Passage Number of 4T1 Cells Influences the Development of Tumour and the Progression of Metastasis in 4T1 Orthotopic Mice

BACKGROUND: The study was aimed to elucidate the influence of passage number of 4T1 cells for the development of the ideal tumour model. METHODS: A total of 24 female BALB/c mice was divided equally into three groups: i) control (phosphate buffered saline [PBS] only); ii) group A (subjected to 4T1 cells of passage number 9) and iii) group B (subjected to 4T1 cells of passage number 10). The injections were introduced at the 3rd mammary pad of the mice. The net volume of the tumours was examined. Histopathological analysis was conducted to compare the extent of metastasis in the different groups of mice. RESULTS: Group B had a higher net volume of 4T1 tumour as compared to group A (P = 0.042). The coefficient of variation in the net volume of 4T1 tumour for group A was higher (135.3%) as compared to group B (40.79%). Group A only exhibited metastasis on the lungs, liver and spleen whereas group B showed metastasis to the heart, spleen, lungs and liver. CONCLUSION: The use of 4T1 cells from passage number 10 is more ideal for the development of 4T1 tumour.