COX-1 and COX-2 were differentially sensitive to inhibition in vitro by NSAID. Meloxicam and tolfenamic acid were selective for COX-2. Effects of carprofen and ketoprofen approached equipotency against both isoenzymes. Selective COX-2 inhibitors are a new class of drugs with anti-inflammatory effects similar to conventional NSAID but with fewer adverse effects. Development of these agents for veterinary use would be facilitated by the convenience of using a canine cell line as a model system to screen COX-1 and COX-2 inhibitor activities in vitro.

HACS1 is a Src homology 3 and sterile alpha motif domain-containing adaptor that is preferentially expressed in normal hematopoietic tissues and malignancies including myeloid leukemia, lymphoma, and myeloma. Microarray data showed HACS1 expression is up-regulated in activated human B cells treated with interleukin (IL)-4, CD40L, and anti-immunoglobulin (Ig)M and clustered with genes involved in signaling, including TNF receptor-associated protein 1 , signaling lymphocytic activation molecule , IL-6 , and DEC205 . Immunoblot analysis demonstrated that HACS1 is up-regulated by IL-4, IL-13, anti-IgM, and anti-CD40 in human peripheral blood B cells. In murine spleen B cells, Hacs1 can also be up-regulated by lipopolysaccharide but not IL-13. Induction of Hacs1 by IL-4 is dependent on Stat6 signaling and can also be impaired by inhibitors of phosphatidylinositol 3-kinase, protein kinase C, and nuclear factor B. HACS1 associates with tyrosine-phosphorylated proteins after B cell activation and binds in vitro to the inhibitory molecule paired Ig-like receptor B. Overexpression of HACS1 in murine spleen B cells resulted in a down-regulation of the activation marker CD23 and enhancement of CD138 expression, IgM secretion, and Xbp-1 expression. Knock down of HACS1 in a human B lymphoma cell line by small interfering ribonucleic acid did not significantly change IL-4-stimulated B cell proliferation. Our study demonstrates that HACS1 is up-regulated by B cell activation signals and is a participant in B cell activation and differentiation.

SH3 and SAM domains are protein interaction motifs that are predominantly seen in signaling molecules, adaptors, and sca old proteins. We have identi®ed a novel family of putative adaptor genes that includes HACS1. HACS1 encodes a 441 amino acid protein that is di erentially expressed in hematopoietic cells and has restricted expression in human tissues. Its SH3 domain is most similar to the same motif in Crk and its SAM domain shares homology with a family of uncharacterized putative sca old and adaptor proteins. HACS1 maps to human chromosome 21q11.2 in a region that is frequently disrupted by translocation events in hematopoietic malignancies. Polyclonal antibodies against HACS1 recognized a 49.5 kDa protein whose mRNA is expressed in human immune tissues, bone marrow, heart, lung, placenta and brain. Cell lines and primary cells from acute myeloid leukemias and multiple myeloma patients express HACS1. Immunostaining and cellular fractionation studies localized the HACS1 protein predominantly to the cytoplasm. Oncogene (2001) 20, 5373 ± 5377.

No abstract