Noncoding Genomics in Gastric Cancer and the Gastric Precancerous Cascade: Pathogenesis and Biomarkers

Table 2

Types of human noncoding RNAs.

Types	Subclasses	Symbol	Biological functions	Illustrative examples	References
Small noncoding RNAs (~20–200 nt)	PIWI-interacting RNAs	piRNAs	Repression of mobile elements and other genetic elements in germ line cells	LINE1 piRNAs; piR-823	[74, 75]
	Small interfering RNAs	siRNAs	Gene silencing and defense against pathogen nucleic acids	Oocyte endo-siRNAs; L1-specific siRNA	[76, 77]
	microRNAs	miRNAs	Posttranscriptional regulation of gene expression	lin-4; miR-139	[78, 93]
Long noncoding RNAs (200 nt to ~100 kb)	Intergenic noncoding RNAs	lincRNAs	Regulation of chromatin remodeling and imprinting	HOTAIR; XIST	[108]
	Transcribed ultraconserved regions	T-UCRs	Regulation of genes miRNAs and methylation	uc.160; uc.283A	[109]
	Circular RNAs	circRNAs	Modulation of miRNA and RNA-binding proteins	CDR1as; SRY	[110]