Objective

Docetaxel remains a main treatment for metastatic castration-resistant prostate cancer (mCRPC); however, the development of docetaxel resistance has been found in some mCRPC patients. The aim of this work is to identify an effective biomarker for predicting therapeutic effectiveness of docetaxel in mCRPC patients.

Methods

We examined DNA polymerase theta (POLQ) expression in The Cancer Genome Atlas (TCGA) database and Tissue microarray. Kaplan-Meier analyses were performed to estimate the prognostic significance of POLQ. A series of functional analyses were conducted in cell lines and xenograft models. Regulated pathways were predicted by Geneset Enrichment Analysis (GSEA) software and further investigated by luciferase reporter and RT-PCR assays.

Results

We found that POLQ mRNA levels in CRPC tissues was significantly higher than that of other DNA polymerases in non-CRPC prostate tissues. POLQ upregulation was extensively detected in mCRPC and strongly predicted a poor prognosis. POLQ knockdown enhanced docetaxel sensitivity in a cell-based cytotoxicity assay and promoted the therapeutic effect on the tumor growth of metastatic PC-3M cells in xenograft models. The computational simulation by GSEA software significantly predicted the association between POLQ upregulation and the activation of E2F/G2M checkpoint-related pathways. Moreover, luciferase reporter and RT-PCR assays demonstrated that POLQ knockdown downregulated the transcriptional regulatory activity of E2F and repressed E2F/G2M checkpoint-regulated CDK1 in mCRPC cells.

Conclusion

Our results suggest that POLQ serves as a predictive factor for poor docetaxel response and provide a novel strategy to enhance the anticancer effects of docetaxel therapy by targeting POLQ in mCRPC patients.

中文翻译：

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DNA聚合酶theta抑制增强转移性去势抵抗性前列腺癌中的多西他赛反应。

目的

多西紫杉醇仍然是转移性去势抵抗性前列腺癌（mCRPC）的主要治疗方法；但是，在某些mCRPC患者中发现了多西他赛耐药性的发展。这项工作的目的是确定一种有效的生物标志物，以预测多西他赛在mCRPC患者中的治疗效果。

方法

我们检查了癌症基因组图谱（TCGA）数据库和组织微阵列中的DNA聚合酶θ（POLQ）表达。进行Kaplan-Meier分析以评估POLQ的预后意义。在细胞系和异种移植模型中进行了一系列功能分析。可通过基因组富集分析（GSEA）软件预测受调控的途径，并通过萤光素酶报告基因和RT-PCR分析进行进一步研究。

结果

我们发现，CRPC组织中的POLQ mRNA水平显着高于非CRPC前列腺组织中的其他DNA聚合酶。在mCRPC中广泛检测到POLQ上调，并强烈预示不良预后。POLQ组合在基于细胞的细胞毒性试验中增强了多西他赛的敏感性，并促进了对异种移植模型中转移性PC-3M细胞肿瘤生长的治疗作用。GSEA软件的计算仿真显着预测了POLQ上调与E2F / G2M检查点相关途径的激活之间的关联。此外，荧光素酶报告基因和RT-PCR分析表明，POLQ敲低下调了mCRPC细胞中E2F的转录调节活性并抑制了E2F / G2M检查点调节的CDK1。

结论

我们的结果表明，POLQ可作为多西紫杉醇不良反应的预测因素，并提供一种针对mCRPC患者的POLQ来增强多西紫杉醇治疗的抗癌作用的新策略。