[Interleukin-6 and bone metastasis of renal cancer: molecular bases and therapeutic implications]

Interleukin-6 (IL-6) is a multifunctional cytokine which provides multiple signals on various tissues and cells. In addition, IL-6 is produced by some human renal carcinoma cell lines in vitro and is expressed in a majority of primary renal cell carcinoma (RCC). Serum IL-6 influence the response to immunotherapy. IL-6 appears as a target for rational drug design highly promising for development of new cancer therapies. IL-6 effects are mediated by Stat. Stat (Signal transducers and activators of transcription) signaling pathways represent novel molecular targets for therapeutic implications in metastatic renal cell carcinoma. Inhibitors of Stat signaling pathway will not only block tumor growth by inducing apoptosis, but may also increase the sensitivity of tumors to conventional treatment (immunotherapy). The processes involved in tumor associated angiogenesis should lead to compounds able to interfere with angiogenesis. Il-6 has been implicated in the osteoclastic bone resorption and hypercalcemia associated with metastatic RCC. Different agents were shown to be effective in treating lytic bone disease mediated by osteoclast activation: bisphosphonates and osteoprotegerin.