Abstract P4-08-04: Downregulation of DYRK2 contributes to tumor cell proliferation by enhancing CDK14 expression in breast cancer
Authors: Imawari Yoshimi , Mimoto Rei , Yamaguchi Noriko , Kamio Makiko , Nogi Hiroko , Uchida Ken , Takeyama Hiroshi , Yoshida Kiyotsugu 
Published: March 2020

Introduction: 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.

The aim of this study is to clarify whether DYRK2 suppresses the proliferation of breast cancer cells through CDK14 expression.

Methods: Cell lines: We established stable DYRK2-depleted cells. MCF-7 cells were transfected with pSuper-puro vector (pSuper control) or pSuper-puro DYRK2 shRNAs (shDYRK2) along with puromycin to isolate stable cell lines.

We generated stable DYRK2-overexpressing MDA-MB-231 cells using GFP-DYRK2 (GFP-DYRK2 cells). A GFP vector was transfected as a vehicle control (GFP control cells) with G418 to isolate stable cell lines.

Moreover, we established both stable DYRK2- and CDK14-depleted cells. The shDYRK2 cells were transfected with the pSuper-neo vector (shDYRK2-pSuper control) or pSuper-neo CDK14 shRNAs (shDYRK2-shCDK14). The pSuper control cells were transfected with the pSuper-neo vector (pSuper control-pSuper control cells) as a vehicle control with puromycin and G418 to isolate stable cell lines.

These manipulated cells were compared with the control cells by various assays.

Immunohistological staining: Sixty samples from surgically treated breast cancer patients were obtained from the Surgery Department at the Jikei University Hospital between 2001 and 2002. The Jikei University School of Medicine Ethics Review Committee approved the study protocol, and informed consent was obtained.

Results: We analyzed cancer cell proliferation by MTS and colony formation assays. We investigated the effects of CDK14 in DYRK2-depleted cells in a breast tumor xenograft model. We found that reduced DYRK2 expression increased CDK14 expression to promote cancer cell proliferation in vitro and tumorigenicity in vivo.

We further identified androgen receptor (AR) as a candidate of DYRK2-dependent transcription factors to control CDK14. Real-time RT-PCR and western blotting revealed that inhibition of AR activity using an AR inhibitor MDV3100 decreased both mRNA and protein levels of CDK14 in shDYRK2 and GFP control cells. In contrast, knocking down DYRK2 induced AR transcription activity in MCF-7 cells. shDYRK2 cells were more sensitive to MDV3100 compared with pSuper control cells.

Immunohistological staining of sixty samples from surgically treated breast cancer patients showed an inverse correlation between DYRK2 and CDK14 expression.

Conclusion: These findings demonstrate that reduced DYRK2 expression in breast cancer promotes tumor cell proliferation by modulating CDK14 expression via AR.

Citation Format: Yoshimi Imawari, Rei Mimoto, Noriko Yamaguchi, Makiko Kamio, Hiroko Nogi, Ken Uchida, Hiroshi Takeyama, Kiyotsugu Yoshida. Downregulation of DYRK2 contributes to tumor cell proliferation by enhancing CDK14 expression in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-08-04.