Ack1: A Critical Regulator of Hormone-Refractory Prostate Cancer

摘要 雄激素受体（AR）在前列腺癌的进展中起着关键作用。我们最近 表明Ack 1（也称为TNK 2）调节AR Tyr 267-磷酸化， 反式激活结构域虽然多种酪氨酸激酶的AR转录激活是 Ack 1介导的AR Tyr 267 - 267的确切作用作为AR激活的一种替代模式出现， 在AR募集到雄激素应答增强子（ARE）和雄激素- 独立AR应答基因转录尚未完全理解。在这份赠款提案中，我们 证实激活的Ack 1（pTyr 284-Ack 1）表达在前列腺癌中上调， 并且这种激活与前列腺癌的存活率呈负相关 患者由于Ack 1通过其磷酸化调节雄激素非依赖性AR活性， Tyr 267，我们产生了特异性识别pTyr 267-AR的抗体。pTyr267-AR 表达或其转录激活均受抗雄激素， 比卡鲁胺/casodex和氟西汀。然而，Ack 1，4-氨基-5，6- 联芳基-呋喃并[2，3-d]嘧啶（YL 3 -026）不仅抑制Ack 1活化，而且能够 抑制pTyr 267-AR磷酸化，与PSA、NKX3.1和TMPRS 2启动子结合， 抑制AR转录活性，如PSA基因表达显著降低所示。我们 因此，有证据表明，在前列腺癌患者中靶向Ack 1激酶可能是 非常有效的治疗策略。在本提案中，我们将确定AR Tyr 267- 磷酸化调节雄激素非依赖性生长。此外，我们还将研究 Ack 1抑制剂YL 3 -026抑制雄激素非依赖性转录和异种移植肿瘤 阵此外，我们将评估Ack 1抑制剂YL 3 -026抑制AR的能力， Prob-Ack 1中Tyr 267磷酸化和前列腺上皮内瘤形成（PIN） 转基因小鼠

ABSTRACT Androgen receptor (AR) plays a critical role in progression of prostate cancer. We have recently demonstrated that Ack1 (also known as TNK2) regulates AR Tyr267-phosphorylation within the transactivation domain. While AR transcriptional activation by multiple tyrosine kinases is emerging as an alternate mode of AR activation, the precise role of Ack1 mediated AR Tyr267- phosphorylation in AR recruitment to the androgen responsive enhancers (ARE) and androgen- independent AR-responsive gene transcription is not fully understood. In this grant proposal we demonstrate that activated Ack1(pTyr284-Ack1) expression is upregulated as prostate cancer progresses and this activation is inversely correlated with the survival of prostate cancer patients. Since Ack1 regulates androgen-independent AR activity by its phosphorylation at Tyr267, we generated antibodies that specifically recognize pTyr267-AR. Neither pTyr267-AR expression nor its transcriptional activation was affected by anti-androgens e.g. bicalutamide/casodex and flutamide. However, a small molecule inhibitor of Ack1, 4-Amino-5,6- biaryl-furo[2,3-d]pyrimidine (YL3-026) not only inhibited Ack1 activation, but was able to suppress pTyr267-AR phosphorylation, binding to PSA, NKX3.1 and TMPRS2 promoters and inhibit AR transcription activity as seen by significant decrease in PSA gene expression. Our evidence indicates that targeting Ack1 kinase in prostate cancer patients could therefore be highly effective therapeutic strategy. In this proposal we will determine how AR Tyr267- phosphorylation regulates Androgen-Independent growth. Further, we will examine the ability of Ack1 inhibitor, YL3-026, to suppress androgen-independent transcription and xenograft tumor formation. Moreover, we will assess the ability of Ack1 inhibitor YL3-026 to suppress AR Tyr267-phosphorylation and prostatic intraepithelial neoplasia (PINs) formation in Prob-Ack1 transgenic mice.