Yoshimi Imawari

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.

Retrospective Comparison of Non-Skin-Sparing Mastectomy and Skin-Sparing Mastectomy with Immediate Breast Reconstruction

Background. We compared Skin-sparing mastectomy (SSM) with immediate breast reconstruction and Non-skin-sparing mastectomy (NSSM), various types of incision in SSM. Method. Records of 202 consecutive breast cancer patients were reviewed retrospectively. Also in the SSM, three types of skin incision were used. Type A was a periareolar incision with a lateral extension, type B was a periareolar incision and axillary incision, and type C included straight incisions, a small elliptical incision (base line of nipple) within areolar complex and axillary incision. Results. Seventy-three SSMs and 129 NSSMs were performed. The mean follow-up was 30.0 (SSM) and 41.1 (NSSM) months. Respective values for the two groups were: mean age 47.0 and 57; seven-year cumulative local disease-free survival 92.1% and 95.2%; post operative skin necrosis 4.1% and 3.1%. In the SSM, average areolar diameter in type A & B was 35.4 mm, 43.0 mm in type C and postoperative nipple-areolar plasty was performed 61% in type A & B, 17% in type C, respectively. Conclusion. SSM for early breast cancer is associated with low morbidity and oncological safety that are as good as those of NSSM. Also in SSM, Type C is far superior as regards cost and cosmetic outcomes.

Impairment of DYRK2 augments stem-like traits by promoting KLF4 expression in breast cancer

Whereas accumulating studies have supported the cancer stem cell theory, a specific therapy targeting a cancer stem cell subpopulation has not been established. Here, we show that dual-specificity tyrosine phosphorylation-kinase 2 (DYRK2) is a novel negative regulator for formation of breast cancer stem cells. Downregulation of DYRK2 promotes cancer stem-like traits in vitro, tumourigenesis in vivo and the proportion of the cancer stem cell population in human breast cancer tissues. We found that Krupple-like factor 4 (KLF4) serves as a key mediator of DYRK2’s control over the cancer stem phenotype. Reduced DYRK2 expression increases KLF4 expression, which induces cancer stem-like properties. We identified androgen receptor (AR) as a transcription factor binding to the KLF4 promoter region; this process is dependent on DYRK2 kinase activity. Our findings delineate a mechanism of cancer stem cell regulation by the DYRK2–AR–KLF4 axis in breast cancer. Targeting of this pathway may be a promising strategy against breast cancer stem cells.

An extracellular matrix molecule, secreted by the epithelial-mesenchymal transition is associated with lymph node metastasis of thyroid papillary carcinoma.

Background: Papillary thyroid carcinoma often has lymph node metastasis, compared with follicular thyroid carcinoma. The study showed that epithelial-mesenchymal transition occurs in carcinoma cells during the first stage of metastasis, where some extracellular matrix molecules are secreted in large quantities. Sialic acid carried by fibronectin as the antigen of the monoclonal antibody (MoAb) JT-95, was detected in 90% of papillary thyroid carcinoma cases, and in a few follicular thyroid carcinomas, in the extracellular matrix of thyroid carcinoma cells. Objectives: The current study was conducted to investigate the association between increasing the number of extracellular matrix molecules, fibronectin, and lymph node metastasis. We also co-cultured a thyroid carcinoma cell line and lymphocyte cell line, with and without MoAb JT-95, in order to investigate the mechanism of cell to cell interaction. Patients and Methods: Immunostaining with JT-95 was performed in 45 papillary thyroid carcinoma cases, and 20 follicular type tumors, to investigate the association between the quantity of fibronectin expression and the frequency of lymph node metastasis. The thyroid carcinoma cell line (SW1736), which secreted fibronectin, and the B cell-lymphoma cell line (Daudi), which held integrin on the cell surface, were co-cultured to observe the adhesion of cells to each other. The SW1736 cell line, pretreated with JT-95, was also co-cultured with the Daudi cell line. Results: There were 39 cases with lymph node metastasis in 59 malignant tumors, and 0 cases in 6 benign follicular type tumors. The staining scores by JT-95 of the 39 tumors with lymph node metastasis were 5+ in eight cases and 6+ in 31 cases. On the other hand, the scores of 20 malignant tumors without lymph node metastasis were < 4+ in all of the cases. In the co-cultured assay, numerous adhesions were observed between the SW1736 and Daudi cells. In contrast, the inhibition of adherences was observed in proportion to the concentrations of JT-95. Conclusions: Increased fibronectin expression in thyroid malignancies is correlated with lymph node metastasis.

