Characterization of KIF20B as a novel prognostic biomarker and therapeutic target for breast cancer.

Despite advances in treatment and early detection, breast cancer remains one of the most common types of cancer and is the second leading cause of cancer death after lung cancer in women. Therefore, there is an urgent need to develop new biomarkers and therapeutic targets for the treatment of breast cancer. Based on gene expression profiles and subsequent screening performed in a preliminary study, kinesin family member 20B (KIF20B) was selected as a candidate target molecule, because it was highly and frequently expressed in all subtypes of breast cancer and barely detected in normal tissues. Reverse transcription­quantitative PCR and western blotting revealed that KIF20B mRNA and protein expression levels were upregulated in most breast cancer cell lines but were scarcely expressed in normal mammary epithelial cells. Immunohistochemical staining of a tissue microarray showed that KIF20B was detected in 145 out of 251 (57.8%) breast cancer tissues. Strong KIF20B expression was significantly related to advanced pathological N stage. Moreover, patients with breast cancer and strong KIF20B expression exhibited a significantly worse prognosis than those with weak or negative KIF20B expression (P<0.0001, log­rank test). In multivariate analysis, strong expression was an independent prognostic factor for patients with breast cancer. Furthermore, knockdown of KIF20B expression by small interfering RNA inhibited breast cancer cell proliferation and induced apoptosis. In addition, Matrigel cell invasion assays revealed that the invasiveness of breast cancer cells was significantly decreased by KIF20B silencing. Since KIF20B is an oncoprotein that is strongly expressed in highly malignant clinical breast cancer and serves a pivotal role in breast cancer cell proliferation, survival and invasion, KIF20B could be considered a candidate biomarker for prognostic prediction and a potential molecular target for developing new therapeutics, such as small molecule inhibitors, for a wide variety of breast cancers.

Holliday junction recognition protein as a prognostic biomarker and therapeutic target for oral cancer.

Since oral cancer (OC) is highly malignant and the efficacy of standard treatments is limited, the development of new therapeutics is urgently awaited. To identify potential molecular targets for new OC diagnosis and therapies, we screened oncoantigens by gene expression profile and focused on Holliday junction recognition protein (HJURP), a mammalian centromere­specific chaperone. HJURP was found to be highly expressed in the majority of OC cell lines and tissues as compared to normal oral epithelial cells. Tissue microarray analysis confirmed that HJURP was expressed in 103 (67.8%) of 152 OC tissue specimens, but expression in normal oral tissues was limited. Positive HJURP expression was significantly correlated with shorter overall survival (P=0.003). Depletion of HJURP by small­interfering RNAs dramatically inhibited the growth of OC cells by inhibition of cell cycle progression and induced senescence of OC cells. In addition, inhibition of the interaction between HJURP and CENP­A significantly suppressed the growth of OC cells. These results indicate that HJURP is a potential prognostic biomarker, and targeting HJURP and its molecular pathway presents a new strategy for the development of treatments against OC.

Characterization of Opa interacting protein 5 as a new biomarker and therapeutic target for oral cancer.

Oral cancer is a leading cause of cancer­related death worldwide. Current treatment for oral cancer includes surgery, radiotherapy, and chemotherapy; however, their effectiveness is still limited. To identify a new prognostic biomarker and therapeutic target for oral cancer, the Opa interacting protein 5 (OIP5), which plays an essential role in the proper segregation of chromosomes, was examined. Immunohistochemical staining using tissue microarrays indicated that OIP5 was expressed in 120 of 164 (73.2%) oral cancers but was minimally expressed in normal oral tissues. OIP5 expression was significantly associated with poor prognosis in patients with oral cancer. Overexpression of OIP5 enhanced the growth of oral cancer cells, whereas OIP5 knockdown using small interfering RNAs (siRNAs) significantly inhibited cell growth through cell cycle arrest at the G2/M phase. Suppression of OIP5 expression also induced senescence of oral cancer cells. Overall, the findings of the present study suggest that OIP5 may be a candidate prognostic biomarker and therapeutic target in oral cancer.

Characterization of KIF20A as a prognostic biomarker and therapeutic target for different subtypes of breast cancer.

The aim of the present study was to identify novel prognostic biomarkers and therapeutic targets for breast cancer; thus, genes that are frequently overexpressed in several types of breast cancer were screened. Kinesin family member 20A (KIF20A) was identified as a candidate molecule during this process. Immunohistochemical staining performed using tissue microarrays from 257 samples of different breast cancer subtypes revealed that KIF20A was expressed in 195 (75.9%) of these samples, whereas it was seldom expressed in normal breast tissue. KIF20A protein was expressed in all types of breast cancer observed. However, it was more frequently expressed in human epidermal growth factor receptor 2 (HER2)­positive and triple­negative breast cancer than in the luminal type. Moreover, KIF20A expression was significantly associated with the poor prognosis of patients with breast cancer. A multivariate analysis indicated that KIF20A expression was an independent prognostic factor for patients with breast cancer. The suppression of endogenous KIF20A expression using small interfering ribonucleic acids or via treatment with paprotrain, a selective inhibitor of KIF20A, significantly inhibited breast cancer cell growth through cell cycle arrest at the G2/M phase and subsequent mitotic cell death. These results suggest that KIF20A is a candidate prognostic biomarker and therapeutic target for different types of breast cancer.