Epithelioid Cells

In this priority report, we briefly describe the establishment and
characterization of a bona fide esophageal adenocarcinoma cell line, JH-EsoAd1. This
cell line was derived from a 66-year-old caucasian male undergoing surgical
resection for a distal esophageal malignancy (pT3N0M0). Histopathological
examination confirmed the presence of an infiltrating, moderately to poorly
differentiated adenocarcinoma (Fig. 1A) and
metaplastic Barrett epithelium at the periphery of the tumor (Fig. 1B). A p53 immunostain^{12 (link)} demonstrated nuclear overexpression in the cancer cells
(Fig. 1C), consistent with mutational
inactivation and stabilization of p53 in the primary tumor. A fresh sample of the
resected cancer was directly passaged in tissue culture, as previously
described,^{13 (link)} for
establishment of JH-EsoAd1. In addition, the patient’s peripheral lymphocytes
were Epstein Barr virus (EBV)-immortalized, as a perpetual source of matched
germline DNA. As seen in Figure 1D, the
cultured epithelioid cells grew adherent in a monolayer with pleomorphic nuclei and
abundant cytoplasm, with a doubling time of 20 hours in RPMI 20% FBS. In order to
generate DNA fingerprinting of JH-EsoAd1 for posterity, we utilized the
PowerPlex^® 1.2 System (Promega Corporation) and profiled DNA obtained from
the archival normal esophageal tissue, the archival microdissected Barrett
adenocarcinoma and the resulting cell line. The Powerplex microsatellite results
(see Suppl. Table 1)
confirm the identity of JH-EsoAd1 with its parental tumor. Additional molecular
characterization of JH-EsoAd1 cells included epithelial marker positivity for
cytokeratin and lack of expression of the stromal marker vimentin (Fig. 1E and F respectively). Consistent with the
results of the p53 immunohistochemistry in the archival tumor, JH-EsoAd1 cells
express high levels of p53 expression (Fig.
1G) and also harbor a somatic G → A mutation at
base 797 (Fig. 1H and I), resulting in a
previously described non-synonymous Gly 266 Glu alteration in TP53(which also confirmed in the primary tumor).^{14 (link)} However, KRAS2 is wild type at codons 12,
13, 61 and 146, the four most commonly mutated loci in this oncogene (data
not shown). In addition, there is no genomic evidence for
wnt pathway activation, as discerned by absence of mutations in
APC and in the exon 3 “hot spot” of
CTNNB1 (data not shown). We were also
successful in establishing JH-EsoAd1 subcutaneous xenografts in 6 of 6 NOD/SCID mice
(Fig. 2A and B), which generated tumors
with an adenocarcinomatous morphology (Fig.
2C). Based on the xenografting data, we believe JH-EsoAd1 will be a useful
preclinical tool for assessing the impact of modulating cellular pathways using
genetic or pharmacological measures on the growth of esophageal adenocarcinoma.
In summary, we have created an authenticated esophageal adenocarcinoma cell
line that should restitute some of the current deficit resulting from mistaken
identities of the most commonly used models in this disease. The JH-EsoAd1 is being
deposited in a commercial cell line repository (American Type Culture Collection;
www.atcc.org), in order to
facilitate rapid dissemination to the scientific community.