Gene expression of hCG-treated rat mammosphere culture

We previously showed that recombinant human chorionic gonadotropin (r-hCG) induces mammary gland differentiation and inhibits mammary tumorigenesis in rats. The present study investigates the impact of r-hCG on the stemness of mammary epithelial cells by using a rat model. We performed microarray analysis of RNA isolated from mammospheres formed by normal mammary epithelial cells extracted from rats treated for 21 days either with r-hCG or vehicle (control). Female Sprague Dawley rats at age 55 days were treated daily via intraperitoneal injection with 100 IU/day r-hCG; or vehicle control (phosphate buffered saline) for 21 days. Rat mammary gland 4&5 from three animals from each group were resected 21 days after the last day of treatment. Mammary epithelial cell enriched single cells were plated in 6-well ultra-low attachment plate. The formation of mammosphere was checked daily. After 7 days of culture, the mammospheres were used for RNA extraction and Affymetrix microarray analysis.