Expression of thyroid-specific transcription factors in thyroid carcinoma, contralateral thyroid lobe and healthy thyroid gland in dogs

Repeatable and objective method for evaluating angiogenesis using real-time RT-PCR of endoglin expression in canine tumours

Anti-angiogenic therapy is a cancer treatment strategy targeting new blood vessel formation. Microvessel density (MVD) is a histopathological method for evaluating angiogenesis and endoglin is used as an activated endothelial marker in human medicine. The assessment of the treatment effect using MVD is difficult because it is a non-repeatable method. To develop a repeatable method for evaluating angiogenesis, we investigated correlations among MVD, mRNA transcription levels of endothelial markers and angiogenesis factors, and confirmed the agreement of mRNA transcription levels between tissue samples and small samples obtained by fine needle aspiration (FNA). The various types of spontaneous tumours were collected from 51 dogs. MVD was assessed by immunostaining for von Willebrand factor (vWF). mRNA transcription levels of vWF, endoglin, vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR2) were analysed using real-time reverse transcription polymerase chain reaction (real-time RT-PCR). There were significant correlations between MVD and mRNA transcription levels of vWF, endoglin and VEGFR2. VEGFR2 was more strongly correlated with endoglin (P <.01, Rs = 0.649) than vWF (P <.01, Rs = 0.512), indicating that angiogenesis can be evaluated more accurately by the measurement of mRNA transcription levels of endoglin. The mRNA transcription levels in tissue and FNA samples were strongly correlated, suggesting that evaluating angiogenesis using FNA samples is possible. In conclusion, we developed a repeatable and objective method for angiogenesis evaluation using mRNA transcription levels of endothelial markers by FNA sampling.

In vitro efficacy of a first-generation valosin-containing protein inhibitor (CB-5083) against canine lymphoma

Valosin-containing protein (VCP), through its critical role in the maintenance of protein homeostasis, is a promising target for the treatment of several malignancies, including canine lymphoma. CB-5083, a first-in-class VCP inhibitor, exerts cytotoxicity through the induction of irreversible proteotoxic stress and possesses a broad spectrum of anticancer activity. Here, we determined the cytotoxicity CB-5083 in canine lymphoma cells and its mechanism of action in vitro. Canine lymphoma cell lines were treated with varying concentrations of CB-5083 and assessed for viability by trypan blue exclusion and apoptosis by caspase activity assays. The mechanism of CB-5083 action was determined by immunoblotting and RT-qPCR analyses of Lys48 ubiquitination and markers of ER stress (DDIT3), autophagy (SQSTM1, MAP1LC3A) and DNA damage (γH2AX). Unfolded protein response markers were also evaluated by immunoblotting (eIF2α, P-eIF2α) and RT-qPCR (ATF4). CB-5083 treatment resulted in preferential cytotoxicity in canine lymphoma cell lines over control peripheral blood mononuclear cells. CB-5083 rapidly disrupted the ubiquitin-dependent protein degradation system, inducing sustained ER stress as indicated by a dramatic increase in DDIT3. Activation of the unfolded protein response occurred through the increase eIF2α phosphorylation and increased transcription of ATF4, but did not re-establish protein homeostasis. Cells rapidly underwent apoptosis through activation of the caspase cascade. These results further validate VCP as an attractive target for the treatment of canine lymphoma and identify CB-5083 as a novel therapy with clinical potential for this malignancy.

Pax8, Napsin A, and CD10 as Immunohistochemical Markers of Canine Renal Cell Carcinoma

Pax8, napsin A, and CD10 are useful immunohistochemical markers of human renal cell carcinoma (RCC); however, their diagnostic utility in canine RCC is unclear. Forty formalin-fixed paraffin-embedded renal cell carcinomas from dogs (15 papillary, 12 solid, and 13 tubular) and 10 metastases were evaluated for expression of Pax8, napsin A, and CD10. Thirty-nine (98%), 24 (60%), and 19 (50%) tumors expressed Pax8 (nuclear labeling), napsin A (cytoplasmic labeling), and CD10 (cytoplasmic and membranous labeling), respectively. Pax8 was expressed in 92% of solid, 100% of papillary, and 100% of tubular tumors. Napsin A was expressed in 58% of solid, 60% of papillary, and 62% of tubular RCC. CD10 was expressed in 33% of solid, 47% of papillary, and 62% of tubular RCC. Pax8 was expressed in 80% of the metastatic tumors, napsin A in 60%, and CD10 in 50%. Additionally, Pax8 immunoreactivity was stronger overall than that of napsin A or CD10. In summary, Pax8 is a more sensitive marker than napsin A or CD10 for primary and metastatic canine RCC; its nuclear and more intense reactivity also makes it easier to interpret. Tubular and papillary RCCs were more likely than solid RCC to express all 3 markers. These findings highlight the utility of Pax8 as an immunohistochemical marker in diagnosing all major subtypes of canine primary and metastatic renal cell carcinoma.