CHFR and Paclitaxel Sensitivity of Ovarian Cancer.

Amy K Bruzek,Karen S Flatten,Krista M Goergen,Melissa C Larson,Andrea E Wahner Hendrickson,Hunter J Atkinson ,Ann L Oberg,S John Weroha ,Rachel M Hurley ,Wilma L Lingle,Vivian Negron,Kevin Peterson ,Jill M Wagner,Kimberly R Kalli,Matthew J Maurer ,Thomas G Beito,Xiaonan Hou,Paula A Schneider,Scott H Kaufmann,Daniel W Visscher

doi:10.3390/cancers13236043

Abstract

Simple SummaryStudies in tissue culture cell lines have indicated that silencing of the mitotic regulator CHFR is associated with increased paclitaxel sensitivity. More recently, it has been suggested that a UBC13-DNMT1-CHFR pathway also modulates sensitivity of ovarian cancer to paclitaxel in the clinic. Here we have credentialed an anti-CHFR monoclonal antibody for immunohistochemistry and directly examined the association of CHFR expression with outcome of paclitaxel-containing ovarian cancer therapy. While CHFR levels were higher in high grade, high stage ovarian cancer, after correction for stage and debulking status there was no association between CHFR levels and progression-free survival in high grade serous ovarian cancer treated with surgery followed by platinum/taxane therapy. Moreover, there was no association between CHFR expression and response of patient-derived ovarian cancer xenografts treated with paclitaxel monotherapy. These studies indicate that CHFR varies among ovarian cancers but is unlikely to be an independent biomarker for poor response to taxanes.The poly(ADP-ribose) binding protein CHFR regulates cellular responses to mitotic stress. The deubiquitinase UBC13, which regulates CHFR levels, has been associated with better overall survival in paclitaxel-treated ovarian cancer. Despite the extensive use of taxanes in the treatment of ovarian cancer, little is known about expression of CHFR itself in this disease. In the present study, tissue microarrays containing ovarian carcinoma samples from 417 women who underwent initial surgical debulking were stained with anti-CHFR antibody and scored in a blinded fashion. CHFR levels, expressed as a modified H-score, were examined for association with histology, grade, time to progression (TTP) and overall survival (OS). In addition, patient-derived xenografts from 69 ovarian carcinoma patients were examined for CHFR expression and sensitivity to paclitaxel monotherapy. In clinical ovarian cancer specimens, CHFR expression was positively associated with serous histology (p = 0.0048), higher grade (p = 0.000014) and higher stage (p = 0.016). After correction for stage and debulking, there was no significant association between CHFR staining and overall survival (p = 0.62) or time to progression (p = 0.91) in patients with high grade serous cancers treated with platinum/taxane chemotherapy (N = 249). Likewise, no association between CHFR expression and paclitaxel sensitivity was observed in ovarian cancer PDXs treated with paclitaxel monotherapy. Accordingly, differences in CHFR expression are unlikely to play a major role in paclitaxel sensitivity of high grade serous ovarian cancer.

Highlights

The Checkpoint with Forkhead-associated and RING finger domains (CHFR) protein is a cell cycle checkpoint component that, based on its frequent mutation [1]or methylationinduced silencing [2,3], is thought to be a tumor suppressor [4,5]
We describe the generation and credentialing of an anti-CHFR antibody generated for immunohistochemistry (IHC), use this antibody to examine the relationship between CHFR expression and treatment outcome in newly diagnosed epithelial ovarian cancers
Based on previous studies showing an association between CHFR protein levels and taxane resistance in various cancers both in vitro [16,21,27,37] and in the clinical setting [26], we examined the relationship between CHFR expression and clinical outcome in patients with epithelial ovarian cancer

Summary

Introduction

The Checkpoint with Forkhead-associated and RING finger domains (CHFR) protein is a cell cycle checkpoint component that, based on its frequent mutation [1]or methylationinduced silencing [2,3], is thought to be a tumor suppressor [4,5]. By downregulating Polo-like kinase 1 (PLK1) and/or Aurora A, CHFR is thought to diminish cyclin dependent kinase 1 activity and delay entry into mitosis. Studies in isogenic cell lines have established a role for CHFR in sensitivity to spindle poisons. CHFR deficient cells fail to arrest in late G2 in response to these agents [16,19] and instead enter mitosis, arrest because of spindle assembly checkpoint activation, and acquire lethal damage that leads to apoptosis upon checkpoint adaptation [16,19,20]. Cells with CHFR loss are more sensitive to spindle poisons such as paclitaxel [16,21]

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