Site-Specific Genomic Alterations in a Well-Differentiated Pancreatic Neuroendocrine Tumor With High-Grade Progression.

The major categories of pancreatic neuroendocrine tumor (PanNET) are well-differentiated NET and poorly differentiated neuroendocrine carcinoma. Sequencing of these tumors has identified multiple important genes in the pathogenesis of PanNETs, such as DAXX/ATRX, MEN1, TP53, RB, and mTOR pathway genes. We identified a case of well-differentiated PanNET with high-grade progression with simultaneous low- and high-grade histologic regions containing variable genomic profiles. We performed tumor microdissection and analyzed both regions using a 409-gene comprehensive cancer panel using next-generation sequencing in addition to immunohistochemical and morphologic studies. The low-grade region showed a change in the DAXX gene as a copy number variant (CNV) deletion. The high-grade region showed CNV deletion changes in the DAXX gene as well as the MEN1 gene. We observed additional mutational changes in the PTEN gene and SMAD4 gene in the high-grade region. Our data support that high-grade progression in PanNETs may be the result of the progressive accumulation of genetic changes (CNVs and point mutational changes) within the body of the tumor. Next generation sequencing may provide pathologists and clinicians with ancillary information to accurately characterize and treat these tumors.

Influence of TP53 and CDH1 genes in hepatocellular cancer spheroid formation and culture: a model system to understand cancer cell growth mechanics.

BACKGROUND: Spheroid based culture methods are gaining prominence to elucidate the role of the microenvironment in liver carcinogenesis. Additionally, the phenomenon of epithelial-mesenchymal transition also plays an important role in determining the metastatic potential of liver cancer. Tumor spheroids are thus important models to understand the basic biology of liver cancer. METHODS: We cultured, characterized and examined the formation of compact 3-D micro-tumor spheroids in five hepatocellular carcinoma (HCC) cell lines, each with differing TP53 mutational status (wt vs mutant vs null). Spheroid viability and death was systematically measured over a course of a 10 day growth period using various assays. We also examined the TP53 and E-cadherin (CDH1) mRNA and protein expression status in each cell line of the 2-D and 3-D cell models. RESULTS: A novel finding of our study was the identification of variable 3-D spheroid morphology in individual cell lines, ranging from large and compact, to small and unstable spheroid morphologies. The observed morphological differences between the spheroids were robust and consistent over the duration of spheroid culture growth of 10 days in a repeatable manner. Highly variable CDH1 expression was identified depending on the TP53 mutational status of the individual HCC cell line, which may explain the variable spheroid morphology. We observed consistent patterns of TP53 and CDH1 expression in both 2-D and 3-D culture models. CONCLUSIONS: In conclusion, we show that 3-D spheroids are a useful model to determine the morphological growth characteristics of cell lines which are not immediately apparent in routine 2-D culture methods. 3-D culture methods may provide a better alternative to study the process of epithelial-mesenchymal transition (EMT) which is important in the process of liver cancer metastasis.