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.

Abstract P5-07-07: DYRK2 contributes to the generation of breast cancer stem cells through KLF4

Cancer stem cells (CSCs) have been defined by the potential to self-renew and to differentiate. CSCs pose a major hurdle in the treatment of cancer. However, the mechanisms by which cells acquire CSC properties such as drug resistance remain unclear. Dual-specificity tyrosine-regulated kinase 2 (DYRK2) is a protein kinase that phosphorylates its substrates on serine/threonine. Initially, we found that DYRK2 phosphorylates p53 at Ser 46 to regulate apoptotic cell death in response to DNA damage. Recently, we have shown that DYRK2 controls Snail degradation in breast cancer and ovarian serous adenocarcinoma. We also found that knockdown of DYRK2 in luminal-type breast cancer MCF-7 cells increased the cancer stem cell population. Kruppel-like factor 4 (KLF4) is one of the Yamanaka factors. It has been reported that pluripotent stem cells from mouse embryonic or adult fibroblasts are induced by introducing four factors, Oct3/4, Sox2, c-Myc, and Klf4. This finding led us to determine if KLF4 is indispensable for the maintenance of CSCs. The aim of this study is to clarify whether DYRK2 regulates CSCs through KLF4 in breast cancer. Cell lines: MCF-7 (human mammary carcinoma: ATCC) cells were grown according to standard protocols. We established stable DYRK2-depleted cells. MCF-7 cells were transfected with pSuper-puro vector (pSuper control) or pSuper-puro DYRK2 shRNAs (shDYRK2) with puromycin to isolate stable cell lines. In turn, we established both stable DYRK2- and KLF4-depleted cells. shDYRK2 cells were transfected with pSuper-neo vector (pSuper-neo control) or pSuper-neo KLF4 shRNAs (shKLF4) with puromycin and G418. Knockdown of DYRK2 or KLF4 was confirmed by real-time RT-PCR and immunoblotting. The depleted cells were compared with the control cells using real-time RT-PCR, immunoblotting, flow cytometric analysis, mammosphere assay, xenograft models and immunohistological staining. We analyzed the population of breast cancer stem cells by flow cytometric analysis and in vitro mammosphere assay. The results showed that knockdown of DYRK2 was associated with the increase of CD44+/CD24- cells. While pSuper control cells formed mammospheres, they did in a lesser extent compared to shDYRK2 cells. In real-time RT-PCR and immunoblotting analysis, stable DYRK2 depletion in MCF-7 cells induced KLF4 accumulation. We then investigated the effect of KLF4 on stemness by flow cytometric analysis and in vitro mammosphere assay. The results showed that knockdown of KLF4 in shDYRK2 cells reduced the proportion of CD44+/CD24- cells. Whereas shDYRK2/shKLF4 cells formed mammospheres, they did in a lesser extent compared to shDYRK2/pSuper-neo control cells. Moreover, the scale of the mammospheres formed in shDYRK2/shKLF4 cells was significantly smaller, as compared with that in shDYRK2/pSuper-neo control cells. In xenograft models, the loss of KLF4 protein expression significantly decreased tumor formation. Immunohistological staining of fifty-nine samples from surgically treated breast cancer patients showed an inverse correlation between DYRK2 and KLF4 expression. These findings revealed that DYRK2 contributes to the generation of breast cancer stem cells through KLF4. Citation Format: Imawari Y, Mimoto RK, Yamaguchi N, Kamio M, Kato K, Nogi H, Toriumi Y, Uchida K, Takeyama H, Yoshida K. DYRK2 contributes to the generation of breast cancer stem cells through KLF4 [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-07-07.

