Evidence For Cutaneous Squamous Tumors Derived From Carcinogen-Exposed Bone Marrow

Cytokeratins are frequently found in the blood and bone marrow of patients with epithelial cancers and are attributed to metastasis. We wondered whether we could find keratin expression in blood and bone marrow in untreated adult mice. To address this problem, we have used classical immunoreactivity, Krt1-14;mTmG transgenic mice together with fluorescence activated cell sorting, and quantitative reverse transcriptase polymerase chain reaction. We have made several novel findings. First, we discovered, rare but distinctive, keratin-14 and keratin-15 immunoreactive cells the size of small lymphocytes in blood and bone marrow of untreated mice. Second, using Krt1-14;mTmG transgenic mice, we found low (8.6 GFP positive cells per 10^6 cells analyzed), but significant numbers (pl 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-332.