USF2-Mediated Transcription of BZW2 Contributes to CRC Malignant Progression by Affecting LAMP3

Colorectal cancer (CRC) is one of the most frequent causes of cancer death in China, and its occurrence, development, and prognosis are closely related to the living state of patients. Basic leucine zipper and W2 domains 2 (BZW2), also known as eIF5-mimin protein 1 (5MP1), is a translational regulatory protein and highly expressed in CRC and promotes malignant progression of CRC, but the specific mechanism has not been clarified.

The databases were used to mine related genes. The expression levels of genes were detected by quantitative real-time PCR (qRT-PCR) and western blot. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) staining, flow cytometry, transwell assay, and sphere formation assay were employed to examine the effects of BZW2 on the phenotypes in CRC cells in vitro. The mechanism of BZW2 in CRC progression was determined by chromatin immunoprecipitation (CHIP) and dual luciferase reporter assay. In vivo, xenograft animal model was performed to verify the results.

BZW2 was elevated in CRC tissues and cells and was associated with poor prognosis of patients. Functionally, BZW2 enhanced CRC cell proliferation, invasion, and sphere formation but restrained apoptosis. CHIP and dual luciferase reporter assay confirmed that upstream transcription factor 2 (USF2) regulated BZW2 transcription. Also, BZW2 could attenuate the effects of USF2 defection in CRC progression. Meanwhile, lysosomal associated membrane protein 3 (LAMP3) acted as the target of BZW2 and restored the action of BZW2 knockdown. Similarly, BZW2 was involved in tumorigenesis in vivo by the same mechanism in vitro.

These findings revealed a molecular basis for BZW2's promotion of CRC malignant progression and highlighted the role of BZW2 in promoting cancer stemness.