Liver development and cancer formation in zebrafish

Liver is the largest organ in the human body, and it regulates many physiological processes. Many studies on liver development in different model organisms have demonstrated that the mechanism of hepatogenesis is conserved in vertebrates. The identification of the genes and regulatory pathways involved in liver formation provides a basis for the diagnosis of liver diseases and therapeutic interventions. Hepatocellular carcinoma is the third leading cause of mortality worldwide. In the last decade, genetic alterations, which include the gain and loss of DNA, as well as mutations and epigenomic changes, have been identified as important factors in liver cancer. Many genetic pathways are dysregulated during carcinogenesis. Here, we review the gene regulatory networks that underlie liver organogenesis and the dysregulation of these pathways in liver cancer. The genes and pathways involved in hepatogenesis and liver cancer are largely conserved between zebrafish and humans, making this an ideal model organism for the study of this disease. A better understanding of liver development may aid in the development of new diagnostic and therapeutic approaches to liver cancer.     

Fate restriction in the growing and regenerating zebrafish fin

We use transposon-based clonal analysis to identify the lineage classes that make the adult zebrafish caudal fin. We identify nine distinct lineage classes, including epidermis, melanocyte/xanthophore, iridophore, intraray glia, lateral line, osteoblast, dermal fibroblast, vascular endothelium, and resident blood. These lineage classes argue for distinct progenitors, or organ founding stem cells (FSCs), for each lineage, which retain fate restriction throughout growth of the fin. Thus, distinct FSCs exist for the four neuroectoderm lineages, and dermal fibroblasts are not progenitors for fin ray osteoblasts; however, artery and vein cells derive from a shared lineage in the fin. Transdifferentiation of cells or lineages in the regeneration blastema is often postulated. However, our studies of single progenitors or FSCs reveal no transfating or transdifferentiation between these lineages in the regenerating fin. This result shows that, the same as in growth, lineages retain fate restriction when passed through the regeneration blastema.     

A rapid and sensitive HPLC-MS/MS analysis and preliminary pharmacokinetic characterization of sibiricaxanthone F in rats

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantifying sibiricaxanthone F (SF) in rat plasma following oral and intravenous dosings. After addition of the internal standard (IS) kaempferol and the antioxidant, 20% ascorbic acid, plasma samples were precipitated with acetonitrile and separated on an Aglient Zorbax XDB-C(18) column (50 mm × 4.6mm I.D., 2.1 μm) with gradient acetonitrile and water (both containing 0.01% formic acid) as the mobile phase. The detection was performed on a Sciex API 4000 LC-MS/MS with electrospray ionization (ESI) inlet in the negative multiple reaction monitoring (MRM) mode. Good linearity was achieved over the concentration range of 0.5-500.0ng/mL (r>0.996). Intra- and inter-day precisions were less than 7.60%, and accuracy ranged from 97.18% to 99.84%. The lower limit of quantification for SF was 0.5 ng/mL, and analytes were stable under various conditions (during freeze-thaw, at room temperature and under deep-freeze conditions). This validated method was successfully applied to the preliminary pharmacokinetic study of SF in rats for the first time, and the absolute bioavailability of SF was found to be only 0.22 ± 0.15%.     

Inhibition of autophagy may suppress the development of hepatoblastoma

Hepatoblastoma (HB) is a rare cancer but represents the most common liver malignancy in children under 3 years of age. Nevertheless, a clear understanding of the pathogenesis is lacking. Although the treatment of HB has been dramatically improved by combining chemotherapy regimens with surgery, its fatal outcome of fast development and recurrence makes new treatment strategies for HB, based on an improved understanding of the pathogenesis, essential. Autophagy is believed to be important in the progression of cancers. However, the role of autophagy in HB remains to be elucidated. Here, we show that autophagy is activated in HB tissues and cells under the conditions of starvation or chemotherapy, coupled with the over-expression of autophagic-related genes BECN1 and ATG5. Suppression of autophagy with pharmacological agents and small interfering RNAs significantly increased cell apoptosis and retarded proliferation in response to nutrition deprivation and treatment with chemotherapeutics. Our data demonstrate that the BECN1 and ATG5-dependent phosphoinositide 3-kinase (PI3K) signaling pathway is essential for the survival of HB cells and their tolerance to chemotherapy and starvation-induced death, and suggests that modifying such autophagic genes may suppress the development of HB, thus offering a therapeutic potential for patients with HB.     

