Luu Anita K, Schott Courtney R, Jones Robert, Poon Andrew C, Golding Brandon, Hamed Roa'a, Deheshi Benjamin, Mutsaers Anthony, Wood Geoffrey A, Viloria-Petit Alicia M
Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
Department of Pathobiology, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
BMC Vet Res. 2018 Nov 26;14(1):365. doi: 10.1186/s12917-018-1651-5.
Osteosarcoma (OSA) is the most common bone cancer in canines. Both transforming growth factor beta (TGFβ) and Hippo pathway mediators have important roles in bone development, stemness, and cancer progression. The role of Hippo signalling effectors TAZ and YAP has never been addressed in canine OSA. Further, the cooperative role of TGFβ and Hippo signalling has yet to be explored in osteosarcoma. To address these gaps, this study investigated the prognostic value of TAZ and YAP alone and in combination with pSmad2 (a marker of active TGFβ signalling), as well as the involvement of a TGFβ-Hippo signalling crosstalk in tumourigenic properties of OSA cells in vitro. An in-house trial tissue microarray (TMA) which contained 16 canine appendicular OSA cases undergoing standard care and accompanying follow-up was used to explore the prognostic role of TAZ, YAP and pSmad2. Published datasets were used to test associations between TAZ and YAP mRNA levels, metastasis, and disease recurrence. Small interfering RNAs specific to TAZ and YAP were utilized in vitro alone or in combination with TGFβ treatment to determine their role in OSA viability, proliferation and migration.
Patients with low levels of both YAP and pSmad2 when evaluated in combination had a significantly longer time to metastasis (log-rank test, p = 0.0058) and a longer overall survival (log rank test, p = 0.0002). No similar associations were found for TAZ and YAP mRNA levels. In vitro, TAZ knockdown significantly decreased cell viability, proliferation, and migration in metastatic cell lines, while YAP knockdown significantly decreased viability in three cell lines, and migration in two cell lines, derived from either primary tumours or their metastases. The impact of TGFβ signaling activation on these effects was cell line-dependent.
YAP and pSmad2 have potential prognostic value in canine appendicular osteosarcoma. Inhibiting YAP and TAZ function could lead to a decrease in viability, proliferation, and migratory capacity of canine OSA cells. Assessment of YAP and pSmad2 in larger patient cohorts in future studies are needed to further elucidate the role of TGFβ-Hippo signalling crosstalk in canine OSA progression.
骨肉瘤（OSA）是犬类中最常见的骨癌。转化生长因子β（TGFβ）和Hippo信号通路介质在骨骼发育、干性和癌症进展中均发挥重要作用。Hippo信号效应分子TAZ和YAP在犬类OSA中的作用从未得到研究。此外，TGFβ与Hippo信号的协同作用在骨肉瘤中仍有待探索。为填补这些空白，本研究调查了单独的TAZ和YAP以及与pSmad2（活性TGFβ信号的标志物）联合使用时的预后价值，以及TGFβ-Hippo信号串扰在体外OSA细胞致瘤特性中的作用。使用包含16例接受标准治疗并伴有随访的犬类附肢OSA病例的内部试验组织微阵列（TMA）来探究TAZ、YAP和pSmad2的预后作用。利用已发表的数据集来测试TAZ和YAP mRNA水平、转移和疾病复发之间的关联。单独或与TGFβ处理联合使用针对TAZ和YAP的小干扰RNA，以确定它们在OSA细胞活力、增殖和迁移中的作用。
联合评估时YAP和pSmad2水平均较低的患者发生转移的时间显著更长（对数秩检验，p = 0.0058），总生存期也更长（对数秩检验，p = 0.0002）。未发现TAZ和YAP mRNA水平有类似关联。在体外，敲低TAZ显著降低了转移细胞系中的细胞活力、增殖和迁移能力，而敲低YAP显著降低了源自原发性肿瘤或其转移灶的三个细胞系中的活力以及两个细胞系中的迁移能力。TGFβ信号激活对这些效应的影响因细胞系而异。
YAP和pSmad2在犬类附肢骨肉瘤中具有潜在的预后价值。抑制YAP和TAZ功能可能导致犬类OSA细胞的活力、增殖和迁移能力下降。未来研究需要在更大的患者队列中评估YAP和pSmad2，以进一步阐明TGFβ-Hippo信号串扰在犬类OSA进展中的作用。
