| Prostate cancer remains the second leading cause of death in men and is the most commonly diagnosed cancer among American men. Although therapies targeting the androgen signaling axis have early success, prostate cancer eventually relapses to an advanced disease which is no longer dependent upon hormone. Understanding the molecular mechanisms involved in the transition to hormone refractory disease is vital to the development of the next generation of prostate cancer therapies. In this report, I describe the initial characterization of a novel cell line, LN/TC-AR which, using a tightly controlled and doxycycline inducible expression system, expresses a ligand binding domain deleted form of the androgen receptor (TC-AR) which I show can function as a key component in the androgen independent growth of prostate cancer. TC-AR localizes to the cell nucleus and is transcriptionally active in the absence of androgen. Furthermore, I demonstrate that this allele is able to confer androgen independent growth to the normally androgen dependent LNCaP cell line when expressed at physiologically relevant levels. Using microarray and ChIP-to-chip methods, TC-AR is revealed as a transcription factor for many genes regulated by wild-type AR, but also activates expression of a subset of genes not regulated by wild-type AR. However, even among genes regulated by both TC-AR and wild-type AR, variation in precise binding sites is observed and described. Among those genes regulated by TC-AR but not endogenous AR is RHOB which is shown to be an effector of changes to cell shape and migration in LN/TC-AR following induction of TC-AR. Finally, I describe the use of the LN/TC-AR cell line to study the effect of IL-6 on neuroendocrine differentiation. In this model, IL-6 mediated silencing of endogenous and exogenous AR is described as a potential mechanism for IL-6 induced neuroendocrine differentiation and that this silencing is shown to be dependent upon the PI3K/AKT pathway. |
