Targeting LINC02320 prevents colorectal cancer growth via GRB7-dependent inhibition of MAPK signaling pathway.

Background: It is estimated that over 85% of human transcripts are non-coding RNAs, which play an important role in the regulation of numerous biological processes and are closely associated with the development of human cancers. Nevertheless, the functions of the vast majority of non-coding RNAs are yet to be clearly elucidated.

Methods: Long non-coding RNA (lncRNA) LINC02320 was screened out by RNA-sequencing using paired CRC samples. The level of LINC02320 in colorectal cancer (CRC) tissues and cell lines was validated by qRT-PCR and in situ hybridization (ISH). CCK8, colony formation, transwell, wound healing and xenograft experiments were carried out to investigate the function of LINC02320. Antisense oligonucleotide (ASO) was used to target LINC02320. Mass spectrometry, pull-down, western blot and CUT&Tag assays were conducted to investigate the molecular mechanism of LINC02320, ILF2, GRB7, MAPK and FOS.

Results: LINC02320 was highly expressed in metastatic colorectal cancer (CRC) tissues based on RNA-sequencing. ISH staining using tissue microarray (TMA) indicated that LINC02320 is associated with the clinical stage and survival rate of patients with CRC. The results of loss-of-function and gain-of-function experiments demonstrated that LINC02320 facilitates cancer cell proliferation and metastasis in vitro and in vivo while simultaneously inhibiting apoptosis. LINC02320 is present in both the nucleus and cytoplasm, with a nuclear function. Mechanistically, LINC02320 recruits the transcriptional regulator ILF2 to the GRB7 promoter, thereby initiating its transcription. GRB7 then activates the mitogen-activated protein kinase (MAPK) signaling pathway, which contributes to CRC progression and leads to increased phosphorylation of the transcription factor FOS. Phosphorylated FOS directly promotes LINC02320 transcription, forming a positive feedback loop and amplifies this pro-cancer signal. Notably, LINC02320-targeted ASO therapy significantly blocked tumor growth in vivo.

Conclusion: In summary, our findings demonstrate the essential role of LINC02320 involved in CRC progression, which provides novel insights into the importance of lncRNA as a therapeutic target in cancer treatment.