Article

PDZ-binding kinase/T-LAK cell-originated protein kinase, a putative cancer/testis antigen with an oncogenic activity in breast cancer.

Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
Cancer Research (Impact Factor: 9.28). 10/2006; 66(18):9186-95. DOI: 10.1158/0008-5472.CAN-06-1601
Source: PubMed

ABSTRACT Breast cancer is one of the most common cancers among women. To discover molecular targets that are applicable for development of novel breast cancer therapy, we previously did genome-wide expression profile analysis of 81 breast cancers and found dozens of genes that were highly and commonly up-regulated in breast cancer cells. Among them, we here focused on one gene that encodes PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK), including a kinase domain. Northern blot analyses using mRNAs of normal human organs, breast cancer tissues, and cancer cell lines indicated this molecule to be a novel cancer/testis antigen. Reduction of PBK/TOPK expression by small interfering RNA resulted in significant suppression of cell growth probably due to dysfunction in the cytokinetic process. Immunocytochemical analysis with anti-PBK/TOPK antibody implicated a critical role of PBK/TOPK in an early step of mitosis. PBK/TOPK could phosphorylate histone H3 at Ser10 in vitro and in vivo, and mediated its growth-promoting effect through histone H3 modification. Because PBK/TOPK is the cancer/testis antigen and its kinase function is likely to be related to its oncogenic activity, we suggest PBK/TOPK to be a promising molecular target for breast cancer therapy.

0 Followers
 · 
69 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The increased expression of PDZ binding kinase/lymphokine-activated killer T-cell-originated protein kinase (PBK/TOPK) is associated with some human malignant tumors. In this study, we analyzed PBK/TOPK expression in hepatic primary tumor and explored its role in cholangiocarcinoma biology. Seventy-four cholangiocarcinomas, 33 hepatocellular carcinomas, and 10 normal liver tissues were prepared from paraffin-embedded specimens. PBK/TOPK protein was assessed by immunohistochemical staining, and the survival time was analyzed with the Kaplan-Meier method. The protein, mRNA of PBK/TOPK, and cell cycle of cholangiocarcinoma cell line after PBK/TOPK suppression with small interfere RNA were studied by Western blot, semiquantitative reverse transcriptase-polymerase chain reaction, and flow cytometry, respectively. PBK/TOPK was usually expressed in normal bile duct epithelial cells and much more frequently expressed in cholangiocarcinoma (68/74) but never expressed in hepatocytes and hepatocellular carcinomas (0/33). PBK/TOPK down-regulation was related to the poor prognosis of patients with cholangiocarcinoma (P = .013). Epidermal growth factor can enhance PBK/TOPK expression in cholangiocarcinoma QBC 939 cells, but suppression of PBK/TOPK in the cells did not affect their proliferation. PBK/TOPK protein could serve as a useful indicator for histopathologic differentiation between cholangiocarcinoma and hepatocellular carcinomas and the low expression of PBK/TOPK is predicative of poor survival in cholangiocarcinoma patients.
    Human pathology 11/2009; 41(3):415-24. DOI:10.1016/j.humpath.2009.05.016 · 2.81 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Our aim was to investigate the prognostic and predictive value of the oncogenic MAPKK-like protein T-cell-originated protein kinase (TOPK) stratified by KRAS and BRAF mutations in patients with sporadic, hereditary and metastatic colorectal cancer (CRC) treated with anti-EGFR therapy. Immunohistochemistry (IHC) for TOPK was performed on four study groups. Group 1 included two subgroups of 543 and 501 sporadic CRC patients used to test the reliability of TOPK expression by IHC. In Group 2, representing an additional 222 sporadic CRCs, the prognostic effect of TOPK stratified by KRAS and BRAF was assessed. The prognostic effect of TOPK was further analysed in Group 3, representing 71 hereditary Lynch syndrome-associated CRC patients. In Group 4, the predictive and prognostic value of TOPK was analysed on 45 metastatic patients treated with cetuximab or panitumumab stratified by KRAS and BRAF gene status. In both sporadic CRC subgroups (Group 1), associations of diffuse TOPK expression with clinicopathological features were reproducible. Molecular analysis of sporadic CRCs in Group 2 showed that diffuse TOPK expression was associated with KRAS and BRAF mutations (p<0.001) and with poor outcome in patients with either mutation in univariate and multivariate analysis (P=0.017). In hereditary patients (Group 3), diffuse TOPK was linked to advanced pT stage. In metastatic patients treated with anti-EGFR therapy (Group 4), diffuse TOPK expression was linked to dismal outcome despite objective response to treatment (P=0.01). TOPK expression is an unfavourable prognostic indicator in sporadic patients with KRAS or BRAF mutations and also in patients with metastatic disease experiencing a response to anti-EGFR therapies. The inhibition of TOPK, which could benefit 30-40% of CRC patients, may represent a new avenue of investigation for targeted therapy.
    British Journal of Cancer 11/2009; 102(1):151-61. DOI:10.1038/sj.bjc.6605452 · 4.82 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Breast cancer is known to be a hormone-dependent disease, and estrogens through an interaction with estrogen receptor (ER) enhance the proliferative and metastatic activity of breast tumor cells. Here we show a critical role of transactivation of BIG3, brefeldin A-inhibited guanine nucleotide-exchange protein 3, in activation of the estrogen/ER signaling in breast cancer cells. Knocking-down of BIG3 expression with small-interfering RNA (siRNA) drastically suppressed the growth of breast cancer cells. Subsequent coimmunoprecipitation and immunoblotting assays revealed an interaction of BIG3 with prohibitin 2/repressor of estrogen receptor activity (PHB2/REA). When BIG3 was absent, stimulation of estradiol caused the translocation of PHB2/REA to the nucleus, enhanced the interaction of PHB2/REA and ERalpha, and resulted in suppression of the ERalpha transcriptional activity. On the other hand, when BIG3 was present, BIG3 trapped PHB2/REA in the cytoplasm and inhibited its nuclear translocation, and caused enhancement of ERalpha transcriptional activity. Our results imply that BIG3 overexpression is one of the important mechanisms causing the activation of the estrogen/ERalpha signaling pathway in the hormone-related growth of breast cancer cells.
    Cancer Science 06/2009; 100(8):1468-78. DOI:10.1111/j.1349-7006.2009.01209.x · 3.53 Impact Factor

Preview

Download
0 Downloads