Lack of expression of podoplanin by microvenular hemangioma

Microvenular hemangioma (MH) is not a very common type of hemangioma, and it can occasionally be difficult to distinguish it from other benign vascular tumors and malignant tumors such as Kaposi's sarcoma. The latter has been shown to be negative for the marker D2-40. Nevertheless, the status of MH for D2-40 has not been established yet. We therefore studied the expression of podoplanin in three cases of MH using D2-40 antibody. No expression was seen, while the dermal lymphatics were clearly immunostained. Nevertheless, the vessels of the MHs were positive for CD34, CD31, and von Willebrand Factor. This study adds MH to the list of vascular lesions that fail to express the allegedly lymphatic marker podoplanin.     

Angiogenesis and Lymphangiogenesis in Salivary Gland Adenoid Cystic Carcinoma and Mucoepidermoid Carcinoma

Background and Purpose: This study aimed to investigate the immunohistochemical expression of CD31 and podoplanin in order to examine angiogenesis and lymphangiogenesis, respectively in common malignant tumors of salivary glands. Materials and Methods: Forty formalin-fixed, paraffinated blocks (20 adenoid cystic carcinoma and 20 mucoepidermoid carcinoma blocks) were selected from the medical archives of Amir A’lam Hospital of Tehran, Iran. Sections from the blocks were stained by CD31 and D2-40 markers via immunohistochemistry. Clinical and demographic information was extracted from the patients’ records. Findings: There was a significant difference between tumors in terms of intratumoral microvessel density (MVD) (P< 0.001), total MVD (P< 0.001), and intratumoral lymphatic vessel density (LVD) (P= 0.011). In mucoepidermoid carcinoma, intratumoral MVD and LVD were greater than peritumoral MVD and LVD (P= 0.001 and P< 0.001, respectively). In mucoepidermoid carcinoma, there was no relationship between histological grade with MVD (total, intratumoral or peritumoral) or LVD (total, intratumoral or peritumoral) (P> 0.05). A similar finding was reported with respect to the histopathological grade of adenoid cystic carcinoma (P> 0.05). Conclusion: The higher level of angiogenesis and lymphangiogenesis in mucoepidermoid carcinoma, specifically at the center of tumor, compared to adenoid cystic carcinoma, may be attributed to differences in the clinical behaviors and metastasis of tumors. Moreover, considering the high LVD at the center of tumor in mucoepidermoid carcinoma and infrequency of metastasis to regional lymph nodes in adenoid cystic carcinoma, it can play a significant role in metastasis to regional lymph nodes.     

Clear cell mesothelioma presenting as an incarcerated abdominal hernia

A clear cell mesothelioma presenting as an incarcerated ventral abdominal hernia in a 67-year-old man who had no history of asbestos exposure is described. The cause of the cytoplasmic clearing was the presence of large amounts of glycogen. Although uncommon, this variant of mesothelioma is important to recognize because it can be easily confused with other clear cell tumors involving the serosal membranes. Significant recent advances in the immunohistochemistry of epithelioid mesothelioma are briefly reviewed because immunohistochemical studies can be helpful in establishing the correct diagnosis.     

Podoplanin promotes the invasion of oral squamous cell carcinoma in coordination with MT1-MMP and Rho GTPases

