Cell Line Derived Xenograft Mouse Models Are a Suitable in vivo Model for Studying Tumor Budding in Colorectal Cancer.

Laurent M C Georges,Pieter Demetter,Olivier De Wever,Inti Zlobec,Heather Dawson,Alessandro Lugli,José A Galván

doi:10.3389/fmed.2019.00139

Abstract

Tumor budding (TB) is an important prognostic parameter in colorectal cancer (CRC) and associated with metastasis. However, the mechanisms of TB have not been fully elucidated and a major limitation is the absence of in vivo models. Here, we determine the suitability of human cell line derived xenografts (CDX) as models of TB in CRC. Pan-cytokeratin (CK)-stained next-generation Tissue Microarrays (ngTMA) of two CDX models (HT-29, n = 12 and HCT-8, n = 8) and human CRC (n = 27 high-grade and 25 low-grade budding tumors, each) were evaluated for TB. Immunohistochemistry for E-cadherin, β-catenin, Ki-67, ZEB1, and TWIST1 was performed. HT-29 and HCT-8 were predominantly high-grade and no/low-grade TB tumors, respectively. TB counts in the tumor center (intratumoral budding, ITB) were significantly higher in HT-29 CDX tumors compared to human CRC (p = 0.0099). No difference was found in TB counts at the invasion front (peritumoral budding, PTB; p=0.07). ITB and PTB were strongly correlated (r = 0.438 and r = 0.62 in CDX and human CRC, respectively). Immunohistochemistry profiles were comparable in CDX and human CRC tissues. TB in the CDX mouse models is phenotypically similar to human CRCs and highlights comparable protein profiles. The HT-29 CDX could be a suitable model for the in vivo assessment of TB.

Highlights

Tumor budding (TB) in colorectal cancer reflects the detachment of tumor cells from the main tumor mass and is defined by the presence of single tumor cells or small tumor cell clusters
The aim of this study is to investigate whether colorectal cancer (CRC) cell line derived xenograft mouse models (CDX) show TB that is phenotypically similar to human cancers and suitable as model for the study of TB in CRC
The novel findings of this study show that different orthotopic mouse xenograft models (HT-29 and HCT-8) can show a range of TB counts in both the center and the invasion front similar to what is seen in human tumors

Summary

Introduction

Tumor budding (TB) in colorectal cancer reflects the detachment of tumor cells from the main tumor mass and is defined by the presence of single tumor cells or small tumor cell clusters. The “International Tumor Budding Consensus Conference” (ITBCC) presented guidelines for the evaluation of TB, which is useful in two clinical scenarios [4]: First, the presence of high-grade PTB at the invasion front in endoscopically resected pT1 colorectal tumors is positively associated with lymph node metastasis. These patients are recommended to undergo surgical resection. High-grade PTB in patients with stage II colorectal cancers have unfavorable prognosis and are recommended for adjuvant chemotherapy. A third scenario currently under investigation is the TB in CDX Mouse Models presence of ITB in preoperative biopsies of patients with neoadjuvant treated rectal cancer, which may help predict the presence of the presence of lymph node and distant metastases [5, 6]

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