Nodal inhibition alters proliferation:apoptosis ratios in micrometastases.

<p>(A) GUSB staining of pulmonary micrometastases from MDA-MB-231 cells transfected with a Control shRNA (231+shControl) or a shRNA to Nodal (231+shNodal) in NOD/SCID/MPSVII mice 4 weeks post-intravenous injection (red and outlined with white dotted line). (B) Scatter plot representing the average number of micrometastases (<100 cells) per section of lung from NOD/SCID/MPSVII mice 4 weeks after injection with 231+shControl or 231+shNodal cells. The number of 231+shNodal micrometastases that formed after 4 weeks in NOD/SCID/MPSVII mice was not significantly reduced compared to the number of 231+shControl micrometastases (n≥5, p>0.05). Each point represents the average mean number of micrometastases per section per mouse. Black bars represent the median number of micrometastases per section per mouse. (C) Immunohistochemical analysis of Ki67 expression (brown) and TUNEL (brown) staining in pulmonary micrometastases from 231+shControl cells or 231+shNodal cells in NOD/SCID/MPSVII mice 4 weeks post-intravenous injection. Proliferation is indicated by Ki67 staining and apoptotic nuclei were detected with TUNEL. (D) Proliferation:apoptosis ratios in 4 week micrometastases were determined with immunohistochemical localization of Ki67 and TUNEL. At 4 weeks, lesions from 231+shControl cells had a positive proliferation ratio (1.57) whereas lesions from 231+shNodal cells had a negative proliferation:apoptosis ratio (0.74) (n≥3, p<0.05). Values represent mean average proliferation:apoptosis ratio in tumour lesions per mouse ± S.E.M.