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Identification of Junctionally-Transmitted Growth Inhibitors

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Annual rept. 15 Jul 1998-14 Jul 1999

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We have proposed the identification of junctionally transmitted growth control signals which we hypothesize to be responsible for the growth inhibition of tumor cells when in junctional communication with normal cells. In order to test this hypothesis rigorously, we have genetically engineered human breast cancer cells to contain the gap junction gene connexin 43, under the control of a tetracycline inducible promoter. We have been successful in producing several clones in which connexin 43 is strongly induced on withdrawal of tetracycline and in which connexin 43 is integrated into the plasma membrane and is functional as determined by dye. injection studies. We have moreover shown that exposure of isolated cells to EGTA results in the opening of hemi--channels to the extra-cellular environment expression of connexin 43 is required for this effect. To determine that any responses of cells are due to junctional transfer of signals, rather than the presence of a trans- membrane protein, we have similarly produced breast cancer cell lines containing a mutant connexin 43 gene in which the pore is predicted to be blocked. These molecular and biological tools put us in a good position to carefully address the stated hypothesis.

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  • Biochemistry
  • Genetic Engineering and Molecular Biology
  • Medicine and Medical Research

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