Cabozantinib is selectively cytotoxic in acute myeloid leukemia cells with FLT3-internal tandem duplication (FLT3-ITD).

Cabozantinib is an oral multikinase inhibitor that exhibits anti-tumor activity in several cancers. We found that cabozantinib was significantly cytotoxic to MV4-11 and Molm-13 cells that harbored FLT3-ITD, resulting in IC50 values of 2.4 nM and 2.0 nM, respectively. However, K562, OCI-AML3 and THP-1 (leukemia cell lines lacking FLT3-ITD) were resistant to cabozantinib, showing IC50 values in the micromolar range. Cabozantinib arrested MV4-11 cell growth at the G0/G1 phase within 24 h, which was associated with decreased phosphorylation of FLT3, STAT5, AKT and ERK. Additionally, cabozantinib induced MV4-11 cell apoptosis in a dose-dependent manner (as indicated by annexin V staining and high levels of cleaved caspase 3 and PARP-1), down-regulated the anti-apoptotic protein survivin and up-regulated the pro-apoptotic protein Bak. Thus, cabozantinib is selectively cytotoxic to leukemia cells with FLT3-ITD, causing cell-cycle arrest and apoptosis. In mouse xenograft model, cabozantinib significantly inhibited MV4-11 and Molm-13 tumor growth at a dosage of 10 mg/kg and showed longer survival rate. Clinical trials evaluating the efficacy of cabozantinib in acute myeloid leukemia (AML) with FLT3-ITD are warranted.

Zebrafish as a disease model for studying human hepatocellular carcinoma.

Liver cancer is one of the world's most common cancers and the second leading cause of cancer deaths. Hepatocellular carcinoma (HCC), a primary hepatic cancer, accounts for 90%-95% of liver cancer cases. The pathogenesis of HCC consists of a stepwise process of liver damage that extends over decades, due to hepatitis, fatty liver, fibrosis, and cirrhosis before developing fully into HCC. Multiple risk factors are highly correlated with HCC, including infection with the hepatitis B or C viruses, alcohol abuse, aflatoxin exposure, and metabolic diseases. Over the last decade, genetic alterations, which include the regulation of multiple oncogenes or tumor suppressor genes and the activation of tumorigenesis-related pathways, have also been identified as important factors in HCC. Recently, zebrafish have become an important living vertebrate model organism, especially for translational medical research. In studies focusing on the biology of cancer, carcinogen induced tumors in zebrafish were found to have many similarities to human tumors. Several zebrafish models have therefore been developed to provide insight into the pathogenesis of liver cancer and the related drug discovery and toxicology, and to enable the evaluation of novel small-molecule inhibitors. This review will focus on illustrative examples involving the application of zebrafish models to the study of human liver disease and HCC, through transgenesis, genome editing technology, xenografts, drug discovery, and drug-induced toxic liver injury.

Zebrafish as a Model for the Study of Human Myeloid Malignancies.

Myeloid malignancies are heterogeneous disorders characterized by uncontrolled proliferation or/and blockage of differentiation of myeloid progenitor cells. Although a substantial number of gene alterations have been identified, the mechanism by which these abnormalities interact has yet to be elucidated. Over the past decades, zebrafish have become an important model organism, especially in biomedical research. Several zebrafish models have been developed to recapitulate the characteristics of specific myeloid malignancies that provide novel insight into the pathogenesis of these diseases and allow the evaluation of novel small molecule drugs. This report will focus on illustrative examples of applications of zebrafish models, including transgenesis, zebrafish xenograft models, and cell transplantation approaches, to the study of human myeloid malignancies.