Long noncoding RNA GAPLINC promotes invasion in colorectal cancer by targeting SNAI2 through binding with PSF and NONO

This study aimed to investigate the role of long noncoding RNAs (lncRNAs) in the metastasis of colorectal cancer (CRC). Metastasis is an important prognostic factor of CRC, and lncRNAs have been implicated in tumor proliferation and metastasis. The human CRC cell lines HCT116, HT29, SW480, DLD-1, and SW620 were used in the study. Genome-wide lncRNA expression patterns in metastatic lymph nodes compared with paired normal lymph nodes of CRC were assessed by microarray analysis. Gastric adenocarcinoma predictive long intergenic noncoding (GAPLINC) RNA was detected via functional prediction. The increased expression of GAPLINC was found to be positively correlated with larger tumor size, advanced tumor stage (T stage), advanced node stage (N stage), increased death, and shorter survival of patients with CRC by in situ hybridization analysis. Besides, the decreased expression of GAPLINC could significantly repress CRC cell invasion in vitro and also inhibit proliferation in vitro and in vivo. RNA pull-down with mass spectrum experiments revealed that PTB-associated splicing factor (PSF) and non-POU-domain-containing octamer-binding (NONO) protein bound to GAPLINC and reversed the effect of GAPLINC on cell invasion. Gene array and bioinformatics analyses identified that snail family zinc finger 2 (SNAI2) was involved in the biological processes of GAPLINC/PSF/NONO. This study indicated the importance of GAPLINC in promoting CRC invasion via binding to PSF/NONO and partly by stimulating the expression of SNAI2. Hence, GAPLINC may serve as a promising target for CRC diagnosis and therapy. The findings may help in developing a novel therapeutic strategy for patients with CRC.

Protocol publication

[…] Total RNA was extracted from cells using TRIzol reagent (Invitrogen, Shanghai, China). The RNA integrity was assessed using standard denaturing agarose gel electrophoresis. Labeled samples were hybridized to the Agilent Human 4×44K Gene Expression Microarrays v2 (KangChen Biotech, Shanghai, China). After washing, the microarray slides were scanned using an Agilent DNA microarray scanner. The array images were analyzed by the Agilent Feature Extraction Software (version 11.0.0.1, CA, USA). Then, further bioinformatics analyses were performed using the Agilent GeneSpring GX software (version 12.1, CA, USA). Finally, pathway analysis and Gene Ontology (GO) analysis were performed to determine the roles of differentially expressed genes in these biological pathways or GO terms. […]