CPEB2 enhances cell growth and angiogenesis by upregulating ARPC5 mRNA stability in multiple myeloma

BACKGROUND: The process of multiple myeloma (MM) is the result of the combined action of multiple genes. This study aims to explore the role and mechanism of cytoplasmic polyadenylation element binding protein2 (CPEB2) in MM progression. METHODS: The mRNA and protein expression levels of CPEB2 and actin-related protein 2/3 complex subunit 5 (ARPC5) were assessed by quantitative real-time PCR and western blot analysis. Cell function was determined by cell counting kit 8 assay, soft-agar colony formation assay, flow cytometry and tube formation assay. Fluorescent in situ hybridization assay was used to analyze the co-localization of CPEB2 and ARPC5 in MM cells. Actinomycin D treatment and cycloheximide chase assay were performed to assess the stability of ARPC5. The interaction between CPEB2 and ARPC5 was confirmed by RNA immunoprecipitation assay. RESULTS: CPEB2 and ARPC5 mRNA and protein expression levels were upregulated in CD138+ plasma cells from MM patients and cells. CPEB2 downregulation reduced MM cell proliferation, angiogenesis, and increased apoptosis, while its overexpression had an opposite effect. CPEB2 and ARPC5 were co-localized at cell cytoplasm and could positively regulate ARPC5 expression by mediating its mRNA stability. ARPC5 overexpression reversed the suppressive effect of CPEB2 knockdown on MM progression, and it knockdown also abolished CPEB2-promoted MM progression. Besides, CPEB2 silencing also reduced MM tumor growth by decreasing ARPC5 expression. CONCLUSION: Our results indicated that CPEB2 increased ARPC5 expression through promoting its mRNA stability, thereby accelerating MM malignant process.