In Vitro | In vitro activity: JANEX-1 (WHI-P131) shows potent JAK3-inhibitory activity (IC50 of 78 μM), does not inhibit JAK1 and JAK2, the ZAP/SYK family tyrosine kinase SYK, the TEC family tyrosine kinase BTK, the SRC family tyrosine kinase LYN, or the receptor family tyrosine kinase insulin receptor kinase, even at concentrations as high as 350 μM. JANEX-1 induces apoptosis in JAK3-expressing human leukemia cell lines NALM-6 and LC1;19 but not in melanoma (M24-MET) or squamous carcinoma (SQ20B) cells. WHI-P131 inhibits the clonogenic growth of JAK3-positive leukemia cell lines DAUDI, RAMOS, LC1;19, NALM-6, MOLT-3, and HL-60 (but not JAK3-negative BT-20 breast cancer, M24-MET melanoma, or SQ20B squamous carcinoma cell lines) in a concentration-dependent fashion. WHI-P131 inhibits clonogenic growth in a concentration-dependent fashion with EC50s of 24.4 μM for NALM-6 cells and 18.8 μM for DAUDI cells. At 100 μM, WHI-P131 inhibits the in vitro colony formation by these leukemia cell lines by>99%. In contrast, JANEX-1 does not inhibit the clonogenic growth of JAK3-negative M24-MET melanoma or SQ20B squamous carcinoma cell lines.
Kinase Assay: JANEX-1 inhibits JAK3 but not JAK1 or JAK2. The ZAP/SYK family tyrosine kinase SYK, TEC family tyrosine kinase Bruton’s tyrosine kinase (BTK), SRC family tyrosine kinase LYN, and receptor family tyrosine kinase insulin receptor kinase (IRK) are not inhibited by JANEX-1. JANEX-1 suppresses IL-1β and IFN-γ-induced phosphorylation of STAT-1, STAT-3, and STAT-5 proteins. JANEX-1 has a potent inhibitory effect on cytokine-induced β-cell damage.
Cell Assay: The following cell lines are used in various biological assays: NALM-6 (pre-B-ALL), LC1;19 (pre-B-ALL), DAUDI (B-ALL), RAMOS (B-ALL), MOLT-3 (T-cell ALL), HL60 (acute myelogenous leukemia), BT-20 (breast cancer), M24-MET (melanoma), SQ20B (squamous cell carcinoma), and PC3 (prostate cancer). These cell lines are maintained in culture. Cells are seeded in six-well tissue culture plates at a density of 50×104 cells/well in a treatment medium containing various concentrations of JANEX-1 (0.1, 0.2, 0.3, 0.4 and 0.5 nM) and incubated for 24-48 h at 37°C in a humidified 5% CO2 atmosphere. Cells are examined for apoptotic changes after treatment with JANEX-1 by the in situ TdT-mediated dUTP end-labeling assay using the ApopTag apoptosis detection kit. |
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