Background: BRD7 has been confirmed to be lowly expressed in nasopharyngeal carcinoma (NPC) tissues and exerts tumour suppressive roles. However, the molecular mechanism of the downregulation of BRD7 expression and whether the strategy of activating BRD7 expression plays anti-tumour effects still needs to be clarified.
Methods: Methylation-specific polymerase chain reaction (PCR) was used to identify the methylation levels of BRD7 promoter. In vitro experiments were used to evaluate the effects of BRD7-targeted demethylation system on the malignant progression of NPC cells. Chromatin immunoprecipitation (ChIP)-qPCR experiment was employed to examine the regulatory mechanisms underlying the demethylation system. Xenograft tumour models were used to assess impact of this demethylation system on tumour growth in vivo and the anti-tumour effects of the lentivirus-mediated demethylation system in NPC.
Results: There was hypermethylation modification in BRD7 promoter, which was negatively correlated with BRD7 expression. Next, we constructed a LentiCRISPRv2/dCas9-TET1CD-sgRNAs system targeting specific methylation sites of BRD7 promoter based on five sgRNAs, and confirmed that all five sgRNA-guided CRISPR/dCas9 systems could activate BRD7 and inhibit cell proliferation to varying degrees, among which sgRNA2&sgRNA5 were the most significant. Further, we constructed NPC cell lines stably transfected with LentiCRISPRv2/dCas9-TET1CD-sgRNA2&5, and confirmed that both sgRNA2&sgRNA5 could promote the transcriptional activation by reducing its methylation, and inhibit the cell proliferation, migration, invasion and tumour growth in vivo of NPC, and the combination of them has a more significant demethylation, transcriptional activation and anti-tumour effect. In addition, BRD7 had hypermethylation modification in its promoter and decreased expression in NPC tissues, and both of them were negatively correlated, making it a potential diagnostic marker for NPC diagnosis.
Conclusions: The hypermethylation modification of BRD7 is an important mechanism leading to the inactivation of BRD7, and targeting demethylation of BRD7 inhibits the malignant progression of NPC, which might be a promising targeted therapeutic approach for treating NPC.
| [1] |
Chen YP, Chan ATC, Le QT, Blanchard P, Sun Y, Ma J. Nasopharyngeal carcinoma. Lancet. 2019; 394: 64-80.
|
| [2] |
Tang LL, Chen WQ, Xue WQ, et al. Global trends in incidence and mortality of nasopharyngeal carcinoma. Cancer Lett. 2016; 374(1): 22-30.
|
| [3] |
Zhang XY, Chen YH, Liang JT, et al. Out-of-Africa migration and clonal expansion of a recombinant Epstein-Barr virus drives frequent nasopharyngeal carcinoma in southern China. Natl Sci Rev. 2024; 12(4):nwae438.
|
| [4] |
Zhou J, Ma J, Zhang BC, et al. BRD7, a novel bromodomain gene, inhibits G1-S progression by transcriptionally regulating some important molecules involved in ras/MEK/ERK and Rb/E2F pathways. J Cell Physiol. 2004; 200: 89-98.
|
| [5] |
Peng C, Liu HY, Zhou M, et al. BRD7 suppresses the growth of nasopharyngeal carcinoma cells (HNE1) through negatively regulating beta-catenin and ERK pathways. Mol Cell Biochem. 2007; 303: 141-149.
|
| [6] |
Wu MH, Li XY, Li XL, Li GY. Signaling transduction network mediated by tumor suppressor/susceptibility genes in NPC. Curr Genomics. 2009; 10(4): 216-222.
|
| [7] |
Wang H, Zhao R, Zhou M, et al. Preparation of polyclonal antibody highly specific for mouse BRD7 protein and its application. Acta Biochim Biophys Sin (Shanghai). 2014; 46: 163-166.
|
| [8] |
Xue CN, Meng HB, Niu WH, et al. TRIM28 promotes tumor growth and metastasis in breast cancer by targeting the BRD7 protein for ubiquitination and degradation. Cell Oncol (Dordr). 2024; 47(5): 1973-1993.
|
| [9] |
Liu YK, Zhao R, Wei YM, et al. BRD7 expression and c-Myc activation forms a double-negative feedback loop that controls the cell proliferation and tumor growth of nasopharyngeal carcinoma by targeting oncogenic miR-141. J Exp Clin Cancer Res. 2018; 37(1): 64.
|
| [10] |
Portela A, Esteller M. Epigenetic modifications and human disease. Nat Biotechnol. 2010; 28(10): 1057-1068.
