Cancer Stem Cell and Epithelial Mesenchymal Transition (EMT) in Canine Transmissible Venereal Tumour- A Preliminary Study

Background: Cancer stem cell (CSC) and Epithelial to Mesenchymal Transition (EMT) transforms conversion of normal cells in the tumor microenvironment into CSC which is the main cause of embryogenesis, carcinogenesis and metastasis. Methods: Nineteen canine patients with recurrent transmissible venereal tumor (TVT) and metastasis of inguinal lymph node were the subjects of present study. Preoperative work up and clinical staging involving radiography, ultrasonography, hematobiochemical analysis and histopathology or biopsy were done to confirm the type of cancerous tissue. Tumor tissues were collected in ice cold RPMI-1640 and phosphate buffer solution. Flow cytometry analysis was performed following established protocol from surgically excised tissue sample. Trypan blue dye exclusion test was done to quantify the live/dead cell count. CD24PE, CD44FITC, CD133APC and EpCAM antibody with conjugates were chosen markers for flow cytometry analysis. Result: Nineteen canine patients were diagnosed with Transmissible Venereal tumor (TVT) (common sexually transmitted disease in male dog) through biopsy of excised surgical tissue following Haematoxylin and Eosin staining protocol. Recurrence was seen even after adjuvant chemotherapy with Vincristine injection @ 0.25 mg/m2 2 at weekly interval for 5 weeks. Trypan blue dye exclusion test confirms 98% live cell count in transmissible venereal granuloma after digestion and incubation for flow cytometry. Flow cytometry analysis of the cells from the TVT showed surface biomarkers for EpCAM+ cells, EpCAM CD24+ cells, EpCAM CD44+ cells, EpCAM CD133+ indicating cells with CSC and EMT properties. Presence of CSC and EMT cells in this patient was responsible for chemoresistance, distant metastasis and recurrence. Identification of specific CSC in a malignant cancer will yields deeper insight into biological aspects of metastasis and formulation of targeted therapy in fighting with cancer.