A natural animal model for human
head and neck squamous cell carcinoma (H/N SCC) has not been described. The domestic cat has a high spontaneous occurrence of oropharyngeal SCC, which is similar to the human disease in aggressiveness and incurability. We have developed a cell line (SCCF1) from a laryngeal SCC of a cat. Keratinocytes were maintained in culture for greater than 50 passages. SCCF1 had strong
cytokeratin immunohistochemical staining, weak
vimentin staining, and no p53 staining. Ultrastructual features included
cytokeratin filaments and desmosomes, as well as features of
anaplasia (irregular cytoplasmic and nuclear margins, surface filopodia, and abnormal intermediate filament production). Karyotype analysis revealed
aneuploidy, with a stemline chromosomal number of 34. The cells grew logarithmically for 6 d until confluency. SCCF1 expressed
parathyroid hormone-related protein (
PTHrP) messenger
ribonucleic acid (
mRNA) and
protein, and secreted the
protein into the medium. Treatment of SCCF1 with
transforming growth factor-beta increased
PTHrP production but did not affect
PTHrP mRNA stability.
Reverse transcriptase-polymerase chain reaction was used to amplify a 282-base pair region of feline
PTHrP mRNA, encoding portions of the pre-pro and coding regions. The complementary
deoxyribonucleic acid (
cDNA) was cloned and sequenced. The
cDNA and the predicted amino acid sequences had a high degree of homology to human and canine
PTHrP. RT-PCR was used to confirm alternate splicing of
PTHrP mRNA for translation of
PTHrP 1-139 and
PTHrP 1-141. The SCCF1 cell line will permit mechanistic experiments on genetic dysregulation in neoplastic keratinocytes of the feline oropharynx, and development of an in vitro model for H/N
cancer.