Saturday, October 29, 2011
Hall 1-2 (San Jose Convention Center)
SLIT expression is reduced in majority of cancers, establishing a correlation between SLIT and deregulated cell division. In the mammary gland, SLIT acts as a signaling molecule through ROBO receptors, ROBO1 and ROBO2. Preliminary data show that serial transplantation of Slit2-/-;Slit3-/- mammary gland tissue results in enhanced longevity. Moreover, we see the opposite effect in vitro, by treating mammospheres with SLIT2. Together these results suggest that SLIT functions as a non-renewal factor for mammary stem cells. Given these data, my project is to determine which receptor, ROBO1 or ROBO2, is responsible for SLIT signaling. Further, we have two cell types of interest, myoepithelial and luminal cells that generate the epithelial tree of the mammary gland. We enriched for Robo1-/- and +/+ mammary stem cells using FACS (Fluorescent Activated Cell Sorting) and then plated and cultured these cells in Matrigel. The cultures were treated with 1,000 ng/mL or 2,000 ng/mL of SLIT2. Preliminary results show that SLIT2 treatment of Robo1-/- mammary stem cells at either concentration, results in an increase in luminal cell fate. These data appear to rule out ROBO1 as the operative receptor since we observe an effect with Robo1-/- cells. Our next step will be to analyze Robo2-/- mammary stem cells in similar experiments, and also use qPCR along with immunohistochemistry to validate the observation that ROBO2 is the receptor that mediates SLIT/ROBO signaling.