|
| [11] |
Wu YL, Lin ZJ, Li CC, et al. Epigenetic regulation in metabolic diseases: mechanisms and advances in clinical study. Signal Transduct Target Ther. 2023; 8(1): 98.
|
| [12] |
Jung I, An J, Ko M. Epigenetic regulators of DNA cytosine modification: promising targets for cancer therapy. Biomedicines. 2023; 11(3): 654.
|
| [13] |
Jones PA, Baylin SB. The fundamental role of epigenetic events in cancer. Nat Rev Genet. 2002; 3(6): 415-428.
|
| [14] |
Esteller M, Herman JG. Cancer as an epigenetic disease: DNA methylation and chromatin alterations in human tumours. J Pathol. 2002; 196(1): 1-7.
|
| [15] |
Choudhury JH, Das R, Laskar S, et al. Detection of p16 promoter hypermethylation by methylation-specific PCR. Methods Mol Biol. 2018; 1726: 111-122.
|
| [16] |
Ferres-Marco D, Gutierrez-Garcia I, Vallejo DM, Bolivar J, Gutierrez-Aviño FJ, Dominguez M. Epigenetic silencers and Notch collaborate to promote malignant tumours by Rb silencing. Nature. 2006; 439(7075): 430-436.
|
| [17] |
Rastetter M, Schagdarsurengin U, Lahtz C, et al. Frequent intra-tumoural heterogeneity of promoter hypermethylation in malignant melanoma. Histol Histopathol. 2007; 22(9): 1005-1015.
|
| [18] |
Buckingham L, Penfield Faber L, Kim A, et al. PTEN, RASSF1 and DAPK site-specific hypermethylation and outcome in surgically treated stage I and II nonsmall cell lung cancer patients. Int J Cancer. 2010; 126(7): 1630-1639.
|
| [19] |
He W, Lin S, Guo Y, et al. Targeted demethylation at ZNF154 promotor upregulates ZNF154 expression and inhibits the proliferation and migration of esophageal squamous carcinoma cells. Oncogene. 2022; 41(40): 4537-4546.
|
| [20] |
Esteller M. Relevance of DNA methylation in the management of cancer. Lancet Oncol. 2003; 4(6): 351-358.
|
| [21] |
Smeets E, Lynch AG, Prekovic S, et al. The role of TET-mediated DNA hydroxymethylation in prostate cancer. Mol Cell Endocrinol. 2018; 462(pt A): 41-55.
|
| [22] |
Liao CG, Liang XH, Ke Y, et al. Active demethylation upregulates CD147 expression promoting non-small cell lung cancer invasion and metastasis. Oncogene. 2022; 41(12): 1780-1794.
|
| [23] |
Jones PA, Issa JP, Baylin S. Targeting the cancer epigenome for therapy. Nat Rev Genet. 2016; 17(10): 630-641.
|
| [24] |
Kantarjian HM, Thomas XG, Dmoszynska A, et al. Multicenter, randomized, open-label, phase III trial of decitabine versus patient choice, with physician advice, of either supportive care or low-dose cytarabine for the treatment of older patients with newly diagnosed acute myeloid leukemia. J Clin Oncol. 2012; 30(21): 2670-2677.
|
| [25] |
Kaminskas E, Farrell AT, Wang YC, Sridhara R, Pazdur R. FDA drug approval summary: azacitidine (5-azacytidine, Vidaza) for injectable suspension. Oncologist. 2005; 10(3): 176-182.
|
| [26] |
Kaminskas E, Farrell A, Abraham S, et al. Approval summary: azacitidine for treatment of myelodysplastic syndrome subtypes. Clin Cancer Res. 2005; 11(10): 3604-3608.
|
| [27] |
Dawson MA. The cancer epigenome: concepts, challenges, and therapeutic opportunities. Science. 2017; 355(6330): 1147-1152.
|
| [28] |
Ansari I, Chaturvedi A, Chitkara D, Singh S. CRISPR/Cas mediated epigenome editing for cancer therapy. Semin Cancer Biol. 2022; 83: 570-583.
|
| [29] |
Liu Z, Liao Z, Chen Y, Han L, Yin Q, Xiao H. Application of various delivery methods for CRISPR/dCas9. Mol Biotechnol. 2020; 62(8): 355-363.
|
| [30] |
Elumalai P, Ezhilarasan D, Lakshmi T. Targeting head and neck cancer epigenetics with CRISPR-dCas9: an emerging therapeutic approach. Oral Oncol. 2022; 127:105801.
|
| [31] |
Yin X, Xu Y. Structure and function of TET enzymes. Adv Exp Med Biol. 2016; 945: 275-302.
