Novel esophageal squamous cell carcinoma bone metastatic clone isolated by scintigraphy, X ray and micro PET/CT

To establish a Chinese esophageal squamous cell carcinoma (ESCC) cell line with high bone metastasis potency using (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) micro-pinhole scintigraphy, X ray and micro-positron emission tomography/computed tomography (PET/CT) for exploring the mechanism of occurrence and development in esophageal cancer.

The cells came from a BALB/c nu/nu immunodeficient mouse, and oncogenic tumor tissue was from a surgical specimen from a 61-year-old male patient with ESCC. The cell growth curve was mapped and analysis of chromosome karyotype was performed. Approximately 1 × 10⁶ oncogenic cells were injected into the left cardiac ventricle of immunodeficient mice. The bone metastatic lesions of tumor-bearing mice were detected by (99m)Tc-MDP scintigraphy, micro-PET/CT and X-ray, and were resected from the mice under deep anesthesia. The bone metastatic cells in the lesions were used for culture and for repeated intracardiac inoculation. This in vivo/in vitro experimental metastasis study was repeated for four cycles. All of the suspicious bone sites were confirmed by pathology. Real-time polymerase chain reaction was used to compare the gene expression in the parental cells and in the bone metastatic clone.

The surgical specimen was implanted subcutaneously in immunodeficient mice and the tumorigenesis rate was 100%. First-passage oncogenic cells were named CEK-Sq-1. The chromosome karyotype analysis of the cell line was hypotriploid. The bone metastasis rate went from 20% with the first-passage oncogenic cells via intracardiac inoculation to 90% after four cycles. The established bone metastasis clone named CEK-Sq-1BM had a high potential to metastasize in bone, including mandible, humerus, thoracic and lumbar vertebrae, scapula and femur. The bone metastasis lesions were successfully detected by micro-pinhole bone scintigraphy, micro-PET/CT, and X-ray. The sensitivity, specificity and accuracy of the micro-pinhole scintigraphy, X-ray, and micro-PET/CT imaging examinations were: 89.66%/32%/80%, 88.2%/100%/89.2%, and 88.75%/77.5%/87.5%, respectively. Some gene expression difference was found between parental and bone metastasis cells.

This newly established Chinese ESCC cell line and animal model may provide a useful tool for the study of the pathogenesis and development of esophageal carcinoma.