IL-6 causes multiple effects in androgen-sensitive and -insensitive prostate cancer cell lines

Abstract

The androgen receptor (AR) is expressed in most human prostate cancers. It can be activated in a hypersensitive manner by androgens, nonandrogenic steroids, nonsteroidal anti-androgens and in a ligand-independent manner. IL-6 is a proinflammatory cytokine that activates several signaling pathways. It can either stimulate or inhibit growth of prostate cancer cells. IL-6 is an important positive regulator of AR activity and can stimulate the expression of prostate-specific antigen in a ligand-independent manner. IL-6/AR interaction may either result in growth stimulation (MDA PCa 2b cells) or inhibition (LAPC-4 cells). IL-8 and IL-4 have also been observed to activate AR. Cells generated by prolonged treatment with IL-6 acquire a growth advantage. There are several therapeutic options to target IL-6 in prostate cancer and most laboratory studies have been performed with the monoclonal antibody siltuximab. Endogenous suppressors of cytokine signaling (SOCS)-3 and -1 are expressed in prostate cancer tissue. SOCS-3 inhibits apoptosis in AR-negative cells. However, in androgen-sensitive prostate cancer cell lines, SOCS-3 is induced by androgen and blocks its effects on proliferation and secretion. It is currently understood that there are numerous interactions between androgen and IL-6 signaling in human prostate cancer.

Keywords::

• androgen receptor
• apoptosis
• IL-6
• prostate cancer
• siltuximab

Acknowledgement

The editorial assistance of Robert Schober is gratefully acknowledged.

Financial & competing interests disclosure

The work in the author’s laboratory was supported by Austrian Science Fund (grants P19933 and W1101). The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.