Downregulation of dual-specificity tyrosine-regulated kinase 2 promotes tumor cell proliferation and invasion by enhancing cyclin-dependent kinase 14 expression in breast cancer.

Tumor progression is the main cause of death in patients with breast cancer. Accumulating evidence suggests that dual-specificity tyrosine-regulated kinase 2 (DYRK2) functions as a tumor suppressor by regulating cell survival, differentiation, proliferation and apoptosis. However, little is known about the mechanisms of transcriptional regulation by DYRK2 in cancer progression, particularly with respect to cancer proliferation and invasion. Here, using a comprehensive expression profiling approach, we show that cyclin-dependent kinase 14 (CDK14) is a target of DYRK2. We found that reduced DYRK2 expression increases CDK14 expression, which promotes cancer cell proliferation and invasion in vitro, in addition to tumorigenicity in vivo. CDK14 and DYRK2 expression inversely correlated in human breast cancer tissues. We further identified androgen receptor (AR) as a candidate of DYRK2-dependent transcription factors regulating CDK14. Taken together, our findings suggest a mechanism by which DYRK2 controls CDK14 expression to regulate tumor cell proliferation and invasion in breast cancer. Targeting of this pathway may be a promising therapeutic strategy for treating breast cancer.

Dual-specificity tyrosine-regulated kinase 2 is a suppressor and potential prognostic marker for liver metastasis of colorectal cancer.

Colorectal cancer is a common cancer and a leading cause of cancer-related death worldwide. The liver is a dominant metastatic site for patients with colorectal cancer. Molecular mechanisms that allow colorectal cancer cells to form liver metastases are largely unknown. Activation of epithelial-mesenchymal transition is the key step for metastasis of cancer cells. We recently reported that dual-specificity tyrosine-regulated kinase 2 (DYRK2) controls epithelial-mesenchymal transition in breast cancer and ovarian serous adenocarcinoma. The aim of this study is to clarify whether DYRK2 regulates liver metastases of colorectal cancer. We show that the ability of cell invasion and migration was abrogated in DYRK2-overexpressing cells. In an in vivo xenograft model, liver metastatic lesions were markedly diminished by ectopic expression of DYRK2. Furthermore, we found that patients whose liver metastases expressed low DYRK2 levels had significantly worse overall and disease-free survival. Given the findings that DYRK2 regulates cancer cell metastasis, we concluded that the expression status of DYRK2 could be a predictive marker for liver metastases of colorectal cancer.

DYRK2 regulates epithelial-mesenchymal-transition and chemosensitivity through Snail degradation in ovarian serous adenocarcinoma.

Epithelial-mesenchymal-transition (EMT) plays essential roles in ovarian cancer invasion, metastasis, and drug resistance. A hallmark of EMT is the loss of E-cadherin, which is regulated by Snail. Recently, it was shown that dual-specificity tyrosine-regulated kinase 2 (DYRK2) controls Snail degradation in breast cancer. The aim of this study is to clarify whether DYRK2 regulates EMT through Snail degradation in ovarian serous adenocarcinoma (SA). Expression of DYRK2 and Snail in two pairs of cisplatin-resistant and the original cisplatin-sensitive ovarian cancer cell line were analyzed by immunoblotting and real-time RT-PCR analysis. Morphological change, invasion ability, and chemosensitivity were evaluated by using DYRK2 stable knockdown cell line in 2008 (2008 shDYRK2). Immunohistochemical analyses for DYRK2 and Snail were performed with surgical specimens. The correlations between the expression of these proteins and the clinicopathological parameters, including prognosis, were determined. Moreover, we conducted a hypodermic administration test in nude mice and examined reproductive and cisplatin response activities. DYRK2 protein expression was posttranslationally reduced in cisplatin-resistant SA cell lines. 2008 shDYRK2 showed mesenchymal phenotype and resistant to cisplatin. Immunohistochemistry demonstrated that DYRK2 expression inversely correlated with Snail expression, and reduced expression of DYRK2 was associated with shorter overall survival in SA. DYRK2 may regulate EMT through Snail degradation in ovarian SA and might be a predictive marker for a favorable prognosis in the treatment of this cancer.

Clinical relevance and low tumor-initiating properties of oligometastatic breast cancer in pulmonary metastasectomy.

