METHODS: Two independent public datasets (TCGA-PRAD and GSE21032), containing 648 PCa samples in total, were employed to comprehensively examine the mRNA expression changes of ST6GALNAC family members in PCa, as well as their associations with clinicopathological parameters and prognosis. The dysregulation of ST6GALNAC5 was further validated in a mouse PCa model and human PCa samples from our cohort (n = 64) by immunohistochemistry (IHC). Gene Set Enrichment Analysis, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and drug sensitivity analyses were performed to enrich the biological processes most related to ST6GALNAC5. Sulforhodamine B, transwell, luciferase reporter and chromatin immunoprecipitation (ChIP) assays were used to examine the PCa cell proliferation, invasion and transcriptional regulation, respectively.
RESULTS: Systematical investigation of six ST6GALNAC family members in public datasets revealed that ST6GALNAC5 was the only gene consistently and significantly upregulated in metastatic PCa, and ST6GALNAC5 overexpression was also positively associated with Gleason score and predicted poor prognosis in PCa patients. IHC results showed that (1) ST6GALNAC5 protein expression was increased in prostatic intraepithelial neoplasia and further elevated in PCa from a PbCre;PtenF/F mouse model; (2) overexpressed ST6GALNAC5 protein was confirmed in human PCa samples comparing with benign prostatic hyperplasia samples from our cohort (p < 0.001); (3) ST6GALNAC5 overexpression was significantly correlated with perineural invasion of PCa. Moreover, we first found transcription factor GATA2 positively and directly regulated ST6GALNAC5 expression at transcriptional level. ST6GALNAC5 overexpression could partially reverse GATA2-depletion-induced inhibition of PCa cell invasion. The GATA2-ST6GALNAC5 signature exhibited better prediction on the poor prognosis in PCa patients than GATA2 or ST6GALNAC5 alone.
CONCLUSIONS: Our results indicated that GATA2-upregulated ST6GALNAC5 might serve as an adverse prognostic biomarker promoting prostate cancer cell invasion.
方法:两个独立的公共数据集(TCGA-PRAD和GSE21032),总共包含648个PCa样本,全面检查了ST6GALNAC家族成员在PCa中的mRNA表达变化,以及它们与临床病理参数和预后的关系。通过免疫组织化学(IHC)在来自我们队列(n=64)的小鼠PCa模型和人PCa样品中进一步验证了ST6GALNAC5的失调。基因集富集分析,基因本体论,进行《京都基因和基因组百科全书》和药物敏感性分析以丰富与ST6GALNAC5最相关的生物过程。磺酰罗丹明B,transwell,荧光素酶报告基因和染色质免疫沉淀(ChIP)测定用于检查PCa细胞增殖,入侵和转录调控,分别。
结果:对公开数据集中的六个ST6GALNAC家族成员的系统调查显示,ST6GALNAC5是转移性PCa中唯一一致且显着上调的基因,ST6GALNAC5过表达也与Gleason评分呈正相关,预测PCa患者预后不良。IHC结果显示:(1)ST6GALNAC5蛋白表达在前列腺上皮内瘤变中增加,在PbCre的PCa中进一步升高;PtenF/F小鼠模型;(2)与我们队列中的良性前列腺增生样品相比,在人类PCa样品中证实了ST6GALNAC5蛋白的过表达(p<0.001);(3)ST6GALNAC5过表达与PCa此外,我们首次发现转录因子GATA2在转录水平上直接调节ST6GALNAC5的表达。ST6GALNAC5过表达可以部分逆转GATA2耗尽诱导的PCa细胞侵袭抑制。GATA2-ST6GALNAC5特征比GATA2或ST6GALNAC5对PCa患者的不良预后表现出更好的预测。
结论:我们的结果表明GATA2上调的ST6GALNAC5可能作为促进前列腺癌细胞侵袭的不良预后生物标志物。