SOX12: a novel potential target for acute myeloid leukaemia.

The role of SRY-related high-mobility-group box (SOX) 12 in leukaemia progression and haematopoiesis remains elusive. This study aimed to examine the expression and function of SOX12 in acute myeloid leukaemia (AML) using human myeloid leukaemia samples and the acute myeloid cell line THP1. Mononuclear cells were isolated from the bone marrow of AML patients and healthy donors. SOX12 expression in haematopoietic cells was evaluated by reverse transcription polymerase chain reaction (RT-PCR). SOX12 short hairpin RNAs (shRNAs) were transduced into THP1 cells, and gene knockdown was confirmed by quantitative RT-PCR and Western blot analysis. SOX12 was preferentially expressed in CD34+ cells in AML patients. The THP1 cells transduced with SOX12 shRNAs exhibited significantly reduced SOX12 expression and cell proliferation. SOX12 knockdown had no effect on apoptosis, but it induced cell cycle arrest at G1 phase and reduced the number of colonies. The transduced THP1 and primary AML cells were reconstituted in non-obese diabetic-severe combined immunodeficient (NOD/SCID) mice, and their numbers were significantly reduced 6-12 weeks after transplantation. The mRNA and protein levels of ß-catenin were significantly diminished following SOX12 knockdown, accompanied by a decrease in TCF/Wnt activity. SOX12 may be involved in leukaemia progression by regulating the expression of ß-catenin and then interfering with TCF/Wnt pathway, which may be a target for AML.

Inhibitory effect of nordihydroguaiaretic acid on ß-catenin/Tcf signalling in ß-catenin-activated cells.

Activated ß-catenin/T-cell factor (Tcf) signalling plays a role in human carcinogenesis. We identified the inhibitory effect of nordihydroguaiaretic acid (NDGA) against ß-catenin/Tcf signalling in ß-catenin activated cells. NDGA inhibited the transcriptional activity of ß-catenin/Tcf in HEK293 cells transiently transfected with a constitutively active mutant ß-catenin gene. To investigate the inhibitory mechanism, electrophoresis mobility shift assay, immunoprecipitation and Western blot experiments were performed. The shift assay showed that the binding of Tcf complexes with its specific DNA-binding sites was suppressed by NDGA. Immunoprecipitation analysis also showed that the binding of ß-catenin to Tcf-4 was also disrupted by NDGA. Western blot analysis showed a decreased level of ß-catenin in nucleus caused by NDGA. NDGA did not decrease phosphorylation of Akt and GSK3ß. Taken together, these results suggest that the NDGA acts as a negative regulator of ß-catenin/Tcf signalling and its inhibitory mechanism is related to the decreased binding of ß-catenin/Tcf complexes to consensus DNA.

Design and synthesis of novel diaminoquinazolines with in vivo efficacy for beta-catenin/T-cell transcriptional factor 4 pathway inhibition.

We are introducing a novel series of 2,4-diaminoquinazolines as beta-catenin/Tcf4 inhibitors which were identified by ligand-based design. Here we elucidate the SAR of this series and explain how we were able to improve key molecular properties such as solubility and cLogP leading to compound 9. Analogue 9 exhibited better biological activity and improved physical and pharmacological properties relative to the HTS hit 49. Furthermore, 9 demonstrated good cell growth inhibition against several human colorectal cancer lines such as LoVo and HT29. In addition, treatment with compound 9 led to gene expression changes that overlapped significantly with the transcriptional profile resulting from the pathway inhibition by siRNA knockdown of beta-catenin or Tcf4. Subsequently, 9 was tested for efficacy in a beta-catenin/RKE-mouse xenograft, where it led to more then 50% decrease in tumor volume.

Indole-2-amide based biochemical antagonist of Dishevelled PDZ domain interaction down-regulates Dishevelled-driven Tcf transcriptional activity.

We designed and synthesized a series of indole-2-amide-based compounds that antagonize interaction between the Dishevelled (Dvl) PDZ domain and a peptide derived from the natural PDZ ligand Frizzled-7 (Fz7). These compounds inhibit Tcf-mediated transcription activated by exogenous Dvl via the biochemical antagonism. We confirmed tumor cell-selective activation of caspases by these compounds.

Additional scalarane sesterterpenes from the sponge Phyllospongia papyracea.

A chemical investigation of the marine sponge Phyllospongia papyracea, collected in Papua New Guinea, initiated by the screening result of a beta-catenin/Tcf4 disruption assay afforded six new bishomoscalarane sesterterpenes containing two rare scalaranes with a cyclobutane ring in the molecule, together with one known scalarane sesterterpene. The structures of the new compounds were elucidated by 1D and 2D spectroscopic techniques. The compounds isolated in this study did not show activity against the beta-catenin and Tcf4 complex.