Analysis of the expression and prognostic significance of DDK complex in Hepatocarcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) remains one of the most common and lethal malignancies worldwide. Although DBF4-dependent kinase (DDK) complex composed of CDC7 kinase and its regulatory subunit DBF4 has been shown to be overexpressed in primary tumors and promotes tumor development, while its role and prognostic value in HCC remain largely unknown. In the present study, the expression of DBF4 and CDC7 and their relationship with clinical characteristics were comprehensively analyzed. METHODS: The mRNA expression profiles of HCC and the corresponding clinical data of HCC patients were downloaded from TCGA and GEO databases, respectively. The differences in DBF4 and CDC7 expression in tumor tissues and adjacent normal tissues were analyzed. HCC-derived tissue microarray (TMA) was used to evaluate and score the expression of CDC7 by immunohistochemistry (IHC) staining. The Kaplan-Meier method and the Cox regression method were used to analyze the relationship between overall survival and clinical characteristics of the patients. Gene set enrichment analysis (GSEA) was used to analyze the pathway enrichment of DBF4 and CDC7. RESULTS: DBF4 and CDC7 had similar expression patterns in HCC patients. Detailly, compared with adjacent tissues, both mRNA and protein of DBF4 and CDC7 were significantly higher in HCC, and their expression was positively correlated with AJCC_T stage, clinical stage and G stage (grade) of liver cancer patients, and higher DBF4 or CDC7 expression predicted a worse prognosis in HCC patients with shorter overall survival (OS), recurrence-free survival (RFS), disease-specific survival (DSS) and progress-free survival (PFS). Cox regression analysis suggested that both DBF4 and CDC7 were independent risk factors for the prognosis of HCC patients in TCGA dataset. GSEA suggested that both DBF4 and CDC7 were positively correlated with cell cycle and DNA replication. Finally, the prognostic value of CDC7 was furtherly confirmed by TMA-based IHC staining results. CONCLUSIONS: Our study showed that DDK complex was significantly increased in HCC. Both DBF4 and CDC7 may be potential diagnostic and prognostic markers for HCC, and high expression of DDK members predicts a worse prognosis in patients with HCC, which may be associated with high tumor cell proliferation rate.

Histone deacetylase 3 promotes liver regeneration and liver cancer cells proliferation through signal transducer and activator of transcription 3 signaling pathway.

Histone deacetylase 3 (HDAC3) plays pivotal roles in cell cycle regulation and is often aberrantly expressed in various cancers including hepatocellular carcinoma (HCC), but little is known about its role in liver regeneration and liver cancer cells proliferation. Using an inducible hepatocyte-selective HDAC3 knockout mouse, we find that lack of HDAC3 dramatically impaired liver regeneration and blocked hepatocyte proliferation in the G1 phase entry. HDAC3 inactivation robustly disrupted the signal transducer and activator of transcription 3 (STAT3) cascade. HDAC3 silencing impaired the ac-STAT3-to-p-STAT3 transition in the cytoplasm, leading to the subsequent breakdown of STAT3 signaling. Furthermore, overexpressed HDAC3 was further associated with increased tumor growth and a poor prognosis in HCC patients. Inhibition of HDAC3 expression reduced liver cancer cells growth and inhibited xenograft tumor growth. Our results suggest that HDAC3 is an important regulator of STAT3-dependent cell proliferation in liver regeneration and cancer. These findings provide novel insights into the HDAC3-STAT3 pathway in liver pathophysiological processes.

Elevated expression of Gsα in intrahepatic cholangiocarcinoma associates with poor prognosis.

BACKGROUND: The stimulatory G protein a subunit (Gsα) plays important roles in diverse cell processes including tumorigenesis. Activating mutations in Gsα gene (GNAS) have been reported to be associated with poor prognosis in various human carcinomas. Furthermore, Gsα signaling is crucial in promoting liver regeneration by interacting with growth factor signaling, indicating that Gsα might play a promoting role in cancer development. However, little is known about the correlation between Gsα levels and clinicopathological parameters in intrahepatic cholangiocarcinoma (ICC). METHODS: We performed immunoblotting to examine the expression levels of Gsα and Ki67 proteins in tumor tissues and the corresponding adjacent tissues. A total of 74 pair of specimens resected from 74 ICC patients were examined. The association between Gsα levels and clinicopathological findings and prognosis of the patients was evaluated. RESULTS: Western blotting demonstrated that the expression of Gsα was significantly higher in ICC tissues compared with that in their corresponding adjacent tissues. Gsα protein was highly expressed in about half of ICC tissues (48.6%, 36/74) while only 28.4% (21/74) of tumor adjacent tissues showed Gsα high expression (P=0.011). High Gsα expression in ICC was significantly associated with the numbers of tumor nodules (P=0.037) and lymph node metastases (P=0.010). Moreover, the level of Gsα was significantly and positively correlated with Ki67 expression (P<0.001). In addition, the recurrence-free survival rate and overall survival rate in the Gsα high group were significantly lower than those in the Gsα low group (P=0.004 and P=0.005, respectively). CONCLUSIONS: High Gsα expression is correlated with poor prognosis in ICC patients. Gsα might serve as a potential prognostic indicator of ICC.

Loss of Dicer1 impairs hepatocyte survival and leads to chronic inflammation and progenitor cell activation.

AIM: To investigate the continuous hepatic histopathological processes which occur in response to the loss of Dicer1. METHODS: We generated a hepatocyte-selective Dicer1 knockout mouse and observed the gradual hepatic histopathological changes in the mutant liver. Immunohistochemistry and Western blotting were performed to detect Dicer1 expression. We performed hematoxylin and eosin staining, Periodic acid-Schiff staining, Oil Red O staining, and Masson's trichrome staining to detect histological changes in Dicer1-deficient livers. Ki67 immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, and Western blotting were used to determine hepatocyte proliferation and apoptosis. Serum biochemistry, cytokine assays, and flow cytometric analysis were performed to quantity liver necrosis and inflammation. Fibrogenic markers were determined by Western blotting and qPCR. CK19, CD133, and OV6 immunofluorescence were used to observe liver progenitor cells. Immunofluorescence and qPCR were performed to reveal embryonic gene expression. We also performed histological staining and Western blotting to analyze hepatocellular carcinoma (HCC) development. RESULTS: Dicer1 inactivation resulted in significant architecture disorganization and metabolism disruption in the liver. Dicer1 disruption impaired hepatocyte survival and resulted in profound cell apoptosis and continuous necrosis. In contrast to previous reports, the mutant liver exhibited chronic inflammation and progressive fibrosis, and could not be repopulated by Dicer1-positive cells. In addition, extensive activation of hepatic progenitor cells was observed. Primary HCC was observed as early as 4 mo after birth. CONCLUSION: Hepatic loss of Dicer1 results in complex chronic pathological processes, including hepatocyte death, inflammatory infiltration, chronic fibrosis, compensatory proliferation, progenitor activation, and spontaneous hepatocarcinogenesis.