title: Aptamer-functionalized hybrid nanoparticle for the treatment of breast cancer.
abstract: OBJECTIVE
  Resistance to chemotherapeutic agents such as doxorubicin is a major reason for cancer treatment failure. At present the treatment option for metastatic breast cancer is very poor. Therefore, development of an effective therapeutic strategy to circumvent MDR of metastatic breast cancer is highly anticipated. The MDR of metastatic breast cancer cells was accompanied with the overexpression of P-gp transporter. Even though the overexpression of P-gp could be minimized by silencing with siRNA, the question is how they can be selectively targeted to the cancer cells. We propose that aptamer surface labeling of the nanoparticles could enhance the selectively delivery of p-gp siRNA into the metastatic breast cancer cells. Our hypothesis is that conjugating nanoparticles with a cancer cell specific aptamer should allow selective delivery of therapeutic drugs to tumor cells leading to enhanced cellular toxicity and antitumor effect as compared to unconjugated nanoparticles. The primary objective of this study is to develop a targeted nanocarrier delivery system for siRNA into breast cancer cells.
  
  
  METHODS
  For targeted delivery, Aptamer A6 has been used which can bind to Her-2 receptors on breast cancer cells. For aptamer binding to particle surface, maleimide-terminated PEG-DSPE (Mal-PEG) was incorporated into the nanoparticles. Initially, three blank hybrid nanoparticles (i.e. F21, F31, and F40) out of nine different formulations prepared by high pressure homogenization (HPH) using different amount of DOTAP, cholesterol, PLGA or PLGA-PEG and Mal-PEG were chosen. Then protamine sulfate-condensed GAPDH siRNA (TRITC conjugated; red) or P-gp siRNA was encapsulated into those nanoparticles. Finally, the particles were incubated with aptamer A6 (FITC conjugated; green) for surface labeling.
  
  
  RESULTS
  Aptamer labeled-nanoparticles having PLGA are smaller in size than those having PLGA-PEG. Surface charge was reduced when the particles were labeled with aptamer. Cell transfection was increased significantly in Her-2 (+) SKBR-3 and 4T1-R cells but not in Her-2 poorly expressed MDA MB-231 and MCF-7 cells. The knockdown of P-gp was increased significantly when the particles were labeled with aptamer. No significant cellular toxicity was observed for any of these formulations.
  
  
  CONCLUSIONS
  This preliminary study concludes that aptamer-functionalized hybrid nanoparticles could be used to deliver P-gp targeted siRNA into the breast cancer cells to overcome chemoresistance.
authors.affiliation: Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: David
authors.initials: D
authors.lastname: Powell
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Sruti
authors.initials: S
authors.lastname: Chandra
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Kyra
authors.initials: K
authors.lastname: Dodson
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Farhana
authors.initials: F
authors.lastname: Shaheen
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Kylar
authors.initials: K
authors.lastname: Wiltz
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Shubha
authors.initials: S
authors.lastname: Ireland
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Muniruzzaman
authors.initials: M
authors.lastname: Syed
authors.affiliation: Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, United States.
authors.forename: Srikanta
authors.initials: S
authors.lastname: Dash
authors.affiliation: Center for Nanomedicine and Drug Delivery, Xavier University College of Pharmacy, New Orleans, LA 70125, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wiese
authors.affiliation: Center for Nanomedicine and Drug Delivery, Xavier University College of Pharmacy, New Orleans, LA 70125, United States.
authors.forename: Tarun
authors.initials: T
authors.lastname: Mandal
authors.affiliation: Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, United States. Electronic address: akundu@xula.edu.
authors.forename: Anup
authors.initials: A
authors.lastname: Kundu
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000627:therapeutic use*; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001943:Breast Neoplasms / Q000188:drug therapy*; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems; D005079:Excipients; D005260:Female; D020868:Gene Silencing; D006801:Humans; D008081:Liposomes; D061986:MCF-7 Cells; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000627:therapeutic use*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D052157:Aptamers, Nucleotide; D005079:Excipients; D008081:Liposomes; D034741:RNA, Small Interfering; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
keywords: Aptamer; Her-2; Nanoparticle; P-glycoprotein; siRNA