Histone Deacetylase Inhibitors and Microtubule Inhibitors Induce Apoptosis in Feline Luminal Mammary Carcinoma Cells.

Filipe Almeida,Fernando Ferreira,Jorge Correia,Andreia Gameiro

doi:10.3390/ani11020502

Abstract

Simple SummaryFeline mammary tumors (FMT) are very common in cats, associated with very aggressive behavior and a short life expectancy. Surgery is the most used treatment but tumor recurrence is common. Currently, available therapies are insufficient, therefore, new molecular targets are needed to develop more efficient therapeutics. Histone deacetylases inhibitors (HDACis) have been developed to target tumor cells, by disrupting gene expression and leading to cell death. Microtubules inhibitors (MTIs) have also been a focus of research, to target polymerization of microtubules, and consequently disturbing the cytoskeleton and leading to cell cycle arrest and apoptosis. However, there are few studies on the use of HDACis and MTIs in cats. In this study, we addressed if these two drug classes could be used as new therapeutic options in FMTs. All HDACis and MTIs exhibited suitable and dose-dependent antitumor effects in FMT cell lines. Immunoblot analysis confirmed that the mode of action of HDACis is conserved in feline mammary tumor cell lines. Finally, flow cytometry showed that exposure with HDACis and MTIs lead to the induction of cellular apoptosis. In summary, HDACis and MTIs possess antitumor properties suggesting further studies on their use in the treatment of feline mammary tumors.Feline mammary carcinoma (FMC) is the third most common type of neoplasia in cats, sharing similar epidemiological features with human breast cancer. In humans, histone deacetylases (HDACs) play an important role in the regulation of gene expression, with HDAC inhibitors (HDACis) disrupting gene expression and leading to cell death. In parallel, microtubules inhibitors (MTIs) interfere with the polymerization of microtubules, leading to cell cycle arrest and apoptosis. Although HDACis and MTIs are used in human cancer patients, in cats, data is scarce. In this study, we evaluated the antitumor properties of six HDACis (CI-994, panobinostat, SAHA, SBHA, scriptaid, and trichostatin A) and four MTIs (colchicine, nocodazole, paclitaxel, and vinblastine) using three FMC cell lines (CAT-MT, FMCp, and FMCm), and compared with the human breast cancer cell line (SK-BR-3). HDACis and MTIs exhibited dose-dependent antitumor effects in FMC cell lines, and for all inhibitors, the IC50 values were determined, with one feline cell line showing reduced susceptibility (FMCm). Immunoblot analysis confirmed an increase in the acetylation status of core histone protein HDAC3 and flow cytometry showed that HDACis and MTIs lead to cellular apoptosis. Overall, our study uncovers HDACis and MTIs as promising anti-cancer agents to treat FMCs.

Highlights

While the CAT-MT cell line derives from a highly malignant tubular adenocarcinoma [16], the FMCp and FMCm cell lines were originated from an adenocarcinoma, collected from a primary and a lymph node metastatic lesion, respectively, from the same diseased cat [17]
The human SK-BR-3 cell line was selected for comparison purposes and derives from an adenocarcinoma collected from a metastatic site [18]
The expressions of the estrogen receptor (ER), progesterone receptor (PR), feline and human epidermal growth factor receptor type 2 (HER2), cytokeratin 5/6 (CK 5/6), and proliferation index (Ki-67) were evaluated in all cell lines and the results obtained are depicted in Figure 1 and Table 1

Summary

Introduction

In addition to the clinicopathological characteristics, the molecular immunophenotyping of feline mammary carcinomas (FMCs) is similar to what is described for human breast creativecommons.org/licenses/by/ 4.0/). Cats share a common environment with humans and exposure to environmental contributors to the development of cancer is similar. Due to these resemblances, the domestic cat has been proposed as a model for comparative oncology [1,3,4,5]. FMCs are predominantly malignant with metastases occurring in most cases, resulting in a poor prognosis and associated with a short life expectancy [6]. Surgery is the most widely used treatment for mammary carcinoma in cats, either alone or in association with chemotherapy. New molecular targets are needed to develop more efficient therapeutics

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