Molecular characterization of chordoma xenografts generated from a novel primary chordoma cell source and two chordoma cell lines

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Chordoma cells can generate solid-like tumors in xenograft models that express some molecular characteristics of the parent tumor, including positivity for brachyury and cytokeratins. However, there is a dearth of molecular markers that relate to chordoma tumor growth, as well as the cell lines needed to advance treatment. The objective in this study was to isolate a novel primary chordoma cell source and analyze the characteristics of tumor growth in a mouse xenograft model for comparison with the established U-CH1 and U-CH2b cell lines.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Primary cells from a sacral chordoma, called “DVC-4,” were cultured alongside U-CH1 and U-CH2b cells for more than 20 passages and characterized for expression of CD24 and brachyury. While brachyury is believed essential for driving tumor formation, CD24 is associated with healthy nucleus pulposus cells. Each cell type was subcutaneously implanted in NOD/SCID/IL2Rγ<jats:sup>null</jats:sup> mice. The percentage of solid tumors formed, time to maximum tumor size, and immunostaining scores for CD24 and brachyury (intensity scores of 0–3, heterogeneity scores of 0–1) were reported and evaluated to test differences across groups.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The DVC-4 cells retained chordoma-like morphology in culture and exhibited CD24 and brachyury expression profiles in vitro that were similar to those for U-CH1 and U-CH2b. Both U-CH1 and DVC-4 cells grew tumors at rates that were faster than those for U-CH2b cells. Gross tumor developed at nearly every site (95%) injected with U-CH1 and at most sites (75%) injected with DVC-4. In contrast, U-CH2b cells produced grossly visible tumors in less than 50% of injected sites. Brachyury staining was similar among tumors derived from all 3 cell types and was intensely positive (scores of 2–3) in a majority of tissue sections. In contrast, differences in the pattern and intensity of staining for CD24 were noted among the 3 types of cell-derived tumors (p &lt; 0.05, chi-square test), with evidence of intense and uniform staining in a majority of U-CH1 tumor sections (score of 3) and more than half of the DVC-4 tumor sections (scores of 2–3). In contrast, a majority of sections from U-CH2b cells stained modestly for CD24 (scores of 1–2) with a predominantly heterogeneous staining pattern.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>This is the first report on xenografts generated from U-CH2b cells in which a low tumorigenicity was discovered despite evidence of chordoma-like characteristics in vitro. For tumors derived from a primary chordoma cell and U-CH1 cell line, similarly intense staining for CD24 was observed, which may correspond to their similar potential to grow tumors. In contrast, U-CH2b tumors stained less intensely for CD24. These results emphasize that many markers, including CD24, may be useful in distinguishing among chordoma cell types and their tumorigenicity in vivo.</jats:p></jats:sec>

Characterization of a Clival Chordoma Xenograft Model Reveals Tumor Genomic Instability

“…Copy number data were analyzed using Partek Genomic Suite 6.6 v6. 15.1207 (Partek, St. Louis, MO). Samples were imported, background was normalized using Partek Defaults, and the copy number was calculated from allele-specific intensity.…”

Effects of primary and recurrent sacral chordoma on the motor and nociceptive function of hindlimbs in rats: an orthotopic spine model

“…Other subcutaneous xenograft chordoma models derived from human tissues have been used to produce rodent tumors; however, they do not replicate the human disease in terms of neurological function, largely due to the ectopic location of tumors (hence a lack of influence on nociception and locomotion of the gait). 9,19,21,23,40 In this study, we sought to develop and evaluate an orthotopic animal model involving human-derived chordoma growing in the L-5 vertebral body of immunocompromised rats. With progressive growth, these tumors affected the locomotion and nociceptive behavior of rats as well as the bone anatomy, based on imaging evidence.…”

Chordoma‐derived cell line U‐CH1‐N recapitulates the biological properties of notochordal nucleus pulposus cells

“…Of note, chordoma is caused by a malignant transformation of the cellular remnants of the embryonic notochord. 23,24 While there are several human chordoma cell lines reported in the literature, [8][9][10][11][12] most of these cell lines have a relatively long doubling time and are not suitable for practical use. For example, the first validated chordoma cell line, U-CH1 has a doubling time of approximately 7 day.…”

“…Because many cell lines that are currently used were derived from tumor tissues, and both notochord and chordoma originate from the same progenitor cells, we sought to identify a chordoma‐derived cell line that retains the biological properties of notochordal NP cells. Most of human chordoma cell lines reported to date have a relatively long doubling time and are not suitable for in vitro analysis . In the course of screening, we found U‐CH1‐N, a cell line sub‐cloned from a chordoma‐derived cell line U‐CH1, as a potential candidate .…”

“…Most of human chordoma cell lines reported to date have a relatively long doubling time and are not suitable for in vitro analysis. [8][9][10][11][12] In the course of screening, we found U-CH1-N, a cell line sub-cloned from a chordoma-derived cell line U-CH1, as a potential candidate. 13 U-CH1-N has a relatively short doubling-time compared to other chordomaderived cell lines and maintains its phenotype, at least in terms of morphology, over passages under regular culture conditions.…”