Epirubicin-[Anti-HER2/] Synthesized with an Epirubicin-(C-)-EMCS Analog: Anti-Neoplastic Activity against Chemotherapeutic-Resistant SKBr-3 Mammary Carcinoma in Combination with Organic Selenium.

PURPOSE

Discover the anti-neoplastic efficacy of epirubicin-(C-imino)-[anti-HER2/neu] against chemotherapeutic-resistant SKBr-3 mammary carcinoma and delineate the capacity of selenium to enhance it's cytotoxic anti-neoplastic potency.

METHODS

In molar excess, EMCH was combined with epirubicin to create a covalent epirubicin-(C-imino)-EMCH-maleimide intermediate with sulfhydryl-reactive properties. Monoclonal immunoglobulin selective for HER2/neu was then thiolated with 2-iminothiolane at the terminal ε-amine group of lysine residues. The sulfhydryl-reactive epirubicin-(C-imino)-EMCH intermediate was then combined with thiolated anti-HER2/neu monoclonal immunoglobulin. Western-blot analysis was utilized to characterize the molecular weight profiles while binding of epirubicin-(C-imino)-[anti-HER2/neu] to membrane receptors was determined by cell-ELISA utilizing populations of SKBr-3 mammary carcinoma that highly over-expresses HER2/neu complexes. Anti-neoplastic potency of epirubicin-(C-imino)-[anti-HER2/neu] between the epirubicin-equivalent concentrations of 10 M and 10 M was determined by vitality staining analysis with and without the presence of selenium (5 μM).

RESULTS

Epiribucin-(C-imino)-[anti-HER2/neu] between epirubicin-equivalent concentrations of 10 M to 10 M consistently evoked higher anti-neoplastic potency than "free" non-conjugated epirubicin which corresponded with previous investigations utilizing epirubicin-(C-amide)-[anti-HER2/neu] and epirubicin-(C-amide)-[anti-EGFR]. Selenium at 5 mM consistently enhanced the cytotoxic anti-neoplastic potency of epirubicin-(C13-imino)-[anti-HER2/neu] at epirubicin equivalent concentrations (10-12 to 10-7 M).

CONCLUSIONS

Epirubicin-(C-imino)-[anti-HER2/neu] is more potent than epirubicin against chemotherapeutic-resistant SKBr-3 mammary carcinoma and selenium enhances epirubicin-(C-imino)-[anti-HER2/neu] potency. The methodology applied for synthesizing epirubicin-(C-imino)-[anti-HER2/neu] is relatively time convenient and has low instrumentation requirements.