Reproducibility and quantitation of amplicon sequencing-based detection

To determine the reproducibility and quantitation of the amplicon sequencing-based detection approach for analyzing microbial community structure, a total of 24 microbial communities from a long-term global change experimental site were examined. Genomic DNA obtained from each community was used to amplify 16S rRNA genes with two or three barcode tags as technical replicates in the presence of a small quantity (0.1% wt/wt) of genomic DNA from Shewanella oneidensis MR-1 as the control. The technical reproducibility of the amplicon sequencing-based detection approach is quite low, with an average operational taxonomic unit (OTU) overlap of 17.2%±2.3% between two technical replicates, and 8.2%±2.3% among three technical replicates, which is most likely due to problems associated with random sampling processes. Such variations in technical replicates could have substantial effects on estimating β-diversity but less on α-diversity. A high variation was also observed in the control across different samples (for example, 66.7-fold for the forward primer), suggesting that the amplicon sequencing-based detection approach could not be quantitative. In addition, various strategies were examined to improve the comparability of amplicon sequencing data, such as increasing biological replicates, and removing singleton sequences and less-representative OTUs across biological replicates. Finally, as expected, various statistical analyses with preprocessed experimental data revealed clear differences in the composition and structure of microbial communities between warming and non-warming, or between clipping and non-clipping. Taken together, these results suggest that amplicon sequencing-based detection is useful in analyzing microbial community structure even though it is not reproducible and quantitative. However, great caution should be taken in experimental design and data interpretation when the amplicon sequencing-based detection approach is used for quantitative analysis of the β-diversity of microbial communities.     

CCND1 as a predictive biomarker of neoadjuvant chemotherapy in patients with locally advanced head and neck squamous cell carcinoma

Background

Cyclin D1 (CCND1) has been associated with chemotherapy resistance and poor prognosis. In this study, we tested the hypothesis that CCND1 expression determines response and clinical outcomes in locally advanced head and neck squamous cell carcinoma (HNSCC) patients treated with neoadjuvant chemotherapy followed by surgery and radiotherapy.

Methodology and Findings

224 patients with HNSCC were treated with either cisplatin-based chemotherapy followed by surgery and radiotherapy (neoadjuvant group, n = 100) or surgery and radiotherapy (non-neoadjuvant group, n = 124). CCND1 expression was assessed by immunohistochemistry. CCND1 levels were analyzed with chemotherapy response, disease-free survival (DFS) and overall survival (OS). There was no significant difference between the neoadjuvant group and non-neoadjuvant group in DFS and OS (p = 0.929 and p = 0.760) when patients treated with the indiscriminate administration of cisplatin-based chemotherapy. However, in the neoadjuvant group, patients whose tumors showed a low CCND1 expression more likely respond to chemotherapy (p<0.001) and had a significantly better OS and DFS than those whose tumors showed a high CCND1 expression (73% vs 8%, p<0.001; 63% vs 6%, p<0.001). Importantly, patients with a low CCND1 expression in neoadjuvant group received more survival benefits than those in non-neoadjuvant group (p = 0.016), however patients with a high CCND1 expression and treated with neoadjuvant chemotherapy had a significantly poor OS compared to those treated with surgery and radiotherapy (p = 0.032). A multivariate survival analysis also showed CCND1 expression was an independent predictive factor (p<0.001).

Conclusions

This study suggests that some but not all patients with HNSCC may benefit from neoadjuvant chemotherapy with cisplatin-based regimen and CCND1 expression may serve as a predictive biomarker in selecting patients undergo less than two cycles of neoadjuvant chemotherapy.     

Genotypes and toxin gene profiles of Staphylococcus aureus clinical isolates from China

A total of 108 S. aureus isolates from 16 major hospitals located in 14 different provinces in China were characterized for the profiles of 18 staphylococcal enterotoxin (SE) genes, 3 exfoliatin genes (eta, etb and etd), and the toxic shock syndrome toxin gene (tsst) by PCR. The genomic diversity of each isolate was also evaluated by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and accessory gene regulator (agr) typing. Of these strains, 90.7% (98/108) harbored toxin genes, in which tsst was the most prevalent toxin gene (48.1%), followed by sea (44.4%), sek (42.6%) and seq (40.7%). The see and etb genes were not found in any of the isolates tested. Because of high-frequency transfer of toxin gene-containing mobile genetic elements between S. aureus strains, a total of 47 different toxin gene combinations were detected, including a complete egc cluster in 19 isolates, co-occurrence of sea, sek and seq in 38 strains, and sec and sel together in 11 strains. Genetic typing by PFGE grouped all the strains into 25 clusters based on 80% similarity. MLST revealed 25 sequence types (ST) which were assigned into 16 clonal complexes (CCs) including 2 new singletons. Among these, 11 new and 6 known STs were first reported in the S. aureus strains from China. Overall, the genotyping results showed high genetic diversity of the strains regardless of their geographical distributions, and no strong correlation between genetic background and toxin genotypes of the strains. For genotyping S. aureus, PFGE appears to be more discriminatory than MLST. However, toxin gene typing combined with PFGE or MLST could increase the discriminatory power of genotyping S. aureus strains.