Podoplanin overexpression has been reported in various cancers, however, the precise mechanism for podoplanin to promote tumor progression remains elusive. In the present study, podoplanin overexpression was found associated with invasiveness both in OSCC tissues and cell lines. Moreover, the cell invasiveness increased with forced podoplanin expression and decreased when podoplanin was knockdown, indicating podoplanin-mediated cell invasion during OSCC progression. To further identify the role of podoplanin in tumor invasion, cell spreading and immunofluorescence assay were performed firstly. It was found that podoplanin knockdown caused an impaired cell spreading with reduced filopodia and the premature assembly of stress fibers while podoplanin overexpression induced an increase in cellular protrusions and stress fibers with extensive parallel bundles. Then, pull-down assays revealed forced podoplanin expression increased Cdc42 activity and reduced RhoA activity while podoplanin knockdown decreased Cdc42 and increased RhoA markedly. Moreover, a hierarchy of crosstalk between RhoA and Cdc42 was confirmed in podoplanin-mediated cell motility. On the other hand, a significant correlation between podoplanin and MT1-MMP expression in OSCCs was found both in vivo and in vitro, co-located in invasive cells and cellular protrusions. Furthermore, our data showed MT1-MMP knockdown significantly blocked the upregulation of cell motility by forced podoplanin expression, indicating that MT1-MMP played a role in podoplanin-mediated tumor invasion. To further confirm the interaction between RhoA/Cdc42 complex, MT1-MMP and podoplanin, co-precipitation experiments were performed. Both the co-precipitation of podoplanin with MT1-MMP and the podoplanin-induced specific binding of MT1-MMP to Cdc42 were found, and immunofluorescence revealed the co-location of podoplanin, MT1-MMP and Cdc42 at the plasma membrane and filopodia induced an increase in cellular protrusion and stress fibers formation. Moreover, MT1-MMP inhibition could partly rescue the increase of Cdc42 activity caused by forced podoplanin expression. Taken together, our data demonstrated a hierarchy of crosstalk between RhoA and Cdc42 was involved in podoplanin-mediated cytoskeleton remodeling and invasion; the co-location and co-ordination of podoplanin, Cdc42 and MT1-MMP in the invadopodia might induce cytoskeleton remodeling, ECM degradation and tumor invasion, while podoplanin-induced EMT may not be indispensible during OSCC progression.     

Alternative NF‐κB signaling regulates mTEC differentiation from podoplanin‐expressing precursors in the cortico‐medullary junction

The thymic epithelium forms specialized niches to enable thymocyte differentiation. While the common epithelial progenitor of medullary and cortical thymic epithelial cells (mTECs and cTECs) is well defined, early stages of mTEC lineage specification have remained elusive. Here, we utilized in vivo targeting of mTECs to resolve their differentiation pathways and to determine whether mTEC progenitors participate in thymocyte education. We found that mTECs descend from a lineage committed, podoplanin (PDPN)‐expressing progenitor located at the cortico‐medullary junction. PDPN⁺ junctional TECs (jTECs) represent a distinct TEC population that builds the thymic medulla, but only partially supports negative selection and thymocyte differentiation. Moreover, conditional gene targeting revealed that abrogation of alternative NF‐κB pathway signaling in the jTEC stage completely blocked mTEC development. Taken together, this study identifies jTECs as lineage‐committed mTEC progenitors and shows that NF‐κB‐dependent progression of jTECs to mTECs is critical to secure central tolerance.     

Podoplanin及CD34在脉管畸形中表达的意义

目的:探讨Podoplanin及CD34在口腔颌面部脉管畸形诊断中的意义。方法:收集30例病理诊断为脉管畸形的标本,进行HE染色,采用免疫组织化学方法观察Podoplanin和CD34的表达。结果:Podoplanin和CD34双重染色结果显示,淋巴管对Podoplanin有较好的阳性表达,呈现深褐色;而毛细血管对CD34有较好的阳性表达,呈现蓝色。结论:Podoplanin和CD34双重染色,在畸形血管和淋巴管中有较好的表达,能够辨别脉管畸形中的毛细淋巴管和毛细血管,可以作为组织学诊断的辅助。     

