Overexpression of Replication-Dependent Histone Signifies a Subset of Dedifferentiated Liposarcoma with Increased Aggressiveness.

Yongjin Yoo,Sang-Yoon Park,Jae Berm Park,Sung Wook Seo,Sungjoo Kim,Kyo Won Lee,Eun Byeol Jo,Yoon-La Choi,Sangmoon Lee,Minji Choi,Youngha Lee,Jae-Young Um,Murim Choi,Seok-Geun Lee,Cho-Rong Lee,Doopyo Hong

doi:10.3390/cancers13133122

Abstract

Simple SummaryAlthough the genetic event that initiates liposarcoma is relatively well studied, understanding how the tumor progresses and displays differential severities will shed new insights into the diagnosis and prognosis determination of patients with liposarcoma. We analyzed the genome and transcriptome of liposarcoma samples and found that the overexpression of the histone gene cluster is an important determinant for dedifferentiated liposarcoma in predicting genome instability and cell proliferation. The overexpression of histone genes was caused by increased HMGA2 with amplification of chromosome 12q13-14. This dedifferentiated liposarcoma-specific genetic signature may serve as a biomarker for prognosis prediction.Liposarcoma (LPS) is an adult soft tissue malignancy that arises from fat tissue, where well-differentiated (WD) and dedifferentiated (DD) forms are the most common. DDLPS represents the progression of WDLPS into a more aggressive high-grade and metastatic form. Although a few DNA copy-number amplifications are known to be specifically found in WD- or DDLPS, systematic genetic differences that signify subtype determination between WDLPS and DDLPS remain unclear. Here, we profiled the genome and transcriptome of 38 LPS tumors to uncover the genetic signatures of subtype differences. Replication-dependent histone (RD-HIST) mRNAs were highly elevated and their regulation was disrupted in a subset of DDLPS, increasing cellular histone molecule levels, as measured using RNA-seq (the averaged fold change of 53 RD-HIST genes between the DD and WD samples was 10.9) and immunohistochemistry. The change was not observed in normal tissues. Integrated whole-exome sequencing, RNA-seq, and methylation analyses revealed that the overexpressed HMGA2 (the fold change between DD and WD samples was 7.3) was responsible for the increased RD-HIST level, leading to aberrant cell proliferation. Therefore, HMGA2-mediated elevation of RD-HISTs were crucial events in determining the aggressiveness of DDLPS, which may serve as a biomarker for prognosis prediction for liposarcoma patients.

Highlights

Liposarcomas (LPSs), which are malignant tumors of adipocyte origin, are the most common type of soft tissue sarcoma [1,2]
We subsequently identify a signal cascade that progresses differentiated LPS (DDLPS) toward further malignancy through increased cell proliferation and Replication-dependent histone (RD-HIST) overexpression
Primary surgical and core biopsy sarcoma tumor tissues were transported from the operating room and were stored in cold Dulbecco’s Modified Eagle Medium (DMEM) at −80 ◦C

Summary

Introduction

Liposarcomas (LPSs), which are malignant tumors of adipocyte origin, are the most common type of soft tissue sarcoma [1,2]. Among the four main subtypes, well-differentiated LPS (WDLPS) and de-differentiated LPS (DDLPS) constitute the majority [2,3]. WDLPS still possesses adipocyte characteristics, whereas DDLPS loses them and de-differentiates into actively dividing cells [2,4]. WDLPS and DDLPS often coexist in a patient, but many are discovered isolated, suggesting variable initiation and progression mechanisms [2]. DDLPS typically displays more aggressive clinical features with increased recurrences (~40%) and metastasis (20–30% to the lungs) [2]. Given that they are mostly radio- and chemoinsensitive and have variable immunosensitivity, LPS requires new treatment methods

Methods

Results

Conclusion