MiR‐137 functions as a tumor suppressor in neuroblastoma by downregulating KDM1A

Abstract

Neuroblastoma is the most common extracranial solid tumor of childhood, and accounts for~15% of all childhood cancer deaths. The histone demethylase, lysine-specific demethylase 1 (KDM1A, previously known as LSD1), is strongly expressed in neuroblastomas, and overexpression correlates with poor patient prognosis. Inducing differentiation in neuroblastoma cells has previously been shown to down regulate KDM1A, and siRNA-mediated KDM1A knockdown inhibited neuroblastoma cell viability. The microRNA, miR-137, has been reported to be downregulated in several human cancers, and KDM1A mRNA was reported as a putative target of miR-137 in colon cancer. We hypothesized that miR-137 might have a tumor-suppressive role in neuroblastoma mediated via downregulation of KDM1A. Indeed, low levels of miR-137 expression in primary neuroblastomas correlated with poor patient prognosis. Re-expressing miR-137 in neuroblastoma cell lines increased apoptosis and decreased cell viability and proliferation. KDM1A mRNA was repressed by miR-137 in neuroblastoma cells, and was validated as a direct target of miR-137 using reporter assays in SHEP and HEK293 cells. Furthermore, siRNA-mediated KDM1A knockdown phenocopied the miR-137 re-expression phenotype in neuroblastoma cells. We conclude that miR-137 directly targets KDM1A mRNA in neuroblastoma cells, and activates cell properties consistent with tumor suppression. Therapeutic strategies to re-express miR-137 in neuroblastomas could be useful to reduce tumor aggressiveness.Neuroblastoma is the most common extracranial childhood tumor, accounting for >15% of all childhood cancer deaths. 1 The clinical hallmark of neuroblastoma is its heterogeneity. Neuroblastomas with favorable biology (Stages 1, 2 and 4s) often undergo complete regression or differentiation even without therapy, while high-stage, highly aggressive neuroblastoma often ends fatally despite recent therapeutic improvements. 2 Several biological markers have been identified defining high-risk neuroblastoma, such as amplification of the MYCN oncogene, low expression of the NTRK1 neurotrophic tyrosine kinase receptor and LOH of chromosome 1p or 11q. 2,3 MYCN amplification occurs in >30% of highstage neuroblastomas and only in 5% of Stage 1, 2 and 4s tumors. 3 In contrast, 30% of neuroblastomas express high NTRK1 levels, most prominently occurring in Stage 1 tumors, and this correlates with good patient prognosis. 4,5 Lysine (K)-specific demethylase 1A (KDM1A, previously known as LSD1) is a histone demethylase, which specifically catalyzes the demethylation of di-and monomethylated lysine 4 in histone 3 through amine oxidation. 6 KDM1A is highly conserved in eukaryotes, and targeted disruption of the Kdm1a gene locus in mice results in embryonic lethality. 7 Overexpression of KDM1A has been shown in a variety of human cancers, including prostate, bladder, breast, colorectal,

Lysine-Specific Histone Demethylases Contribute to Cellular Differentiation and Carcinogenesis

“…Consistent with these data, the micro-RNA 137 (miR-137) in neuroblastoma cells was found to directly target KDM1A mRNA and activate cell properties consistent with tumor suppression [47].…”

“…High levels of this protein often correlate with cancer recurrence and progression [9,[40][41][42][43][44][45][46][47][48][49][50]. In hormone-dependent tumors, such as prostrate, bladder, and breast cancer, KDM1A associates with steroid hormone receptors (HR) to regulate HR-mediated gene transcription and cell proliferation [9,[42][43][44].…”

Quantitative Nuclear Proteomics Identifies that miR-137-mediated EZH2 Reduction Regulates Resveratrol-induced Apoptosis of Neuroblastoma Cells*

“…Interestingly, miR-137-mediated EZH2 down-regulation is involved in adult neurogenesis (14). Althoff et al reported that low levels of miR-137 expression correlated with a poor prognosis of neuroblastoma patients (13). This study demonstrated that EZH2 expression was modulated by miR-137 in neuroblastoma cells, which would contribute to tumor progression.…”

“…Dysregulation of miRNAs expression plays oncogenic or tumorsuppressive role in a wide variety of cancers including neuroblastoma (12). In neuroblastoma, miR-137 is low expressed and it functions as a tumor suppressor by decreasing LSD1 (13). MiR-137 post-transcriptionally represses the expression of EZH2 in stem cells, modulating the proliferation and differentiation (14).…”

The LSD1 Family of Histone Demethylases and the Pumilio Posttranscriptional Repressor Function in a Complex Regulatory Feedback Loop

“…The lack of PUM-binding sites in the shortened 3= UTR of LSD1 could allow for other ways to regulate LSD1, thus differentiating LSD1 and LSD2. For example, previous studies have identified additional posttranscriptional mechanisms, such as miRNA 137 (miR-137) (50), in constraining LSD1 levels. These results suggest that in human cells, the translation of both KDM1 family members is tightly regulated by different components of the posttranscriptional network.…”