胃癌中VEGF-A、VEGF-D和podoplanin的表达及其与淋巴道转移的研究

目的探讨胃癌患者血管内皮生长因子A和D(vascular endothelial growth factor-A and-D,VEGF-A andVEGF-D)在胃癌组织、癌旁组织、正常胃组织中的表达及其在胃癌进展中的作用。观察淋巴管内皮细胞podopla-nin的表达,为研究胃癌淋巴道转移的分子机制提供形态学依据。方法应用免疫组织化学SP法检测54例胃癌组织、癌旁组织和12例正常胃组织中VEGF-A、VEGF-D、podoplanin的表达,检测胃癌组织及癌旁组织中的微淋巴管密度(lymphatic microvessel density,LMVD)。结果胃癌癌组织、癌旁组织中VEGF-A和VEGF-D表达阳性率明显高于正常胃组织(P<0.01),其中在淋巴结转移组两者的表达明显高于淋巴结未转移组(P<0.05)。VEGF-A和VEGF-D在胃癌组织中的表达呈正相关(r=0.365,P=0.007),并与淋巴结转移有关(P<0.01)。胃癌癌组织血管内皮podoplanin不染色,淋巴管内皮细胞podoplanin阳性表达,经计数微淋巴管数量,癌组织和癌旁组织LMVD明显高于正常组织,VEGF-A、VEGF-D阳性组LMVD值分别为(9.23±2.49)、(9.29±2.18),较阴性组(7.53±1.81)、(7.44±1.88)显著增高。结论胃癌中VEGF-A与VEGF-D高表达与胃癌淋巴结转移密切相关,podoplanin可选择性的在胃癌组织淋巴管内皮表达,能明确地区分血管及淋巴管成分,可作为一个淋巴管内皮细胞较特异的标记物。由于微淋巴管密度在VEGF-A与VEGF-D阳性表达组癌组织中的表达明显增高,表明淋巴管数量的增加可能与两者协同作用有关。     

妊娠期子宫蜕膜淋巴管研究进展

近年通过对淋巴管透明质酸受体-1和肾小球足突细胞膜蛋白等淋巴管表面标志的研究发现,妊娠期子宫内膜(蜕膜)也有大量淋巴管出现.而体内外实验表明,胎盘滋养细胞可能参与蜕膜淋巴管的形成.并起调控作用.这种蜕膜淋巴管的功能主要是:影响螺旋动脉血流、激活免疫细胞以及参与母胎免疫耐受等.关于其产生和作用的机制将是未来研究的方向.     

Angiogenesis and lymphangiogenesis in sporadic hepatic angiomyolipoma

Angiogenesis and lymphangiogenesis are critical processes for tumor growth, invasion, and metastasis. The present study aimed to investigate the distribution and clinical significance of angiogenesis and lymphangiogenesis in hepatic angiomyolipoma (AML). We performed immunohistochemical staining for endothelial cell markers (CD34 and podoplanin) on 80 cases of sporadic hepatic AMLs. Microvessel density (MVD) and lymphatic vessel density (LVD) were determined in intratumoral and peritumoral regions and adjacent non-tumorous liver tissues. All hepatic AMLs showed positive staining for CD34 and podoplanin. Intratumoral and peritumoral MVDs and LVDs were significantly higher than those in adjacent liver tissues (P < 0.001). No statistical difference in both MVD and LVD was found between intratumoral and peritumoral areas. Large tumors (>5 cm) had a significantly increased MVD and LVD as compared with smaller tumors. A significant positive correlation was found between average LVDs and MVDs (r = 0.567, P < 0.001), and LVDs were a relatively lower event as compared with MVDs. Double immunostaining revealed that no neoplastic cells positive for HMB-45, an antibody reacting with melanosome-associated antigen, were concurrently immunoreactive for endothelial cell markers. In conclusion, intratumoral and peritumoral angiogenesis and lymphangiogenesis commonly occur in hepatic AMLs, thus representing potential therapeutic targets for this disease.     

血管内皮生长因子受体3和Podoplanin在人结肠癌组织中的表达

目的:观察血管内皮生长因子受体3(vascular endothelial growth factor receptor-3,VEGFR-3)和Podoplanin在人结肠癌组织中的表达,以探讨二者标记淋巴管的特异性。方法:选择55例人结肠癌组织标本,应用免疫组织化学法观察VEGFR-3和Podoplanin在人结肠癌组织中的表达。结果:Podoplanin主要表达于淋巴管内皮细胞上,微血管极少着色;VEGFR-3主要表达于淋巴管内皮细胞上,另外在小血管内皮也有较丰富的表达。结论:Podoplanin在淋巴管内皮细胞的表达具有较高特异性,可以用来标记淋巴管。