IMMUNOHISTOCHEMICAL CHARACTERIZATION OF TRANSPLANTABLE RAT SQUAMOUS-CELL CARCINOMA (FF-6) IN SKIN AND THYMUS

FF-6 is a transplantable squamous cell carcinoma which originally aros e in the facial skin of a DA rat. It was established-after maintaining the tumor in the subcutaneous tissue or peritoneal cavity of DA rats conventionally for over 30 generations. When the soybean-sized origina l FF-6 tumor was transplanted subcutaneously, it became an oval, hard, whitish, solitary and thumb-head-sized nodule within one month. After intraperitoneal transplantation of FF-6, it formed many nodules rangi ng from miliary to thumb-head size, which adhered and/or metastasized to many abdominal organs. When FF-6, cut into small pieces, was inject ed into the lower lip, the tumor grew bigger in situ, and metastasized to regional lymph nodes. Histologically, FF-6 was characterized as a well-differentiated squamous cell carcinoma, showing positive staining with anti-keratin, anti-laminin, anti-collagen type IV, anti-fibronec tin and UB-14 antibodies. This transplantable tumor may be useful for analyzing the mechanisms of proliferation and metastasis of squamous c ell carcinoma in vivo, and the host defence mechanism in rats, as well as being a suitable model of human squamous cell carcinoma.