Bruton's tyrosine kinase as a new therapeutic target.

Targeting Bruton's tyrosine kinase (BTK) with a small molecule inhibitor may be useful in treatment of BTK-expressing malignancies because of the anti-apoptotic function of BTK in cancer cells. Furthermore, BTK inhibitors also exhibit anti-thrombotic properties that may be desirable in the context of the increased risk of thromboembolic complications in cancer patients. This review will focus on the role of BTK in drug resistance in cancer, thromboembolism, and various pathologic immune responses, such as graft versus host disease.

Targeting JAK3 and BTK tyrosine kinases with rationally-designed inhibitors.

Multifunctional rational drug design of protein tyrosine kinases inhibitors allows a potent drug to be utilized to treat more than one disease for greater patient benefits. Many protein tyrosine kinases (PTK), including Janus kinase 3 (JAK3) and Bruton's tyrosine kinase (BTK), have been identified as potential drug targets to treat diverse diseases including cancer and disorders of the immune system. Here we review advances in JAK3 and BTK inhibitors and describe the therapeutic potential of these potent agents in the clinical setting.

Anti-proliferative and anti-leukemic activity of DDE46 (compound WHI-07), a novel bromomethoxylated arylphosphate derivative of zidovudine, and related compounds. Studies using human acute lymphoblastic leukemia cells and the zebrafish model.

The anti-proliferative effects of a novel bromomethoxylated arylphosphate derivative of zidovudine (compound DDE46, CAS 213982-96-8) were first examined in a zebra fish embryo model. DDE46 blocked the cell division at the 2-cell stage of the embryonic development followed by total cell fusion. DDE46 also inhibited the proliferation of the leukemic cell lines NALM-6 and MOLT-3.

CNS activity of Pokeweed anti-viral protein (PAP) in mice infected with lymphocytic choriomeningitis virus (LCMV).

Background: Others and we have previously described the potent in vivo and in vitro activity of the broad-spectrum antiviral agent PAP (Pokeweed antiviral protein) against a wide range of viruses. The purpose of the present study was to further elucidate the anti-viral spectrum of PAP by examining its effects on the survival of mice challenged with lymphocytic choriomeningitis virus (LCMV).

Methods: We examined the therapeutic effect of PAP in CBA mice inoculated with intracerebral injections of the WE54 strain of LCMV at a 1000 PFU dose level that is lethal to 100% of mice within 7-9 days.

Anti-cancer activity profile of 3'-azidothymidine 5'-[p-methoxyphenyl methoxyalaninyl phosphate] (Compound 003), a novel nucleoside analog.

The novel cytotoxic nucleoside analog Compound 003 (3'-azidothymidine 5'-[p-methoxyphenyl methoxyalaninyl phosphate], CAS 149560-32-7) prevented bipolar mitotic spindle assembly and caused a G2 arrest in human cancer cells. Compound 003 was very well tolerated by both mice and rats without any toxicity at cumulative dose levels >2 g/kg. Notably, Compound 003 prolonged cancer-free survival in the MMTVneu transgenic mouse model of HER2 positive breast cancer.

Stampidine prevents mortality in an experimental mouse model of viral hemorrhagic fever caused by lassa virus.

Background: The potential use of microorganisms as agents of biological warfare (BW) is a growing concern. Lassa virus, a member of the Arenavirus class of Hemorrhagic fever (HF) viruses has emerged as a worldwide concern among public health officials. The purpose of the present study was to further elucidate the antiviral activity spectrum of stampidine, a novel nucleoside analog with potent anti-viral activity against the immunodeficiency viruses HIV-1, HIV-2, and FIV, by examining its effects on survival of mice challenged with Lassa virus.

Defective expression of Bruton's tyrosine kinase in acute lymphoblastic leukemia.

Bruton's tyrosine kinase (BTK) is a cytoplasmic tyrosine kinase that serves an essential role in B cell signaling and development. We examined the BTK expression profile of primary leukemic cells from infants with newly diagnosed acute lymphoblastic leukemia (ALL) (N = 14) and from pediatric patients with newly diagnosed (N = 10) or relapsed (N = 5) B-lineage ALL. Analysis of BTK protein and mRNA expression in the infant patient cells (N = 14) showed variable levels of BTK expression with the majority of samples having reduced to absent BTK expression.

CD95 (APO-1/FAS) deficiency in infant acute lymphoblastic leukemia: detection of novel soluble Fas splice variants.

Fas (APO-1/CD95) is a 45-kDa membrane protein which regulates apoptosis in many lymphoid cell types. In the present study, FAS expression was examined in primary leukemic cells from infants with acute lymphoblastic leukemia (ALL). The cells were resistant to apoptosis induction by an anti-FAS antibody and expressed nearly undetectable amounts of FAS protein.

SYK and LYN mediate B-cell receptor-independent calcium-induced apoptosis in DT-40 lymphoma B-cells.

Here, we report that the calcium ionophore ionomycin induces a massive Ca2+-dependent apoptosis in wildtype DT-40 chicken B lymphoma cells, as well as in BTK-deficient, PLCgamma2-deficient and IP3 receptor-deficient DT-40 cells, but not in LYN- or SYK-deficient DT-40 cells. Notably, the deficiency of CSK, a negative regulator of Src-family PTK, promoted ionomycin-induced apoptosis of DT-40 cells. Reconstitution of SYK-deficient cells with wild-type SYK restored the apoptotic response of the cells to ionomycin, but the expression of FYN or LCK in LYN-deficient cells did not restore the apoptotic response of LYN-deficient cells.

Role of the leukemia-associated transcription factor STAT3 in platelet physiology.

Actinomycin D, a transcriptional inhibitor, was found to inhibit platelet potentiation by thrombopoietin (TPO), suggesting that TPO stimulation of platelets involves mitochondrial transcription. We sought to determine a possible role for leukemia-associated signal transducers and activators of transcription (STAT) proteins as mitochondrial transcription factors, focusing specifically on STAT3 in human platelets. We found TPO stimulation of platelets activated STAT3 in vitro, that STAT3 was present in platelet mitochondrial-rich fractions as determined by Western Blot analysis and was capable of binding to the regulatory D-loop region of human mitochondrial DNA upon activation.

Thrombopoietin induces p-selectin expression on platelets and subsequent platelet/leukocyte interactions.

Ligation of thrombopoietin (TPO) to the platelet c-Mpl receptor induces numerous biochemical pathways in the absence of aggregation. Two forms of recombinant TPO are currently in clinical trials for the treatment of thrombocytopenia. This study focuses on the effects of the full-length recombinant human TPO (rhTPO) on platelets in a whole blood system.