Expression of Connexins and Cadherins in Actinic Keratosis and Squamous Cell Carcinoma of Domestic Felines.

• Grant number: 24/18145-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: August 01, 2025
• End date: November 30, 2029
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Pathology
• Principal Investigator: Maria Lucia Zaidan Dagli
• Grantee: Lorena Santos Bezerra
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Squamous cell carcinoma (SCC) is a highly aggressive and prevalent skin neoplasm in both humans and animals. This neoplasm has a major medical and economic impact due to its local invasiveness, limited treatment approaches, and tendency to recur. Companion animals with spontaneous cancers are a natural model that can be used for comparative studies and for the development of new anticancer drugs. Many types of cancer in dogs and cats have pathological, molecular, and clinical features similar to those of their human counterparts. Domestic felines, especially those with white fur and light skin, frequently develop squamous cell carcinoma (SCC) preceded by skin changes called actinic keratosis (AK) associated with exposure to UV radiation, especially UVA and UVB. Cells in multicellular organisms communicate with each other directly, by contact, or indirectly, by secretion of soluble factors or extracellular vesicles. Nexus-type communicating junctions, or "gap" junctions, are membrane specializations composed of 6 protein subunits called connexins. They are present in all cell types except cardiac muscle fibers and erythrocytes, and allow the direct passage of solutes up to 1000 Daltons between adjacent cells. Gap junctions have a widely recognized role in tumorigenesis and progression of metastatic disease. Studies have demonstrated a decrease in the capacity for communication between adjacent cells and changes in the subcellular localization of connexins during the stages of carcinogenesis, and a reversal of this decrease when agents that increase the expression of connexins and send them to the plasma membrane are used. Cadherins are adhesion molecules that allow the connection between neighboring cells and their function is to maintain tissue integrity. The objective of this project is to study the expression of connexins and cadherins in actinic keratosis (AK) and squamous cell carcinoma (SCC) in domestic felines. To this end, skin fragments from at least 50 domestic felines clinically diagnosed with AK and/or SCC will be retrieved from paraffin block archives of Animal Pathology Services, or obtained from oncology surgery services, routinely processed for paraffin embedding, and the histological sections in Hematoxylin and Eosin will be analyzed by light microscopy. Subsequently, additional histological sections will be processed for immunofluorescence staining for connexins 43, 26 and 31, in addition to e-cadherin. The histological sections stained by immunofluorescence will be photographed under a fluorescence microscope, and analyzed for the subcellular localization of connexins. They will also be subjected to immunohistochemical staining for p53, aiming to evaluate alterations in this tumor suppressor protein, and Ki67, to study cell proliferation. The mRNA alterations for connexins will be evaluated by Real-Time PCR, while the quantification of connexins will be performed by Western blot with the same samples. A comparison will be made between the markings obtained in QA and SCC. Since SCC metastasizes easily via the lymphatic system, it is expected to obtain lymph nodes from animals with SCC to perform the same markings and provide comparative studies with primary neoplasms. In this way, it is expected to obtain information about epithelial carcinogenesis in felines and its molecular alterations involving connexins and cadherins.