TCF3 is epigenetically silenced by EZH2 and DNMT3B and functions as a tumor suppressor in endometrial cancer

Abstract

Endometrial cancer (EC) is the most common gynecological malignancy worldwide. However, the molecular mechanisms underlying EC progression are still largely unknown, and chemotherapeutic options for EC patients are currently very limited. In this study, we found that histone methyltransferase EZH2 and DNA methyltransferase DNMT3B were upregulated in EC samples from patients, and promoted EC cell proliferation as evidenced by assays of cell viability, cell cycle, colony formation. Mechanistically, we found that EZH2 promoted EC cell proliferation by epigenetically repressing TCF3, a direct transcriptional activator of CCKN1A (p21WAF1/Cip1), in vitro and in vivo. In addition, we found that DNMT3B specifically methylated the TCF3 promoter, repressing TCF3 expression and accelerating EC cell proliferation independently of EZH2. Importantly, elevated expression of EZH2 or DNMT3B in EC patients inversely correlated with expression of TCF3 and p21, and was associated with shorter overall survival. We show that combined treatment with GSK126 and 5-Aza-2d treatment wit synergistically inhibited methyltransferase activity of EZH2 and DNMT3B, resulting in a profound block of EC cell proliferation as well as EC tumor progression in cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models. These findings reveal that TCF3 functions as a tumor suppressor epigenetically silenced by EZH2 and DNMT3B in EC, and support the notion that targeting the EZH2/DNMT3B/TCF3/p21 axis may be a novel and effective therapeutic strategy for treatment of EC.

Emerging role of different DNA methyltransferases in the pathogenesis of cancer

“…Furthermore, there are few reports on DNMT3B in cancer. However, studies have previously reported that DNMT3B was an oncogene that played a crucial role in the progression of various types of cancer, including endometrial cancer (EC) ( Gui et al, 2021 ), lung cancer ( Yang et al, 2014 ), and PCa( Agarwal et al, 2013 ), and conversely DNMT3B has implicated as a TSG in lymphoma ( Hlady et al, 2012 ).…”

TRIM7 modulates NCOA4-mediated ferritinophagy and ferroptosis in glioblastoma cells

“…Cell proliferation was determined by a BrdU Cell Proliferation ELISA Kit according to a previous study [ 38 ]. In addition, colony formation assay was also performed to evaluate glioblastoma cells proliferation [ 39 , 40 ]. Briefly, glioblastoma cells were seeded into 6-well plates and cultured for 14 days, which were then fixed in methanol for 30 min, stained with 0.5% crystal violet at room temperature for 15 min and carefully rinsed with tap water.…”

Misregulation of the expression and activity of DNA methyltransferases in cancer

“…DNMT1 and DNMT3B expression in cancerous lung tissue is correlated with gene promoter hypermethylation at multiple TSG promoters, including FHIT and p16 INK4a ( 155 ). A recent study found that in endometrial cancer, concurrent DNMT3B and EZH2 upregulation in cancer cells results in the epigenetic silencing of TCF3 ( 156 ). TCF3 is a transcriptional activator of CCKN1A (p21 WAF1/Cip1 ), and its silencing results in accelerated endometrial cancer cell proliferation ( 156 ).…”

“…A recent study found that in endometrial cancer, concurrent DNMT3B and EZH2 upregulation in cancer cells results in the epigenetic silencing of TCF3 ( 156 ). TCF3 is a transcriptional activator of CCKN1A (p21 WAF1/Cip1 ), and its silencing results in accelerated endometrial cancer cell proliferation ( 156 ).…”