BORA regulates cell proliferation and migration in bladder cancer

(2020) 20:290 Cheng et al. Cancer Cell Int https://doi.org/10.1186/s12935-020-01392-8 Cancer Cell International Open Access PRIMARY RESEARCH BORA regulates cell proliferation and migration in bladder cancer Songtao Cheng1,2,3†, Tianchen Peng1,3†, Xiaolu Zhu4, Fenfang Zhou1,3, Gang Wang5,6,7, Lingao Ju5,6,7, Yu Xiao1,3,5,6,7, Xuefeng Liu2 and Xinghuan Wang1* Abstract Background: Bladder cancer is having a gradually increasing incidence in China. Except for the traditional chemotherapy drugs, there are no emerging new drugs for almost 30 years in bladder cancer. New potential therapeutic targets and biomarkers are urgently needed. Methods: BORA is the activator of kinase Aurora A and plays an important role in cell cycle progression. To investigate the function of BORA in BCa, we established BORA knockdown and overexpression cell models for in vitro studies, xenograft and pulmonary metastasis mouse models for in vivo studies. Results: Our results indicated that BORA was upregulated in human bladder cancer (BCa) compared to the normal bladder and paracancerous tissues at transcriptional and translational levels. We found that BORA was positively related to BCa cell proliferation. Furthermore, BORA knockdown induced cell cycle arrest in G2/M phase while BORA overexpression decreased the proportion of cells in G2/M, associated with PLK1–CDC25C–CDK1 alteration. Interestingly, we observed that knockdown of BORA inhibited BCa cell migration and invasion, accompanied with alterations of epithelial–mesenchymal transition (EMT) pathway related proteins. In vivo studies confirmed the inhibition effect of BORA knockdown on BCa cell growth and migration. Conclusions: Our study indicates that BORA regulates BCa cell cycle and growth, meanwhile influences cell motility by EMT, and could be a novel biomarker and potential therapeutic target in BCa. Keywords: Bladder cancer, BORA, Proliferation, Cell cycle, Epithelial-mesenchymal transition Background As the ninth most common cancer worldwide [1], bladder cancer (BCa) is having a gradually increasing incidence in China [2]. Most of the newly diagnosed cases are non-muscle invasive BCa. Even with transurethral resection of tumor, BCa still has a very high recurrence rate [3]. Chemotherapy based on cisplatin has improved the outcome modestly. For cisplatin-ineligible patients, T-cell checkpoint inhibitors have presented some benefits to *Correspondence: † Songtao Cheng and Tianchen Peng contributed equally to this work 1 Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China Full list of author information is available at the end of the article those having high PD-L1 expression in some trials [4–6]. Except for the traditional chemotherapy drugs, there are no emerging new drugs for almost 30 years in BCa [7]. Therefore, to enhance the targeted and personalized therapy, molecular analysis to find more new specific markers and therapeutic targets is of great urgent. BORA encoded protein activates kinase Aurora A, and is very important in spindle assembly, centrosome maturation and the process of mitosis. BORA was identified as a cell cycle co-factor protein of Aurora A in the first place [8]. Binding with pole-like kinase 1 (PLK1), BORA forms a PLK1/BORA complex and recruits Aurora A to the T-loop of PLK1 T210 phosphorylation site to activate PLK1, thus promote mitotic entry [9]. PLK1 and Aurora A are critical regulators of cell cycle, which has © The Author(s) 2020. 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The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/ zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Cheng et al. Cancer Cell Int (2020) 20:290 a fundamental role in cell proliferation, and related to the checkpoint recovery when DNA damage appears in cells where it leads to DNA repair or progress to apoptosis [10, 11]. A variety of cell cycle related regulators have been explored as therapeutic targets and biomarkers [12]. PLK1 and Aurora A inhibitors have been extensively explored over the last few years and some of them showed prospective clinical benefits [13–16]. Moreover, compounds affecting the interaction of BORA and PLK1 may also have a good therapeutic potential [17]. Zhang et al. revealed that BORA was overexpressed in lung, breast, and gastric adenocarcinomas, and was an independent biomarker associated with poor prognosis [18]. Furthermore, recent studies reported that BORA was significantly related to radiosensitivity by influencing DNA repair and MDC1 [19]. Therefore, the genome stability and cell cycle regulated by Aurora A/BORA/PLK1 axis have a great important role in tumorigenesis and progress [20]. The roles of Aurora A and PLK1 have been extensively explored in a variety of cancers. However, the expression of BORA and its effects on tumor biology are rarely reported especially in BCa. Our group have screened a lot of differentially expressed genes through bioinformatics analysis of microarray data from BCa and normal bladder tissues [21, 22], and have verified several potential therapeutic targets and biomarkers associated with tumor progress and prognosis [23–26]. In the present study, we have verified that BORA was highly expressed in BCa compared to the normal bladder and paired paracancerous tissues, which was consistent with our microarray results. Further analysis indicated that BORA was positively associated with BCa cell proliferation. Knockdown of BORA induced cell cycle arrest in G2/M phase. Interestingly, we first found that reduced BORA repressed BCa cell mobility. Mouse model verified our in vitro results. Methods Ethical statement of human tissues Bladder tissues were collected from the surgery of patients at Zhongnan Hospital of Wuhan University, and the normal tissues were from donors with accidental death. Tissues were obtained and stored following the protocol of Zhongnan Hospital Biobank. The study was conducted in accordance with the Declaration of Helsinki. Informed consent was obtained from all subjects and legally authorized representatives, and the approval of bladder (...truncated)