Kinase-independent role of cyclin D1 in chromosomal instability and mammary tumorigenesis.

Mathew C Casimiro,Gabriele Di Sante,Zuoren Yu,Chenguang Wang,Andrew Arnold,Michael P Lisanti,Marco Crosariol,Sankar Addya,Zhiping Li,Erik S Knudsen,Paolo Fortina,Alexandros Papanikolaou,Adam Ertel,Aydin Tozeren,William Dampier,Elizabeth A Saria,Emanuele Loro,Robert D Cardiff,Richard G Pestell

doi:10.18632/oncotarget.3267

Mathew C Casimiro, Gabriele Di Sante + Show 17 more

Open Access

https://doi.org/10.18632/oncotarget.3267

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Abstract

Cyclin D1 is an important molecular driver of human breast cancer but better understanding of its oncogenic mechanisms is needed, especially to enhance efforts in targeted therapeutics. Currently, pharmaceutical initiatives to inhibit cyclin D1 are focused on the catalytic component since the transforming capacity is thought to reside in the cyclin D1/CDK activity. We initiated the following study to directly test the oncogenic potential of catalytically inactive cyclin D1 in an in vivo mouse model that is relevant to breast cancer. Herein, transduction of cyclin D1(-/-) mouse embryonic fibroblasts (MEFs) with the kinase dead KE mutant of cyclin D1 led to aneuploidy, abnormalities in mitotic spindle formation, autosome amplification, and chromosomal instability (CIN) by gene expression profiling. Acute transgenic expression of either cyclin D1(WT) or cyclin D1(KE) in the mammary gland was sufficient to induce a high CIN score within 7 days. Sustained expression of cyclin D1(KE) induced mammary adenocarcinoma with similar kinetics to that of the wild-type cyclin D1. ChIP-Seq studies demonstrated recruitment of cyclin D1(WT) and cyclin D1(KE) to the genes governing CIN. We conclude that the CDK-activating function of cyclin D1 is not necessary to induce either chromosomal instability or mammary tumorigenesis.

Highlights

Activation of the cyclin D1 oncogene, often by amplification or rearrangement, is a major driver of multiple types of human tumors including breast and squamous cell cancers, B-cell lymphoma, myeloma, nd parathyroid adenoma [1, 2]
Recent studies using Spectral karyotyping (SKY) analysis and gene expression profiling have demonstrated that re-expression of cyclin D1WT in cyclin D1-deficient cells results in chromosomal instability (CIN) [22]
In order to test the kinase-independent function of cyclin D1 in aneuploidy and tumorigenesis, we utilized a cyclin D1 point mutant, cyclin D1 K112E, which contains a lysine to glutamine substitution at amino acid position 112 (Supplementary Figure S1A)

Summary

INTRODUCTION

Activation of the cyclin D1 oncogene, often by amplification or rearrangement, is a major driver of multiple types of human tumors including breast and squamous cell cancers, B-cell lymphoma, myeloma, nd parathyroid adenoma [1, 2]. The cyclin D1 gene is amplified or overexpressed in up to half of human breast cancers and its mammary-targeted overexpression induces mammary tumorigenesis in mice [3]. Cyclin D1 encodes the regulatory subunit of the cyclin-dependent kinase (CDK4/6) holoenzyme. Cyclin D1 regulates a pool of mammary progenitor cells (parity-identified mammary cells: PI-MEC) is kinase-dependent. Cyclin D1 functions as a transcriptional regulator, usually in a CDK4-independent manner [8]. In view of recent findings that cyclin D1 is capable of inducing aneuploidy and prior findings that the cyclin D1 kinase function appears to be dispensable for several activities, and because of the crucial implications of this mechanism for cancer therapeutics, we determined the importance of cyclin D1 kinase function in the induction of CIN and mammary tumorigenesis in vivo

RESULTS

DISCUSSION

MATERIALS AND METHODS