title: MicroRNA-106a targets autophagy and enhances sensitivity of lung cancer cells to Src inhibitors.
abstract: Src tyrosine kinase inhibitors (TKIs) significantly inhibit cell migration and invasion in lung cancer cell lines with minor cytotoxic effects. In clinical trials, however, they show modest activity in combination with chemotherapeutic agents. Possible resistance mechanisms include the induction of cytoprotective autophagy upon Src inhibition. Autophagy is a cellular recycling process that allows cell survival in response to a variety of stress stimuli including responses to various treatments.
  
  
  
  We screened autophagic activity in A549, H460, and H1299 NSCLC cell lines treated with two different Src-TKIs (saracatinib, dasatinib) or shRNA targeting SRC. The autophagy response was determined by LC3B-I to -II conversion, increased ULK1 epxression and increased GFP-LC3B dot formation. Autophagy was inhibited by pharmacological (bafilomycin A, chloroquine) or genetic (ULK1 shRNA) means. Expression of miR-106a and miR-20b was analyzed by qPCR, and we used different lentivral vectors for ectopic expression of either miR-106a mimetics, anti-sense miR-106a or different miR-106a-363 cluster constructs.
  
  
  
  In the current study we found that Src-TKIs induce autophagy in lung adenocarcinoma cell lines and that a combination of autophagy and Src tyrosine kinase inhibition results in cell death. Moreover, Src-TKI induced autophagy depends on the induction of the key autophagy kinase ULK1. This ULK1 upregulation is caused by downregulation of the ULK1-targeting microRNA-106a. An inverse correlation of miR-106a and ULK1 expression was seen in lung adenocarcinoma. Accordingly, ectopic expression of miR-106a in combination with Src-TKI treatment resulted in significant cell death as compared to control transduced cells.
  
  
  
  Autophagy protects lung adenocarcinoma cells from Src-TKIs via a newly identified miR-106a-ULK1 signaling pathway. The combined inhibition of Src and ULK1/autophagy might represent a promising treatment option for future clinical trials. Lastly, our data might challenge the term "oncogenic" miR-106a as it can promote sensitivity to Src-TKIs thereby underlining the context-dependent function of miRNAs.
authors.affiliation: Department of Medical Oncology, Inselspital, Bern University Hospital, Switzerland; Department of Clinical Research, University of Bern, Bern, Switzerland; Department Internal Medicine, Medical Oncology, University Hospital Basel, Basel, Switzerland.
authors.forename: Sacha I
authors.initials: SI
authors.lastname: Rothschild
authors.affiliation: Department of Medical Oncology, Inselspital, Bern University Hospital, Switzerland; Medical Oncology, Cantonal Hospital, Luzern, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Gautschi
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Batliner
authors.affiliation: Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Mathias
authors.initials: M
authors.lastname: Gugger
authors.affiliation: Department of Medical Oncology, Inselspital, Bern University Hospital, Switzerland; Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Martin F
authors.initials: MF
authors.lastname: Fey
authors.affiliation: Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland. Electronic address: mario.tschan@pathology.unibe.ch.
authors.forename: Mario P
authors.initials: MP
authors.lastname: Tschan
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D001343:Autophagy / Q000187:drug effects*; D000071189:Autophagy-Related Protein-1 Homolog / Q000235:genetics; D052117:Benzodioxoles / Q000494:pharmacology; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000069439:Dasatinib / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008168:Lung / Q000473:pathology*; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics*; D008869:Microtubule-Associated Proteins; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000187:drug effects; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D052117:Benzodioxoles; D047908:Intracellular Signaling Peptides and Proteins; C502070:MAP1LC3B protein, human; C542541:MIRN106 microRNA, human; D035683:MicroRNAs; D008869:Microtubule-Associated Proteins; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D034741:RNA, Small Interfering; C515233:saracatinib; D019061:src-Family Kinases; D000071189:Autophagy-Related Protein-1 Homolog; C484754:ULK1 protein, human; D000069439:Dasatinib
keywords: Autophagy; NSCLC; Src tyrosine kinase inhibitor; ULK1; miR-106a; microRNA