• Targeted and enhanced therapy of cisplatin-resistant ovarian cancer cells
  • Somayeh Vandghanooni,1 Morteza Eskandani (Author Contributions †Somayeh Vandghanooni and Morteza Eskandani contributed equally to this work and should be considered as first co-authors.),2 Jaleh Barar,3 Yadollah Omidi,4,*
    1. Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
    2. Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
    3. Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran/Department of Pharmaceutics, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
    4. Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran/Department of Pharmaceutics, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran


  • Introduction: Combination therapy provides an effective way to improve the anticancer efficiency of the therapeutic agents and overcome drug resistance. Chemotherapy and gene therapy are hopeful combination strategy for the treatment of aggressive tumors. MiR-21 has been found to be highly expressed in the cisplatin (CIS)-resistant ovarian cancer (OC) cells. Therefore, inhibiting the function of up-regulated miRNAs involved in drug resistance might decrease the sensitivity of cancer cells to anticancer drugs. Antisense oligonucleotides (ASOs) have widely been used for the inhibition of oncogenic microRNAs. Receptor-mediated delivery using nanoscaled delivery systems have recently provided great hope for delivery of the anticancer drugs/genes. Aptamers (Aps), are single-stranded DNA/RNA or even peptide motifs, can fold into a three-dimensional (3D) structure and specifically bind to the relevant targets with a high affinity. They are considered as an excellent targeting ligands for the receptor-mediated targeting delivery of anticancer drugs because of their unique features, including simple and cost-effective synthesis and modification, non/low toxicity and nonimmunogenicity. AS1411 Ap is a G-rich 26 nucleotide (nt) oligodeoxynucleotide with a stable G-quadruplex 3D structure that can specifically bind to the nucleolin – a protein highly expressed on the surface/cytoplasm of the most malignant cells. Unique properties of the polymeric nanocarriers in terms of functionalization with various targeting and/or imaging agents together with the protection of anticancer drugs make them a suitable carrier for delivery of anticancer agents. In this study we aimed to inhibit overexpressed oncomiR-21 in cisplatin (CIS)-resistant OC and perform targeted therapy of sensitized cells using PLGA NPs
  • Methods: The PLGA-COOH and NH2-PEG-COOH polymers were used for synthesis of PLGA-PEG-COOH copolymer via EDC/NHS chemistry. The synthesized PLGA-PEG-COOH copolymer was then subjected for the preparation of polymeric NPs containing CIS (CIS-PLGA NPs) and anti-miR-21 (anti-miR-21-PLGA NPs) using W/O/W emulsification technique and then NPs were functionalized with AS1411 Ap as targeting agent. The prepared NPs were physicochemically characterized and the cancer-targeting ability of Ap-conjugated NPs were assessed using flow cytometry analysis. For the assessment of the mechanism of cellular uptake, nucleolin receptor was blocked with endostatin in the Nu+ cells, and the in vitro uptake of the Ap–NPs through the cell surface nucleolin was revalidated. The CIS-resistant-OC cells were then infected with Ap-functionalized anti-miR-21-PLGA NPs (Ap-anti-miR-21-PLGA NPs) and the suppression of miR-21 was investigated. Subsequently, the anti-proliferative effects of Ap-functionalized CIS-PLGA NPs (Ap-CIS-PLGA NPs) on miR-21 inhibited CIS-resistant cells were studied by MTT assay and FITC-labeled Annexin V/PI flow cytometry analysis. In addition, the cell cycle analysis was performed to investigate the cell cycle distributions in treated cells. Further the chromatin integrity and nucleus morphological changes in the apoptotic cells were assessed by genotoxicity assays including DNA ladder and DAPI staining respectively.
  • Results: The 1H NMR data validated the successful synthesis of PLGA-PEG copolymer. The resulted homogenous NPs were physically stable and exhibited a spherical shape with size range between 89.2 ± 7.6 nm and 142.4 ± 5.9 nm, and acceptable EE%, DL and DC%. The Ap decorated NPs were found to be more tended to the nucleolin overexpressed (Nu+) cells (A2780 R and A2780 S cells) mainly through nucleolin mediated endocytosis, whereas not intended to the (Nu-) CHO cells. The downregulation of oncomir-21 was confirmed in Ap-anti-mir-21-PLGA NPs treated resistant OC cells. Also, Results showed the high frequency of apoptotic cells in the miR-21-inhibited A2780 R cells in comparison with the uninfected cells upon treatment with the Ap–CIS–PLGA NPs confirmed the successful effect of mir-21 inhibiting in sensitizing the resistant cells to CIS.
  • Conclusion: Our findings suggest that targeted knockdown of oncomiR using antisense oligonucleotides increases the sensitivity of drug-resistant cancer cells to chemotherapeutic agents, which may enhance the efficiency of targeted drug delivery systems with less unwanted effects and more hopeful effects.
  • Keywords: Antisense , AS1411 Aptamer, Chemoresistant , Mir-21, Cisplatin