Department of Pathology, University of Cincinnati College of Medicine, the Metabolic Diseases Institute, Cincinnati, OH 45237, USA.
Int J Oncol. 2010 Mar;36(3):623-33. doi: 10.3892/ijo_00000538.
Our previous studies revealed that Vav3 oncogene is overexpressed in human prostate cancer, enhances androgen receptor (AR)-mediated signaling, and may play a role in prostate cancer development and progression. The purpose of this study was to determine the molecular mechanisms responsible for AR activation by Vav3. We found that interaction between N-terminus and C-terminus of AR is essential for its elevated activity stimulated by Vav3. The DH and PH domains of Vav3 are involved in direct interaction with AR. Both cytoplasmic and nuclear levels of AR and Vav3 are elevated and their nuclear localization is further stimulated by DHT in androgen-independent LNCaP-AI cells relative to their parental androgen-dependent LNCaP cells. Vav3 is colocalized with AR, phospho(P)-Akt, and HER2 with a short term stimulation by EGF and DHT. PI3K inhibitor LY294002 blocks colocalization of Vav3 with P-Akt. Consistently, EGF and DHT stimulate Vav3 and AR interaction and enhance PI3K-Akt signaling. Mutation of tyrosines to phenylalanines in the acidic domain or deletion of the SH2 and SH3 domains significantly enhances Vav3 ability for AR activation, while deletion of the DH domain abolishes this activity. Given that an elevated interaction of Vav3 with AR, P-Akt, and HER2 in both cytoplasm and nucleus upon the short-term of DHT stimulation, our data suggest that Vav3 may enhance non-genomic AR activity via PI3K-Akt signaling in addition to AR transcriptional activity and further support a role in androgen-independent growth in prostate cancer.
我们之前的研究表明，Vav3 癌基因在人前列腺癌中过度表达，增强了雄激素受体（AR）介导的信号转导，可能在前列腺癌的发展和进展中发挥作用。本研究的目的是确定 Vav3 激活 AR 的分子机制。我们发现，AR 的 N 端和 C 端之间的相互作用对于 Vav3 刺激的其活性升高是必需的。Vav3 的 DH 和 PH 结构域参与与 AR 的直接相互作用。与亲本雄激素依赖性 LNCaP 细胞相比，雄激素非依赖性 LNCaP-AI 细胞中 AR 和 Vav3 的细胞质和核水平升高，其核定位进一步受到 DHT 的刺激。Vav3 与 AR、磷酸化（P）-Akt 和 HER2 共定位，短期受到 EGF 和 DHT 的刺激。PI3K 抑制剂 LY294002 阻断 Vav3 与 P-Akt 的共定位。一致地，EGF 和 DHT 刺激 Vav3 和 AR 相互作用，并增强 PI3K-Akt 信号。在酸性结构域中的酪氨酸突变为苯丙氨酸或缺失 SH2 和 SH3 结构域显著增强了 Vav3 激活 AR 的能力，而 DH 结构域的缺失则消除了这种活性。鉴于 Vav3 与 AR、P-Akt 和 HER2 在细胞质和核中的相互作用在 DHT 刺激的短期时间内升高，我们的数据表明，Vav3 可能通过 PI3K-Akt 信号通路增强非基因组 AR 活性，除了 AR 转录活性，并进一步支持其在前列腺癌中雄激素非依赖性生长中的作用。
