The NADPH oxidase NOX5 protects against apoptosis in ALK-positive anaplastic large-cell lymphoma cell lines

Abstract

Reactive oxygen species (ROS) are key modulators of apoptosis and carcinogenesis. One of the important sources of ROS is NADPH oxidases (NOXs). The isoform NOX5 is highly expressed in lymphoid tissues, but it has not been detected in any common Hodgkin or non-Hodgkin lymphoma cell lines. In diverse, nonlymphoid malignant cells NOX5 exerts an antiapoptotic effect. Apoptosis suppression is the hallmark feature of a rare type of lymphoma, termed anaplastic lymphoma kinase-positive (ALK(+)) anaplastic large-cell lymphoma (ALCL), and a major factor in the therapy resistance and relapse of ALK(+) ALCL tumors. We applied RT-PCR and Western blot analysis to detect NOX5 expression in three ALK(+) ALCL cell lines (Karpas-299, SR-786, SUP-M2). We investigated the role of NOX5 in apoptosis by small-interfering RNA (siRNA)-mediated gene silencing and chemical inhibition of NOX5 using FACS analysis and examining caspase 3 cleavage in Karpas-299 cells. We used immunohistochemistry to detect NOX5 in ALK(+) ALCL pediatric tumors. NOX5 mRNA was uniquely detected in ALK(+) ALCL cells, whereas cell lines of other lymphoma classes were devoid of NOX5. Transfection of NOX5-specific siRNA and chemical inhibition of NOX5 abrogated calcium-induced superoxide production and increased caspase 3-mediated apoptosis in Karpas-299 cells. Immunohistochemistry revealed focal NOX5 reactivity in pediatric ALK(+) ALCL tumor cells. These results indicate that NOX5-derived ROS contribute to apoptosis blockage in ALK(+) ALCL cell lines and suggest NOX5 as a potential pharmaceutical target to enhance apoptosis and thus to suppress tumor progression and prevent relapse in pediatric ALK(+) ALCL patients that resist classical therapeutic approaches.

Paradoxical roles of dual oxidases in cancer biology

“…The lack of NOX5 from the rodent genome has limited our understanding of its biological role, but several recent studies have highlighted the potential importance of NOX5, based on findings of increased NOX5 expression and/or NOX5-derived ROS in various cancers, e.g. prostate [75, 76], hairy cell leukemia[77], esophageal [78], ALK lymphoma [79], and others[80, 81]. NOX2 has also been implicated in promoting the oncogenic phenotype in various cancers such as breast cancer[82], myelomonocytic leukemia[83], rectal cancer cells[84], prostate[85], and expression of NOX2 mRNA or protein was found to correlate with an invasive phenotype and poor prognosis in gastric cancer[86].…”

Taurine Attenuates Calpain‐2 Induction and a Series of Cell Damage via Suppression of NOX‐Derived ROS in ARPE‐19 Cells

“…Except for NOX5 and DUOX1/2, p22phox is required for regulating NOX isoforms [ 3 , 21 ]. Unlike other NOX homologues, NOX5 has the ability to bind and be activated by intracellular calcium directly and its function to produce ROS is regulated by intracellular calcium mobilization, influx, and phosphorylation [ 22 , 23 ]. Calcium/calmodulin-dependent kinase II can activate NOX5 via direct phosphorylation [ 15 ].…”

NADPH oxidase 5 (NOX5)—induced reactive oxygen signaling modulates normoxic HIF‐1α and p27Kip1 expression in malignant melanoma and other human tumors

“…29,35,36 Several studies report correlations between NOX5 expression and tumorigenesis 23,37 ; yet, limited evidence exists detailing the signaling role of NOX5 in tumor biology. Such studies include, but are not limited to, explorations of the role of NOX5 in hairy cell leukemia, 38 ALK-positive anaplastic large-cell lymphoma, 39 prostate cancer, 22,24,40 and esophageal adenocarcinoma. 25,41,42 Recently, our laboratory reported the characterization of NOX5 expression in human tumors and tumor cell lines using a new NOX5 monoclonal antibody.…”