Abstract 5510: Tranilast Inhibits Growth of Skin Tumor Cells in a Xenograft Mouse Model of Tuberous Sclerosis Complex.

Abstract Pharmacological approaches for treating tumors in patients with tuberous sclerosis complex (TSC) are inadequate. Although mTORC1 inhibitors such as rapamycin represent a major new avenue for treatment, we and others have shown that rapamycin improves but does not eradicate TSC skin tumors. We tested the effects of tranilast, an antiallergic and antifibrotic drug with antiproliferative effects, on fibroblasts grown from angiofibromas, forehead plaques, periungual fibromas, and normal-appearing skin from 5 patients with TSC. Tumor cells showed loss of TSC2 expression and hyperactivation of the mTORC1 signaling pathway. Tranilast (5, 10, 20, 40 μM) inhibited the viability of TSC skin tumor cells from five patients in an MTT assay. These effects on cell viability appeared to be independent of mTORC1 activity, since tranilast did not inhibit phosphorylation of ribosomal protein S6. Four paired samples of RNA from tumor and normal cells, treated with or without tranilast, were studied using gene expression arrays, revealing that tranilast significantly altered the expression of at least 36 genes, of which 12 are involved in transcription. In a xenograft model in which dermal-epidermal constructs comprising normal human keratinocytes with either TSC angiofibroma cells or TSC normal fibroblasts from a TSC patient were grafted to nude mice (6-8 mice per group), tranilast treatment (300 mg/kg/day) reduced the number of skin tumor cells compared to vehicle control group (P< 0.05). Tranilast treatment did not block angiogenesis or lymphangiogenesis in the xenograft model. These results indicate that tranilast has antiproliferative effects independent of mTORC1 and suggest that tranilast may be useful as an adjunctive agent for the treatment of TSC skin tumors. Citation Format: Shaowei Li, Ji-an Wang, Rajesh L. Thangapazham, Peter Klover, Joel Moss, Thomas N. Darling. Tranilast inhibits growth of skin tumor cells in a xenograft mouse model of tuberous sclerosis complex. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5510. doi:10.1158/1538-7445.AM2013-5510