Baiting for Cancer: Using the Zebrafish as a Model in Liver and Pancreatic Cancer

Polygoni multiflori radix exacerbates idiosyncratic inflammatory liver injury through the FXR-SHP pathway and altered pharmacokinetic behavior

Polygoni multiflori radix (PM) is a well-known tonic herb. It has been reported that PM could cause idiosyncratic inflammatory liver injury in some individuals. In this study, we investigated the mechanism of PM-induced idiosyncratic inflammatory liver injury in zebrafish and rat models based on pharmacodynamics and pharmacokinetics. The zebrafish were administered with polygoni multiflori radix extract (PME), emodin (EMO), and 2,3,5,4'-tetrahydroxystilbene-2-Ο-β-D-glucoside (TSG) after lipopolysaccharide (LPS) treatment, to establish an idiosyncratic inflammation model. In zebrafish with idiosyncratic inflammation, PME, EMO, and TSG decreased liver area and brightness and increased the number of immune cells around the colliculi. PME+LPS produced hepatocyte damage, aggravated mitochondrial and endoplasmic reticulum damage, and increased AST and ALT activity. RT-PCR showed that PME and EMO up-regulated the expression of IL-6, IL-1β, and INF-γ, and PME down-regulated expression of FXR and SHP. In rats with idiosyncratic inflammation, AST and ALT activities increased significantly, and liver tissues showed pathological damage. An efficient and sensitive LC-MS/MS method was established for the pharmacokinetic study of EMO and TSG in rats with idiosyncratic inflammation. The AUC_0-t was higher for EMO and TSG in the model group compared with the normal group. The MRT_0-t was significantly prolonged in EMO, while CL_z/F was significantly reduced. The present results suggested that the absorption of potentially toxic components of PM increased and metabolism slowed down under inflammatory stress, and PM induced idiosyncratic liver injury via the FXR-SHP axis.

Progressively De-Differentiated Pancreatic Cancer Cells Shift from Glycolysis to Oxidative Metabolism and Gain a Quiescent Stem State

Pancreatic ductal adenocarcinoma (PDAC) is typically characterized by high chemoresistance and metastatic spread, features mainly attributable to cancer stem cells (CSCs). It is of central interest the characterization of CSCs and, in particular, the study of their metabolic features in order to selectively identify their peculiarities for an efficient therapeutic approach. In this study, CSCs have been obtained by culturing different PDAC cell lines with a specific growth medium. Cells were characterized for the typical stem/mesenchymal properties at short-, medium-, and long-term culture. Metabolomics, proteomics, analysis of oxygen consumption rate in live cells, and the effect of the inhibition of lactate transporter on cell proliferation have been performed to delineate the metabolism of CSCs. We show that gradually de-differentiated pancreatic cancer cells progressively increase the expression of both stem and epithelial-to-mesenchymal transition markers, shift their metabolism from a glycolytic to an oxidative one, and lastly gain a quiescent state. These quiescent stem cells are characterized by high chemo-resistance, clonogenic ability, and metastatic potential. Re-differentiation reverts these features, re-activating their proliferative capacity and glycolytic metabolism, which generally correlates with high aggressiveness. These observations add an important piece of knowledge to the comprehension of the biology of CSCs, whose metabolic plasticity could be exploited for the generation of promising and selective therapeutic approaches for PDAC patients.

There Is Something Fishy About Liver Cancer: Zebrafish Models of Hepatocellular Carcinoma

The incidence of hepatocellular carcinoma (HCC) and the mortality resulting from HCC are both increasing. Most patients with HCC are diagnosed at advanced stages when curative treatments are impossible. Current drug therapy extends mean overall survival by only a short period of time. Genetic mutations associated with HCC vary widely. Therefore, transgenic and mutant animal models are needed to investigate the molecular effects of specific mutations, classify them as drivers or passengers, and develop targeted treatments. Cirrhosis, however, is the premalignant state common to 90% of HCC patients. Currently, no specific therapies are available to halt or reverse the progression of cirrhosis to HCC. Understanding the genetic drivers of HCC as well as the biochemical, mechanical, hormonal, and metabolic changes associated with cirrhosis could lead to novel treatments and cancer prevention strategies. Although additional therapies recently received Food and Drug Administration approval, significant clinical breakthroughs have not emerged since the introduction of the multikinase inhibitor sorafenib, necessitating alternate research strategies. Zebrafish (Danio rerio) are effective for disease modeling because of their high degree of gene and organ architecture conservation with human beings, ease of transgenesis and mutagenesis, high fecundity, and low housing cost. Here, we review zebrafish models of HCC and identify areas on which to focus future research efforts to maximize the advantages of the zebrafish model system.

Zebrafish in Translational Cancer Research: Insight into Leukemia, Melanoma, Glioma and Endocrine Tumor Biology

Over the past 15 years, zebrafish have emerged as a powerful tool for studying human cancers. Transgenic techniques have been employed to model different types of tumors, including leukemia, melanoma, glioblastoma and endocrine tumors. These models present histopathological and molecular conservation with their human cancer counterparts and have been fundamental for understanding mechanisms of tumor initiation and progression. Moreover, xenotransplantation of human cancer cells in embryos or adult zebrafish offers the advantage of studying the behavior of human cancer cells in a live organism. Chemical-genetic screens using zebrafish embryos have uncovered novel druggable pathways and new therapeutic strategies, some of which are now tested in clinical trials. In this review, we will report on recent advances in using zebrafish as a model in cancer studies—with specific focus on four cancer types—where zebrafish has contributed to novel discoveries or approaches to novel therapies.

Analysis of pancreatic disease in zebrafish

One of the appeals of the zebrafish model is the relative ease of studying disease progression from embryonic or larval stages through to adulthood. Because of this, the zebrafish has become an important model for postembryonic pancreatic disease, particularly diabetes and pancreatic cancer. Here we present methods for using the adult zebrafish to analyze pancreas function and structure, with an emphasis on the endocrine pancreas and the beta cells. The methods include fasting, weighing adults, and anesthetizing adults, and intraperitoneal injection of glucose based on body weight. We also present dissection methods for removing the pancreas intact for histological studies and for sterile dissection of the principal islet followed by dissociation for cell culture-based studies of beta-cell function.