MicroRNA 4423 is a primate-specific regulator of airway epithelial cell differentiation and lung carcinogenesis

Abstract

Smoking is a significant risk factor for lung cancer, the leading cause of cancer-related deaths worldwide. Although microRNAs are regulators of many airway gene-expression changes induced by smoking, their role in modulating changes associated with lung cancer in these cells remains unknown. Here, we use next-generation sequencing of small RNAs in the airway to identify microRNA 4423 (miR-4423) as a primate-specific microRNA associated with lung cancer and expressed primarily in mucociliary epithelium. The endogenous expression of miR-4423 increases as bronchial epithelial cells undergo differentiation into mucociliary epithelium in vitro, and its overexpression during this process causes an increase in the number of ciliated cells. Furthermore, expression of miR-4423 is reduced in most lung tumors and in cytologically normal epithelium of the mainstem bronchus of smokers with lung cancer. In addition, ectopic expression of miR-4423 in a subset of lung cancer cell lines reduces their anchorage-independent growth and significantly decreases the size of the tumors formed in a mouse xenograft model. Consistent with these phenotypes, overexpression of miR-4423 induces a differentiated-like pattern of airway epithelium gene expression and reverses the expression of many genes that are altered in lung cancer. Together, our results indicate that miR-4423 is a regulator of airway epithelium differentiation and that the abrogation of its function contributes to lung carcinogenesis. airway epithelium development | microRNA discovery | next-generation sequencing technology | noncoding RNA | tumor suppressor

Growth differentiation factor-15 encodes a novel microRNA 3189 that functions as a potent regulator of cell death

“…[16][17][18][19][20]41,43 Although it is possible that GDF15 exerts pleiotropic effects on the growth of cancer cells, prior studies may have conflated the function of GDF15 with that of the embedded miR-3189. For example, p53-independent upregulation of GDF15 by the long non-coding RNA MEG3 causes growth arrest in HCT116-p53KO cells, 21,44 which conflicts with earlier reports regarding GDF15 function, [22][23][24]45,46 yet is completely consistent with our results showing the p53-independent effects of miR-3189-3p. We have shown that the knockdown of GDF15 has a growth inhibitory miR-3189 regulates cell cycle and apoptosis MF Jones et al effect, whereas antagonizing miR-3189-3p causes an increase in proliferation, which highlights the importance of distinguishing the effects of miR-3189 from those of its host gene.…”

“…Among the few primate-specific miRNAs that have been studied, miR-4423 was recently shown to mediate airway epithelial differentiation in the lung and suppress tobacco-associated carcinogenesis. 23 The miR-548 family is conserved only among primates, 24 yet has significant effects on tumorigenicity and angiogenesis. 25 Here, we identify miR-3189 as a miRNA produced through canonical miRNA biogenesis pathways and conserved between humans and old-world apes.…”

“…Recent studies have implicated primate-specific miRNAs in several important physiological processes. 23,26 Because GDF15 is a target of p53, we hypothesized that the embedded miR-3189 is also p53-responsive. Indeed, the pattern of pri-miR-3189 expression closely matched that of its host gene following p53 activation.…”

The Roles of MicroRNAs and Protein Components of the MicroRNA Pathway in Lung Development and Diseases

“…The expression of miR-4423 is also significantly reduced in a large fraction of lung cancers, including both squamous carcinomas and adenocarcinomas, relative to matched adjacent normal tissues. In addition, overexpression of miR-4423 in several lung cancer cell lines reduces their anchorage-independent growth and the size of tumors formed in xenograft model (104). The finding of primate-specific miRNAs, or large-animal-specific response or function of miR-124 (105), presents a need to develop additional model systems other than murine models.…”

Assessment of microRNA differential expression and detection in multiplexed small RNA sequencing data

“…Highthroughput sequencing can be used to quantify and compare the levels of microRNA expression between biological conditions or disease states. Additionally, as sequencing does not require a priori knowledge about the microRNA sequences, it can be used to find novel sequences such as novel microRNA and microRNA isoforms (Friedländer et al 2008;Cloonan et al 2011;Perdomo et al 2013). …”