title: Gemcitabine-(C4-amide)-[anti-HER2/neu] Anti-Neoplastic Cytotoxicity in Dual Combination with Mebendazole against Chemotherapeutic-Resistant Mammary Adenocarcinoma.
abstract: BACKGROUND
  Gemcitabine is a pyrimidine nucleoside analog that becomes triphosphorylated and 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, chemotherapeutic-resistance and sequelae restrict 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 of 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. Cytotoxic anti-neoplastic potency of gemcitabine-(C4-amide)-[anti-HER2/neu] and the benzimidazole tubulin/microtubule inhibitors, albendazole, flubendazole and mebendazole 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 mebendazole to evoke increased levels of cytotoxic anti-neoplatic potency compared to gemcitabine-(C4-amide)-[anti-HER2/neu].
  
  
  RESULTS
  Covalent gemcitabine-(C4-amide)-[anti-HER2/neu] immunochemotherapeutic and each benzimidazole (n=3) exerted cytotoxic anti-neoplastic potency against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3). Covalent gemcitabine-(C4-amide)-[anti-HER2/neu] immunochemotherapeutic or gemcitabine in dual combination with mebendazole created increased levels of cytotoxic anti-neoplastic potency that were greater than attained with gemcitabine-(C4-amide)-[anti-HER2/neu] or gemcitabine alone.
  
  
  CONCLUSIONS
  Gemcitabine-(C4-amide)-[anti-HER2/neu] in dual combination with benzimidazoles can produce enhanced levels of cytotoxic anti-neoplastic activity 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 benzimidazoles 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 benzimidazole tubulin/microtubule inhibitors.
authors.affiliation: Department of Basic Sciences (College of Veterinary Medicine), Mississippi State University, USA.
authors.forename: C P
authors.initials: CP
authors.lastname: Coyne
authors.affiliation: Department of Basic Sciences (College of Veterinary Medicine), Mississippi State University, USA.
authors.forename: Toni
authors.initials: T
authors.lastname: Jones
authors.affiliation: College of Veterinary Medicine at Wise Center, Mississippi State University, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Bear
keywords: Anti-HER2/neu; Benzimidazoles; Chemotherapeutic-resistant; Covalent immunochemotherapeutic; Cytotoxic anti-neoplastic potency; Dual combination anti-cancer therapy; Gemcitabine-(C4-amide)-[anti-HER2/neu]; Mammary adenocarcinoma