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Overexpression of a synthetic phosphotyrosine protein phosphatase gene inhibits normal and transformed cell growth
Author(s) -
Ramponi Giampietro,
Ruggiero Marco,
Raugei Giovanni,
Berti Andrea,
Modesti Alessandra,
Innocenti Donatella Degl',
Magnelli Lucia,
Pazzagli Claudia,
Chiarugi Vincenzo P.,
Camici Guido
Publication year - 1992
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.2910510424
Subject(s) - phosphatase , dephosphorylation , biology , cell growth , 3t3 cells , transfection , enzyme , microbiology and biotechnology , cell , biochemistry , gene
We studied the level of the cytosolic phosphotyrosine protein phosphatase (PTPase) (originally termed low‐M r acid phosphatase) in normal NIH/3T3 and in v‐erb B‐transformed fibroblasts. The level of the enzyme, assayed by ELISA, was inversely related to cell proliferation, normally growing cells had less enzyme than their contact‐inhibited counterparts and v‐erbB transformants had less enzyme than normal NIH/3T3. In order to overexpress the enzyme and study its effects in normal and transformed cells, we transfected a synthetic gene coding for the PTPase in control NIH/3T3 and v‐erbB transformants. The overexpressed enzyme was recognized by antibodies raised against the native enzyme and, in cells overexpressing the PTPase, we observed a marked dephosphorylation of tyrosyl residues of cellular proteins. Cell proliferation, in both normal and v‐erbB transformants overexpressing the PTPase, was measured. We observed that PTPase overexpression was accompanied by significantly reduced thymidine incorporation in both cell types, either serum‐starved or serum‐stimulated. The ability of transformed v‐erbB cells to grow in soft agar was also markedly decreased by overexpression of the enzyme. Taken together, our results indicate that overexpression of PTPase might interfere with mitogenic signalling pathways in both normal and transformed cells, and propose a role for PTPase in the control of cell proliferation.