Abstract P2-06-14: Clinical relevance and biological properties of oligometastatic breast cancer in lung; prognostic impact of CD44+/CD24−/low cells

Background: Metastatic breast cancer is a systemic disease. Our aim was to evaluate the clinical outcomes of pulmonary metastasectomy of recurrent breast tumors and to identify possible prognostic factors. Methods: We reviewed data from a registry of patients with lung metastases from breast tumors who received pulmonary metastasectomy in Jikei University Hospital between 2004 and 2011. We analyzed prognostic factors for overall survival (OS) and progression free survival (PFS) after metastasectomy. We also investigated lung metastases for the prevalence of CD44+/CD24−/low tumor cells and evaluated their prognostic significance. Results: Among 17 patients with lung metastasis of breast tumors, 5-year OS and PFS were 72% and 36%, respectively. Better OS was observed among patients with oligometastatic breast cancer (OMBC). Patients with OMBC, estrogen receptor (ER) positive cells, and disease free intervals (DFI) of >8 years had better PFS. The average prevalence of CD44+/CD24−/low tumor cells in lung metastases of breast cancer was 21%, ranging from 0 to 90%. The presence of CD44+/CD24−/low tumor cells influenced the progression after lung metastasectomy, with median PFS times of only 6 months in patients with high-prevalence of cancer-initiating cells. CD44+/CD24−/low cells with cancer-initiating properties were present in only 9% ± 12 of patients with OMBC but were found in 73% ± 21 of patients with non-OMBC. Conclusion: Pulmonary metastasectomy may be a treatment option for OMBC patients with lung metastases. Better prognosis of OMBC may be related to low levels of cancer-initiating cells. Citation Format: Rei Mimoto, Tadashi Kobayashi, Yoshimi Imawari, Makiko Kamio, Kumiko Kato, Hiroko Nogi, Yasuo Toriumi, Ken Uchida, Hiroshi Takeyama. Clinical relevance and biological properties of oligometastatic breast cancer in lung; prognostic impact of CD44+/CD24−/low cells [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-06-14.

Abstract P4-06-11: HER2 type DCIS acquires histological diversity by p53 mutation

[Introduction] It is widely known that breast cancer is a heterogeneous disease of various phenotypes and biological characteristics. Several studies have identified distinct subtypes of invasive ductal carcinoma by gene expression profiling or staining pattern of estrogen receptor (ER), progesterone receptor (PR), and HER2/neu protein. Ductal carcinoma in situ (DCIS) is a non-invasive form of breast cancer, and is thought to be the precursor of invasive breast cancer. One of the most well-known hypothesis shows that breast cancer occurs in a normal terminal duct lobular unit, and a histological continuity exists between the precursor and breast cancer. The aim of this analysis is to reveal how DCIS acquires histological diversity and progresses to invasive ductal carcinoma. We hypothesized that p53 gene mutation is responsible for this acquisition of histological diversity, and performed immunohistochemical analysis to pursue this hypothesis. [Material and methods] The participants of this study were taken from a database established by Jikei University School of Medicine. Between the period of April 2000 and April 2011, 84 cases of pure DCIS patients underwent operation. Patients were classified into 4 subtypes by a combination of hormone receptor (HR) status and HER2 status. The status of ER, PR, HER2, and p53 was determined by immunohistochemical staining. Tumors with Allred score above 2 ER / PR nuclear staining were classified as ER / PR positive. Tumors with HER2 membranous staining equivalent to 3+ intensity with Hercep test in more than 30% of the cells were scored as overexpression. p53 was defined as positive when nuclear staining was equal to or greater than 10%. We evaluated histological nuclear atypia to assess histological diversity of DCIS. When DCIS included different type of atypia cells more than 10%, we judged the histological diversity as positive. [Results] Patient characteristics are presented in table1. The classifications by the immunohistochemical subtype of DCIS are as follows: HR+/HER2- 62 cases (74%), HR+/HER2+ 5 cases (6%), HR-/HER2+ 13 cases (15%), HR-/HER2- 4 cases (5%). p53 expression in HR-/HER2+ and HR-/HER2- subtype was significantly higher than HR+/HER2- and HR+/HER2+ subtype (p The frequency of histological diversity by nuclear atypia was high in HR+/HER2- and HR-HER2+ subtype (p = 0.009). In HR-HER2+ subtype, p53 expression was associated with histological diversity (p = 0.021). But in HR-HER2+ subtype, there was no association with p53 expression and histological diversity. [Conclusion] This analysis demonstrates that HR-HER2+ subtype DCIS acquires histological diversity by p53 mutation. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-06-11.

