Stimulation of surface IgM of chronic lymphocytic leukemia cells induces an unfolded protein response dependent on BTK and SYK.

B-cell receptor (BCR) signaling plays a key role in the behavior of chronic lymphocytic leukemia (CLL). However, cellular consequences of signaling are incompletely defined. Here we explored possible links between BCR signaling and the unfolded protein response (UPR), a stress response pathway that can promote survival of normal and malignant cells.

Identification in CLL of circulating intraclonal subgroups with varying B-cell receptor expression and function.

Chronic lymphocytic leukemia (CLL) is a tumor of circulating B cells, variably stimulated and anergized following exposure to antigen in lymphoid tissues. Down-modulation of surface IgM (sIgM) occurs, but expression and signal capacity can recover in vitro and apparently in vivo during recirculation. We have now dissected individual circulating clones of CLL cases according to sIgM expression level by differential binding to bead-bound anti-IgM.

Glycosylation of surface Ig creates a functional bridge between human follicular lymphoma and microenvironmental lectins.

Surface Ig (sIg) of follicular lymphoma (FL) is vital for tumor cell survival. We found previously that the Ig in FL is unusual, because the variable region genes carry sequence motifs for N-glycan addition. These are introduced by somatic mutation and are tumor specific.

Surface IgM of CLL cells displays unusual glycans indicative of engagement of antigen in vivo.

Surface IgM (sIgM) has a key influence on the clinical behavior of chronic lymphocytic leukemia (CLL). We now report that it exists in 2 forms with different N-glycosylation patterns in the mu-constant region. One glycoform is similar to normal B cells in bearing mature complex glycans common to most cell-surface glycoproteins.

Surface expression of gpA33 is dependent on culture density and cell-cycle phase and is regulated by intracellular traffic rather than gene transcription.

The cell-surface marker, gpA33, a new member of the immunoglobulin superfamily, is expressed by gastrointestinal cells and by 95% of colon cancers. It has become a promising target of immunologic therapy strategies, but its biologic function and potential role in tumorigenesis are unknown. In this study, we have investigated the expression of gpA33 on the mRNA and cell-surface protein levels by quantitative reverse transcriptase polymerase chain reaction and flow cytometry, respectively, in response to cell density in the culture and to cell-cycle arrest in the G1, S, or G2/M phases.

Production of bifunctional single-chain antibody-based fusion proteins in Pichia pastoris supernatants.

Recombinant antibody fusion constructs with heterologous functional domains are a promising approach to new therapeutic targeting strategies. However, expression of such constructs is mostly limited to cost and labor-intensive mammalian expression systems. Here we report on the employment of Pichia pastoris for the expression of heterologous antibody fusion constructs with green fluorescent protein, A33scFv::GFP, or with cytosine deaminase, A33scFv::CDy, their production in a biofermenter and a modified purification strategy.

A33scFv-green fluorescent protein, a recombinant single-chain fusion protein for tumor targeting.

Chemical conjugates of monoclonal antibodies with fluorophores or enzymes have long been used for diagnostic purposes and experimental therapeutic approaches. Recombinant technology allows for the design and expression of tailored genuine fusion proteins, providing defined molecules as to size, molar ratios of the functional components and stability. The production of functional protein, however, is often limited or impossible due to refolding and solubility problems.

Design, construction, and in vitro analysis of A33scFv::CDy, a recombinant fusion protein for antibody-directed enzyme prodrug therapy in colon cancer.

Antibody-directed enzyme-prodrug therapy (ADEPT) aims at improving the specificity of conventional chemotherapy by employing artificial antibody-enzyme constructs to convert a non-toxic prodrug into a cytotoxic agent specifically localized to the tumor site. The gpA33 antigen is a promising target for ADEPT in colon cancer, as it is expressed by >95% of human colon cancers, but is absent in all non-gastrointestinal tissues. We designed a recombinant fusion construct of a phage display-generated anti-gpA33 single chain fragment, A33scFv, with cytosine deaminase from yeast (CDy), which converts 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU).

Association of the A870G cyclin D1 gene polymorphism with genetic susceptibility to nasopharyngeal carcinoma.

Background: Nasopharyngeal cancer (NPC) is multifactorial, and the genetic background may be a crucial etiologic factor. Cyclin D1 (CCND1) is a key regulator of the cell cycle, and its altered activity is associated with the development of cancer.

Methods: We analyzed the A870G CCND1 polymorphism by polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) in 281 individuals, including 94 patients with NPC and 187 healthy individuals.