|
| [32] |
Choudhury SR, Cui Y, Lubecka K, Stefanska B, Irudayaraj J. CRISPR-dCas9 mediated TET1 targeting for selective DNA demethylation at BRCA1 promoter. Oncotarget. 2016; 7(29): 46545-46556.
|
| [33] |
Kardooni H, Gonzalez-Gualda E, Stylianakis E, Saffaran S, Waxman J, Kypta RM. CRISPR-mediated reactivation of DKK3 expression attenuates TGF-β signaling in prostate cancer. Cancers (Basel). 2018; 10(6): 165.
|
| [34] |
Yang B, Tang H, Wang N, Gu J, Wang Q. Targeted DNA demethylation of the ZNF334 promoter inhibits colorectal cancer growth. Cell Death Dis. 2023; 14(3): 210.
|
| [35] |
Zhao R, Liu Y, Wu C, et al. BRD7 promotes cell proliferation and tumor growth through stabilization of c-Myc in colorectal cancer. Front Cell Dev Biol. 2021; 9:659392.
|
| [36] |
Liu Y, Zhao R, Wang H, et al. miR-141 is involved in BRD7-mediated cell proliferation and tumor formation through suppression of the PTEN/AKT pathway in nasopharyngeal carcinoma. Cell Death Dis. 2016; 7(3):e2156.
|
| [37] |
Li M, Wei Y, Liu Y, et al. BRD7 inhibits enhancer activity and expression of BIRC2 to suppress tumor growth and metastasis in nasopharyngeal carcinoma. Cell Death Dis. 2023; 14(2): 121.
|
| [38] |
Wei J, Li M, Chen S, et al. CircBRD7 attenuates tumor growth and metastasis in nasopharyngeal carcinoma via epigenetic activation of its host gene. Cancer Sci. 2024; 115(1): 139-154.
|
| [39] |
Zhan Y, Chen X, Zheng H, et al. YB1 associates with oncogenetic roles and poor prognosis in nasopharyngeal carcinoma. Sci Rep. 2022; 12(1): 3699.
|
| [40] |
Li M, Wei J, Xue C, et al. BRD7 enhances the radiosensitivity of nasopharyngeal carcinoma cells by negatively regulating USP5/METTL3 axis-mediated homologous recombination repair. Int J Biol Sci. 2024; 20(15): 6130-6145.
|
| [41] |
Wang X, Ma C, Rodríguez Labrada R, et al. Recent advances in lentiviral vectors for gene therapy. Sci China Life Sci. 2021; 64(11): 1842-1857.
|
| [42] |
Sakuma T, Barry MA, Ikeda Y. Lentiviral vectors: basic to translational. Biochem J. 2012; 443(3): 603-618.
|
| [43] |
Wang Y, Qian G, Zhu L, et al. HIV-1 Vif suppresses antiviral immunity by targeting STING. Cell Mol Immunol. 2022; 19(1): 108-121.
|
| [44] |
Yin H, Kauffman KJ, Anderson DG. Delivery technologies for genome editing. Nat Rev Drug Discov. 2017; 16(6): 387-399.
|
| [45] |
Li X, Le Y, Zhang Z, Nian X, Liu B, Yang X. Viral vector-based gene therapy. Int J Mol Sci. 2023; 24(9): 7736.
|
| [46] |
Sarno F, Goubert D, Logie E, et al. Functional validation of the putative oncogenic activity of PLAU. Biomedicines. 2022; 11(1): 102.
|
| [47] |
Qu N, Song K, Ji Y, et al. Albumin nanoparticle-based drug delivery systems. Int J Nanomed. 2024; 19: 6945-6980.
|
| [48] |
De Jong WH, Borm PJ. Drug delivery and nanoparticles:applications and hazards. Int J Nanomed. 2008; 3(2): 133-149.
|
| [49] |
Kretzmann JA, Evans CW, Moses C, et al. Tumour suppression by targeted intravenous non-viral CRISPRa using dendritic polymers. Chem Sci. 2019; 10(33): 7718-7727.
|
| [50] |
Guo Y, Lu J, Li X, et al. BRD7 inhibited immune escape in nasopharyngeal carcinoma via inhibiting PD-L1 expression. Int J Biol Sci. 2025; 21(5): 1914-1931.
|
| [51] |
Kim Y, Andrés Salazar Hernández M, Herrema H, Delibasi T, Park SW. The role of BRD7 in embryo development and glucose metabolism. J Cell Mol Med. 2016; 20(8): 1561-1570.
|
RIGHTS & PERMISSIONS
2026 The Author(s). Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.
PDF
