Expression of epidermal growth factor receptor (EGF-r) and the effects of exogenous intraperitoneal infusion of EGF on growth rates in murine adenocarcinoma of the colon

OBJECTIVE To investigate the correlation between epidermal growth factor receptor (EGF-r) expression and growth rates in colon cancer, and the effects of exogenous intraperitoneal infusion of EGF on growth rates in murine adenocarcinoma of the colon. Met hod Seven well characterised sterile tumor solid and cell lines were used. These tumors were induced by injecting NMRI mice with 1,2-dimethylhydrazine, a known carcinogen producing colon cancer. Fragments of the primary tumors were then transplanted into hosting NMRI mice intraperitoneally and subcutaneously, and grown in tissue culture to produce a panel of tumors of different histology and growth characteristics (MAC15, MAC15A ip, MAC15A T/C, MAC15A S/C, MAC29, MAC30T, MAC31). The volume doubling times varied between 0.9 days (MAC15A T/C cells) and 8.0 days (MAC31 solid line). These tumors were originally produced in the Bradford Oncology Unit, Bradford University, UK, and transferred to the Medico-Biology Research Center of the Academy of Athens, Greece. EGF-r single point screening assay and Scatchard analysis of the binding data were made on the MAC lines. Results The results clearly showed an inverse relationship between EGF-r expression and doubling times of the solid lines. MAC15A lines also showed different EGF-r expression, a finding that raises the possibility that EGF-r expression is strongly influenced by environmental changes. Exogenous intraperitoneal infusion of 5 mu M. EGF induced inhibition of growth of the rapid growing MAC15A S/C and the same dose also resulted in inhibition of growth of the slow growing MAC31. Conclusions Colorectal cancer is the second leading cause of death from cancer world wide. There is no effective systemic therapy and current diagnostic techniques find fewer than half of the cases early enough to be cured by surgery. Since over-expression of EGF-r may play a role in carcinogenesis, it could be used as a possible therapeutic method through immuno-or hormonal therapy.