57 research outputs found
The chimeric antibody chLpMab-7 targeting human podoplanin suppresses pulmonary metastasis via ADCC and CDC rather than via its neutralizing activity
Podoplanin (PDPN/Aggrus/T1α) binds to C-type lectin-like receptor-2 (CLEC-2) and induces platelet aggregation. PDPN is associated with malignant progression, tumor metastasis, and poor prognosis in several types of cancer. Although many anti-human PDPN (hPDPN) monoclonal antibodies (mAbs), such as D2-40 and NZ-1, have been established, these epitopes are limited to the platelet aggregation-stimulating (PLAG) domain (amino acids 29-54) of hPDPN. Recently, we developed a novel mouse anti-hPDPN mAb, LpMab-7, which is more sensitive than D2-40 and NZ-1, using the Cancer-specific mAb (CasMab) method. The epitope of LpMab-7 was shown to be entirely different from that of NZ-1, a neutralizing mAb against the PLAG domain according to an inhibition assay and lectin microarray analysis. In the present study, we produced a mouse-human chimeric anti-hPDPN mAb, chLpMab-7. ChLpMab-7 showed high antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Furthermore, chLpMab-7 inhibited the growth of hPDPN-expressing tumors in vivo. Although chLpMab-7 recognizes a non-PLAG domain of hPDPN, it suppressed the hematogenous metastasis of hPDPN-expressing tumors. These results indicated that chLpMab-7 suppressed tumor development and hematogenous metastasis in a neutralization-independent manner. In conclusion, hPDPN shows promise as a target in the development of a novel antibody-based therapy
Chimeric Anti-PDPN Antibody ChLpMab-2
Human podoplanin (hPDPN ), a platelet aggregationâinducing transmembrane glycoprotein, is expressed in different types of tumors, and it binds to Câtype lectinâlike receptor 2 (CLEC â2). The overexpression of hPDPN is involved in invasion and metastasis. AntiâhPDPN monoclonal antibodies (mAbs) such as NZ â1 have shown antitumor and antimetastatic activities by binding to the platelet aggregationâstimulating (PLAG ) domain of hPDPN . Recently, we developed a novel mouse antiâhPDPN mAb, LpMabâ2, using the cancerâspecific mAb (CasMab) technology. In this study we developed chLpMabâ2, a humanâmouse chimeric antiâhPDPN antibody, derived from LpMabâ2. chLpMabâ2 was produced using fucosyltransferase 8âknockout (KO ) Chinese hamster ovary (CHO )âS cell lines. By flow cytometry, chLpMabâ2 reacted with hPDPN âexpressing cancer cell lines including glioblastomas, mesotheliomas, and lung cancers. However, it showed low reaction with normal cell lines such as lymphatic endothelial and renal epithelial cells. Moreover, chLpMabâ2 exhibited high antibodyâdependent cellular cytotoxicity (ADCC ) against PDPN âexpressing cells, despite its low complementâdependent cytotoxicity. Furthermore, treatment with chLpMabâ2 abolished tumor growth in xenograft models of CHO /hPDPN , indicating that chLpMabâ2 suppressed tumor development via ADCC . In conclusion, chLpMabâ2 could be useful as a novel antibodyâbased therapy against hPDPN âexpressing tumors
Podoplanin Is Regulated by AP-1 and Promotes Platelet Aggregation and Cell Migration in Osteosarcoma
Podoplanin is a type-I transmembrane sialomucin-like protein, which is expressed in a wide range of cell types and is involved in platelet aggregation and tumor metastasis. Here, we investigated the function, regulation, and expression of podoplanin in osteosarcoma. Podoplanin expression was observed in three osteosarcoma cell lines (MG-63, HOS, and U-2 OS) with platelet aggregationâinducing ability, which was blocked by podoplanin small-interfering RNA or a neutralizing antibody. Overexpression of podoplanin in nonmetastatic Dunn osteosarcoma cells promoted cell migration without attenuating cell proliferation. Both podoplanin and TGF-ÎČ1 were up-regulated by c-Fos induction in MC3T3-E1 osteoblastic cells, and were highly expressed in c-Fos transgenic mouse osteosarcomas and c-Fosâtransformed osteosarcoma cell lines. Immunohistochemistry of human osteosarcoma tissue microarrays (n = 133) showed staining of tumor cells embedded in an excess of irregular neoplastic bone matrix in 100% of tumors undergoing so-called ânormalization/maturation.â Podoplanin was also expressed in osteosarcoma subtypes, with 65% of osteoblastic, 100% of chondroblastic, and 79% of fibroblastic tumors. CD44 and pERM immunohistochemistry showed coexpression with podoplanin in both mouse and human osteosarcoma. Podoplanin expression was significantly higher in metastatic osteosarcomas (n = 6) than in primary osteosarcomas (n = 10). Our data suggest that podoplanin, which is not expressed in normal osteoblasts but in osteocytes, is aberrantly expressed in transformed osteoblasts and in osteosarcoma, and is under AP-1 transcriptional control. Thus podoplanin is a candidate molecule for therapeutic targeting
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