title: Liposomal delivery of MicroRNA-7-expressing plasmid overcomes epidermal growth factor receptor tyrosine kinase inhibitor-resistance in lung cancer cells.
abstract: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) have been strikingly effective in lung cancers harboring activating EGFR mutations. Unfortunately, the cancer cells eventually acquire resistance to EGFR-TKI. Approximately 50% of the acquired resistance involves a secondary T790M mutation. To overcome the resistance, we focused on EGFR suppression using microRNA-7 (miR-7), targeting multiple sites in the 3'-untranslated region of EGFR mRNA. Two EGFR-TKI-sensitive cell lines (PC-9 and H3255) and two EGFR-TKI-resistant cell lines harboring T790M (RPC-9 and H1975) were used. We constructed miR-7-2 containing miR-7-expressing plasmid. After transfection of the miR-7-expressing plasmid, using cationic liposomes, a quantitative PCR and dual luciferase assay were conducted to examine the efficacy. The antiproliferative effect was evaluated using a cell count assay and xenograft model. Protein expression was examined by Western blotting. The miR-7 expression level of the transfectants was approximately 30-fold higher, and the luciferase activity was ablated by 92%. miR-7 significantly inhibited cell growth not only in PC-9 and H3255 but also in RPC-9 and H1975. Expression of insulin receptor substrate-1 (IRS-1), RAF-1, and EGFR was suppressed in the four cell lines. Injection of the miR-7-expressing plasmid revealed marked tumor regression in a mouse xenograft model using RPC-9 and H1975. EGFR, RAF-1, and IRS-1 were suppressed in the residual tumors. These findings indicate promising therapeutic applications of miR-7-expressing plasmids against EGFR oncogene-addicted lung cancers including T790M resistance by liposomal delivery.
authors.affiliation: Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Kammei
authors.initials: K
authors.lastname: Rai
authors.forename: Nagio
authors.initials: N
authors.lastname: Takigawa
authors.forename: Sachio
authors.initials: S
authors.lastname: Ito
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kashihara
authors.forename: Eiki
authors.initials: E
authors.lastname: Ichihara
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Yasuda
authors.forename: Kenji
authors.initials: K
authors.lastname: Shimizu
authors.forename: Mitsune
authors.initials: M
authors.lastname: Tanimoto
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Kiura
mesh_terms: D020413:3' Untranslated Regions; D000230:Adenocarcinoma / Q000235:genetics / Q000628:therapy*; D000077192:Adenocarcinoma of Lung; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005260:Female; D015870:Gene Expression; D018014:Gene Transfer Techniques; D006801:Humans; D008081:Liposomes; D008175:Lung Neoplasms / Q000235:genetics / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics*; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010957:Plasmids / Q000008:administration & dosage* / Q000235:genetics; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction; D047368:Tumor Burden / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D020413:3' Untranslated Regions; D000970:Antineoplastic Agents; D066246:ErbB Receptors; D008081:Liposomes; D035683:MicroRNAs; D051058:Oncogene Protein v-akt; D047428:Protein Kinase Inhibitors; C549242:MIRN7-1 microRNA, human