Somatostatin receptor type 2-based reporter expression after plasmid-based in vivo gene delivery to non-small cell lung cancer

Mol Imaging. 2013 Oct;12(7):1-10.

Abstract

Plasmids tend to have much lower expression than viruses. Gene expression after systemic administration of plasmid vectors has not been assessed using somatostatin receptor type 2 (SSTR2)-based reporters. The purpose of this work was to identify gene expression in non-small cell lung cancer (NSCLC) after systemic liposomal nanoparticle delivery of plasmid containing SSTR2-based reporter gene. In vitro, Western blotting was performed after transient transfection with the plasmid cytomegalovirus (CMV)-SSTR2, CMV-TUSC2-IRES-SSTR2, or CMV-TUSC2. SSTR2 is the reporter gene, and TUSC2 is a therapeutic gene. Mice with A549 NSCLC lung tumors were injected intravenously with CMV-SSTR2, CMV-TUSC2-IRES-SSTR2, or CMV-TUSC2 plasmids in DOTAP:cholesterol-liposomal nanoparticles. Two days later, mice were injected intravenously with 111In-octreotide. The next day, biodistribution was performed. The experiment was repeated including single-photon emission computed tomography/computed tomography (SPECT/CT). Immunohistochemistry was performed. In vitro, SSTR2 expression was similar in cells transfected with CMV-SSTR2 or CMV-TUSC2-IRES-SSTR2. TUSC2 expression was similar in cells transfected with CMV-TUSC2 or CMV-TUSC2-SSTR2. Biodistribution demonstrated significantly greater 111In-octreotide uptake in tumors from mice injected with CMV-TUSC2-IRES-SSTR2 or CMV-SSTR2 than the control plasmid, CMV-TUSC2 (p < .05). Gamma-camera and SPECT/CT imaging illustrated SSTR2 expression in tumors in mice injected with CMV-TUSC2-IRES-SSTR2 or CMV-SSTR2 versus background with control plasmid. Immunohistochemistry corresponded with imaging. SSTR2-based reporter imaging can visualize gene expression in lung tumors after systemic liposomal nanoparticle delivery of plasmid containing SSTR2-based reporter gene or SSTR2 linked to a second therapeutic gene, such as TUSC2.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Carcinoma, Non-Small-Cell Lung / genetics*
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / therapy*
  • Cell Line, Tumor
  • Cytomegalovirus / genetics
  • Female
  • Genes, Reporter
  • Genetic Therapy*
  • Genetic Vectors
  • Heterografts
  • Humans
  • Indium Radioisotopes
  • Liposomes
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / therapy*
  • Mice
  • Mice, Nude
  • Neoplasm Transplantation
  • Octreotide / analogs & derivatives
  • Plasmids
  • Radiopharmaceuticals
  • Receptors, Somatostatin / genetics*
  • Receptors, Somatostatin / metabolism
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tumor Cells, Cultured
  • Tumor Suppressor Proteins / genetics*
  • Tumor Suppressor Proteins / metabolism

Substances

  • Indium Radioisotopes
  • Liposomes
  • Radiopharmaceuticals
  • Receptors, Somatostatin
  • TUSC2 protein, human
  • Tumor Suppressor Proteins
  • indium-111-octreotide
  • somatostatin receptor 2
  • Octreotide