Abstract P5-04-02: DYRK2 regulates breast cancer invasion via Snail/E-cadherin pathway

Introduction: Epithelial-Mesenchymal Transition (EMT) is characterized by the loss of cellular adhesion molecule E-cadherin, and plays a fundamental role during early steps of breast cancer invasion. An important regulator of E-cadherin expression is Snail, a zinc finger transcriptional repressor. Snail is posphorylated by GSK3β and then degraded by βTrCP mediated ubiquitination. Here we found another kinase, DYRK2, regulates the stability of Snail. Knockdown of DYRK2 promoted the EMT and cancer invasion both in vitro and in vivo experiments. Methods: Cell lines: MCF-7 cells were transfected with pSuper vector (pSuper control) and pSuper shRNA DYRK2 (shRNA-DYRK2) with G418 to isolate stable cell lines. Immunoblotting: Expression of pertinent molecular markers was determined by western blotting. RT-PCR: RNA was extracted using TRIsure and 500 ng of total RNA was amplified using Primer Script One Step RT-PCR Kit Ver.2. Invasion assay: Various cancer cell lines were seeded on the top of the upper chamber with serum free medium while the bottom chambers were filled with medium containing 10% FBS. In vivo metastasis assay: Cells in PBS were injected into the left ventricle of 7-week-old female nude mice. Metastases to distant organs were confirmed by IVIS2000. Immunohistochemistry: We acquired paraffin-embedded tissue sections from primary breast tumor cores and from Jikei University of Medicine. Immunohistochemistry for DYRK2 was performed. Results: In MCF-7 cells, knockdown of DYRK2 increased Snail in the protein level but not in mRNA level. Upon DYRK2 knockdown, MG132 treatment had no effect on additional increase in Snail. DYRK2 knockdown decreased Snail ubiquitination. Stable DYRK2 depletion led to Snail accumulation and E-cadherin abrogation. Fibroblast marker, Vimentin, emerged in DYRK2 depleted cells. For further analysis, we carried out invasion assays. The invasion potential in DYRK2-depleted cells was substantially higher than that in control cells. In xenograft model, we used nude mice received intracardial injections of pSuper control or shRNA-DYRK2 cells. 6 weeks after injections, a significant increase in bone and lung metastasis was observed in shRNA-DYRK2 group. The patients with tumors expressed low DYRK2 showed significantly poor prognosis. Conclusion: In breast cancer cells, Snail is phosphorylated by DYRK2 and then acquires the ability to be ubiquitinated. In the absence of DYRK2, Snail is unable to be degraded by ubiquitin-proteasome machinery. Accumulation of Snail promotes EMT and cancer invasion, so low expression of DYRK2 leads to poor prognosis in breast cancer. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-04-02.