title: Anti-Neoplastic Cytotoxicity of Gemcitabine-(C4-amide)-[anti-HER2/neu] in Combination with Griseofulvin against Chemotherapeutic-Resistant Mammary Adenocarcinoma (SKBr-3).
abstract: BACKGROUND
  Gemcitabine is a pyrimidine nucleoside analog that becomes triphosphorylated and in this form it competitively inhibits cytidine incorporation into DNA strands. Diphosphorylated gemcitabine irreversibly inhibits ribonucleotide reductase thereby preventing deoxyribonucleotide synthesis. Functioning as a potent chemotherapeutic, gemcitabine decreases neoplastic cell proliferation and induces apoptosis which accounts for its effectiveness in the clinical treatment of several leukemia and carcinoma cell types. A brief plasma half-life due to rapid deamination, chemotherapeuticresistance and sequelae restricts gemcitabine utility in clinical oncology. Selective "targeted" gemcitabine delivery represents a molecular strategy for prolonging its plasma half-life and minimizing innocent tissue/organ exposure.
  
  
  METHODS
  A previously described organic chemistry scheme was applied to synthesize a UV-photoactivated gemcitabine intermediate for production of gemcitabine-(C4-amide)-[anti-HER2/neu]. Immunodetection analysis (Western-blot) was applied to detect the presence of any degradative fragmentation or polymerization. Detection of retained binding-avidity for gemcitabine-(C4-amide)-[anti-HER2/neu] was determined by cell-ELISA using populations of chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) that highly over-express the HER2/neutrophic membrane receptor. Anti-neoplastic cytotoxicity of gemcitabine-(C4-amide)-[anti-HER2/neu] and the tubulin/microtubule inhibitor, griseofulvin was established against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3). Related investigations evaluated the potential for gemcitabine-(C4-amide)-[anti-HER2/neu] in dual combination with griseofulvin to evoke increased levels of anti-neoplastic cytotoxicity compared to gemcitabine-(C4-amide)-[anti-HER2/neu].
  
  
  RESULTS
  Covalent gemcitabine-(C4-amide)-[anti-HER2/neu] immunochemotherapeutic and griseofulvin exerted anti-neoplastic cytotoxicity against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3). Covalent gemcitabine-(C4-amide)-[anti-HER2/neu] immunochemotherapeutic or gemcitabine in dual combination with griseofulvin created increased levels of anti-neoplastic cytotoxicity that were greater than was attainable with gemcitabine-(C4-amide)-[anti-HER2/neu] or gemcitabine alone.
  
  
  CONCLUSIONS
  Gemcitabine-(C4-amide)-[anti-HER2/neu] in dual combination with griseofulvin can produce enhanced levels of anti-neoplastic cytotoxicity and potentially provide a basis for treatment regimens with a wider margin-of-safety. Such benefits would be possible through the collective properties of; [i] selective "targeted" gemcitabine delivery; [ii] relatively lower toxicity of griseofulvin compared to many if not most conventional chemotherapeutics; [iii] reduced total dosage requirements faciliated by additive or synergistic anti-cancer properties; and [iv] differences in sequelae for gemcitabine-(C4-amide)-[anti-HER2/neu] compared to griseofulvin functioning as a tubulin/microtubule inhibitor.
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine at Wise Center, Mississippi State University, Mississippi State, Mississippi 39762, USA.
authors.forename: C P
authors.initials: CP
authors.lastname: Coyne
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine at Wise Center, Mississippi State University, Mississippi State, Mississippi 39762, USA.
authors.forename: Toni
authors.initials: T
authors.lastname: Jones
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine at Wise Center, Mississippi State University, Mississippi State, Mississippi 39762, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Bear
keywords: Anti-HER2/neu; Anti-neoplastic cytotoxicity; Chemotherapeutic-resistant; Covalent immunochemotherapeutic; Dual combination anti-cancer therapy; Gemcitabine-(C4-amide)-[anti-HER2/neu]; Griseofulvin; Mammary adenocarcinoma; Tubulin/microtubule inhibitor