Selective Phosphorylation of Cytosol Proteins Associated with Transformation and Restoration of Normal Phenotype in AKR Mouse Embryo Fibroblasts

Subhas Chakrabarty, Yih Jan, Julie Son, Charles A. Miller, Michael G. Brattain

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Phosphoproteins from cytosol preparations of methylcholan-threne-transformed AKR mouse (AKR-MCA) cells were compared to those of their untransformed counterparts, AKR-2B cells, by two-dimensional electrophoresis following an in vitro 32P phosphorylation procedure using endogenous kinases and substrates. Five proteins were phosphorylated in the AKR-MCA cells which were not observed in the AKR-2B cells, while six proteins were phosphorylated in the untransformed cells which were not observed in the malignant cells. Treatment of AKR-MCA cells with 1% N,N-dimethylformamide induced the reversion of the malignant cells to a phenotype similar to that of untransformed AKR-2B cells (S. Chakrabarty et a/., Cancer Res., 44: 2181, 1984). Treatment of AKR-MCA cells with dimethyl formamide resulted in the restoration of five of the AKR-2B-associated phosphorylations and abolished 2 of the AKR-MCA-associated phosphorylations. AKR-2B cells have been shown to respond to transforming growth factors with reversible phenotypic transformation (R. F. Tucker et al., Cancer Res., 43: 1581, 1983). Transforming growth factor treatment of AKR-2B cells induced all five of the AKR-MCA-associated phosphoproteins and the loss of all six of the AKR-2B phosphoproteins. Epidermal growth factor treatment of AKR-2B cells resulted in the phosphorylation of several proteins which were not observed in either AKR-MCA or untreated AKR-2B cells. Some, but not all, of the AKR-2B-associated phosphorylations were also observed in epidermal growth factor-treated cells. The results of these studies demonstrated qualitative and/or quantitative changes in cytosolic protein kinase-phosphatase activities between transformed and normal AKR-2B cells. Treatment of AKR-MCA cells with di-methylformamide resulted in the restoration of some of the normal AKR-2B cell-associated protein kinase-phosphatase activities.

Original languageEnglish (US)
Pages (from-to)2170-2176
Number of pages7
JournalCancer Research
Volume45
Issue number5
StatePublished - May 1 1985

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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