Prognostic biomarkers of cancer in animals: A systemic approach

Abstract

Cancer is a condition characterized by uncontrolled cell proliferation, tissue invasion and metastasis. Animal cancers, which are on rise in the recent past, resemble human cancers and serve as valuable models for comparative research in cancer biology and drug development. Biomarkers are defined as measurable molecules indicating biological processes, disease or treatment response to cancer. Historical evolution of biomarkers spans from simple protein markers like alpha-fetoprotein (AFP) to advanced microRNAs and circulating tumour cells (CTCs). Ideal biomarkers must be tumor-specific, detectable in minimally invasive samples, correlate with tumor burden and enable high-throughput testing. Important proliferation markers of cancer include Ki-67, which is higher in malignant tumors, PCNA (Proliferating Cell Nuclear Antigen) which correlates with tumor grade and invasion, AgNORs (Argyrophilic Nucleolar Organizer Regions) which distinguish tumors as benign/malignant and telomerase which is 95% tumor-specific. Tumor suppressors like p53 and adhesion molecules like E-cadherin predict aggressiveness of tumors. Serum markers like AFP, TK1 (Thymidine Kinase-1), VEGF (Vascular Endothelial Growth Factor) aid in diagnosis and prognosis of hemangiosarcoma, osteosarcoma and prostate cancers. Tumor biomarker detection includes immunological methods, cytogenetic analysis and genetic analysis. Tumour biomarkers are beneficial in early detection of cancer, assessing prognosis, therapy response and monitoring relapse across species.