FLLL32 is an effective JAK2/STAT3 inhibitor (IC50 of <5 μM).

In MDA-MB-231 breast and PANC-1 pancreatic cancer cells, FLLL32 downregulates STAT3 phosphorylation and DNA-binding activity. In MDA-MB-231 cells, FLLL32 inhibit the formation of colonies and cell invasion. [1] In human multiple myeloma, glioblastoma, liver cancer, and colorectal cancer cell lines, FLLL32 also leads to the inhibition of cell proliferation and the induction of caspase-3 and PARP cleavages. [2]

In MDA-MB-231 xenografted mice, FLLL32 (50 mg/kg, i.p.) significantly reduces tumor burdens. [1] In mouse xenografts with OS-33 osteosarcoma cells, FLLL32 (50 mg/kg, i.p.) also inhibits tumor growth by targeting STAT3. [3]

JAK2 and other human kinase activity assays: JAK2 kinase activity was assessed with the HTScan JAK2 Kinase Assay Kit per manufacturer's protocol. The possible effects of FLLL32 on the other 10 purified human protein kinases were determined by using a Kinase Profiler Assay.

Cells are seeded in 96-well plates (3,000 per well) in triplicate and then treated with 0.5 to 5 μM of FLLL31 or FLLL32 or with 0.5 to 30 μM of curcumin for 72 h. MTT (25 μL) is added to each sample and incubated for 3.5 h. Then, 100 μL of N,N-dimethylformamide solubilization solution are added to each well. The absorbance at 450 nm is read the following day. IC50 are determined using Sigma Plot 9.0 software.(Only for Reference)