title: Inhibition of matrix metalloproteinase-2 enhances radiosensitivity by abrogating radiation-induced FoxM1-mediated G2/M arrest in A549 lung cancer cells.
abstract: Matrix metalloproteinase-2 (MMP-2), is known to degrade the collagen IV, plays a role in radiation-induced lung injury. We therefore investigated the antitumor effects of combining MMP-2 inhibition using an adenovirus expressing siRNA against MMP-2 (Ad-MMP-2-Si) with radiation therapy (IR) on A549 lung cancer cells in vitro and in vivo. IR increased MMP-2 mRNA, protein and activity in lung cancer cells. MMP-2 inhibition along with IR enhanced radiosensitivity as determined by clonogenic assay, flow cytometry and TUNEL assay. We show that MMP-2 inhibition prior to irradiation reduced p53 phosphorylation, with a corresponding reduction in the expression of the p53 downstream target gene p21(Cip1/Waf1). Irradiated tumor cells induced the FoxM1-mediated DNA repair gene, XRCC1 and Checkpoint kinases 2/1, which were abrogated with combined treatment of Ad-MMP-2-Si and IR. Further, the combination of Ad-MMP-2-Si with radiotherapy significantly increased antitumor efficacy in vivo compared to either agent alone. Indeed, histological analysis of tumor sections collected from the combination group revealed more apoptotic cells. These studies suggest that MMP-2 inhibition in combination with radiotherapy abrogates G2 cell cycle arrest leading to apoptosis and provide evidence of the antitumor efficacy of combining MMP-2 inhibition with irradiation as a new therapeutic strategy for the effective treatment of NSCLC patients.
authors.affiliation: Program of Cancer Biology, Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL 61605, USA.
authors.forename: Chandramu
authors.initials: C
authors.lastname: Chetty
authors.forename: Praveen
authors.initials: P
authors.lastname: Bhoopathi
authors.forename: Jasti S
authors.initials: JS
authors.lastname: Rao
authors.forename: Sajani S
authors.initials: SS
authors.lastname: Lakka
mesh_terms: D017209:Apoptosis; D001483:Base Sequence; D002455:Cell Division / Q000502:physiology / Q000528:radiation effects*; D045744:Cell Line, Tumor; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D017931:DNA Primers; D004260:DNA Repair / Q000502:physiology; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors / Q000502:physiology*; D016195:G2 Phase / Q000502:physiology / Q000528:radiation effects*; D006801:Humans; D020287:In Situ Nick-End Labeling; D008175:Lung Neoplasms / Q000201:enzymology / Q000473:pathology*; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011836:Radiation Tolerance; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; C107585:FOXM1 protein, human; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases