Tumor protein D52 (TPD52): a novel B-cell/plasma-cell molecule with unique expression pattern and Ca2+-dependent association with annexin VI

We generated a murine monoclonal antibody (B28p) detecting an antigenic determinant shared by the immunoglobulin superfamily receptor translocation-associated 1 (IRTA1) receptor (the immunogen used to raise B28p) and an unrelated 28-kDa protein that was subsequently subjected to extensive characterization. The expression of the 28-kDa protein in normal lymphohematopoietic tissues was restricted to B cells and plasma cells and clearly differed from that expected for IRTA1 (selectively expressed by mucosa-associated lymphoid tissue [MALT] marginal zone B cells). Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE)/mass-spectrometry analysis identified the 28-kDa protein as human tumor protein D52 (TPD52), whose expression had been previously described only in normal and neoplastic epithelia. Specific B28p reactivity with TPD52 was confirmed by immunostaining/immunoblotting of TPD52-transfected cells. TPD52 expression pattern in normal and neoplastic B cells was unique. In fact, unlike other B-cell molecules (paired box 5 [PAX5], CD19, CD79a, CD20, CD22), which are down-regulated during differentiation from B cells to plasma cells, TPD52 expression reached its maximum levels at the plasma cell stage. In the Thiel myeloma cell line, TPD52 bound to annexin VI in a Ca(2+)-dependent manner, suggesting that these molecules may act in concert to regulate secretory processes in plasma cells, similarly to what was observed in pancreatic acinar cells. Finally, the anti-TPD52 monoclonal antibody served as a valuable tool for the diagnosis of B-cell malignancies.

2,4-Dimethyl-6 H-pyrido[3,2-b]carbazole, an isomer of the antitumor alkaloid ellipticine via the Combes-Beyer reaction

The synthesis of 2,4-dimethyl-6 H-pyrido[3,2-b]carbazole (2a) and of its 9-methoxy (2b) and 9-hydroxy (2c) derivatives via the Combes-Beyer reaction is described. Pyridocarbazole 2a has been obtained by two different routes. In the course of the synthesis of 2b either a partial or a total demethoxylation has been observed depending on the route employed.

Synthesis of 1-O-alkyl-2-O-methyl-glycerophospholipids with potential antitumor activity

Some synthetic alkyl-lysophospholipid analogs have been described as a new class of immunopotentiating and antitumor agents. Among them, 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine has been reported to possess the highest antitumor activity. A new method for the synthesis of this compound and of the ethanolamine- and serine-containing analog is reported. 1-Alkyl-2-methyl-rac-glycerol, prepared from 1,2-isopropylidene-glycerol, is phosphorylated and the intermediate is condensed either with N-t-BOC-protected ethanolamine or with N-t-BOC-protected serine benzhydryl ester. The choline-derivative is obtained by methylation with CH3I of the ethanolamine derivative. The same synthetic sequence has been used also for synthesizing compounds unsaturated at the fatty alkyl chain in position 1 of the glycerol moiety. Preliminary observation are reported on the selective cytolytic action of the compounds on a tumor cell line.