Department of Pathobiology, AURIC-Auburn University Research Initiative in Cancer, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849, USA.
Department of Pediatrics, Division of Pulmonology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
In Vitro Cell Dev Biol Anim. 2021 May;57(5):519-530. doi: 10.1007/s11626-021-00571-9. Epub 2021 May 20.
The cyclin-dependent kinase inhibitors (CKIs) belong to a group of key cell cycle proteins that regulate important cancer drug targets such as the cyclin/CDK complexes. Gene defects in the INK4A/B CKI tumor suppressor locus are frequently associated with human cancers and we have previously identified similar defects in canine models. Many of the cancer-associated genetic alterations, known to play roles in mammary tumor development and progression, appear similar in humans and dogs. The objectives of this study were to characterize expression defects in the INK4 genes, and the encoded p16 family proteins, in spontaneous canine primary mammary tumors (CMT) as well as in canine malignant melanoma (CML) cell lines to further develop these models of spontaneous cancers. Gene expression profiles and characterization of p16 protein were performed by rtPCR assay and immunoblotting followed by an analysis of relevant sequences with bioinformatics. The INK4 gene family were expressed differentially and the genes encoding the tumor suppressor p16, p14, and p15 proteins were often identified as defective in CMT and CML cell lines. The altered expression profiles for INK4 locus encoded tumor suppressor genes was also confirmed by the identification of similar gene defects in primary canine mammary tumor biopsy specimens which were also comparable to defects found in human breast cancer. These data strongly suggest that defects identified in the INK4 locus in canine cell lines are lesions originating in spontaneous canine cancers and are not the product of selection in culture. These findings further validate canine tumor models for use in developing a clear understanding of the gene defects present and may help identify new therapeutic cancer treatments that restore these tumor suppressor pathways based on precision medicine in canine cancers.
细胞周期蛋白依赖性激酶抑制剂 (CKI) 属于一组关键的细胞周期蛋白，可调节细胞周期蛋白/CDK 复合物等重要的癌症药物靶点。INK4A/B CKI 肿瘤抑制基因座中的基因缺陷与人类癌症频繁相关，我们之前已经在犬模型中发现了类似的缺陷。许多与癌症相关的遗传改变，已知在乳腺肿瘤发生和进展中发挥作用，在人类和犬中似乎相似。本研究的目的是表征 INK4 基因在自发性犬原发性乳腺肿瘤 (CMT) 以及犬恶性黑色素瘤 (CML) 细胞系中的表达缺陷，并进一步开发这些自发性癌症模型。通过 rtPCR 检测和免疫印迹分析以及生物信息学分析相关序列来进行基因表达谱分析和 p16 蛋白的特征分析。INK4 基因家族表达存在差异，编码肿瘤抑制蛋白 p16、p14 和 p15 的基因在 CMT 和 CML 细胞系中通常被鉴定为缺陷。INK4 基因座编码的肿瘤抑制基因的改变表达谱也通过鉴定原发性犬乳腺肿瘤活检标本中的类似基因缺陷得到证实，这些缺陷与人类乳腺癌中的缺陷相似。这些数据强烈表明，在犬细胞系中鉴定的 INK4 基因座缺陷是起源于自发性犬癌的病变，而不是培养过程中选择的产物。这些发现进一步验证了犬肿瘤模型在深入了解存在的基因缺陷方面的用途，并可能有助于确定基于犬癌症精准医学的新的治疗癌症的治疗方法，以恢复这些肿瘤抑制途径。
