Activation of the Anaphase Promoting Complex Restores Impaired Mitotic Progression and Chemosensitivity in Multiple Drug-Resistant Human Breast Cancer

Mathew Lubachowski; Cordell VanGenderen; Sarah Valentine; Zach Belak; Gerald Floyd Davies; Terra Gayle Arnason; Troy Anthony Alan Harkness

doi:10.3390/cancers16091755

Activation of the Anaphase Promoting Complex Restores Impaired Mitotic Progression and Chemosensitivity in Multiple Drug-Resistant Human Breast Cancer

Cancers (Basel). 2024 Apr 30;16(9):1755. doi: 10.3390/cancers16091755.

Authors

Mathew Lubachowski^{1

2}, Cordell VanGenderen³, Sarah Valentine³, Zach Belak¹, Gerald Floyd Davies¹, Terra Gayle Arnason^{3

4

5}, Troy Anthony Alan Harkness^{1

2

6}

Affiliations

¹ Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.
² Division of Geriatrics, Department of Medicine, University of Alberta, Edmonton, AB T6G 2S2, Canada.
³ Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.
⁴ Division of Endocrinology, Department of Medicine, University of Alberta, Edmonton, AB T6G 2S2, Canada.
⁵ Department of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.
⁶ 320 Heritage Medical Research Centre, University of Alberta, 11207-87 Ave NW, Edmonton, AB T6G 2S2, Canada.

Abstract

The development of multiple-drug-resistant (MDR) cancer all too often signals the need for toxic alternative therapy or palliative care. Our recent in vivo and in vitro studies using canine MDR lymphoma cancer cells demonstrate that the Anaphase Promoting Complex (APC) is impaired in MDR cells compared to normal canine control and drug-sensitive cancer cells. Here, we sought to establish whether this phenomena is a generalizable mechanism independent of species, malignancy type, or chemotherapy regime. To test the association of blunted APC activity with MDR cancer behavior, we used matched parental and MDR MCF7 human breast cancer cells, and a patient-derived xenograft (PDX) model of human triple-negative breast cancer. We show that APC activating mechanisms, such as APC subunit 1 (APC1) phosphorylation and CDC27/CDC20 protein associations, are reduced in MCF7 MDR cells when compared to chemo-sensitive matched cell lines. Consistent with impaired APC function in MDR cells, APC substrate proteins failed to be effectively degraded. Similar to our previous observations in canine MDR lymphoma cells, chemical activation of the APC using Mad2 Inhibitor-1 (M2I-1) in MCF7 MDR cells enhanced APC substrate degradation and resensitized MDR cells in vitro to the cytotoxic effects of the alkylating chemotherapeutic agent, doxorubicin (DOX). Using cell cycle arrest/release experiments, we show that mitosis is delayed in MDR cells with elevated substrate levels. When pretreated with M2I-1, MDR cells progress through mitosis at a faster rate that coincides with reduced levels of APC substrates. In our PDX model, mice growing a clinically MDR human triple-negative breast cancer tumor show significantly reduced tumor growth when treated with M2I-1, with evidence of increased DNA damage and apoptosis. Thus, our results strongly support the hypothesis that APC impairment is a driver of aggressive tumor development and that targeting the APC for activation has the potential for meaningful clinical benefits in treating recurrent cases of MDR malignancy.

Keywords: Anaphase Promoting Complex; PDX mouse model; cell culture; multiple-drug-resistant breast cancer.

Grants and funding

702368/Canadian Cancer Society