Table 3.

Molecular functions of lncRNAs.

Mechanism Type	Mode of Function	Examples	Reference
Signal	Serves as a molecular signal to reflect development or disease status	XIST is typically transcribed by the inactive X chromosome; can be used to indicate X chromosome inactivation	[47,48]
Decoy	Sequestering regulatory factors (transcription factors, chromatin modifiers, miRNAs, etc.) modulate transcription	PANDAR inhibits proptosis by directly sequestering NF-YA. H19 acts as ceRNAs * both for miR-17-5p in thyroid cancer and for miR-152 in breast cancer	[49,50,51]
Guide	Essential for the proper localization of proteins to their site-specific reaction	MEG3 guides PRC2 and forms a complex with DNA	[52]
Scaffold	Provides platforms to assist in the assembly of regulatory complexes	HOTAIR interacts with polycomb repressive complex 2 (PRC2) to recruit EZH2 to promote H3K27 trimethylation or LSD1 to demethylate H3K4me2	[53,54]

* ceRNAs: competing endogenous RNAs regulate other RNA transcripts by competing for shared miRNAs.