Spleen tyrosine kinase (Syk), a novel target of curcumin, is required for B lymphoma growth

• Published in: Journal of Immunology Vol. 178; no. 1; pp. 111 - 121
• Main Authors: Gururajan, Murali, Dasu, Trivikram, Shahidain, Seif, Jennings, C Darrell, Robertson, Darrell A, Rangnekar, Vivek M, Bondada, Subbarao
• Format: Journal Article
• Language: English
• Published: United States 01-01-2007
• Subjects: Animals; Antineoplastic Agents - pharmacology; Apoptosis; bcl-Associated Death Protein - metabolism; bcl-X Protein - metabolism; Caspases - metabolism; CD79 Antigens - metabolism; Cell Proliferation - drug effects; Curcuma longa; Curcumin - pharmacology; Female; Glycogen Synthase Kinase 3 - metabolism; Glycogen Synthase Kinase 3 beta; Humans; Intracellular Signaling Peptides and Proteins - antagonists & inhibitors; Lymphoma, B-Cell - enzymology; Lymphoma, B-Cell - pathology; Mice; Mice, Inbred Strains; Phosphorylation - drug effects; Protein Kinase Inhibitors - pharmacology; Protein-Tyrosine Kinases - antagonists & inhibitors; Proto-Oncogene Proteins c-akt - antagonists & inhibitors; Proto-Oncogene Proteins c-akt - metabolism; Receptors, Antigen, B-Cell; Substrate Specificity; Syk Kinase; Tumor Cells, Cultured
• ISSN: 0022-1767; 1550-6606; 1365-2567
• DOI: 10.4049/jimmunol.178.1.111

Curcumin (diferuloylmethane), a component of dietary spice turmeric (Curcuma longa), has been shown in recent studies to have therapeutic potential in the treatment of cancer, diabetes, arthritis, and osteoporosis. We investigated the ability of curcumin to modulate the growth of B lymphomas. Curcumin inhibited the growth of both murine and human B lymphoma in vitro and murine B lymphoma in vivo. We also demonstrate that curcumin-mediated growth inhibition of B lymphoma is through inhibition of the survival kinase Akt and its key target Bad. However, in vitro kinase assays show that Akt is not a direct target of curcumin. We identified a novel target for curcumin in B lymphoma viz spleen tyrosine kinase (Syk). Syk is constitutively activated in primary tumors and B lymphoma cell lines and curcumin down-modulates Syk activity accompanied by down-regulation of Akt activation. Moreover, we show that overexpression of Akt, a target of Syk, or Bcl-x(L), a target of Akt can overcome curcumin-induced apoptosis of B lymphoma cells. These observations suggest a novel growth promoting role for Syk in lymphoma cells.