunoreactivity in a series of 22 chordomas, 20 chondrosarcomas, and 12 enchondromas, in conjunction with cytokeratin and S100 immunostaining. We found that D2-40 robustly and reliably immunostains low-grade chondroid neoplasms (100% of enchondromas and 94% of grades I and II chondrosarcomas), but not chordomas. By contrast, we observed generally strong and diffuse cytokeratin positivity in all cases of chordoma, but not in cases of enchondroma or low-grade chondrosarcoma. Thus, we show that D2-40 behaves as a chondroid marker differentiating true chondroid neoplasms from chordoma. We also demonstrate D2-40 immunoreactivity in two cases of chordoid meningioma and, in doing so, tentatively provide a means to distinguish this tumor from chordoma.     

Expression analysis of lymphangiogenic factors in human colorectal cancer with quantitative RT-PCR

Lymphatic spread of colorectal cancer cells to regional lymph nodes is one of the early events in metastatic cancers and often is associated with distant metastatic spread and a poor prognosis. The expression levels of newly described lymphatic endothelial markers, LYVE-1 and podoplanin, were assessed in our study. Paired (tumor and corresponding normal tissue) samples were obtained. The expression level of each factor was determined by using RT-PCR and quantified by using a real-time quantitative PCR (RT-QPCR) technique. The expression of podoplanin was significantly greater in patients with lymph node metastasis than in those without metastasis, but no different expression level of LYVE-1 was detected in 2 groups of patients. These results indicate that quantitative analysis of lymphangiogenic marker podoplanin in colorectal cancer specimens may be useful in predicting metastasis of colorectal cancer to regional lymph nodes, but the role of LYVE-1 in predicting metastasis of colorectal cancer still needs further analysis.     

Podoplanin expression profiles characteristic of odontogenic tumor-specific tissue architectures

Podoplanin, a representative immunohistochemical marker for lymphatic endothelial cells, is also expressed in many other kinds of cancer cells, although its pathophysiological function is largely unknown. Our aim was to determine immunolocalization modes of podoplanin among odontogenic tumors to discuss possible roles of podoplanin in their characteristic tissue architecture formation. Immunohistochemical profiles of podoplanin were investigated in 40 surgical specimens from ameloblastoma (AM), adenomatoid odontogenic tumor (AOT), calcifying cystic odontogenic tumor (CCOT), and keratocystic odontogenic tumor (KCOT) in comparison with those of proliferating cell nuclear antigen (PCNA), integrin β1, fibronectin, and matrix metalloproteinase 9 (MMP-9). Podoplanin was localized in the basal cell layer or in the peripheral zone of AM foci. It was found in spindle-shaped tumor cells of AOT, in both the basal and polyhedral cells of CCOT, and in the basal and parabasal cells of KCOT linings. Podoplanin-positive (+) cells were located within areas of PCNA+ cells, and integrin β1 was localized in the cell membrane of podoplanin+ cells in the intercellular space where fibronectin and MMP-9 were deposited. In conclusion, podoplanin+ cells and areas in odontogenic tumors are in close associations with extracellular matrix signalings as well as cell proliferation.     

An Interstitial Network of Podoplanin-Expressing Cells in the Human Endolymphatic Duct

The human endolymphatic duct (ED) with encompassing interstitial connective tissue (CT) is believed to be important for endolymph resorption and fluid pressure regulation of the inner ear. The periductal CT cells are interconnected via numerous cellular extensions, but do not form vessel structures. Here we report that the periductal CT is populated by two distinct cell phenotypes; one expressing podoplanin, a protein otherwise found on lymph endothelia and on epithelia involved in fluid fluxes, and a second expressing a fibroblast marker. A majority of the interstitial cells expressed podoplanin but not the lymphatic endothelial cell markers hyaluronan receptor (LYVE-1) or vascular endothelial growth factor receptor-3 (VEGFR-3). The fibroblast marker positive cells were found close to the ED epithelium. In the mid- and distal parts of the ED, these cells were enriched under folded epithelia. Furthermore, subepithelial CT cells were found to express activated platelet derived growth factor (PDGF)-β receptors. Cultured CT cells from human inner ear periductal and perisaccular explant tissues were identified as fibroblasts. These cells compacted a three-dimensional collagen lattice by a process that could be promoted by PDGF-BB, a factor involved in interstitial fluid pressure regulation. Our results are compatible with the notion that the periductal CT cells are involved in the regulation of inner ear fluid pressure. By active compaction of the periductal CT and by the formation of villous structures, the CT cells could modulate fluid fluxes over the ED epithelium as well as the longitudinal flow of endolymph in the ED.     

口腔白斑及鳞状细胞癌中Podoplanin的表达及其与微淋巴管密度的关系

doplanin高表达病例22例(81%)、浸润癌中Podoplanin高表达病例25例(78%),而正常口腔黏膜均不表达Podoplanin.在白斑和早期浸润癌病变上皮附近的微淋巴管密度与病变上皮中Podoplanin的表达强度呈正相关(P<0.05),在浸润癌病变上皮中Podoplanin的表达与癌内微淋巴管密度呈正相关(P<0.05).结论 Podoplanin在口腔癌前病变癌变的发生、癌组织的浸润及癌转移中可能起重要作用.     

几种淋巴管特异性标记物在人癌组织中的表达

目的：对已发现的几种淋巴管特异性标记物在人类多种肿瘤中的表达进行观察，从而找出适合于肿瘤组织淋巴管研究的标记物。方法：取人结肠癌、肺癌、胃癌和喉癌手术材料，免疫组化法观察LYVE-1、Podoplanin和VEGFR-3在癌组织的表达。结果：LYVE-1只表达于淋巴管内皮，Podoplanin主要表达于淋巴管，此外在少数小静脉上也有表达，VEGFR-3则同时表达于淋巴管与小血管，在癌细胞的胞浆中也可呈阳性表达。结论：LYVE-1、Podoplanin可以作为肿瘤组织内淋巴管的特异标记物。