KDM2B promotes cell viability by enhancing DNA damage response in canine hemangiosarcoma

Abstract

Epigenetic regulators have been implicated in tumorigenesis of many types of cancer; however, their roles in endothelial cell cancers such as canine hemangiosarcoma (HSA) have not been studied. In this study, we found that lysine-specific demethylase 2B (Kdm2b) was highly expressed in HSA cell lines compared to normal canine endothelial cells. Silencing of Kdm2b in HSA cells resulted to increased cell death in vitro compared to the scramble control by inducing apoptosis through the inactivation of the DNA repair pathways and accumulation of DNA damage. Similarly, doxycycline-induced Kdm2b silencing in tumor xenografts resulted to decreased tumor sizes compared to the scramble control. Furthermore, Kdm2b was also highly expressed in clinical cases of HSA, and its expression levels was higher than in hemangioma, a benign counterpart of HSA. Based on these results, we hypothesized that pharmacological Kdm2b inhibition can also induce HSA cell death and can be used as an alternative treatment for HSA. We treated HSA cells with GSK-J4, a histone demethylase inhibitor, and found that GSK-J4 treatment also induced apoptosis and cell death. On top of that, GSK-J4 treatment in HSA tumor-bearing mice decreased tumor sizes without any obvious side-effects. In this study, we demonstrated that Kdm2b acts as an oncogene in HSA by enhancing DNA damage response and can be used as a biomarker to differentiate HSA from hemangioma. Moreover, we indicated that histone demethylase inhibitor GSK-J4 can be used as a therapeutic alternative to doxorubicin for HSA treatment.

Manipulating Histone Acetylation Leads to Adverse Effects in Hemangiosarcoma Cells

“…Haematoxylin and eosin staining was performed as previously described (Maharani et al, 2018). IHC analysis was performed as previously described (Gulay et al, 2021) with slight modifications. Antigen retrieval was performed in Tris-EDTA buffer (pH 9.0) in a microwave for 10 min.…”

“…ISOS-1, JuB2, JuB4, and Re12 were treated with DMSO or JQ1 for 24 h. ISOS-1 was treated with 10 μM JQ1, and other cell lines were treated with 5 μM JQ1. Cell cycle analysis was performed as previously described (Gulay et al, 2021).…”

“…Protein extraction and western blotting were performed as previously described (Gulay et al, 2021). Antibodies used in this study are listed in Table S2.…”

“…Primers and samples were prepared as described previously (Gulay et al, 2021). RT-qPCR was performed using the primers listed in Table S3.…”

“…Regarding epigenetics in HSA, KDM2B—a histone demethylase—has recently been found to promote tumour viability (Gulay et al, 2021). However, the role of histone acetylation in HSA remains unknown.…”