RESUMO
Cytoplasmic polyadenylation element-binding protein 3 (CPEB3) is a sequence-specific RNA-binding protein. We had reported that CPEB3 is involved in hepatocellular carcinoma (HCC) progression. However, the underlying mechanisms of CPEB3 in HCC remain unclear. In this study, we firstly performed RNA immunoprecipitation to uncover the transcriptome-wide CPEB3-bound mRNAs (CPEB3 binder) in HCC. Bioinformatic analysis indicates that CPEB3 binders are closely related to cancer progression, especially HCC metastasis. Further studies confirmed that metadherin (MTDH) is a direct target of CPEB3. CPEB3 can suppress the translation of MTDH mRNA in vivo and in vitro. Besides, luciferase assay demonstrated that CPEB3 interacted with 3'-untranslated region of MTDH mRNA and inhibited its translation. Subsequently, CPEB3 inhibited the epithelial-mesenchymal transition and metastasis of HCC cells through post-transcriptional regulation of MTDH. In addition, cpeb3 knockout mice are more susceptible to carcinogen-induced hepatocarcinogenesis and subsequent lung metastasis. Our results also indicated that CPEB3 was a good prognosis marker, which is downregulated in HCC tissue. In conclusion, our results demonstrated that CPEB3 played an important role in HCC progression and targeting CPEB3-mediated mRNA translation might be a favorable therapeutic approach.
Assuntos
Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Proteínas de Membrana/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Carcinogênese/genética , Carcinoma Hepatocelular/metabolismo , Moléculas de Adesão Celular/metabolismo , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Neoplasias Hepáticas/metabolismo , Proteínas de Membrana/metabolismoRESUMO
The von Hippel-Lindau tumor suppressor (VHL; E3 ubiquitin ligase gene) is frequently mutated or undetectable in clear cell renal cell carcinoma (CCRCC), and therefore these tumors are highly resistant to chemotherapeutic agents, including adriamycin (ADM) and sunitinib. A mutation in the tumor protein p53 (TP53) also leads to chemoresistance in tumors; however, in CCRCC, TP53 is frequently functional, yet the tumors remain highly insensitive to chemotherapy. This indicates the possibility of a synergistic effect of VHL and P53 in CCRCC. The present study aimed to detect the chemosensitivity of CCRCC. The expression of VHL in the MZ1257 cell line sensitized these cells to ADM and sunitinib, and a knockdown of VHL in the ACHN cells increased their chemoresistance. To confirm that VHL and P53 are both required for chemosensitivity, VHL and P53 were coexpressed in 786O cells. The results of the functional antagonist assay (which assessed the IC50 values, i.e. the half maximal inhibitory concentration) confirmed that VHL and P53 act in synergy to promote chemosensitivity. Cell cycle arrest was measured by propidium iodide staining following treatment with ADM or sunitinib. Further analysis indicated that coexpression of VHL and P53 inhibited cell proliferation by completely inhibiting the cell cycle at the G0/G1 phase, and promoted apoptosis following treatment with ADM or sunitinib. These findings demonstrated that VHL and P53 act synergistically in the regulation of cell proliferation and apoptosis in CCRCC. Overall, VHL and P53 have important roles in the regulation of cell proliferation and apoptosis in CCRCC. Furthermore, the regulatory role of VHL is dependant on the activation P53.