Altered redox status accompanies progression to metastatic human bladder cancer

Abstract

The role of reactive oxygen species (ROS) in bladder cancer progression remains an unexplored field. Expression levels of enzymes regulating ROS levels are often altered in cancer. Search of publicly available micro-array data reveals that expression of mitochondrial manganese superoxide dismutase (Sod2), responsible for the conversion of superoxide (O 2 -. ) to hydrogen peroxide (H 2 O 2 ), is consistently increased in high grade and advanced stage bladder tumors. Here we aim to identify the role of Sod2 expression and ROS in bladder cancer. Using an in vitro human bladder tumor model we monitored the redox state of both non-metastatic (253J) and highly metastatic (253J B-V) bladder tumor cell lines. 253J B-V cells displayed significantly higher Sod2 protein and activity levels compared to their parental 253J cell line. The increase in Sod2 expression was accompanied by a significant decrease in catalase activity, resulting in a net increase in H 2 O 2 production in the 253J B-V line. Expression of pro-metastatic and -angiogenic factors, matrix metalloproteinase 9 (MMP-9) and vascular endothelial derived growth factor (VEGF), respectively, were similarly upregulated in the metastatic line. Expression of both MMP-9 and VEGF were shown to be H 2 O 2 -dependent, as removal of H 2 O 2 by overexpression of catalase attenuated their expression. Similarly, expression of catalase effectively reduced the clonogenic activity of 253J B-V cells. These findings indicate that metastatic bladder cancer cells display an altered antioxidant expression profile, resulting in a net increase in ROS production, which leads to the induction of redox-sensitive protumorigenic and pro-metastatic genes such as VEGF and MMP-9.

Up-regulation of mitochondrial antioxidation signals in ovarian cancer cells with aggressive biologic behavior

“…Another interpretation is that the expressions of MMP-9 and vascular endothelial-derived growth factor (VEGF), an ascertained metastasis-related factor by promoting angiogenesis, were shown to be H 2 O 2 -dependent. Increased SOD2 expression was found to be accompanied by a significant decrease in catalase (CAT) activity, resulting in a net increase in H 2 O 2 production in cells (Hempel et al, 2009). In addition, the high level of SOD2 led to oxidative inactivation of PTEN (phosphatase and tensin homolog deleted from chromosome 10) and resulted in activation of Akt/PI3K signals, and consequently up-regulated the expression of VEGF (Connor et al, 2005).…”

“…For example, the severity of invasion was directly correlated with SOD2 expression levels in fibrosarcoma cells and bladder tumor cells (Connor et al, 2007). Expression of SOD2 was consistently increased in high-grade and advanced-stage bladder tumors (Hempel et al, 2009). Activity of SOD2 was significantly higher in advanced-stage tumor or tumor with nodal metastasis in the head and neck squamous cell carcinoma (HNSCC) (Salzman et al, 2007).…”

Up-regulation of BLT2 is critical for the survival of bladder cancer cells

“…Similarly, we also observed that most bladder cancer cells show enhanced ROS generation compared with control bladder cells (Supplemental Figure 2A). In bladder cancer, it was recently reported that the acquisition of metastatic ability is associated with the level of ROS scavenging enzymes in the bladder cancer cell lines 253J (non-metastatic) and 253J-BV (highly metastatic) (Hempel et al, 2009). However, no direct evidence that NOX-derived ROS are responsible for cell survival has been reported in bladder cancer cells although recently we observed that BLT2-linked ROS generation by NOX1 and NOX4 plays a role of bladder cancer invasion (Kim et al, 2010b).…”

Reactive Oxygen Species in the Biology of Melanoma

“…Particularly, an increase in superoxide dismutase and a decrease in catalase activities were found in epithelial tumour cells and in human melanoma cells. In this sense, a correlation between the endogenous levels of H 2 O 2 and the degree of malignancy was demonstrated in epithelial tumour cell lines from skin, breast and bladder (Hempel et al, 2009;Policastro el al, 2004). These characteristics further perpetuate a state of oxidative stress in cancer cells.…”