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Inhibition of matrix metalloproteinase‐2 enhances radiosensitivity by abrogating radiation‐induced FoxM1‐mediated G2/M arrest in A549 lung cancer cells
Author(s) -
Chetty Chandramu,
Bhoopathi Praveen,
Rao Jasti S.,
Lakka Sajani S.
Publication year - 2009
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.24209
Subject(s) - radiosensitivity , cancer research , a549 cell , clonogenic assay , apoptosis , radiosensitizer , matrix metalloproteinase inhibitor , matrix metalloproteinase , biology , cell cycle , cell cycle checkpoint , lung cancer , radioresistance , radiation therapy , medicine , pathology , biochemistry
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. © 2008 Wiley‐Liss, Inc.