A Splice Variant of the Human Ion Channel TRPM2 Modulates Neuroblastoma Tumor Growth through Hypoxia-inducible Factor (HIF)-1/2α

• Published in: The Journal of biological chemistry Vol. 289; no. 52; pp. 36284 - 36302
• Main Authors: Chen, Shu-jen, Hoffman, Nicholas E., Shanmughapriya, Santhanam, Bao, Lei, Keefer, Kerry, Conrad, Kathleen, Merali, Salim, Takahashi, Yoshinori, Abraham, Thomas, Hirschler-Laszkiewicz, Iwona, Wang, JuFang, Zhang, Xue-Qian, Song, Jianliang, Barrero, Carlos, Shi, Yuguang, Kawasawa, Yuka Imamura, Bayerl, Michael, Sun, Tianyu, Barbour, Mustafa, Wang, Hong-Gang, Madesh, Muniswamy, Cheung, Joseph Y., Miller, Barbara A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26.12.2014; American Society for Biochemistry and Molecular Biology
• Subjects: Adrenal Glands - metabolism; Animals; Antibiotics, Antineoplastic - pharmacology; Autophagy; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Cell Line, Tumor; Cell Proliferation; Cell Survival - drug effects; Down-Regulation; Doxorubicin - pharmacology; Female; Gene Expression Regulation, Neoplastic; Humans; Hypoxia-inducible Factor (HIF); Hypoxia-Inducible Factor 1, alpha Subunit - genetics; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Membrane Potential, Mitochondrial; Membrane Potentials; Mice, Nude; Mitochondria; Mitophagy; Neoplasm Transplantation; Neuroblastoma; Neuroblastoma - metabolism; Neuroblastoma - pathology; Oxidative Stress; Protein Isoforms - physiology; Protein Transport; Signal Transduction; TRP; TRPM; TRPM Cation Channels - physiology; Tumor Burden; Mitochondria; TRP; Oxidative Stress; Hypoxia-inducible Factor (HIF); Neuroblastoma; Mitophagy; TRPM
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.620922

The calcium-permeable ion channel TRPM2 is highly expressed in a number of cancers. In neuroblastoma, full-length TRPM2 (TRPM2-L) protected cells from moderate oxidative stress through increased levels of forkhead box transcription factor 3a (FOXO3a) and superoxide dismutase 2. Cells expressing the dominant negative short isoform (TRPM2-S) had reduced FOXO3a and superoxide dismutase 2 levels, reduced calcium influx in response to oxidative stress, and enhanced reactive oxygen species, leading to decreased cell viability. Here, in xenografts generated with SH-SY5Y neuroblastoma cells stably expressing TRPM2 isoforms, growth of tumors expressing TRPM2-S was significantly reduced compared with tumors expressing TRPM2-L. Expression of hypoxia-inducible factor (HIF)-1/2α was significantly reduced in TRPM2-S-expressing tumor cells as was expression of target proteins regulated by HIF-1/2α including those involved in glycolysis (lactate dehydrogenase A and enolase 2), oxidant stress (FOXO3a), angiogenesis (VEGF), mitophagy and mitochondrial function (BNIP3 and NDUFA4L2), and mitochondrial electron transport chain activity (cytochrome oxidase 4.1/4.2 in complex IV). The reduction in HIF-1/2α was mediated through both significantly reduced HIF-1/2α mRNA levels and increased levels of von Hippel-Lindau E3 ligase in TRPM2-S-expressing cells. Inhibition of TRPM2-L by pretreatment with clotrimazole or expression of TRPM2-S significantly increased sensitivity of cells to doxorubicin. Reduced survival of TRPM2-S-expressing cells after doxorubicin treatment was rescued by gain of HIF-1 or -2α function. These data suggest that TRPM2 activity is important for tumor growth and for cell viability and survival following doxorubicin treatment and that interference with TRPM2-L function may be a novel approach to reduce tumor growth through modulation of HIF-1/2α, mitochondrial function, and mitophagy.TRPM2 channels play an essential role in cell death following oxidative stress. Dominant negative TRPM2-S decreases growth of neuroblastoma xenografts and increases doxorubicin sensitivity through modulation of HIF-1/2α expression, mitophagy, and mitochondrial function. TRPM2 is important for neuroblastoma growth and viability through modulation of HIF-1/2α. Modulation of TRPM2 may be a novel approach in cancer therapeutics.