The kinase inhibitor DMAT reduces experimental HCC growth in mice

Background and Aims: Currently, the most promising strategy to prolong survival of patients with the diagnosis of primary HCC is the use of the multi kinase inhibitor Sorafenib. We now investigated benefits of the serin/threonine kinase inhibitor 2-Dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT), which inhibits activity of CK2, PDK1, PIM-1 and PIM-3 at almost equimolar IC50. We investigated hepatoma cell survival and experimental HCC growth and compared mechanisms of DMAT and Sorafenib action. Methods: Viability and apoptosis following DMAT incubation were measured in the human hepatoma cell lines HepG2 and Huh7 by MTT- and caspase-3-activity-assay. Experimental HCC was induced in NMRI nude mice by subcutaneous injection of HepG2 cells. Tumor growth, proliferation, apoptosis, biochemical and histological changes following DMAT administration were monitored. CK2 activity in tumorous and non-tumorous liver tissue, CK2, PDK1, PIM-1 and PIM-3 expressions in primary mouse hepatocytes and hepatoma cells, as well as effects of DMAT and Sorafenib on NFkB activity and wnt signalling were measured. Inhibition of individual kinases was obtained by the use of cell lines stably expressing shRNA. Results: DMAT incubation of hepatoma cells significantly reduced proliferation, but did not increase apoptosis. DMAT treatment of mice interfered with tumor growth and tumor proliferation without affecting healthy liver tissue. DMAT and Sorafenib interfered with NFkB activation and wnt signaling. Of the DMAT target kinases only CK2 and PIM-3 were found to be over-expressed in hepatoma cells. The knockdown of PIM-3 was most efficient in reduction of hepatoma cell proliferation. Conclusions: PIM-3 and also CK2 contribute to tumor growth e.g. by triggering the wnt signalling pathway and NFkB expression. Inhibition, either by application of inhibitors, such as DMAT, or by specific expressional down modulation, might represent a promising therapeutic approach in future HCC therapy.

CK2 - PIM-3 - Sorafenib