Breast Cancer Xenograft Model Development

MCF7 and MDA-MB-231 breast cancer cell lines were purchased from ATCC. Both cells were authenticated by short tandem repeat analysis and tested for mycoplasma. Xenograft studies were performed by the guidelines of the IACUC of the H. Lee Moffitt Cancer Center (that was approved by University of South Florida IACUC committee) using 8- to 10-week-old female nu/nu mice (Envigo). Mice had free access to water and food for the whole duration of the experiment. For MDA-MB-231 and MCF7 mono-tumor formation, 10 million cells were injected into cleared mammary fat pads as described previously^{4 (link)}. For mixed cultures, a 1:1 mixture of 5 million MDA-MB231 and 5 million MCF7 cells were injected. One week before cell injection, an estrogen pellet (0.72 mg slow-release, Innovative Research of America) was implanted to allow for the growth of ER-positive MCF7 tumors. Five weeks later, tumors were harvested.