The Small Protein LINC01547-ORF Inhibits Colorectal Cancer Progression by Regulating the CLDN18-FAK-AKT Axis

Long non-coding RNA (lncRNA)-encoded small proteins play a major role in colorectal cancer. To identify more functional encoded small proteins, ribosome profiling data from colorectal cancer (CRC) cells were screened for ribosome-associated lncRNAs. The search identified LINC01547 that was shown to encode a small protein of 76 amino acids, termed LINC01547-ORF. Real-time quantitative fluorescence showed that LINC01547 expression was downregulated in colorectal cancer tissues. However, cell functional assays revealed that LINC01547 inhibited the proliferation and migration of colorectal cancer cell lines. Meanwhile, western blot and immunofluorescence assays confirmed that LINC01547 encoded LINC01547-ORF. Cellular functional assays indicated that compared with LINC01547 itself, LINC01547-ORF inhibited the proliferation and migration of colorectal cancer cell lines. Gene set enrichment analysis identified enrichment in the focal adhesion pathway and association with CLDN18 protein, whereas protein molecular docking models revealed interacting domains and amino acid residue sites. Of note, co-immunoprecipitation and immunofluorescence experiments showed that LINC01547-ORF could bind to the CLDN18 protein and that this interaction reduced CLDN18 ubiquitination, thereby promoting protein expression. Finally, western blot and immunofluorescence assays confirmed that LINC01547-ORF could target CLDN18 to inhibit the FAK/PI3K/AKT signaling pathway, suppressing colorectal cancer cell development. These findings suggest that the LINC01547-ORF-encoded small protein inhibits proliferation and migration in colorectal cancer, thereby offering a promising direction for treating this disease.