Andrographolide sensitizes human renal carcinoma cells to TRAIL­induced apoptosis through upregulation of death receptor 4.

ABSTRACT

Tumor necrosis factor­related apoptosis­inducing ligand (TRAIL) selectively induces apoptosis in cancer cells, with minimal toxicity to normal tissues. However, accumulating evidence suggests that certain cancer types are insensitive to TRAIL signaling. The aim of this study was to identify an effective combination regimen, which can overcome TRAIL resistance in renal cancer cell. Herein, we found that human renal carcinoma cells (RCCs) are widely resistant to TRAIL­mediated growth inhibition and subsequently identified that andrographolide (Andro), a major constituent of Andrographis paniculate, an annual herbaceous plant in the family Acanthaceae, counteracts TRAIL resistance in RCCs. Combined treatment with TRAIL and Andro suppressed cell viability as determined by MTS and proliferation as determined by EdU in a dose­dependent manner and inactivated the clonogenic and migration ability of RCCs. Andro significantly enhances TRAIL­mediated cell cycle arrest at the G2/M phase as determined by flow cytometry and senescence. Moreover, Andro restored TRAIL signaling, which in turns activated pro­apoptosis caspases as determined by immunoblot assay. The TRAIL receptor, death receptor (DR)4, but not DR5, was found to be significantly upregulated in Andro­treated RCC cells, which contributed to the role of Andro as a TRAIL sensitizer. The present study demonstrated that the combined treatment of Andro and TRAIL has potential therapeutic value against renal cancer.