Metastatic breast cancer is a systemic disease. However, certain subsets of patients, such as those with oligometastatic breast cancer (OMBC), have long-term survival prospects. Our aim was to evaluate the clinical relevance of OMBC in pulmonary metastasectomy of recurrent breast cancer. We also investigated lung metastases for the prevalence of CD44+/CD24-/low tumor cells and evaluated their prognostic significance. We reviewed data from a registry of breast cancer patients with lung metastases who underwent pulmonary metastasectomy at Jikei University Hospital. We analyzed prognostic factors for overall survival (OS) and progression-free survival (PFS) after metastasectomy and examined the prognostic difference between OMBC and non-OMBC patients. CD44+/CD24-/low tumor cells were detected by immunohistochemical analysis of lung metastases sites. Among 17 breast cancer patients with lung metastasis, 5-year OS and PFS rates were 72 and 36 %, respectively. Better OS was observed among patients with OMBC. Patients with OMBC, estrogen receptor-positive cells, and disease-free intervals of >8 years had better PFS. The presence of CD44+/CD24-/low tumor cells influenced progression after lung metastasectomy, with median PFS of only 6 months in patients with a high prevalence of cancer-initiating cells. CD44+/CD24-/low cells with cancer-initiating properties were present in only 9 % ± 3 of patients with OMBC, but were found in 73 % ± 12 of patients with non-OMBC. Pulmonary metastasectomy may be a treatment option for OMBC patients with lung metastases. Better prognosis of OMBC may be associated with low levels of cancer-initiating cells.

Clinical implications of drug-screening assay for recurrent metastatic hormone receptor-positive, human epidermal receptor 2-negative breast cancer using conditionally reprogrammed cells.

Various new drugs have been developed for treating recurrent hormone receptor-positive (HR+)/human epidermal receptor 2-negative (HER2-) breast cancer. However, directly identifying effective drugs remains difficult. In this study, we elucidated the clinical relevance of cultured cells derived from patients with recurrent HR+/HER2- metastatic breast cancer. The recently established conditionally reprogrammed (CR) cell system enables us to examine heterogeneity, drug sensitivity and cell function using patient-derived tumour samples. The results of microarray analysis, DNA target sequencing and xenograft experiments indicated that the mutation status and pathological features were preserved in CR cells, whereas RNA expression was different from that in the primary tumour cells, especially with respect to cell adhesion-associated pathways. The results of drug sensitivity assays involving the use of primary breast cancer CR cells were consistent with gene expression profiling test data. We performed drug-screening assays using liver metastases, which were sensitive to 66 drugs. Importantly, the result reflected the actual clinical course of this patient. These results supported the use of CR cells obtained from the metastatic lesions of patients with HR+/HER2- breast cancer for predicting the clinical drug efficacy.

Diminished DYRK2 sensitizes hormone receptor-positive breast cancer to everolimus by the escape from degrading mTOR.

Mammalian target of rapamycin (mTOR) inhibitor, everolimus, provides benefit for metastatic hormone receptor positive breast cancer after failure of the endocrine therapy. The present report highlights Dual Specificity Tyrosine Phosphorylation Regulated Kinase 2 (DYRK2) as a predictive marker for everolimus sensitivity. The key node and KEGG pathway analyses revealed that mTORC1 pathway is activated in DYRK2-depleted cells. Everolimus was more effective in DYRK2-depleted cells compared with control cells. In xenograft model, everolimus treatment significantly inhibited tumor growth compared with vehicle or eribulin treatment. In clinical analysis, patients with low DYRK2 expression acquired longer treatment period and had higher clinical benefit rate than those with high DYRK2 expression (171 vs 82 days; P < 0.05 and 50% vs 12.5%, respectively). We further investigated the underlying mechanism by which DYRK2 regulates mTORC1 pathway. The ectopic expression of DYRK2 promoted phosphorylation of Thr631 for the ubiquitination and degradation of mTOR. DYRK2 expression levels may thus predict clinical responses to everolimus.

Long-Term Follow-Up of Node-Negative Breast Cancer Patients Evaluated via Sentinel Node Biopsy After Neoadjuvant Chemotherapy.

BACKGROUND: Sentinel node biopsy (SNB) is used to accurately assess axillary lymph node status in patients with node-negative breast cancer. However, its use after neoadjuvant chemotherapy (NAC) is controversial. We retrospectively assessed the usefulness of SNB after NAC by comparing axillary recurrence rates and other parameters in patients with clinically node-negative breast cancer who underwent SNB after NAC or without NAC. PATIENTS AND METHODS: At our hospital, 1179 patients with clinically node-negative breast cancer underwent SNB from April 2007 to December 2013. The clinicopathological and survival data of patients who underwent SNB after NAC (the NAC group) and those who underwent SNB without NAC (the control group) were compared. Patients with a metastatic sentinel node underwent axillary lymph node dissection. RESULTS: The number of patients in the NAC and control groups was 183 (15.5%) and 996 (84.5%), respectively. At diagnosis, tumors were significantly larger in the NAC group (P < .0001). Sentinel nodes were identified in almost all patients in both groups (99.5% in the NAC group vs. 99.8% in the control group). They were nonmetastatic in 147 (80.8%) patients in the NAC group and 849 (85.5%) patients in the control group. At the median follow-up time of 51.1 months, 6 patients (0.6%) in the control group had axillary lymph node recurrence compared with no patients in the NAC group. CONCLUSION: SNB after NAC was as accurate as SNB without NAC in patients with clinically node-negative breast cancer. Axillary recurrence-free survival rates were excellent regardless of whether NAC was performed before SNB.

