Notch2 signal is required for the maintenance of canine hemangiosarcoma cancer stem cell-like cells

Machine learning determines stemness associated with simple and basal-like canine mammary carcinomas

Simple and complex carcinomas are the most common type of malignant Canine Mammary Tumors (CMTs), with simple carcinomas exhibiting aggressive behavior and poorer prognostic. Stemness is an ability associated with cancer initiation, malignancy, and therapeutic resistance, but is still few elucidated in canine mammary tumor subtypes. Here, we first validated, using CMT samples, a previously published canine one-class logistic regression machine learning algorithm (OCLR) to predict stemness (mRNAsi) in canine cancer cells. Then, using the canine mRNAsi, we observed that simple carcinomas exhibit higher stemness than complex carcinomas and other histological subtypes. Also, we confirmed that stemness is higher and associated with basal-like CMTs and with NMF2 metagene signature, a tumor-specific DNA-repair metagene signature. Using correlation analysis, we selected the top 50 genes correlated with higher stemness, and the top 50 genes correlated with lower stemness and further performed a gene set enrichment analysis to observe the biological processes enriched for these genes. Finally, we suggested two promise stemness-associated targets in CMTs, POLA2 and APEX1, especially in simple carcinomas. Thus, our work elucidates stemness as a potential mechanism behind the aggressiveness and development of canine mammary tumors, especially in simple carcinomas, describing evidence of a promising strategy to target this disease.

Current understanding of comparative pathology and prospective research approaches for canine hemangiosarcoma

Hemangiosarcoma (HSA) is a malignant tumor originating from endothelial cells. HSA typically develops in dogs, but is rare in other animals, including humans. Although surgery and chemotherapy are conventional treatments for HSA, neither treatment can significantly improve patient prognosis. To develop novel and effective therapeutics, a deeper understanding of HSA pathogenesis must be acquired. However, the limited research tools for HSA have been unable to make a breakthrough; therefore, it is crucial to widely utilize or establish novel research tools such as patient-derived xenograft models, organoids, and chicken embryo xenograft models. The pathogenesis of the human counterpart of HSA, angiosarcoma (AS), also remains incompletely understood, preventing the extrapolation of findings from humans to dogs, unlike other diseases. In this review, we summarize the clinicopathological and morphological features of HSA, and then we discuss the current understanding of the molecular pathology of HSA. Finally, we highlight promising research tools that may accelerate HSA basic research toward developing novel therapeutics. We also briefly summarize AS to help researchers comprehend HSA from the perspective of comparative pathology.

Differences in potential key genes and pathways between primary and radiation-associated angiosarcoma of the breast

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Angiosarcoma of the breast is a high-grade malignant soft tissue tumor, it can be divided into primary and secondary.

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The differences between primary and secondary angiosarcomas in terms of pathogenesis, clinical behavior, early diagnosis biomarkers, genetic abnormalities, and therapeutic targets remain to be fully elucidated.

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Due to its rarity, most of the current information relating to angiosarcoma is provided by case reports and single-institution retrospective cohort studies and the research with large-scale genomic studies published to date are very limited.

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We identified the differentially expressed genes (DEGs) between primary and second breast angiosarcomas and identified the hub genes as well as predicted novel biomarkers, pathways, and potential therapeutic targets for primary and secondary breast angiosarcomas.

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We aimed to identify novel biomarkers, pathways, and potential therapeutic targets for primary and secondary breast angiosarcomas to facilitate future research.

Background

Angiosarcoma of the breast is a high-grade malignant soft tissue tumor, it can be divided into primary and radiation-associated angiosarcoma(secondary). However, the differences between primary and secondary angiosarcomas in terms of pathogenesis, clinical behavior, early diagnosis biomarkers, genetic abnormalities, and therapeutic targets remain to be fully elucidated. At the same time, due to its rarity, most of current information relating to angiosarcoma is provided by case reports. Therefore, exploring the mechanisms of primary and secondary breast angiosarcoma have important value for the discovery of new biomarkers and research into potential therapeutic targets.

Methods

The differentially expressed genes (DEGs) between 36 cases of primary angiosarcoma and 54 cases of secondary angiosarcoma were screened. Then, the DEGs were used to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Then, a protein-protein interaction (PPI) network was constructed using the STRING database.

Results

A total of 18 DEGs were identified, of which 13 were upregulated and 5 were downregulated in secondary breast angiosarcoma. The GO enrichment analysis showed that the DEGs were most enriched in metabolism, energy pathways, and protein metabolism in biological processes. The enriched signaling pathways of DEGs were the transforming growth factor-β (TGF-β), Wnt, Hippo and PI3K-Akt signaling pathways. Then, the PPI network was conducted and hub genes were identified and they were involved in thyroid hormone, Hippo and other signaling pathways.

Conclusion

This study lay the foundation for the discovery of effective and reliable molecular biomarkers and essential therapeutic targets for these malignancies.

