title: TIMP-1 Inhibits Apoptosis in Lung Adenocarcinoma Cells via Interaction with Bcl-2.
abstract: Tissue inhibitors of metalloproteinases (TIMPs) are multifaceted molecules that exhibit properties beyond their classical proteinase inhibitory function. Although TIMP-1 is a known inhibitor of apoptosis in mammalian cells, the mechanisms by which it exerts its effects are not well-established. Our earlier studies using H2009 lung adenocarcinoma cells, implanted in the CNS, showed that TIMP-1 overexpressing H2009 cells (HB-1), resulted in more aggressive tumor kinetics and increased vasculature. The present study was undertaken to elucidate the role of TIMP-1 in the context of apoptosis, using the same lung cancer cell lines. Overexpressing TIMP-1 in a lung adenocarcinoma cell line H2009 resulted in an approximately 3-fold increased expression of Bcl-2, with a marked reduction in apoptosis upon staurosporine treatment. This was an MMP-independent function as a clone expressing TIMP-1 mutant T2G, lacking MMP inhibition activity, inhibited apoptosis as strongly as TIMP1 overexpressing clones, as determined by inhibition of PARP cleavage. Immunoprecipitation of Bcl-2 from cell lysates also co-immunoprecipitated TIMP-1, indicative of an interaction between these two proteins. This interaction was specific for TIMP-1 as TIMP-2 was not present in the Bcl-2 pull-down. Additionally, we show a co-dependency of TIMP-1 and Bcl-2 RNA and protein levels, such that abrogating Bcl-2 causes a downregulation of TIMP-1 but not TIMP-2. Finally, we demonstrate that TIMP-1 dependent inhibition of apoptosis occurs through p90RSK, with phosphorylation of the pro-apoptotic protein BAD at serine 112, ultimately reducing Bax levels and increasing mitochondrial permeability. Together, these studies define TIMP-1 as an important cancer biomarker and demonstrate the potential TIMP-1 as a crucial therapeutic target.
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Srilatha
authors.initials: S
authors.lastname: Nalluri
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Sampa
authors.initials: S
authors.lastname: Ghoshal-Gupta
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Ammar
authors.initials: A
authors.lastname: Kutiyanawalla
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Sitaram
authors.initials: S
authors.lastname: Gayatri
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Byung Rho
authors.initials: BR
authors.lastname: Lee
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Shahanawaz
authors.initials: S
authors.lastname: Jiwani
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Amyn M
authors.initials: AM
authors.lastname: Rojiani
authors.affiliation: Department of Pathology, Georgia Regents University-Medical College of Georgia, Augusta, GA, United States of America.
authors.forename: Mumtaz V
authors.initials: MV
authors.lastname: Rojiani
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism; D008175:Lung Neoplasms / Q000473:pathology*; D008928:Mitochondria / Q000378:metabolism; D010539:Permeability; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; C560822:TIMP1 protein, human; D019715:Tissue Inhibitor of Metalloproteinase-1; D051028:bcl-2-Associated X Protein; D019311:Staurosporine