Targeting of Heparanase in the Murine Model Protects against Radiation-Induced Nephropathy

Abstract

<h3>Purpose/Objective(s)</h3> Adverse effects are common in virtually all types of treatment modalities in cancer including that of radiation therapy. Several agents are clinically used to aid in the reduction of side effects of anti-cancer therapy, however these agents <i>per se</i> are typically not endowed with tumor-suppressing properties. Herein we report that the extracellular matrix (ECM)-degrading enzyme heparanase (a valid target for anti-cancer drug development) is also a promising candidate for interventions aimed at preventing development of radiation nephropathy - a significant side effect of radiation therapy in the treatment of abdominal/pelvic malignancies. Heparanase is the sole mammalian endoglucuronidase that cleaves heparan sulfate in the ECM. The enzymatic action of heparanase has not only been found to promote tumor development and progression at various anatomic sites but is upregulated in essentially all tumor types found in the abdominal/pelvic cavity, whose radiation treatment may result in the development of radiation nephropathy. <h3>Materials/Methods</h3> Eleven-week-old female C3H/HeNHsd mice were administered 10 Gy of radiation using brachytherapy to induce radiation nephropathy. Subcutaneous injections of Roneparstat, a specific heparanase inhibitor, were administered to the mice and urine samples were collected over 24h. Urinary albumin was measured using an ELISA kit. Prior to and following irradiation, heparanase and early growth response (Egr1) transcription factor mRNA levels were determined by qRT-PCR in both HK-2 human proximal tubule epithelial cells and HEK-293 human embryonic kidney cells. <h3>Results</h3> In this study, we evaluated the potential of targeting heparanase to diminish radiation therapy-induced kidney damage. We demonstrated that clinically relevant doses of ionizing radiation upregulate heparanase expression in renal cells (most likely through a transcription factor Egr 1 –dependent mechanism). Moreover, utilizing a murine model of abdominal radiation therapy, we found that the specific heparanase inhibitor, Roneparstat, abolished radiation-induced albuminurea –the hallmark of radiation nephropathy. <h3>Conclusion</h3> Given the well-documented anti-cancer effects of heparanase inhibition, our present findings attest this enzyme as a unique target in the landscape of cancer therapy due to its dual action. Indeed, targeting of heparanase exerts not only direct anti-tumor effects but also protects from kidney damage induced by radiation - the backbone of cancer therapy across a broad range of abdominal/pelvic malignancies.