CK2α/CSNK2A1 Phosphorylates SIRT6 and Is Involved in the Progression of Breast Carcinoma and Predicts Shorter Survival of Diagnosed Patients.

Recently, the roles of sirtuins (SIRTs) in tumorigenesis have been of interest to oncologists, and protein kinase CK2 α1 (CSNK2A1) has been shown to be involved in tumorigenesis by phosphorylating various proteins, including SIRT1. Therefore, we evaluated the roles of CSNK2A1, SIRT6, and phosphorylated SIRT6 and their relationships in breast carcinoma. Nuclear expression of CSNK2A1 and SIRT6 predicted shorter overall survival and relapse-free survival by multivariate analysis. Inhibition of CSNK2A1 decreased the proliferative and invasive activity of cancer cells. In addition, CSNK2A1 was bound to SIRT6 and phosphorylated SIRT6; evidence for this is provided from immunofluorescence staining, co-immunoprecipitation of CSNK2A1 and SIRT6, a glutathione S-transferase pull-down assay, an in vitro kinase assay, and transfection of mutant CSNK2A1. Knockdown of SIRT6 decreased the proliferation and invasiveness of cancer cells. Overexpression of SIRT6 increased proliferation, but mutation at the Ser338 phosphorylation site of SIRT6 inhibited the proliferation of MCF7 cells. Moreover, both knockdown of SIRT6 and a mutation at the phosphorylation site of SIRT6 decreased expression of matrix metallopeptidase 9, ß-catenin, cyclin D1, and NF-κB. Especially, SIRT6 expression was associated with the nuclear localization of ß-catenin. This study demonstrates that CSNK2A1 and SIRT6 are indicators of poor prognosis for breast carcinomas and that CSNK2A1-mediated phosphorylation of SIRT6 might be involved in the progression of breast carcinoma.

Expression of nerve growth factor and heme oxygenase-1 predict poor survival of breast carcinoma patients.

BACKGROUND: Nerve growth factor (NGF) is a neurotrophin and has been suggested to induce heme oxygenase-1 (HO1) expression. Although the role of HO1 in tumorigenesis remains controversial, recent evidence suggests NGF and HO1 as tumor-progressing factors. However, the correlative role of NGF and HO1 and their prognostic impact in breast carcinoma is unknown. METHODS: We investigated the expression and prognostic significance of the expression of NGF and HO1 in 145 cases of breast carcinoma. RESULTS: Immunohistochemical expression of NGF and HO1 was observed in 31% and 49% of breast carcinoma, respectively. The expression of NGF and HO1 significantly associated with each other, and both have a significant association with histologic grade, HER2 expression, and latent distant metastasis. The expression of NGF and HO1 predicted shorter overall survival of breast carcinoma by univariate and multivariate analysis. NGF expression was an independent prognostic indicator for relapse-free survival by multivariate analysis. The combined expression pattern of NGF and HO1 was also an independent prognostic indicator of overall survival and relapse-free survival. The patients with tumors expressing NGF had the shortest survival and the patients with tumor, which did not express NGF or HO1 showed the longest survival time. CONCLUSIONS: This study has demonstrated that individual expression of NGF or HO1, and the combined NGF/HO1 expression pattern could be prognostic indicators for breast carcinoma patients.

Expression of peptidyl-prolyl isomerase PIN1 and its role in the pathogenesis of extrahepatic cholangiocarcinoma.

The phosphorylation of proteins on serine/threonine residues that immediately precede proline (pSer/Thr-Pro) is a key signaling mechanism by which cell cycle regulation and cell differentiation and proliferation occur. The peptidyl-prolyl isomerase PIN1-catalyzed conformational changes of the pSer/Thr-Pro motifs may have profound effects on the function of numerous oncogenic and cell signaling pathways. To date, no studies have examined the expression of PIN1 and its potential role in the pathogenesis of extrahepatic cholangiocarcinoma (ECC). Therefore, the present study performed an immunohistochemistry analysis of the expression of PIN1 in 67 cases of ECC and evaluated its association with clinicopathological factors. In addition, the role of PIN1 was examined using synthetic small interfering RNA (siRNA) to silence PIN1 gene expression in human CC RBE cells. Positive PIN1 expression was observed in 35 of the 67 (52.2%) ECC cases and was predominantly localized to the nucleus of the tumor cells. The immunoreactive score for PIN1 was significantly higher in the tumor cells (4.07±0.4) compared with the adjacent benign bile duct cells (1.19±0.4) (P<0.001). PIN1 expression was significantly correlated with tumor cell proliferation (Ki-67 labeling index; P=0.024). Silencing PIN1 expression using siRNA significantly decreased the proliferation, migration and invasion of the tumor cells. In conclusion, the results indicated that the expression of PIN1 may play a key role in the development and progression of ECC.

Expression and role of SIRT1 in hepatocellular carcinoma.

Silent mating type information regulation 2 homolog 1 (SIRT1) is a multifaceted, nicotinamide adenine dinucleotide-dependent protein deacetylase with involvement in a wide variety of cellular processes ranging from cancer to aging. Expression of SIRT1 was evaluated in 90 cases of hepatocellular carcinoma (HCC) and five HCC cell lines. The relationship between the mutation status of p53 and expression of SIRT1 was also investigated in 10 fresh HCC tissues. Synthetic small interfering RNA was used to silence SIRT1 gene expression by RNA interference (RNAi), and cell growth and cell cycle progression were assessed. Expression of SIRT1 was significantly elevated in the HCC tissues when compared to that of non-tumor tissues (p<0.001). Overexpression of SIRT1 and p53 was observed in 56% (50 of 90) and in 30% (27 of 90) of the HCCs, respectively. Expression of SIRT1 showed significant correlation with gender (p=0.023), serum AFP levels (p=0.030), viral infection (p=0.005) and p53 expression (p<0.021). Western blot analysis found no correlation between p53 mutation and expression levels of SIRT1. SIRT1 silencing was found to induce cell growth arrest in HCC cells. These results suggest an association of SIRT1 expression with HCC development and that SIRT1 plays a role in cancer cell growth.