Human interleukin 24 (MDA-7/IL-24) protein kills breast cancer cells via the IL-20 receptor and is antagonized by IL-10 |
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Authors: | Mingzhong Zheng Dora Bocangel Blair Doneske Abner Mhashilkar Rajagopal Ramesh Kelly K Hunt Suhendan Ekmekcioglu R Bryan Sutton Nancy Poindexter Elizabeth A Grimm Sunil Chada |
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Institution: | (1) Introgen Therapeutics Inc., 2250 Holcombe Boulevard, Houston, TX 77030, USA;(2) Department of Thoracic and Cardiovascular Surgery, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA;(3) Department of Surgical Oncology and Tumor Biology, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA;(4) Department of Experimental Therapeutics, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA;(5) Department of Physiology & Biophysics, UTMB, Galveston, TX 77555, USA |
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Abstract: | The melanoma differentiation-associated gene-7 (mda-7/IL-24) is a unique member of the interleukin 10 (IL-10) family of cytokines, with ubiquitous tumor cell pro-apoptotic activity. Recent data have shown that IL-24 is secreted as a glycosylated protein and functions as a pro-Th1 cytokine and as a potent anti-angiogenic molecule. In this study, we analyzed the activity of Ad-mda7 and its protein product, secreted IL-24, against human breast cancer cells. We show that Ad-mda7 transduction of human breast cancer cells results in G2/M phase cell cycle arrest and apoptotic cell death, which correlates with secretion of IL-24 protein. Neutralizing antibody against IL-24 significantly inhibited Ad-mda7 cytotoxicity. IL-24 and IL-10 both engage their cognate receptors on breast cancer cells resulting in phosphorylation and activation of STAT3, however, IL-10 receptor binding failed to induce cell killing, indicating that tumor cell killing by IL-24 is independent of STAT3 phosphorylation. Treatment with exogenous IL-24 induced apoptosis in breast cancer cells and this effect was abolished by addition of anti-IL-24 antibody or anti-IL-20R1, indicating that bystander cell killing is mediated via IL-24 binding to the IL-20R1/IL-20R2 heterodimeric receptor complex. Co-administration of the related cytokine IL-10 inhibited killing mediated by IL-24 and concomitantly inhibited IL-24 mediated up-regulation of the tumor suppressor proteins, p53 and p27Kip1. In summary, we have defined a tumor-selective cytotoxic bystander role for secreted IL-24 protein and identified a novel receptor-mediated death pathway in breast cancer cells, wherein the related cytokines IL-24 and IL-10 exhibit antagonistic activity. |
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Keywords: | MDA-7 Apoptosis IL-24 Gene therapy Receptor Adenovirus Breast cancer |
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