Oncopeptide MBOP Encoded by LINC01234 Promotes Colorectal Cancer through MAPK Signaling Pathway.

Colorectal cancer (CRC) ranks third in incidence rate and second in mortality rate of malignancy worldwide, and the diagnosis and therapeutics of it remain to be further studied. With the emergence of noncoding RNAs (ncRNAs) and potential peptides derived from ncRNAs across various biological processes, we here aimed to identify a ncRNA-derived peptide possible for revealing the oncogenesis of CRC. Through combined predictive analysis of the coding potential of a batch of long noncoding RNAs (lncRNAs), the existence of an 85 amino-acid-peptide, named MEK1-binding oncopeptide (MBOP) and encoded from LINC01234 was confirmed. Mass spectrometry and Western blot assays indicated the overexpression of MBOP in CRC tissues and cell lines compared to adjacent noncancerous tissues and the normal colonic epithelial cell line. In vivo and in vitro migration and proliferation assays defined MBOP as an oncogenic peptide. Immunoprecipitation trials showed that MEK1 was the key interacting protein of MBOP, and MBOP promoted the MEK1/pERK/MMP2/MMP9 axis in CRC. Two E3-ligase enzymes MAEA and RMND5A mediated the ubiquitin-protease-system-related degradation of MBOP. This study indicates that MBOP might be a candidate prognostic indicator and a potential target for clinical therapy of CRC.