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Transformation of human keratinocytes is characterized by quantitative and qualitative alterations of the T‐16 antigen (Trop‐2, MOv‐16)
Author(s) -
Schön Michael P.,
Orfanos Constantin E.
Publication year - 1995
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910600113
Subject(s) - keratinocyte , antigen , immunoprecipitation , glycoprotein , microbiology and biotechnology , cell culture , biology , malignant transformation , transformation (genetics) , tunicamycin , in vitro , immunology , biochemistry , cancer research , gene , genetics , unfolded protein response , endoplasmic reticulum
The regulation of synthesis and post‐translational processing of the T‐16 antigen, a human cell‐surface glycoprotein of 50 to 60 kDa, was investigated in normal and transformed human keratinocytes in vitro. Normal keratinocytes of interfollicular and follicular origin were compared with squamous‐cell‐carcinoma lines, spontaneously immortalized keratinocytes, and SV‐40 transformed keratinocytes. FACS analysis and radio‐immunoprecipitation showed that the synthesis and expression of T‐16 was 3‐ to 4‐fold higher in transformed keratinocytes than in their normal counterparts. In normal keratinocytes, no quantitative differences were observed among freshly prepared cells, primary cultures and sub‐cultures. In SDS‐PAGE, a single broad band at 50 to 60 kDa was observed in normal keratinocytes, whereas 2 bands at 42 and 45 to 55 kDa were detected after transformation. Tunicamycin treatment of living cells and glycosidase digestion of immunopurified T‐16 antigen revealed this molecular heterogeneity to be due to different N‐glycosylation in normal and transformed keratinocytes. In pulse‐chase experiments, 2 distinct precursor proteins at 38 and 42 kDa were detected in transformed keratinocytes, whereas in normal cells the 38‐kDa signal was dramatically decreased. These findings indicate that quantitative and qualitative changes of T‐16 mark the transformation process of human keratinocytes, showing similar post‐translational alterations in all transformed populations investigated. © 1995 Wiley‐Liss, Inc.