Compounds originating from the edible mushroom Auricularia auricula-judae inhibit tropomyosin receptor kinase B activity.

Tropomyosin receptor kinase B (TrkB) serves as a pivotal factor in various cancers. To identify novel natural compounds with TrkB-inhibiting properties, a screening approach was applied using extracts from a collection of wild and cultivated mushroom fruiting bodies, and Ba/F3 cells that ectopically express TrkB (TPR-TrkB). We selected mushroom extracts that selectively inhibited proliferation of the TPR-TrkB cells. We then evaluated the ability of exogenous interleukin 3 to rescue growth inhibition by the selected TrkB-positive extracts. An ethyl acetate extract of Auricularia auricula-judae actively inhibited auto-phosphorylation of TrkB. LC-MS/MS analysis of this extract revealed substances that might be responsible for the observed activity. This screening approach demonstrates, for the first time, that extracts originating from the mushroom A. auricula-judae exhibit TrkB-inhibition properties that might hold therapeutic potential for TrkB-positive cancers.

Overcoming Bcr-Abl T315I mutation by combination of GNF-2 and ATP competitors in an Abl-independent mechanism.

BACKGROUND: Philadelphia positive leukemias are characterized by the presence of Bcr-Abl fusion protein which exhibits an abnormal kinase activity. Selective Abl kinase inhibitors have been successfully established for the treatment of Ph (+) leukemias. Despite high rates of clinical response, Ph (+) patients can develop resistance against these kinase inhibitors mainly due to point mutations within the Abl protein. Of special interest is the 'gatekeeper' T315I mutation, which confers complete resistance to Abl kinase inhibitors. Recently, GNF-2, Abl allosteric kinase inhibitor, was demonstrated to possess cellular activity against Bcr-Abl transformed cells. Similarly to Abl kinase inhibitors (AKIs), GNF-2 failed to inhibit activity of mutated Bcr-Abl carrying the T315I mutation. METHODS: Ba/F3 cells harboring native or T315I mutated Bcr-Abl constructs were treated with GNF-2 and AKIs. We monitored the effect of GNF-2 with AKIs on the proliferation and clonigenicity of the different Ba/F3 cells. In addition, we monitored the auto-phosphorylation activity of Bcr-Abl and JAK2 in cells treated with GNF-2 and AKIs. RESULTS: In this study, we report a cooperation between AKIs and GNF-2 in inhibiting proliferation and clonigenicity of Ba/F3 cells carrying T315I mutated Bcr-Abl. Interestingly, cooperation was most evident between Dasatinib and GNF-2. Furthermore, we showed that GNF-2 was moderately active in inhibiting the activity of JAK2 kinase, and presence of AKIs augmented GNF-2 activity. CONCLUSIONS: Our data illustrated the ability of allosteric inhibitors such as GNF-2 to cooperate with AKIs to overcome T315I mutation by Bcr-Abl-independent mechanisms, providing a possibility of enhancing AKIs efficacy and overcoming resistance in Ph+ leukemia cells.