RESUMO
Aberrated PLK4 expression has been reported in different malignancies and causes centrosome amplification, aneuploidy, and genomic instability. However, the mechanism by which PLK4 is regulated in carcinogenesis remains not fully characterised. Here, we showed that PLK4 was overexpressed in human HCC and overexpression of PLK4 predicted poorer patient prognosis. Unexpectedly, we found that induced expression of PLK4 promotes, but knockdown of PLK4 inhibits, HCC cell migration and invasion. Mechanistically, we found that TEC tyrosine kinase, which also promotes HCC cell migration, stabilizes PLK4 by phosphorylation. TEC directly phosphorylates PLK4 at tyrosine 86 residue, which not only stabilizes the protein but also enhances PLK4-mediated HCC cell invasion. Further investigation by transcriptome sequencing indicated that PLK4 promotes the phosphorylation of focal adhesion kinase to regulate the focal adhesion pathway in HCC cell migration. Taken together, our results demonstrated that PLK4 plays an important role in HCC metastasis and revealed for the first time the mechanism by which PLK4 promotes HCC metastasis via TEC phosphorylation.
Assuntos
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Carcinogênese/genética , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Movimento Celular/genética , Regulação Neoplásica da Expressão Gênica/genética , Instabilidade Genômica/genética , Humanos , Neoplasias Hepáticas/patologia , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Metástase Neoplásica , Fosforilação/genética , Transcriptoma/genéticaRESUMO
Ribonucleotide reductase M2 subunit (RRM2) is one of the two subunits of human ribonucleotide reductase which plays a critical role in tumor progression. The aim of the present study was to analyze its expression, clinical significance and biological functions in gastric adenocarcinoma. We observed the upregulation of RRM2 mRNA and protein in all nine gastric cancer cell lines examined. In paired primary gastric cancers, both mRNA and protein levels of RRM2 were significantly upregulated in tumors compared with the corresponding non-tumorous gastric tissues. RRM2 protein expression correlated with higher tumor grade, advanced T stage and poor disease-specific survival. RRM2 knockdown in gastric cancer cell lines AGS, MKN1 and MKN28 significantly suppressed cell proliferation, inhibited monolayer colony formation, reduced cell invasion and induced apoptosis. Downregulation of RRM2 suppressed xenograft formation in vivo. Collectively, these findings suggest that RRM2 plays a crucial role in gastric tumorigenesis and may serve as a potential prognostic marker and therapeutic target in gastric cancer.