Breast cancer screening and the changing population pyramid of Japan.

BACKGROUND: Breast cancer has been the most prevalent cancer in Japan since the 1990s. The mortality from breast cancer is increasing in Japan, whereas in other industrialized countries it has been decreasing since 1990. On the other hand, Japan faces unparalleled growth in its aging population. The aim of this study was to report the mammography screening among Japanese women and the related upcoming changes in the population pyramid of Japan. DATA SOURCES AND METHODS: The reference data for our study were obtained from the Center for Cancer Control and Information Services, Japan Ministry of Internal Affairs and Communications, Ministry of Health, Labour and Welfare, the Japanese Cancer Society, and the National Institute of Population and Social Security. The survey data were obtained from breast cancer and mammography screenings in the Tokyo Prefecture in 2008. The following parameters were analyzed: annual breast cancer incidence, current screening rates, average life-span, and predicted demographic statistics. RESULTS: Our results showed that breast cancer incidence and mortality have been increasing annually in Japan. The average age of breast cancer patients increased to 58.40 years in 2010. The incidence of breast cancer in women aged 65 years and older increased from 25.3 to 32.9 % in the last 10 years and is expected to continue to increase in the future. The check-up rate was 16.0-20.0 % for women aged 65-74 years and 43.0-46.0 % for women aged 40-54 years. According to our questionnaire survey, concerns about breast cancer and mammography screening were high in the young and low in the elderly women. The Japanese population aged 65 years and older was 30,740 (24.1 %) in 2012 and is estimated to increase by 40 % over the next 20 years despite Japan's declining population size. CONCLUSION: Breast cancer incidence has increased in Japan, even among patients aged 65 years and older. Breast cancer has become increasingly prevalent in older Japanese women. As the population pyramid of Japan changes, women aged 65 years and older, who think that there is no longer need to receive mammography screening and are not educated regarding self-examinations, should be encouraged to receive regular check-ups for breast cancer.

DYRK2 controls the epithelial-mesenchymal transition in breast cancer by degrading Snail.

The epithelial-mesenchymal transition (EMT) plays a fundamental role in the early stages of breast cancer invasion. Snail, a zinc finger transcriptional repressor, is an important regulator of EMT. Snail is phosphorylated by GSK3ß and is subsequently degraded by ßTrCP-mediated ubiquitination. We identified an additional kinase, DYRK2, that regulates Snail stability. Knockdown of DYRK2 promoted EMT and cancer invasion in vitro and in vivo. Consistent with these results, DYRK2 was found to be down-regulated in human breast cancer tissue. Patients with low DYRK2-expressing tumors had a worse outcome than those with high DYRK2-expressing tumors. These findings revealed that DYRK2 regulates cancer invasion and metastasis by degrading Snail.

DYRK2 priming phosphorylation of c-Jun and c-Myc modulates cell cycle progression in human cancer cells.

Dysregulation of the G(1)/S transition in the cell cycle contributes to tumor development. The oncogenic transcription factors c-Jun and c-Myc are indispensable regulators at this transition, and their aberrant expression is associated with many malignancies. Degradation of c-Jun/c-Myc is a critical process for the G(1)/S transition, which is initiated upon phosphorylation by glycogen synthase kinase 3 ß (GSK3ß). However, a specific kinase or kinases responsible for priming phosphorylation events that precede this GSK3ß modification has not been definitively identified. Here, we found that the dual-specificity tyrosine phosphorylation-regulated kinase DYRK2 functions as a priming kinase of c-Jun and c-Myc. Knockdown of DYRK2 in human cancer cells shortened the G(1) phase and accelerated cell proliferation due to escape of c-Jun and c-Myc from ubiquitination-mediated degradation. In concert with these results, silencing DYRK2 increased cell proliferation in human cancer cells, and this promotion was completely impeded by codeprivation of c-Jun or c-Myc in vivo. We also found marked attenuation of DYRK2 expression in multiple human tumor samples. Downregulation of DYRK2 correlated with high levels of unphosphorylated c-Jun and c-Myc and, importantly, with invasiveness of human breast cancers. These results reveal that DYRK2 regulates tumor progression through modulation of c-Jun and c-Myc.