Suppression Of Aberrant Activation Of NF-κB Pathway In Drug-resistant Leukemia Stem Cells Contributes To Parthenolide-potentiated Reversal Of Drug Resistance In Leukemia

Although many drugs that targeted the specific features of leukemia stem cells (LSCs) have substantial application in the clinical treatment of leukemia, the LSCs relapsed and caused drug-resistant leukemia. Therefore, it is necessary to identify the unique features of LSCs in relapsing and drug-resistant leukemia and also to explore the drugs that directed at these features. Our clinical data have indicated that relapsed patients with acute myeloid leukemia have more abundant proportion of LSCs with enhanced breast cancer resistance protein (BCRP) and P-glycoprotein (P-gp) expression when compared to the untreated patients. The results showed that compared with LSCs derived from sensitive K562 cells, LSCs from drug-resistant K562/ADM cells have much higher chemotherapeutic resistance, and so we termed these cells as “drug-resistant LSCs”. Subsequently, aberrant activation of NF-κB pathway in drug-resistant LSCs was further using gene chip analysis. Also, parthenolide (PTL), which is a specific NF-κB inhibitor, effectively eliminated drug-resistant LSCs and enhanced the sensitivity of K562/ADM cells to doxorubicin-induced apoptosis by down-regulating NF-κB pathway-mediated P-gp expression. These findings make the research area of LSCs more abundant and provide a potential therapeutic strategy for the treatment of refractory and relapsed leukemia.

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

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 find that lysine-specific demethylase 2b (KDM2B) is highly expressed in HSA cell lines compared with normal canine endothelial cells. Silencing of KDM2B in HSA cells results in increased cell death in vitro compared with 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 results in decreased tumor sizes compared with the control. Furthermore, KDM2B is also highly expressed in clinical cases of HSA. We hypothesize that pharmacological KDM2B inhibition can also induce HSA cell death and can be used as an alternative treatment for HSA. We treat HSA cells with GSK-J4, a histone demethylase inhibitor, and find that GSK-J4 treatment also induces apoptosis and cell death. In addition, GSK-J4 treatment decreases tumor size. Therefore, we demonstrate that KDM2B acts as an oncogene in HSA by enhancing the DNA damage response. Moreover, we show that histone demethylase inhibitor GSK-J4 can be used as a therapeutic alternative to doxorubicin for HSA treatment.

Understanding of tumourigenesis in canine mammary tumours based on cancer stem cell research

Mammary tumours occur frequently in female dogs, where such tumours exhibit complexity when examined histologically. These tumours are composed not only of proliferative luminal epithelial cells, but also of myoepithelial cells and/or mesenchymal cells with cartilage and osseous tissues in a solitary mass. The origin of this complexed histogenesis remains speculative, but cancer stem cells (CSCs) are likely involved. CSCs possess self-renewing capacity, differentiation potential, high tumourigenicity in immunodeficient mice, and resistance to chemotherapy and radiation. These cells are at the apex of a hierarchy in cancer tissues and are involved in tumour initiation, recurrence, and metastasis. For these reasons, understanding the properties of CSCs is of paramount importance. Analysis of the characteristics of CSCs may contribute to the elucidation of the histogenesis underlying canine mammary tumours, formulation of novel CSC-targeted therapeutic strategies, and development of biomarkers for early diagnostic and prognostic applications. Here, we review research on CSCs in canine mammary tumours, focusing on: (1) identification and properties of CSCs; (2) hypotheses regarding hierarchal structures in simple type, complex type and mixed tumours of the canine mammary gland; and (3) current and prospective studies of CSC metabolism.

High drug efflux pump capacity and low DNA damage response induce doxorubicin resistance in canine hemangiosarcoma cell lines

Canine hemangiosarcoma (HSA) is an aggressive malignant endothelial tumor in dogs and characterized by poor prognosis because of its high invasiveness, high metastatic potential, and poor responsiveness to anti-cancer drugs. Although doxorubicin-based chemotherapy is regularly conducted after surgical treatment, its effects on survival rates are limited. Acquisition of drug resistance is one of the causes of this problem, but the underlying mechanisms remain unclear. In the present study, we aimed to identify the drug-resistance mechanism in canine HSA by establishing doxorubicin-resistant (DR) HSA cell lines. HSA cell lines were exposed to doxorubicin at gradually increasing concentrations. When the cells were able to grow in the presence of a 16-fold higher doxorubicin concentration compared with the initial culture, they were designated DR-HSA cell lines. Characterization of these DR-HSA cell lines revealed higher drug efflux pump capacity compared with the parental cell lines. Furthermore, the DR-HSA cell lines did not show activation of the DNA damage response despite carrying high DNA damage burdens, meaning that apoptosis was not strongly induced. In conclusion, canine HSA cell lines acquired doxorubicin resistance by increasing their drug efflux pump capacity and decreasing the DNA damage response. This study provides useful findings to promote further research on the drug-resistance mechanisms in canine HSA.