ABSTRACT
WEE1 is a serine/threonine protein kinase that inactivates cell division cycle 2 and is therefore a critical cell cycle regulator. Increased WEE1 expression has been observed in numerous types of human malignancies, including hepatocellular carcinoma and melanoma. WEE1 inhibition also results in evident anti-tumor effects in several human tumor cells including colon cancer cells, suggesting WEE1 as a potential therapeutic target for the treatment of cancer. However, the expression pattern of WEE1 in colorectal cancer (CRC) remains unclear. In the present study, WEE1 mRNA expression in 43 cases of CRC tissues matched with adjacent normal tissues was determined by reverse-transcription quantitative polymerase chain reaction. The results demonstrated that WEE1 mRNA expression was significantly increased in CRC tissues and that this upregulation correlated significantly with hepatic metastasis, distant metastasis and high tumor node metastasis (TNM) stage of CRC. Additionally, WEE1 protein in 102 CRC tissue samples was detected by immunohistochemistry, and positive staining of WEE1 was identified in more than half of patients with CRC. WEE1 staining scores were also observed to be associated with distant metastasis and high TNM stage of CRC. In addition, patients with CRC with high WEE1 staining score (2+ or 3+) exhibited either poorer overall survival or poorer disease-free survival compared with those with low WEE1 staining score (0 or 1+). The multivariable Cox model also identified a high WEE1 staining score as well as high TNM stage to be independent prognostic factors for CRC. In conclusion, WEE1 upregulation is associated with a high degree of malignancy and poor prognosis of CRC, suggesting WEE1 as a potential prognostic biomarker for CRC.
ABSTRACT
As a critical endonuclease in DNA repair, Mus81 is traditionally regarded as a tumor suppressor, but recently correlated with the sensitivity of mitomycin C and 5-fluorouracil in colon cancer and breast cancer cells. However, its role in chemosensitivity of other human malignancies still remains unknown. This study therefore aims to investigate the effects of Mus81 knockdown on the chemosensitivity of hepatocellular carcinoma (HCC), a usually chemorefractory tumor, and explore the underlying mechanisms. Mus81 expression in HepG2 and Bel-7402 HCC cell lines was depleted by lentivirus-mediated short hairpin RNA and the elevated sensitivity of these Mus81-inhibited HCC cells to therapeutic agents, especially to epirubicin (EPI), was evidenced by MTT assay and an HCC chemotherapy mouse model. Flow cytometric analysis also showed that Mus81 knockdown lead to an obvious S-phase arrest and an elevated apoptosis in EPI-treated HepG2 and Bel-7402 cells, which could be rescued by CHK1 inhibition. The activation of CHK1/CDC25A/CDK2 pathway was also demonstrated in Mus81-inhibited HepG2 cells and xenograft mouse tumors under EPI treatment. Meanwhile, the apoptosis of HepG2 cells in response to EPI was remarkably promoted by Mus81 knockdown through activating p53/Bax/Caspase-3 pathway under the controlling of CHK1. In addition, CHK2 inhibition slightly raised CHK1 activity, thereby enhancing the S-phase arrest and apoptosis induced by EPI in Mus81-suppressed HCC cells. In conclusion, Mus81 knockdown improves the chemosensitivity of HCC cells by inducing S-phase arrest and promoting apoptosis through CHK1 pathway, suggesting Mus81 as a novel therapeutic target for HCC.
Subject(s)
Apoptosis/genetics , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/metabolism , DNA-Binding Proteins/genetics , Endonucleases/genetics , Liver Neoplasms/genetics , Liver Neoplasms/metabolism , Protein Kinases/metabolism , S Phase Cell Cycle Checkpoints/genetics , Signal Transduction , Animals , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Line, Tumor , Checkpoint Kinase 1 , Disease Models, Animal , Dose-Response Relationship, Drug , Drug Resistance, Neoplasm/genetics , Epirubicin/pharmacology , Gene Knockdown Techniques , Genetic Vectors/genetics , Humans , Lentivirus/genetics , Mice , Mice, Knockout , Protein Kinase Inhibitors/pharmacology , RNA, Small Interfering/genetics , S Phase Cell Cycle Checkpoints/drug effects , Tumor Burden , Xenograft Model Antitumor AssaysABSTRACT
OBJECTIVE: To investigate the association of tumor budding with recurrence and survival of patients with stage II colon cancer, in order to identify patients with high-risk recurrence who may benefit from adjuvant therapy. METHODS: Clinical data of 112 stage II colon cancer patients in Guangzhou Red Cross Hospital between 1998 and 2007 were analyzed retrospectively. The degree of tumor budding was assessed by two observers and classified according to the number of tumor buds in the area with the greatest budding intensity on HE stain slides, as high-grade budding (≥10, n=30) and low-grade budding (≤9, n=82). Progression-free and cancer-specific survival were analyzed using the Kaplan-Meier method and Cox regression. RESULTS: All the patients were followed up and the median follow-up was 78 months. The 5-year progression-free survival rates for patients with high-grade and low-grade budding were 65.3% and 90.7% respectively (P=0.008). The 5-year cancer-specific survival rates were 72.1% and 93.8% respectively (P=0.001). Cox regression analysis demonstrated tumor budding was an independent predictor of disease progression (RR=4.572, 95%CI:2.218-11.746, P=0.002) and cancer-related death (RR=4.116, 95%CI:1.657-10.384, P=0.012). CONCLUSION: Tumor budding is a strong prognostic index for adverse outcome in stage II colon cancer patients,which may serve as a prognostic marker to identify patients with high risk of recurrence who may benefit from adjuvant therapy.
