Cell transformation by the superoxide-generating oxidase Mox1

Abstract

Reactive oxygen species (ROS) generated in some non-phagocytic cells are implicated in mitogenic signalling and cancer. Many cancer cells show increased production of ROS, and normal cells exposed to hydrogen peroxide or superoxide show increased proliferation and express growth-related genes. ROS are generated in response to growth factors, and may affect cell growth, for example in vascular smooth-muscle cells. Increased ROS in Ras-transformed fibroblasts correlates with increased mitogenic rate. Here we describe the cloning of mox1, which encodes a homologue of the catalytic subunit of the superoxide-generating NADPH oxidase of phagocytes, gp91phox. mox1 messenger RNA is expressed in colon, prostate, uterus and vascular smooth muscle, but not in peripheral blood leukocytes. In smooth-muscle cells, platelet-derived growth factor induces mox1 mRNA production, while antisense mox1 mRNA decreases superoxide generation and serum-stimulated growth. Overexpression of mox1 in NIH3T3 cells increases superoxide generation and cell growth. Cells expressing mox1 have a transformed appearance, show anchorage-independent growth and produce tumours in athymic mice. These data link ROS production by Mox1 to growth control in non-phagocytic cells.

Expression of Nox1 in 3T3 cells increases cellular acid production but not proton conductance

“…After 96 hours in culture the number of Nox1 3T3 cells was slightly lower compared to mock 3T3 cells, however, this did not reach statistical significance (n = 8, p = 0.052). Cell growth in this time window was not different from growth curves found in a previous study [2]. The acid production per cell was substantially higher in Nox1 3T3 cells (Fig.…”

“…al. [2] found that Nox1 3T3 cells generate O 2 •-at a rate of 18 to 36 fmole·h -1 ·cell -1 . In comparison, Nox1 expression in 3T3 cells resulted in an increase in acid production of 76 fmole·h -1 ·cell -1 (Fig.…”

“…Mouse 3T3 fibroblasts stably expressing human Nox1 (Nox1 3T3) or vector (mock 3T3) originated in the laboratory of Dr. J. David Lambeth [2] and were kindly provided by Dr. Jason Eiserich, Univ. of California at Davis.…”

“…This was investigated by measuring the pH of the medium over a 4-day period every 24 hours. This time frame was chosen because Nox1 and mock 3T3 cell cultures were previously shown to result in similar cell growth up to 6 days in culture [2]. Fig.…”

DAP kinase regulates JNK signaling by binding and activating protein kinase D under oxidative stress

“…[8][9][10] c-Jun-N-terminal kinase (JNK) is a key node of the cell death network activated under oxidative stress. 9,11,12 Yet, delineation of the upstream components regulating JNK activation, which eventually dictate cell fate, remains lacking.…”