[Correlation of casein kinase 2ß overexpression to the metastatic ability of colorectal cancer cells in vitro].

OBJECTIVE: To investigate the expression of casein kinase 2ß (ck2ß) in colorectal cancer in relation to the metastatic ability of the cancer cells. METHODS: The expression of ck2ß in 46 normal colorectal mucosa, 20 colorectal adenomas and 66 colorectal cancers were detected immunohistochemically. In colorectal cancer cells, Ck2ß protein expression was knockdown by RNA interference using ck2ß-specific small interfering RNA (siRNA) and the interference efficiency was assessed by Western blotting. The effect of ck2ß gene knockdown on the proliferation of the colorectal cancer cells was tested with colony formation assay, and the changes in the invasive ability of the cells were observed using Transwell chamber assay. RESULTS: Negative or weak ck2ß expression was detected in normal colorectal mucosa, with nuclear positivity in 8.7% and cytoplasmic positivity in 13.0% of the cases. Colorectal adenomas showed moderate ck2ß expression, with 60% cases showing positivity in the cell nuclei and 40% in the cytoplasm. In colorectal cancers, significantly stronger expression of ck2ß was found than that in colorectal adenomas and normal colorectal mucosa (P<0.05), and 75.8% cases showed positivity in the cell nuclei and 62.1% showed cytoplasmic positivity; the expression of ck2ß protein in colorectal cancers with lymph node metastasis was even higher (P<0.05). Ck2ß knockdown obviously inhibited the proliferation and invasiveness of colorectal cancer cells in vitro. CONCLUSION: The high expression of ck2ß in colorectal cancer is closely correlated to the carcinogenesis and metastasis of the tumor.

[Effect of protein kinase CK2 gene silencing on radiosensitization in human nasopharyngeal carcinoma cells].

OBJECTIVE: To investigate the effect of protein kinase CK2 gene silencing on the radiosensitization in human nasopharyngeal carcinoma (NPC) cells and its possible mechanism. METHODS: RNA interference (RNAi) technique was used to down-regulate the protein kinase CK2alpha expression in 5-8F cells, and clonogenic assay was employed to observe the changes in the radiosensitivity of the cells. DNA double-strand break was assessed by immunofluorescence staining of gamma-H2AX foci, and the cell apoptosis was examined using Annexin V-FITC/PI double-staining flow cytometry. RESULTS: CK2alpha protein was successfully silenced by siRNA. CK2alpha knockdown significantly decreased the clonogenic activity and increased the radiosensitivity of the NPC cells. After a 15-min exposure of the cells to 1 Gy radiation, significant difference occurred in the gamma-H2AX foci between CK2alpha knockdown cells and the control cells (P<0.01). CK2alpha silencing significantly increased the cell apoptosis after the exposure (P<0.01). CONCLUSIONS: Protein kinase CK2 plays an important role in the radiosensitivity of the NPC cells, and suppression of its expression might be a potential therapeutic approach of cancer.