Redox regulation of matrix metalloproteinase gene family in small cell lung cancer cells

Abstract

It has been implicated that reactive oxygen species (ROS) play important roles in modulating tumor progression. However, the mechanisms by which redox-regulated tumor progression are largely unknown. We previously demonstrated that reduced intracellular redox conditions could be achieved in stably transfected small cell lung cancer cells with gamma-glutamylcysteine synthetase (gamma-GCSh) cDNA which encodes a rate-limiting enzyme in the biosynthesis of glutathione (GSH), a major physiological redox regulator. In the present study, using DNA microarray analyses, we compared the expression profiles between the gamma-GCSh-transfected cells and their nontransfected counterpart. We observed downregulation of several matrix metalloproteinases (MMPs), i.e., MMPI and MMP3, and MMP10 in the transfected cells. Dot blot and Northern blot hybridizations confirmed that, among the 18 MMP gene family members and four tissue inhibitors of matrix metalloprotein family (TIMP) analyzed, the expression levels of these three MMPs were consistently reduced. Transiently increased gamma-GCSh expression using tetracycline-inducible gamma-GCSh adenoviral expression system also showed down-regulation of MMP3 and MMP10, but not MMP1. Our results demonstrated that redox regulation of MMP1, MMP3 and MMP10 expression depend upon different modes of redox manipulation. These results bear implication that antioxidant modulation of antitumor progression may be contributed at least in part by the downregulation of a subset of metrix metalloproteins.

Elevated Glutathione Levels Confer Cellular Sensitization to Cisplatin Toxicity by Up-Regulation of Copper Transporter hCtr1

“…GCLC in the presence (ϩ) or absence (Ϫ) of tet for 24 or 48 h. Levels of GCLC expression were increased approximately 11-and 30-fold in cells grown in the absence of tet for 24 and 48 h, respectively, compared with those treated with tet. Comparable levels of elevated GSH were found in the GCLC-overexpressing samples (Savaraj et al, 2005). Levels of hCtr1 expression were elevated in the GCLC-overexpressing cells (Fig.…”

“…Low levels of hCtr1 up-regulation were also observed in cells treated with tet, which suppress the induced expression of GCLC. The precise mechanism of this induction is not known, but it is perhaps due to adenoviral transduction-associated oxidative stress, which induces the expression of GCLC because similar low levels of GCLC expression were also increased when the cells were transduced with recombinant adenovirus encoding ␤-globin gene (Savaraj et al, 2005). Alternatively, incomplete repression of GCLC by tet could not be ruled out.…”

“…The cells were grown in Dulbecco's modified Eagle's medium containing 10% fetal calf serum at 37°C in 5% CO 2 atmosphere, except as otherwise described and with 400 g/ml Geneticin (G418; Invitrogen, Carlsbad, CA) for the transfected cell lines. Construction and preparation of recombinant adenovirus AdE1.tTA.GCLC [previously referred to as AdE1.tTA.␥-GCSh, with ␥-GCSh being the catalytic (heavy) subunit of GCL] were described previously (Savaraj et al, 2005).…”

“…Recombinant adenoviral vector AdE1.tTA.GCLC (Savaraj et al, 2005) contains two expression cassettes: one constitutively expresses tetregulatable transactivator (rTA), and the other contains a GCL-expression cassette whose expression is under the control of rTA. In the absence of tet, the constitutively expressed rTA binds to the promoter of GCLC and activates the transcription of GCLC, whereas in its presence, expression of GCLC was inhibited.…”

Elevated GSH Level Increases Cadmium Resistance through Down-Regulation of Sp1-Dependent Expression of the Cadmium Transporter ZIP8

“…GCLC in the presence (ϩ) or absence (Ϫ) of tet for 24, 48, or 72 h. Levels of GCLC expression were increased approximately 11-and 30-fold in cells grown in the absence of tet for 24 and 48 h, respectively, compared with those treated with tet. Comparable levels of elevated GSH were found in the GCLC-overexpressing samples (Savaraj et al, 2005). Levels of ZIP8 mRNA were reduced in the GCLC-overexpressing cells (Fig.…”