The interaction between two cell lines derived from the human salivary gland (HSG), neoplastic epithelial duct HSG cells and myoepithelial human
pleomorphic adenoma (HPA) cells, was studied morphologically and immunohistochemically in nude mice
tumors produced by inoculation of HSG and HPA cells.
Transplantation of HSG cells into nude mice resulted in the production of
adenocarcinoma which contained
carcinoembryonic antigen (CEA). The nude mice
tumors induced by HPA cells were interpreted as
myoepithelioma in which the presence of
S-100 protein and
myosin were identified. On the other hand, the occurrence of squamous cell nests was frequently noted in the nude mice
tumors produced by inoculation of a mixture of HSG and HPA cells. The
tumor cells present in the squamous cell nests had abundant tonofilaments in the cytoplasm and were attached with tight junction and distinct desmosomes. In addition, the presence of
keratin in the
tumor cells composing squamous cell nests was demonstrated. When the mixture of HSG and HPA cells treated with
polyethylene glycol (PEG) was transplanted into the nude mice, the
tumors produced consisted almost entirely of areas showing the histologic features of
anaplastic carcinoma, and did not contain all of the specific cell markers observed in the HSG or HPA
tumors. The nude mice
tumors induced by PEG-treated HSG or HPA cells were interpreted as
adenocarcinoma and
myoepithelioma, respectively, and giant cells were occasionally observed in the
tumor sections. These findings indicate that neoplastic cells showing differentiation stages other than those of the original two cells can be induced in nude mice by utilizing HSG and HPA cells.