Optimizing a Pre-Clinical Mouse Model for Breast Cancer Chemotherapy: Establishing the Minimum Amount of 4T1 Cells Needed for Tumor Formation

We are investigating the effect of a novel anti-cancer amidoxime drug (JJMB9) in a mouse model. To induce tumors for this study, 4T1 mouse mammary carcinoma cells, which are highly malignant and metastatic, are injected into mammary tissue. This study focused on determining the least amount of 4T1 cells needed for tumor formation in BALB/c mice. During previous experiments, 10,000 4T1 cells were injected into 6-week old female BALB/c mice to form tumors to be treated with JJMB9. In this study, six mice were each injected with 5,000, 1,000, or 500 4T1 cells and monitored for tumor growth. Although the five surviving mice receiving 5,000 4T1 cells developed tumors, onset of tumors varied from eighteen days up to four weeks. The unpredictability of timing would add a confounding variable to our mouse model, thus we conclude that 10,000 4T1 cells is optimal.