The lncRNA SLNCR Recruits the Androgen Receptor to EGR1-Bound Genes in Melanoma and Inhibits Expression of Tumor Suppressor p21

Mechanism of long noncoding RNAs as transcriptional regulators in cancer

Dysregulation of gene expression, often interpreted by gene transcription as an endpoint response, is tightly associated with human cancer. Long noncoding RNAs (lncRNAs), derived from the noncoding elements in the genome and appeared no less than 200nt in length, have emerged as a novel class of pivotal regulatory component. Recently, great attention has been paid to the cancer-related lncRNAs and growing evidence have shown that lncRNAs act as key transcriptional regulators in cancer cells through diverse mechanisms. Here, we focus on the nucleus-expressed lncRNAs and summarize their molecular mechanisms in transcriptional control during tumorigenesis and cancer metastasis. Six major mechanisms will be discussed in this review: association with transcriptional factor, modulating DNA methylation or histone modification enzyme, influencing on chromatin remodelling complex, facilitating chromosomal looping, interaction with RNA polymerase and direct association with promoter.

Neurogenic differentiation factor 1 promotes colorectal cancer cell proliferation and tumorigenesis by suppressing the p53/p21 axis

Neurogenic differentiation factor 1 (NeuroD1) is a transcription factor critical for promoting neuronal differentiation and maturation. NeuroD1 is involved in neuroblastoma and medulloblastoma; however, its molecular mechanism in promoting tumorigenesis remains unclear. Furthermore, the role of NeuroD1 in non-neural malignancies has not been widely characterized. Here, we found that NeuroD1 is highly expressed in colorectal cancer. NeuroD1-silencing induces the expression of p21, a master regulator of the cell cycle, leading to G₂ -M phase arrest and suppression of colorectal cancer cell proliferation as well as colony formation potential. Moreover, NeuroD1-mediated regulation of p21 expression occurs in a p53-dependent manner. Through chromatin immunoprecipitation and point mutation analysis in the predicted NeuroD1 binding site of the p53 promoter, we found that NeuroD1 directly binds to the p53 promoter and suppresses its transcription, resulting in increased p53 expression in NeuroD1-silenced colorectal cancer cells. Finally, xenograft experiments demonstrated that NeuroD1-silencing suppresses colorectal cancer cell tumorigenesis potential by modulating p53 expression. These findings reveal NeuroD1 as a novel regulator of the p53/p21 axis, underscoring its importance in promoting non-neural malignancies. Furthermore, this study provides insight into the transcriptional regulation of p53.

PAX5-induced upregulation of IDH1-AS1 promotes tumor growth in prostate cancer by regulating ATG5-mediated autophagy

Prostate cancer (PCa) is one of the major malignancies affecting males' health around the world. Long noncoding RNAs (lncRNAs), a class of long transcripts, has been reported as essential regulators in tumorigenesis. IDH1 antisense RNA 1 (IDH1-AS1) is an lncRNA which can interact with genes to regulate the Warburg effect. However, function and mechanism of it in tumorigenesis of PCa remains unclear. Therefore, our current study focused on exploring the role of IDH1-AS1 in PCa tumor growth. At first, the expression of IDH1-AS1 was identified to be upregulated in PCa samples and cell lines. Mechanism associated with the upregulation of IDH1-AS1 was analyzed and demonstrated by mechanism experiments. The result suggested that PAX5 is the transcriptional activator of IDH1-AS1. Functionally, loss-of function assays revealed that silencing of IDH1-AS1 inhibited cell proliferation and induced cell apoptosis both in vitro and in vivo. Through microarray analysis and Gene ontology (GO) analysis, we determined that IDH1-AS1 can affect PCa cell autophagy by upregulating ATG5 expression. Mechanism investigation further validated that IDH1-AS1 posttranscriptionally regulated ATG5 expression by enhancing the mRNA stability of ATG5 or upregulating ATG5 by sequestering miR-216b-5p. Consequently, rescue assays demonstrated that IDH1-AS1 promoted proliferation and apoptosis in PCa via ATG5-induced autophagy. Taken together, our study elucidated the function and regulatory mechanism of IDH1-AS1, thus providing a novel biomarker for PCa.