Microarray analysis of mouse gene expression in metronomic cyclophosphamide-treated human glioma U251 xenografts implanted in scid mice

Cyclophosphamide (CPA) treatment on a six-day repeating metronomic schedule induces a dramatic, innate immune cell-dependent regression of implanted gliomas. However, little is known about the underlying mechanisms of innate immune cell mobilization and recruitment, or about the role of DNA damage and cell stress response pathways in eliciting the anti-tumor immune responses linked to tumor regression. To address these questions, we compared untreated and 6-day metronomic cyclophosphamide-treated human U251 glioblastoma xenografts by mouse microarray analysis to identify responsive mouse (host) cell-specific factors. Human glioma U251 tumors were implanted sc in scid immunodeficient mice then treated with cyclophosphamide at 140 mg/kg every 6 days. Tumors were collected 6 days after the second cyclophosphamide treatment and also 6 days after the third cyclophosphamide treatment. Tumor RNA was then analyzed on two color Agilent mouse expression microarrays comparing cyclophosphamide-treated RNA to untreated control tumor RNA.