4.4. In Vivo Xenograft Studies

Foxn1nu nude mice were purchased from Harlan (Indianapolis, IN, USA), and were maintained at the Northwestern University Center for Comparative Medicine in accordance with the National Institutes of Health guidelines and following protocols approved by the Northwestern University Animal Use and Care Committee (Protocol #IS00003060). In brief, 20,000 OVCAR3 OC cells stably transfected with sh-control or sh-ALDH1A1 lentivirus were subcutaneously injected into the flanks of 6–8-week-old female nude mice. Tumors were assessed and measured twice weekly to assess tumor initiation. Time to tumor initiation was determined as the time from inoculation to the time when tumors were detectable by palpation (measuring at least 2 mm in greatest dimension). Tumors were allowed to form and grow until they reached 1500 mm³. At that point, mice were euthanized and tumors were harvested, measured, and weighed.