Modulators of Prostate Cancer Cell Proliferation and Viability Identified by Short-Hairpin RNA Library Screening

There is significant need to identify novel prostate cancer drug targets because current hormone therapies eventually fail, leading to a drug-resistant and fatal disease termed castration-resistant prostate cancer. To functionally identify genes that, when silenced, decrease prostate cancer cell proliferation or induce cell death in combination with antiandrogens, we employed an RNA interference-based short hairpin RNA barcode screen in LNCaP human prostate cancer cells. We identified and validated four candidate genes (AKT1, PSMC1, STRADA, and TTK) that impaired growth when silenced in androgen receptor positive prostate cancer cells and enhanced the antiproliferative effects of antiandrogens. Inhibition of AKT with a pharmacologic inhibitor also induced apoptosis when combined with antiandrogens, consistent with recent evidence for PI3K and AR pathway crosstalk in prostate cancer cells. Recovery of hairpins targeting a known prostate cancer pathway validates the utility of shRNA library screening in prostate cancer as a broad strategy to identify new candidate drug targets.

鉴于现行激素疗法最终会失效，进而引发耐药性致死性疾病——去势抵抗性前列腺癌（castration-resistant prostate cancer），因此亟需鉴定新型前列腺癌（prostate cancer）药物靶点。为在功能上鉴定经沉默后可降低前列腺癌细胞增殖能力，或在联合抗雄激素药物（antiandrogens）时诱导细胞死亡的基因，我们在LNCaP人前列腺癌细胞中开展了基于RNA干扰（RNA interference）的短发夹RNA（short hairpin RNA）条形码筛选实验。我们最终鉴定并验证了4个候选基因（AKT1、PSMC1、STRADA及TTK）：在雄激素受体（androgen receptor）阳性前列腺癌细胞中沉默这些基因时，可抑制细胞增殖，并增强抗雄激素药物的抗增殖活性。使用药理学抑制剂靶向抑制AKT，联合抗雄激素药物时同样可诱导细胞凋亡（apoptosis），这与近期关于前列腺癌细胞中磷脂酰肌醇3-激酶（PI3K）与AR信号通路串扰的研究证据相符。靶向已知前列腺癌相关通路的短发夹RNA（shRNA）序列可被成功回收，这验证了利用短发夹RNA文库筛选技术在前列腺癌研究中鉴定新型候选药物靶点的实用性，该技术可作为一种通用的候选靶点发掘策略。