No abstract

Combination with other small molecule drugs represents a promising strategy to improve therapeutic efficacy of FLT3 inhibitors in the clinic. We demonstrated that combining ABT-869, a FLT3 inhibitor, with SAHA, a HDAC inhibitor, led to synergistic killing of the AML cells with FLT3 mutations and suppression of colony formation. We identified a core gene signature that is uniquely induced by the combination treatment in 2 different leukemia cell lines. Among these, we showed that downregulation of PTP4A3 (PRL-3) played a role in this synergism. PRL-3 is downstream of FLT3 signaling and ectopic expression of PRL-3 conferred therapeutic resistance through upregulation of STAT (signal transducers and activators of transcription) pathway activity and anti-apoptotic Mcl-1 protein. PRL-3 interacts with HDAC4 and SAHA downregulates PRL-3 via a proteasome dependent pathway. In addition, PRL-3 protein was identified in 47% of AML cases, but was absent in myeloid cells in normal bone marrows. Our results suggest such combination therapies may significantly improve the therapeutic efficacy of FLT3 inhibitors. PRL-3 plays a potential pathological role in AML and it might be a useful therapeutic target in AML, and warrant clinical investigation.

Gastric cancer has one of the highest morbidities and mortalities worldwide. Early detection is key measure to improve the outcome of gastric cancer patients. In our efforts to identify potential markers for gastric cancer detection, we coupled xenotransplantation mouse model with a plasma proteomic approach. MKN45 gastric cancer cells were subcutaneously injected into nude mice and plasma samples from mice bearing different sizes of tumors were collected and subjected to iTRAQ and mass spectrometry analysis. ITIH3 protein was found to be more highly expressed in plasma of tumor bearing mice compared to control. Subsequent screening of ITIH3 expression in 167 clinical plasma samples, including 83 cancer-free subjects and 84 gastric cancer patients, revealed higher ITIH3 level in the plasma of gastric cancer patients. A receiver operating characteristics (ROC) curve estimated a maximal sensitivity of 96% at 66% specificity for ITIH3 in gastric cancer detection. In addition, plasma from early stage gastric cancer patient has significantly (p < 0.001) higher level of ITIH3 compared to that from noncancer subject. Our data suggest that ITIH3 may be a useful biomarker for early detection of gastric cancer.