Abstract LB-118: NC-001 induces apoptosis and necrosis in clear cell renal cell carcinoma in vitro and in a xenograft model in vivo

Abstract

Abstract Renal cancer causes over 100,000 annual deaths worldwide and constitutes about 3% of all solid cancers. The majority of renal cell carcinomas (85%), referred to as clear cell renal cell carcinoma (CCRCC), are notorious for their metastatic frequency and high resistance to conventional cancer therapies. Several new targeted therapies have been approved for treatment of metastatic renal cell carcinoma (mRCC), and although they induce a longer progression free survival, the effect on overall survival has not been statistically significant. One third of the patients with CCRCC present with advanced disease at diagnosis, and another third will develop metastases eventually, even if the original tumor is successfully removed. A metastatic form of the disease correlates with a bad poor prognosis reflected in the 5-year survival, which is less than 11% for this patient group. A fungal toxin from the Cortinarius-family, NC-001, have been shown to be specifically toxic to the proximal tubular cells in the kidney. We have shown that this sensitivity also is extended to renal cancer cells which have evolved from these. Preliminary data demonstrate that NC-001 reduces viability in five renal cancer cell lines, originating both from primary tumors and metastatic lesions. HUVEC cells seem unaffected, however at the highest dose (800µM) a reduction in viability is observed. Presently, we are evaluating the molecular mechanism behind the effect of NC-001. In vitro results show an induction of apoptosis via the intrinsic pathway, by activation of caspase-8 and further downstream by caspase-3. Caspase-9 seems to bewas unaffected. FACS analysis with Alexa Flour488 conjugated Annexin V and phosphatidylserine (PI) of SKRC-52 cells treated with 400µM for 24 hours, shows increased apoptosis and necrosis. A xenograft model of CCRCC, in radiated athymic rats, was developed to further investigate NC-001's effects in vivo. Since NC-001 affects the proximal tubular cells in the kidney and induces severe renal failure, an automated peritoneal dialysis system for rats was developed as renal replacement therapy. The rats were treated via the dialysis solution containing 40µM NC-001 for two days. Six days later, extensive necrosis was evident in the tumors of treated rats (n=5) compared to controls (n=5). In summary, our results indicate that NC-001 induces apoptosis, mainly via the intrinsic pathway, and necrosis in SKRC-52 cells and also in solid CCRCC xenograft tumors. NC-001 has therefore potential as a curative treatment of metastatic CCRCC. The sole expected side effect of NC-001, based on hundreds of case reports of Cortinarius intoxications in the literature, is collateral loss of kidney function. While this may appear dramatic, it is surely preferable to death from metastatic cancer, especially if long term survival can be achieved. Besides, it can be well managed with dialysis, and later on, kidney transplantation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-118. doi:1538-7445.AM2012-LB-118