Detection of cancer cells in the peripheral blood and lung of mice after transplantation of human adenoid cystic carcinoma.

Polymerase chain reaction (PCR) targeting human β-globin gene has been reported to be able to detect micrometastasis in an animal model. We attempted to detect cancer cells from the lung and peripheral blood in nude mice, into which a human adenoid cystic carcinoma (ACC) line (KOA-1 and KOA-1L3) had been transplanted. Positive PCR reaction was observed in the lung of a total of 19 of 47 (40.4%) mice into which KOA-1 tumor cells had been transplanted: none of 10 after 1 month, seven of 18 after 2 months, and 12 of 19 after 3 months or later. The KOA-1L3 tumor showed earlier lung metastasis, that is, two of 24 after 7 days and two of 12 after 14 days. Positive PCR reaction was confirmed in the blood samples of three of 19 mice. The lungs of these mice were positive PCR results after subcutaneous transplantation of the KOA-1 tumor. Three of four mice in these blood samples were confirmed in Positive PCR reaction after subcutaneous transplantation of the KOA-1L3 tumor similarly. The lungs of these mice showed PCR positive reaction as well as the lungs of transplantation KOA-1 tumor mice. On the other hand, negative PCR reaction observed these lungs of 60 mice after subcutaneous transplantation of the KOA-1 or KOA-1L3 tumor. All of them were showed negative PCR results in the blood samples. This experimental model can be expected to provide a more detailed understanding of ACC, as well as help to develop a therapy for metastasis of ACC. Adenoid cystic carcinoma (ACC) is a unique malignant tumor which originated from the salivary gland and is characterized by slow growth, diffuse invasion, and high frequency of distant metastasis (10,15,16). We recently established a new ACC line, designated as KOA-1, which is serially transplantable into the subcutaneous tissue of nude mice and spontaneously metastasizes to the lung (4,15). Further, we established a variant of KOA-1 by means of in vivo selection, and designated it KOA-1L3. This KOA-1L3 showed faster growth and developed earlier lung metastasis than the parental KOA-1. Both these tumor lines showed evidence of having retained the unique ACC characteristics of frequent metastasis. The prognosis for patients with oral cancer, including salivary gland carcinoma, has been remarkably improved over the past several decades. Local cure can be attained for most patients, but occasionally distant metastasis occurs. Diagnosis and treatment of distant