Constitutive expression of insulin-like growth factor 1 and insulin-like growth factor 1 receptor abrogates all requirements for exogenous growth factors. |
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Authors: | Z Pietrzkowski R Lammers G Carpenter A M Soderquist M Limardo P D Phillips A Ullrich R Baserga |
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Affiliation: | Jefferson Cancer Institute, Jefferson Medical College, Philadelphia, Pennsylvania 19107. |
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Abstract: | BALB/c3T3 cells are exquisitely growth regulated and require both platelet-derived growth factor and insulin-like growth factor-1 (IGF-1) for optimal proliferation. BALB/c3T3 cells that constitutively express IGF-1 and elevated levels of IGF-1 receptor (IGF-1R) are capable of growth in serum-free medium without the addition of any exogenous growth factors. BALB/c3T3 cells overexpressing only the IGF-1R plasmid required IGF-1 or insulin for serum-free growth. Antisense oligodeoxynucleotides complementary to IGF-1R mRNA inhibited IGF-1-mediated cell growth. Under these conditions, neither the epidermal growth factor receptor nor phospholipase C gamma 1 was autophosphorylated. These findings indicate that constitutive expression of IGF-1 and IGF-1R allows 3T3 cells to grow in serum-free medium without addition of those exogenous growth factors that are required by the parent cell line. |
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