E. Katsuta1, S. DeMasi1, K. P. Terracina1, H. Aoki1, M. Aoki1, P. Mukhopadhyay1, K. Takabe1 1Virginia Commonwealth University School Of Medicine And Massey Cancer Center,Division Of Surgical Oncology, Department Of Surgery,Richmond, VA, USA
Introduction: We have previously established a murine syngeneic breast cancer model utilizing cell implantation under direct vision technique, which mimic human cancer progression (Rashid, Takabe et al. Breast Cancer Research and Treatment 2014). Other groups have reported that cell implantation using Matrigel produced stable results in xenograft models. Here, we report the establishment of improved syngeneic orthotopic murine breast cancer model using Matrigel. In this study, we determined the maximum amount of Matrigel to be implanted without spillage, the tumor growth with various number of cells, and utilizing this new model, we investigated the growth of murine cancer cell derived from different strain mice.
Methods: Matrigel was injected to #2 and #4 mammary glands. Various number of murine breast cancer E0771cells in Matrigel were implanted into bilateral #2 and #4 mammary gland of C57Blk6 mice. Three weeks after inoculation, tumorigenesis were compared. 1 x 104 of murine breast cancer 4T1-luc2 cells, derived from Balb/C mice, were implanted into the Right side #2 gland of Balb/C or C57Blk6 mice. Tumor growth was monitored by bioluminescence (IVIS) imaging.
Results: We found that implantation of the cells will be more efficient with less variability when the cells are suspended in Matrigel compared with PBS, which was the technique we reported previously. Maximum volume of Matrigel inoculated without spillage was 20 μl in #2 gland, 30 μl in #4 gland, respectively. Therefore, we implanted 20 μl of Matrigel in #2 gland, and 30 μl in #4 gland in the subsequent experiments. In order to determine the difference of tumor development, 504, 105, 505, 106 E0771 cells suspended in 20µl Matrigel were inoculated. Three weeks after inoculation, ‘the take rates’ (tumorigenesis) were 0%, 12.5%, 75%, 75%, 100%, respectively. Utilizing 4T1-luc2 cells in Matrigel suspended cell implantation method, we investigated how long the mouse-derived cancer cells survive in mice from a different background. The fold increase in tumor growth in both backgrounds were nearly identical 24 h after inoculation at 5-fold increase measured by bioluminescence imaging. By 7 days after inoculation, tumor in C57Blk6 reached a maximum increase of approximately 720-fold their Day 0 size, whereas the tumor in Balb/C had almost a 2000-fold increase in tumor size. The Balb/C tumor continued to increase rapidly to reach an almost 3000-fold increase in size, while the C57Blk/6 mice tumors swiftly decreased from Day 7 and was eliminated by Day 14.
Conclusion: We identified the maximum amount of Matrigel that can be implanted into #2 or #4 mammary gland without spillage, and the difference in take rates with various number of cells for murine orthotopic breast cancer model. Utilizing Matrigel implantation method, we found that cancer cells will continue to grow until one week, then it will eliminated by 2 weeks when implanted into different background strain mice.