Yuji Tai

Cyclin D1-CDK4 complex,a possible critical factor for cell proliferation and prognosis in laryngeal squamous cell carcinomas

Cyclin D1 and its catalytic partner CDK4 are known to play important roles in the G1/S checkpoint of the cell cycle. The complex formed by CDK4 and cyclin D1 has been strongly implicated in the control of cell proliferation and prognoses in human malignancies. We investigated the immunohistochemical expression of cyclin D1, CDK4 and proliferating cell nuclear antigen (PCNA) in 102 patients with laryngeal squamous cell carcinoma (LSCC). Cyclin D1 overexpression was observed in 59 cases (57.8%) of LSCC, and was significantly correlated with tumor site, tumor size, lymph node metastasis and advanced stage. CDK4 overexpression was observed in 48 cases (47.1%), and was significantly correlated with tumor size and advanced stage. Cyclin D1 and CDK4 expression was significantly associated with cell proliferation measured by PCNA (r = 0.812, p < 0.0001 and r = 0.725, p < 0.0001, respectively). The Kaplan–Meier analysis showed that cyclin D1 overexpression was significantly associated with disease‐free survival and overall survival. CDK4 overexpression was significantly associated with overall survival. When cyclin D1 and CDK4 are combined, the patients with co‐overexpression of cyclin D1‐CDK4 revealed the poorest overall survival. Additionally, in early‐stage (I‐II) cases, co‐overexpression of cyclin D1‐CDK4 was also revealed to possess a significant prognostic role. By multivariate analysis, cyclin D1 overexpression, lymph node metastasis and advanced stage were independent prognostic factors for disease‐free survival. Cyclin D1 overexpression, CDK4 overexpression, tumor grade, lymph node metastasis and advanced stage were independent prognostic factors for overall survival. These findings indicate that cyclin D1 and CDK4 overexpression and/or co‐overexpression of these proteins may play a pivotal role in the biological behavior of LSCC and may provide a strong prognostic implication.

Cyclin-dependent kinase inhibitor p27 is related to cell proliferation and prognosis in laryngeal squamous cell carcinomas

An immunohistochemical study of both p27 and proliferating cell nuclear antigen (PCNA) was performed on 102 cases of laryngeal squamous cell carcinomas (LSCCs), and large variations in p27 expression were found among the tumours. Reduced expression of p27 was revealed in 54 (52.9 per cent) cases and correlated with tumour size, lymph node metastasis, and clinical stage, but did not correlate with age, sex, tumour site, or tumour grade. A significant positive correlation was found between the percentage of loss of p27 expression and the PCNA index (r = 0.844, p < 0.0001). Reduced expression of p27 was significantly correlated with both reducing disease-free and overall survival by univariate analysis. By multivariate analysis, reduced expression of p27, tumour grade, tumour size, lymph node metastasis as well as clinical stage were independent prognostic factors for overall survival of LSCCs. These findings indicate that reduced expression of p27 may be correlated with the malignant biological behaviour of LSCCs.

Expression and subcellular localization of multifunctional calmodulin-dependent protein kinases-I, -II and -IV are altered in rat hippocampal CA1 neurons after induction of long-term potentiation.

Long-term potentiation (LTP) is considered to be associated with an increase in expression as well as activity of Ca(2+)/calmodulin-dependent protein kinases (CaMKs). LTP-induced and control hippocampal slices were studied by immunohistochemical and electronmicroscopic analyses using anti-CaMK-I, -II and -IV antibodies. All three kinases were demonstrated to increase their expression in CA1 neurons. CaMK-I was shown to mainly localize in the cytoplasm of the control and LTP-induced neurons, and a significant increase of immunoreactivity was observed in the latter neurons. A part of CaMK-I was found to translocate to the nuclei of LTP-induced hippocampal CA1 neurons. Direct evidence of the translocation of CaMK-II from cytoplasm to nuclei in LTP was demonstrated by immuno-electronmicroscopy. A significant increase in expression of CaMK-IV in the nuclei was also observed. Our data suggest that all the three CaMKs were actively involved in nuclear Ca(2+)-signaling in LTP.

Involvement of Annexins I an II in human liver cirrhosis and hepatocellular carcinoma

Annexin (AX) is the name of a new family of Ca2+-dependent membrane binding proteins of which 13 members have been reported to date. Among these, AXI and AXII have been reported to possess many biological functions in vitro. Their actual roles in vivo, however, are as yet unknown. There have been no reports previously demonstrating the direct involvement of AXI and AXII in chronic hepatitis (CH), liver cirrhosis (LC) or hepatocellular carcinoma (HCC). The involvement of AXI and AXII in the etiological processes of CH, LC and HCC was investigated by Western blot and/or immunohistochemistry using anti-AXI and AXII antibodies. AXI and AXII were rarely detected in CH liver tissues, while they were found to be expressed at high levels in LC and HCC. AXI and AXII were present in the hepatocytes of LC and HCC and their subcellular localization was mainly cytoplasmic. These results indicate that AXI and AXII may act together in the occurrence and development of LC and HCC.

Increases in src-related protein tyrosine kinases in human liver cirrhosis and hepatocellular carcinoma

Abstract We examined the involvement of src-related tyrosine kinases (RTK) in various human liver diseases, such as chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular careinoma (HCC), by Western blot and immunohistochemical analysis using an anti-src-RTK polyclonal antibody (α-416). Our results showed that src-RTK were rarely found in the liver tissues from CH patients, while they were found at high amounts in those from LC and HCC patients. In addition, src-RTK were expressed more strongly in HCC than in LC. These results indicate that src-RTK may play important roles in the occurrence and development of LC and HCC.