title: Doxycycline potentiates antitumor effect of cyclophosphamide in mice.
abstract: Cyclophosphamide (CPA) is a widely used chemotherapeutic drug in neoplasias. It is a DNA and protein alkylating agent that has a broad spectrum of activity against variety of neoplasms including breast cancer. The therapeutic effectiveness of CPA is limited by the high-dose hematopoietic, renal, and cardiac toxicity that accompanies the systemic distribution of liver-derived activated drug metabolites. The present study examines the potential of combining well-tolerated antibiotic doxycycline (DOX) with CPA and understanding the mechanism of cell killing. Interestingly, we found that DOX significantly enhances the tumor regression activity of CPA on xenograft mice model bearing MCF-7 cells. DOX also potentiates MCF-7 cell killing by CPA in vitro. In presence of DOX (3 microg/ml), the IC50 value of CPA decreased significantly from 10 to 2.5 mM. Additional analyses indicate that the tumor suppressor p53 and p53-regulated proapoptotic Bax were upregulated in vivo and in vitro following CPA treatment in combination with DOX, suggesting that upregulation of p53 may contribute to the enhancement of antitumor effect of CPA by DOX. Furthermore, downregulation of antiapoptotic Bcl-2 was observed in animals treated with CPA and CPA plus DOX when compared to untreated or DOX-treated groups. Our results raise the possibility that this combination chemotherapeutic regimen may lead to additional improvements in treatment of breast cancer.
authors.affiliation: National Centre for Cell Science, Pune University, Campus Ganeshkhind, NCCS Complex, Pune, Maharashtra, 411 007, India.
authors.forename: Rishi Raj
authors.initials: RR
authors.lastname: Chhipa
authors.forename: Sandeep
authors.initials: S
authors.lastname: Singh
authors.forename: Sachin V
authors.initials: SV
authors.lastname: Surve
authors.forename: Maleppillil Vavachan
authors.initials: MV
authors.lastname: Vijayakumar
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Bhat
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy; D049109:Cell Proliferation / Q000187:drug effects; D003520:Cyclophosphamide / Q000494:pharmacology* / Q000627:therapeutic use; D004318:Doxycycline / Q000494:pharmacology* / Q000627:therapeutic use; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D005434:Flow Cytometry; D015151:Immunoblotting; D066298:In Vitro Techniques; D051379:Mice; D008819:Mice, Nude; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays; D051028:bcl-2-Associated X Protein
chemical_list: D000970:Antineoplastic Agents; C494827:Bax protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D003520:Cyclophosphamide; D004318:Doxycycline