Mechanisms of the apoptosis induced by CD176 antibody in human leukemic cells.

Bin Yi, Min Zhang, Reinhard Schwartz-Albiez, Yi Cao

Laboratory of Molecular and Experimental Pathology, Key Laboratory of Animal Models and Human Disease Mechanism of CAS and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, PR China.

International journal of oncology 2011 Jun

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CD176 (Thomsen-Friedenreich antigen) is a tumor-associated carbohydrate structure. In a previous study, we observed that the anti-CD176 antibody can induce the apoptosis of CD176-positive leukemic cells. In this study, we investigated the mechanisms of apoptosis induced by the CD176 antibody. We found that CD95 (FAS, APO-1) and the death receptor 4 (DR4) (TRAIL-R1) are co-expressed with CD176 on the surface of defined leukemic cells as observed by confocal microscopy and flow cytometry analyses. Further-more, CD95, CD45, CD43 and DR4 are carrier proteins of CD176 in hematopoietic cells recognized by means of sandwich solid-phase enzyme linked immunosorbent assay and co-immunoprecipitation. As shown by microarray analysis, 20 genes which are directly related to the execution, induction or positive regulation of apoptosis, were up-regulated after CD176 antibody treatment of the KG1 cell line. Nine differentially expressed genes observed in the microarray analysis were verified by quantitative real-time polymerase chain reaction in the KG1 and MT4 cell lines. Six genes (DAXX, CASP3, CHUK, RIPK2, NFKBIA and DFFA) out of these nine are involved in five apoptotic pathways: The CD95 signaling pathway, the DR3 and DR4/5 death receptor pathway, caspase cascade in apoptosis, the mitochondrial signaling pathway, and apoptotic DNA fragmentation and tissue homeo-stasis. Thus, we hypothesized that the CD176 antibody binds to the CD176 carbohydrate structure present on apoptosis-associated glycoproteins, such as CD95 and DR4 at the cellular surface, which activates apoptotic pathways, and consequently results in the apoptosis of CD176-positive cells. CD176 is expressed at the surface of human leukemic cells, but is almost absent in normal and benign adult human tissues. Thus, CD176 could be a promising target for anti-tumor therapy based on the induction of tumor-specific apoptosis.

Citation

Bin Yi, Min Zhang, Reinhard Schwartz-Albiez, Yi Cao. Mechanisms of the apoptosis induced by CD176 antibody in human leukemic cells. International journal of oncology. 2011 Jun;38(6):1565-73