Keratin expression of both chemically and virally transformed human epidermal keratinocytes during the process of...

Human epidermal cells, despite being 'immortalized' or 'transformed' by combinations of either oncogenic virus (SV40, adenovirus 12 or Kirsten murine sarcoma virus) or chemical carcinogen (N-methyl-N'-nitro-N-nitrosoguanidine or 4-nitroquinoline-1-oxide) exhibited similar keratins (although quantitatively reduced) to that of control cells when grown in vitro. However, athymic nude mouse tumors derived from such cells exhibited suppression of the 52, 56 and 58 kd (basic type II) keratins and a predominance of small-sized (40-48 or 50 kd) (acidic type I) keratins. The synthesis of these specific keratins was resumed following re-establishment of cell lines in culture. These results suggest that the changes in keratin protein profiles frequently exhibited by human carcinomas represent a component of the pleomorphic transformed phenotype which can be uncoupled from neoplastic growth.